 DEAS 455:2021  
ICS 59.080.30  
 
© EA C 2021                                                                                                                               Third  Edition 
2021   
 DRAFT EAST AFRICAN STANDARD  
Long lasting in secticide treated mosquito nets  — Specification   
EAST AFRICAN COMMUNITY  
 
 
 DEAS 455:2021  
ii © EAC 2021  – All rights reserved  
 Copyright notice  
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participants in the EAC stan dards development process is permitted without prior permission from EAC, 
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© East African Community  2021 — All rights reserved  
East African Community   
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Reproduction for sales purposes may be subject to royalty payments or a licensing agreement.  
Violators may be prosecuted . DEAS 455:2021  
© EAC 2021  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ .............................  v 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative reference s ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  2 
4 Requirements  ................................ ................................ ................................ ................................ .........  3 
4.1 Mono -treated nets  ................................ ................................ ................................ ................................ . 3 
4.1.1  Physical characteristics  ................................ ................................ ................................ .......................  3 
4.1.2  Active ingredient  ................................ ................................ ................................ ................................ ... 4 
4.2 Combin ation nets  ................................ ................................ ................................ ................................ .. 4 
4.3 Shapes, sizes and dimensions  ................................ ................................ ................................ ............  5 
4.3.1  Shape  ................................ ................................ ................................ ................................ ......................  5 
4.3.2  Sizes and dimensions  ................................ ................................ ................................ ...........................  5 
4.4 Manufacture and workmanship  ................................ ................................ ................................ ...........  6 
4.4.1  Construction  ................................ ................................ ................................ ................................ ..........  6 
4.4.2  Net attachments or tying tapes  ................................ ................................ ................................ ............  7 
4.4.3  Top support ring  ................................ ................................ ................................ ................................ .... 7 
4.4.4  Defects  ................................ ................................ ................................ ................................ ....................  7 
5 Restricted Colorants  ................................ ................................ ................................ .............................  7 
6 Packaging  ................................ ................................ ................................ ................................ ...............  7 
7 Labelling  ................................ ................................ ................................ ................................ .................  7 
7.1 Outside packaging  ................................ ................................ ................................ ................................  7 
7.2 Tag ................................ ................................ ................................ ................................ ..........................  8 
8 Sampling  ................................ ................................ ................................ ................................ ................  8 
8.1 Lot ................................ ................................ ................................ ................................ ...........................  8 
8.2 Scale of sampling and testing  ................................ ................................ ................................ ..............  8 
Annex  A (normative)  Determination of Deltamethrin content in long lasting insecticide treated 
mosquito nets b y High Performance Liquid Chromatography  ................................ ......................  10 
A.1 Sampling  ................................ ................................ ................................ ................................ ..............  10 
A.2 Identification tests  ................................ ................................ ................................ ...............................  10 
A.3 Active ingredient  ................................ ................................ ................................ ................................ . 10 
A.3.1  Outline of method  ................................ ................................ ................................ ................................  10 
A.3.2  Scope  ................................ ................................ ................................ ................................ ....................  10 
A.3.3  Reagents  ................................ ................................ ................................ ................................ ..............  10 
A.3.4  Apparatus  ................................ ................................ ................................ ................................ .............  11 
A.4 Procedure  ................................ ................................ ................................ ................................ .............  11 
A.4.1 Operating conditions  ................................ ................................ ................................ ..........................  11 
A.4.2  Preparation of calibration curve  ................................ ................................ ................................ ........  11 
A.4.3  Calibration  ................................ ................................ ................................ ................................ ............  12 
A.4.4  Preparation of sample  ................................ ................................ ................................ .........................  12 
A.4.5  Determination  ................................ ................................ ................................ ................................ ...... 12 
A.4.6  Method validation summary  ................................ ................................ ................................ ...............  12 
Annex  B (normative)  Determination of Permethrin content in long lasting insecticide treated 
mosquito nets  ................................ ................................ ................................ ................................ ...... 14 
B.1 Sampling  ................................ ................................ ................................ ................................ ..............  14 
B.2 Identity tests  ................................ ................................ ................................ ................................ ........  14 
B.3 Permethrin  ................................ ................................ ................................ ................................ ............  14 
B.3.1  Reagents  ................................ ................................ ................................ ................................ ..............  14 DEAS 455:2021  
iv © EAC 2021  – All rights reserved  
 B.3.2  Apparatus  ................................ ................................ ................................ ................................ ............  14 
B.3.3  Procedure  ................................ ................................ ................................ ................................ ............  15 
Annex  C (normative)  Determination of Alphacypermethrin content in long  lasting insecticide 
treated mosquito nets  ................................ ................................ ................................ ........................  18 
C.1 Sampling  ................................ ................................ ................................ ................................ ..............  18 
C.2 Identity test  ................................ ................................ ................................ ................................ ..........  18 
C.3 Alphacypermethrin  ................................ ................................ ................................ .............................  18 
C.4 Reagents  ................................ ................................ ................................ ................................ ..............  18 
C.5 Calibration solutions  ................................ ................................ ................................ ..........................  18 
C.5.1  Preparation of calibration solutions  ................................ ................................ ................................ . 18 
C.5.2  Description of calibration solutions  ................................ ................................ ................................ . 19 
C.5.3  Apparatus  ................................ ................................ ................................ ................................ ............  19 
C.6.1  Operating conditions  ................................ ................................ ................................ ..........................  19 
C.6.2  Preparation of the samples  ................................ ................................ ................................ ................  19 
Annex  D (nor mative)  Determination of Piperonyl butoxide in polyethylene matrix in long lasting 
insecticide treated mosquito nets by Gas Chromatography  ................................ .........................  22 
D.1 Scope  ................................ ................................ ................................ ................................ ...................  22 
D.2 Outline of method  ................................ ................................ ................................ ...............................  22 
D.3 Reagents  ................................ ................................ ................................ ................................ ..............  22 
D.4 Apparatus  ................................ ................................ ................................ ................................ ............  23 
D.5 Operating Procedure  ................................ ................................ ................................ ..........................  23 
D.5.1  Operating conditions (typical)  ................................ ................................ ................................ ...........  23 
D.5.2  Preparation of sample  ................................ ................................ ................................ ........................  24 
D.5.3  System equilibration  ................................ ................................ ................................ ..........................  24 
D.5.4  Determination  ................................ ................................ ................................ ................................ ...... 24 
D.6 Calculation  ................................ ................................ ................................ ................................ ...........  24 
Annex  E (normative)  Measurement of mosquito net dimensions  ................................ .............................  25 
E.1 Rectangular nets: Length, width and height  ................................ ................................ ....................  25 
E.1.1  Apparatus  ................................ ................................ ................................ ................................ ............  25 
E.1.2  Conditioning  ................................ ................................ ................................ ................................ ........  25 
E.1.3  Procedure  ................................ ................................ ................................ ................................ ............  25 
E.1.4  Calculation  ................................ ................................ ................................ ................................ ...........  25 
E.1.5  Report  ................................ ................................ ................................ ................................ ..................  25 
E.2 Circular nets: Top ring diameter, bottom circumference and conical height  ..............................  25 
E.2.2  Conditioning  ................................ ................................ ................................ ................................ ........  25 
E 2.3  Procedure  ................................ ................................ ................................ ................................ ............  26 
Annex  F (normative)  Determina tion of mesh count  ................................ ................................ ....................  27 
F.1 Principle  ................................ ................................ ................................ ................................ ...............  27 
F.2 Procedure  ................................ ................................ ................................ ................................ ............  27 
Bibliography  ................................ ................................ ................................ ................................ .....................  29 
 
 DEAS 455:2021  
© EAC 2021  – All rights reserved  v 
 Foreword  
Development of the East African Standards has been necessitated by the need for harmonizing requirements 
governing quality of products and services in the East African Community. It is envisaged that through 
harm onized standardization, trade barriers that are encountered when goods and services are exchanged 
within the Community will be removed.  
The Community has established an East African Standards Committee  (EASC)  mandated to develop and 
issue East African Sta ndards  (EAS) . The Committee is composed of representatives of the National 
Standards Bodies in Partner States, together with the representatives from the public and private sector 
organizations  in the community .  
East African Standards are developed throug h Technical Committees that are representative of key 
stakeholders including government, academia, consumer groups, private sector and other interested parties. 
Draft East African Standards are circulated to stakeholders through the National Standards Bodi es in the 
Partner States. The comments received are discussed and incorporated before finalization of standards, in 
accordance with the Principles and procedures for develop ment of East African Standards.  
East African Standards are subject to review, to ke ep pace with technological advances. Users of the East 
African Standards are therefore expected to ensure that they always have the latest versions of the standards 
they are implementing .  
The committee responsible  for this document is Technical Committee EASC /TC 061, Textiles, textile products 
and accessories.  
Attention is drawn to the possibility that some of the elements of this document may be subject of patent 
rights. EAC shall not be held responsible for identifying any or all such patent rights.  
This third edition cancels and replaces the second edition EAS 455:2019, which has been technically revised.   
The main changes compared to the previous edition are as follows:  
— reduction of the minimum linear density for the 100 % polyester mono -treated nets f rom 100D to 75D  
— expression of the linear density requirement as a minimum and not a range  
— expression of mesh count as a minimum and not a range  
— adjusting the mesh count specifications to cater for nets made out of 150D  
— adjusting the bursting strength requi rement to cater for nets made out of 75D   
— alignment of the active ingredients in combination nets as per WHO interim specifications  
 
 DRAFT EAST AFRICAN STANDARD  DEAS 455: 2021 
 
© EAC 2021  – All rights reserved  1 
 Long lasting in secticide treated mosquito nets  —Specification  
1 Scope   
This Draft East African Standard specifies  requir ements , sampling  and test methods for treated Long Lasting 
Insecticidal Nets (LLIN).  
2 Normative references   
The following documents are referred to in the text in such a way that some or all of their content constitutes 
requirements of this document.  For dated references, only the edition cited applies. For undated references, 
the latest edition of the referenced document (including any amendments) applies.  
EAS 124, Rounding off number values   
ISO 105 -B01, Textiles — Tests for colour fastness — Part B01: C olour fastness to light: Daylight   
ISO 105 -B02, Textiles -- Tests for colour fastness — Part B02: Colour fastness to artificial light: Xenon arc 
fading lamp test   
ISO 105 -C10, Textiles — Tests for colour fastness — Part C10: Colour fastness to washing with  soap or soap 
and soda  
ISO 139, Standard atmospheres for conditioning and testing   
ISO 1833 -1, Textiles — Quantitative chemical analysis — Part 1: General principles of testing   
ISO 1833 -2, Textiles — Quantitative chemical analysis — Part 2: Ternary fibre  mixtures   
ISO 1833 -5, Textiles — Quantitative chemical analysis — Part 5: Mixtures of viscose, cupro or modal and 
cotton fibres (method using sodium zincate)   
ISO 1833 -11, Textiles — Quantitative chemical analysis — Part 11: Mixtures of cellulose and Poly ester fibres 
(method using sulphuric acid)   
ISO 1833 -16, Textiles — Quantitative chemical analysis — Part 16: Mixtures of polypropylene fibres and 
certain other fibres (method using xylene)   
ISO 1833 -24, Textiles — Quantitative chemical analysis — Part 24: Mixtures of polyester and some other 
fibres (method using phenol and tetrachloroethane)  
ISO 1833 -25, Textiles — Quantitative chemical analysis — Part 25: Mixtures of polyester and certain other 
fibres (method using trichloro acetic acid and chloroform)  
ISO 2060, Textiles — Yarn from packages — Determination of linear density (mass per unit length) by the 
Skein method   
ISO 2076, Textiles — Man-made fibres — Generic names   DEAS 455 :2021  
2 © EAC 2021  – All rights reserved  
 ISO 3758, Textiles — Care labelling code using symbols   
ISO 3759, Textiles — Preparation, marking and measuring of fabric specimens and garments in tests for 
determination of dimensional change   
ISO 380 1, Textiles — Woven fabrics — Determination of mass per unit length and mass per unit area   
ISO 5077, Textiles — Determination of dimensional change in washing and drying   
ISO 6330, Textiles — Domestic washing and drying procedures for textile testing   
ISO 6938, Textiles — Natural fibres — Generic names and definitions   
ISO 8388, Knitted fabrics — Types — Vocabulary   
ISO 8499 , Knitted fabrics — Description of defects — Vocabulary  
ISO 13938 (all parts), Textiles — Bursting properties of fabrics    
ISO 16373 -1, Textiles — Dyestuffs — Part 1: General principles of testing c oloured textiles for dyestuff 
identification  
ISO 16373 -2, Textiles — Dyestuffs — Part 2: General method for the determination of extractable dyestuffs 
including allergenic and carcinogenic dyestuffs (method using pyridine -water)  
ISO 16373 -3, Textiles — Dyestuffs — Part 3: Method for determination of certain carcinogenic dyestuffs 
(method using triethylamine/methanol)   
ISO/TR 11827, Textiles — Composition testing — Identification of fibres  
3 Terms and definitions   
For the purposes of this Standard , the fol lowing terms and d efinitions and those in ISO 6938 and ISO 2076  
shall apply   
3.1  
Long Lasting Insecticidal Nets (LLIN)  
factory treated mosquito net made with a netting material that has insecticide incorporated in the yarn or 
coated on the net 
3.2  
mono -treated net  
finished net treated with a single active ingredient  
3.3  
combination net   
finished net treated with two or more active ingredients  
3.4  
active ingredients  
biologically active substances that form part of the formulation mixture that are in corporated or coated in LLIN 
as approved by World Health Organization or any other internationally recognized body  
3.5  
top ring  
used in conical nets and made of non -corrosive, anti -rust and anti -buckling material, fixed to the roof of the net  DEAS 455 :2021  
© EAC 2021  – All rights reserved  3 
 3.6  
heigh t  
dimension measured along a vertical seam from the top  to the bottom edge of the net  
3.7  
circumference   
perimeter of the net at its bottom edge  
4 Requirements  
4.1 Mono -treated nets  
4.1.1  Physical characteristics  
4.1.1.1  For long lasting insecticidal  mosquito nets, the type of filaments for the fabrics (determined 
through visual examination) shall be as follows:  
a) polypropylene: mono/multi -filament  
b) polyester: multi -filament  
c) polyethylene: mono/multi -filament  
4.1.1.2  Long lasting insecticidal mosquito net s shall conform to the physical characteristics specified in 
Table 1 when tested in accordance with the methods prescribed therein.  
Table 1 — Physical characteristics for long lasting insecticidal mosquito nets  
Parameter  Requirement  
Test method  Polyeste r net Polypropylene net  Polyethylene net  
Fibre  composition  100 % polyester  100 % polypropylene  100 % polyethylene  ISO 1833 -1   
ISO 1833 -2  
ISO 1833 -16  
ISO 1833 -24  
ISO/TR 11827   
Linear density (Denier) , min.   75 100 100 ISO 2060  
Mesh count, holes/cm2, min.  24 for 75D and 100D 
and. 10.6 for 150D  20 8 
Annex F  
Mass per unit area , g/m2, 
min. 28.8 35 28.8 ISO 3801  
Bursting strength at 7.3 cm2, 
kPa, min.  250 for 75D  
350 for 100D and 380 
for 150D  350 250 ISO 13938 -1 
ISO 13938 -2  
Dimensional  
stability after 
1 wash at 30 
°C normal, %, 
max.  Shrinkage  10 10 10 ISO 5077  
ISO 6330  
ISO 3759  Expansion  5 5 10 DEAS 455 :2021  
4 © EAC 2021  – All rights reserved  
 Colour 
fastness  (if 
coloured)  to:   Light   4 or better  ISO 105 -B01,   
ISO 105 -B02   
ISO 105 -C10   Washing  4 or better  
Seam  Sewn using 100 % p olyester or100% polypropylene filament  thread  ISO 1833 -24 
ISO 1833 -16 
 
4.1.2  Active ingredient   
For mono -treated nets, the active ingredient shall comply with the requirements of Table 2 when tested in 
accordance with the methods prescribed therein.  
Table 2 ― Requirements  for active ingredient for mono -treated nets  
S/No.  Ingredienta  Requirement  
g/kg  Test method  
I  Deltamethrin  1.05 – 3.50 Annex A  
ii  Permethrin  15.00 – 25.00 Annex B  
iii  Alpha –cypermethrin  3.38 – 5.63 Annex C  
a In the event that an active ingredient other than those already mentioned above is used, it shall be as  recommended 
by WHO (http://www.who.int/whopes/quali ty/) or any other internationally recognized body and their affiliated entities 
published specifications for public health pesticides for treated mosquito nets.  
4.2 Combination nets  
4.2.1  Combinatio n nets with single fibre construction shall comply with the requirements of Table 1 and 
when the following two active ingredients are used, they shall comply with the requirements of Table 3 when 
tested in accordance with the methods prescribed therein.  
Table 3 ― Requirements for active ingredient for combination nets  
S/No.  Ingredienta  Requirement  
  Test method  
i  Permethrin  20 g/kg ± 25 %    Annex B  
ii  Piperonyl  butoxide 
(PBO)  10 g/kg ± 25 %   Annex D  
a In the event that an active ingredient  other than those already mentioned above is used, it shall be as  recommended 
by WHO (http://www.who.int/whopes/quality/ ) or any other internationally recognized body and their affiliated entities 
published specifications for public health pesticides for treated mosquito nets.  
 
4.2.2  Combination nets constructed with more than one fibre shall co mply with the requirements of Table 4 
when tested in accordance with the methods prescribed therein  DEAS 455 :2021  
© EAC 2021  – All rights reserved  5 
 Table 4 — Requirements for combination nets   
Parameter  Requirement  Test method  
Roof  Sides  
Fibre composition  Polyethylene  Polyester  ISO 1833 -1   
ISO 1833 -2  
ISO 1833 -16  
ISO 1833 -24  
ISO 1833 -25  
ISO/TR 11827  
Linear density (Denier), min.  100  75 with strengthened 70 cm lower 
border or 100 without border  ISO 2060  
Mesh count, holes/cm2, min.   15.5 24 for 75D and 100D and 10.6 for 
150D   Annex F  
Mass per unit area t, g/m2 , min. 28.8 28.8 ISO 3801  
Bursting strength  at 7.3 cm2, kPa, 
min.  300 250 for 75 Denier and 350 for 100  
Denier  ISO 13938 -1 
ISO 13938 -2  
Dimensional 
stability  after 1 
wash  at 30 °C 
normal, %, max.  Shrinkage  10 10 
ISO 50 77  
ISO 6330  Expansion  5 5 
Colour fastness  (if 
coloured)   to:  Light  4 or better  ISO 105 -B01   
ISO 105 -B02   
ISO 105 -C10   Washing  4 or better  
Active ingredienta, g/kg  PBO:  25.0 ± 25% 
DM: 4.0g ± 25% Deltamethrin: 2.8  ± 25 % for 75D 
and 2.1 ± 25 % for 100D and 150D  Annex D   
Annex A  
a As per WHO (http://www.who.int/whopes/quality/ ) or any other internationally recognized body and their affiliated 
entities published specifications for public health pesticides for treated mosquito nets.  
 
4.3 Shapes, sizes and dimensions  
4.3.1  Shape   
The mosquito net shall be rectangular or conical in s hape unless otherwise agreed between the purchaser 
and the supplier .  
4.3.2  Sizes and dimensions  
The nets shall be supplied in sizes and dimensions as specified in Table 5 and Table 6 for rectangular and 
conical nets respectively or in other sizes, as the  purchaser may require  DEAS 455 :2021  
6 © EAC 2021  – All rights reserved  
 Table 5 — Sizes and dimensions for rectangular net   
S/No.  Net size  Width, min.  
cm  Length, min.  
cm   Height, min  
cm   Test method  
i  X-small  70  120  150    
  
Annex E   ii  Small  100  180  170  
iii  Medium  130  180  170  
iv  Large  160  180  170  
v  X- Large  190  180  170  
 
Table 6 — Sizes and dimensions for conical nets  
S/No.  Net size  Height,  
cm, min.   Bottom 
circumference,  
cm, min.   Centre 
circumference, 
cm, min.  Top ring 
diameter,  
cm, min.   Test method  
i  Dome shaped cover net  50  230  -  -    
  
Annex E  ii  X small  120  300  170  40  
iii  Single fitted conical  180  850  470  56  
iv  Double fitted conical  220  1 050  550  56  
v  Extra double fitted  250  1 250  655  65  
  
4.4 Manufacture and w orkmanship  
4.4.1  Construction   
4.4.1.1  Reinforcement at bottom  
The bottom edge of the walls shall be over -lock stitched or reinforced (self -edge finish  or self -binding 
selvedge ). The hem shall be firm and capable of withstanding the normal conditions of  use. 
NOTE  A sheeting border may be used to improve the lifespan of nets.  
4.4.1.2  Seams and stitching  
When visually examined, the seams shall be of even tension throughout and loose ends securely fastened 
off. The net seams shall be made with overlock s titch and the number of stitches per decimetre shall be 27 to 
40. The stitching shall be made by using polyester or polypropylene multifilament sewing thread of matching 
shade.  DEAS 455 :2021  
© EAC 2021  – All rights reserved  7 
 4.4.1.3  Knit type  
The net shall be in any one of the warp knitted constructio ns, for example raschel and tricot as specified in 
ISO 8388.  
4.4.2  Net attachments or tying tapes   
4.4.2.1   Rectangular nets shall be equipped with non -rusting rings or fabric loops.  
4.4.2.2   Conical nets shall be equipped with a loop and non -rusting  rings.  
4.4.2.3  Each ring/loop shall have a corresponding string for suspensions.  
4.4.3  Top support ring  
Conical nets shall have a top support ring made of non -rusting m aterial  which can securely hold the net when 
hanged at the required position . 
4.4.4  Defects  
The mosquito net shall appear clean, be free from visible extraneous matter , visible damage (such as splitting 
or tearing) and visible manufacturing defects (such as poorly made seams ) as described in ISO 8499   
5 Restricted Colorants  
The mosquito ne ts (if coloured)  shall be free from listed amines and carcinogenic dyestuffs specified in ISO 
16373, 1, 2 & 3. Dyestuff classes are identified in accordance with ISO 16373  
6 Packaging  
Mosquito nets shall be packaged in suitable materials so as to prevent  soiling and damage during 
transportation and storage . 
7 Labelling  
7.1 Outside packaging  
The following information shall be legibly and indelibly marked on the outside packaging of individual nets : 
a) fibre composition ;  
b) linear density;  
c) mass per unit area;  
d) net size and dimensions in centimetres (height, width and length for rectangular nets or diameter and 
height for conical nets)[see Annex F];  
e) country of origin;  
f) colour;  
g) name and physical address of the manufacturer and/or importer/distributor;  DEAS 455 :2021  
8 © EAC 2021  – All rights reserved  
 h) lot or ba tch number;  
i) name and amount (in grams per kilogram) of insecticide incorporated in the net; and  
j) care instructions in accordance with ISO 3758.  
7.2 Tag  
The following information shall be legibly and indelibly marked on a permanent tag attached to individ ual nets: 
brand name or registered trademark;  
a) fibre composition;  
b) linear density;  
c) mass per unit area ;  
d) net size and dimensions in centimetres (height, width and length for rectangular nets or diameter and 
height for conical nets;  
e) country of origin;  
f) name of the manufacturer and/or importer/distributor;  
g) lot or batch number;  
h) name and amount (in grams per kilogram) of insecticide incorporated or coated in the net;  
i) the efficacy of the chemical indicated in terms of the number of washes; and  
j) care instructio ns in accordance with ISO 3758.   
8 Sampling   
8.1 Lot   
In any consignment all the pieces of mosquito nets delivered to a consignee against the same dispatch note 
shall constitute a lot.  
8.2 Scale of sampling and testing  
The number of pieces to be selec ted from a lot shall be in accordance with Table 7. Samples shall be tested 
from each lot for ascertaining conformity to the requirements of this standard.  
For the purpose of deciding whether a particular requirement of this standard is complied with, the  final value, 
observed or calculated, expressing the result of a test or analysis shall be rounded off in accordance with EAS 
124.  
Table 7 — Sampling plan  
Number of pieces in a lot  Number of pieces to be sampled  
Up to 8  2  
9 to 15  3  DEAS 455 :2021  
© EAC 2021  – All rights reserved  9 
 16 to 25  4  
26 to 50  5  
51 and above  7  
 DEAS 455 :2021  
10 © EAC 2021  – All rights reserved  
 Annex  A 
(normative)  
 
Determination of Deltamethrin content in long lasting insecticide treated  
mosquito nets by High Performance Liquid Chromatography  
A.1 Sampling  
A sample is defined as one finished bed net taken randomly  from a batch of bed nets. Sub -sample by cutting 
18 pieces of size 100 cm2 randomly from the whole net. Cut 18 pieces into half, one portion is used for 
Deltamethrin content analysis and the other is used for washing test if required.  
The portion used for  Deltamethrin content analysis is cut into pieces of less than 2 cm x 2 cm each. Mix well. 
The sample shall be separately packed in aluminium foil and kept out of direct sunlight at room temperature or 
lower.  
A.2 Identification tests  
Use the HPLC method below. The retention time of Deltamethrin in the sample solution should not deviate by 
more than 15 s from that of the calibration solution if column oven is available.  
A.3 Active ingredient  
A.3.1  Outline of method  
The sample is extracted in a mixture o f iso-octane and 1,4 -dioxane.  
The Deltamethrin content is determined by normal phase high performance liquid chromatography using 
dipropyl phthalate as internal standard and detection at 236 nm.  
A.3.2  Scope  
This method is used for Deltamethrin determina tion in the net sample, before and after washing.  
A.3.3  Reagents  
A.3.3.1   Iso octane , HPLC grade   
A.3.3.2   1,4 Dioxan , HPLC grade. Add 0.15 % (v/v) water before use.  
A.3.3.3   Deltamethrin , neat standard   
A.3.3.4   Dipropyl phthalate    
A.3.3.5  Water, HPLC grade or high    
A.3.3.6  Extraction solvent (ES):  iso octane + 1,4 dioxane = 80 + 20  
A.3.3.7  Mobile Phase (MP):  iso octane + 1,4 dioxane = 95 + 5  DEAS 455 :2021  
© EAC 2021  – All rights reserved  11 
 A.3.3.8  Internal standard solution  (IS), 0.5 mg/ml of dipropyl  phthalate in extraction solvent  
A.3.3.9  Deltamethrin standard solution,  0.6 mg/ml (DS). Weigh 0.03 g (to the nearest of 0.01 mg) of 
Deltamethrin neat standard, quantitatively transfer to a 50 -ml volumetric flask, dissolve completely with 
extraction  solvent, keep regulated by water bath at 20 °C, fill up to mark with extraction solvent.  
A.3.4  Apparatus  
A.3.4.1  Shaker  
A.3.4.2  Ultrasonic bath  
A.3.4.3  HPLC , equipment with pump, auto -injector, column oven (optional) and UV detector, Guard 
Column (Supelguard Si). Analytical Column Supelco Si 5 µm, 1 50 x 4.6 or Lichrosorb Si60, 5 µm, 150 x 4.6  
A.4 Procedure  
A.4.1  Operating conditions  
A.4.1.1  Mobile Phase: iso octan + 1,4 dioxane = 95 + 5  
A.4.1.2  Flow rate: 1.3 ml/min, isocratic  
A.4.1.3  Guard Column: Supelguard Si  
A.4.1.4  Analytical Column: Liche rosorb Si 60, 5 µm, 150 x 4.6 40 °C if column oven is available, or room 
temperature  
A.4.1.5  Inject volume: 5 µl  
A.4.1.6  Wavelength: 236 nm  
A.4.1.7  Run time: 6 min to 8 min  
A.4.2  Preparation of calibration curve  
A.4.2.1  Into a series of clean 20 -ml PT FE liner screw cap vials, add accordingly as table below.  Filter 
through a 0.45 -µm syringe filter before use . 
Code  IS,  
ml  DS,  
ml  ES,  
ml  Delta,  
mg  Total volume,  
ml  
C1  1  0.5  13.5   0.30  15 ml  
C2  1  0.7  13.2 ml  0.42  15 ml  
C3  1  0.9  12.8 ml  0.54  15 ml  
C4  1  1.1  12.4 ml  0.66  15 ml  
C5  1  1.3  12.1 ml  0.78  15 ml  
A.4.2.2  All standards should be kept in the refrigerator (at a temperature of 2 to 8°C ) if not in use in well -
tightened paraffin film sealed cap.  DEAS 455 :2021  
12 © EAC 2021  – All rights reserved  
 A.4.3  Calibratio n  
Daily calibrate HPLC system with full series of 05 standards, beginning with the lowest level standard. The 
correlation coefficient should be less than 0.99 over this range.  
A.4.4  Preparation of sample  
Weigh (to the nearest 0.1 mg) into an Erlenmeyer or a screw cap neutral glass bottle (50 -ml) sufficient sample 
to contain about 0.5 mg of Deltamethrin.  For 75D, 100D and 150D netting sample, suitable weight ( w g) is 0.3 
g, 0.4 g and 0.6 g respectively. Add by pipette 1.0 ml internal standard solution.  Add 14 ml extract solvent. 
Replace the cap closely.  
Put the bottles into the ultrasonic bath, setting temperature 80 °C, running time 15 min.  Vigorously shake the 
bottle using the shaker in 30 min at room temperature, speed of shaking is at level of 150 - 200 beats per 
minute.  
Using a syringe membrane filter with pore size of 0.45 µm or finer, filter 1 ml of extract solution into clean 
amber. The sample shall be injected within 24 h since extraction; for longer waiting time the vial should be 
kept in a r efrigerator.  
A.4.5  Determination  
The Deltamethrin content, expressed as grams per kilogram, shall be calculated as follows:   
 
Where; 
 a  is the Deltamethrin reading, in milligrams, from the analysis; and  
w  is the mass, in grams, of sample taken.  
NOTE  Conventional unit of active ingredient content (Deltamethrin) for netting is milligrams per square metre.  The 
conversion from grams per kilogram (g/kg) to milligrams per square metre (mg/m2) is made as follows:  
Deltamethrin content (mg/m2) = Deltamethri n content (g/kg) x D  
Where; 
D  is the weight per square metre of typical polyester netting:  
• 75 Denier netting, D = 30 g/m2  
• 100 Denier netting, D = 40 g/m2  
• 150 Denier netting, D = 60g/m2 
A.4.6  Method validation summary  
A.4.6.1  Precision  
Analyze 05 rep licates RSD is 1.8 %.  
A.4.6.2   Accuracy  
Recovery of 04 Laboratory Synthetic samples is in the range of 97 % to 101 %.  DEAS 455 :2021  
© EAC 2021  – All rights reserved  13 
 Averaged at 99.3 %.  
A.4.6.3  Linearity  
Over the range of Deltamethrin from 0.30 mg to 0.78 mg, the correlation coefficient R2 is observ ed not less 
than 0.995.  
Determination of release /Retention Index  
 
Figure A.1 ― Chromatogram of calibration solution  
  
Figure A.2 ― Chromatogram of sample  DEAS 455 :2021  
14 © EAC 2021  – All rights reserved  
 Annex  B 
(normative)  
 
Determination of Permethrin content in long lasting insecticide treated 
mosq uito nets  
B.1 Sampling   
Take at least 500 g.  
B.2 Identity tests  
B.2.1  GLC . Use the GLC method below. The retention times of cis- and trans -permethrin should not deviate 
by more than 1% from those of the permethrin standard and the intensities of the per methrin isomers should 
give the same pattern as in the standard (Fig. B.1).  
B.2.2  Infrared.  Extract the sample with a suitable solvent. Filter and evaporate the solvent. Prepare a film 
between NaCl plates and scan from 4000 to 400 cm-1. The spectrum produ ced from the sample should not 
differ significantly from that of the standard (Fig. B.2)  
B.3 Permethrin   
The content of permethrin (sum of cis- and trans -isomers) is determined by capillary GC using flame ionisation 
detection and triphenyl phosphate as i nternal standard. The trans -isomer fraction is calculated from the 
chromatogram obtained.  
B.3.1  Reagents  
B.3.1.1  Heptane   
B.3.1.2  Acetone   
B.3.1.3  Permethrin working standard technical product of certified purity. Store refrigerated.  
B.3.1.4  Triphenyl p hosphate  internal standard. Must not show peaks with the same retention times as cis- 
and trans -permethrin.  
B.3.1.5  Internal standard solution      Dissolve triphenyl phosphate (1.0g) in heptane (150ml). Ensure that 
a sufficient quantity of this solution is  prepared for all samples and calibration standards to be analysed.  
B.3.1.6  Calibration solution    Homogenise the permethrin working standard. When the permethrin is waxy 
solid or partly waxy solid homogenise it by warming it to melting and by stirring. P repare calibration solutions 
in duplicate. Weigh (to the nearest 0.1mg) 72 to 88 mg ( s mg) of permethrin standard into a vial or stoppered 
flask (200ml). Add by pipette internal standard solution (10.0 ml) and dissolve. Add by measuring cylinder 
heptane (9 0ml) and mix well (solutions C A and C B).  
B.3.2  Apparatus   
B.3.2.1  Gas chromatograph  equipped with a split/split less injection and a flame ionisation detector  DEAS 455 :2021  
© EAC 2021  – All rights reserved  15 
 B.3.2.2  Capillary column     fused silica, 30 m x 0.25 mm (i.d.), film t hickness: 0.25 μm, coated with 
crosslinked dimethyl polysiloxane (DB -1 or equivalent)  
B.3.2.3  Electric integrator or data system  
B.3.3  Procedure  
B.3.3.1  Gas chromatographic conditions (typical)  
B.3.3.1.1  Colum n       fused silica, 30 m x 0.25 mm (i.d.) , film thickness: 0.25 μm, coated with cross linked 
dimethyl polysiloxane (DB -1 or equivalent)   
B.3.3.1.2  Injection system   
Injector            split injection  
Split flow         approximately 100 ml/min   
Injection volume    1μm   
B.3.3.1.3  Detector              flame ionisation  
B.3.3.1.4  Temperatures   
Column oven         240 ℃  
B.3.3.1.5  Injection port          265℃  
B.3.3.1.6  Detector          265℃  
B.3.3.1.7  Carrier gas             helium, 30 cm/s  
B.3.3.1.8  Retention times   
triphenyl phosphate: about 6.5  min   
cis-permethrin: about 12.4 min  
trans -permethrin: about 12.9 min   
B.3.3.2  Linearity check    Check the linearity of the detector response by injecting 1 μl of solutions with 
permethrin concentrations 0.5, 1 and 2 times that of the calibration soluti on before conducting analysis.  
B.3.3.3  System equilibration     Prepare two calibration solutions. Inject 1 μl portions of the first one until  
the response factors obtained for two consecutive injections differ by less than 1.0%. Then inject a 1 μl portion  
of the second solution. The response factor for this solution should not deviate by more than 1.0% from that 
for the first calibration solution, otherwise prepare new calibration solutions.    
B.3.3.4  Preparation of sample solution    Clean a pair of sciss ors with acetone before use. Cut the 
sample with scissors into 5 – 10 mm squares. Prepare sample solutions in duplicate for each sample. Weigh 
(to the nearest 0.1mg) sufficient sample to contain 36 to 44 mg (w mg) of permethrin into a vial or stoppered 
flask (100 ml). Add by pipette internal standard solution (5.0 ml) and by measuring cylinder heptane (45 ml). 
Place the vial or stoppered flask in a water bath (85 -90℃) for 45 min. Shake the vial or stoppered flask once 
or twice during the extraction. Filter a portion of each sample solution through a filter paper prior to analysis 
(solutions S A and S B). 
B.3.3.5  Determination    Inject in duplicate 1 μl portions of each sample solution bracketing  them by 
injections of the calibration solutions as follows; cali bration solution C A, sample solution S A, sample  solution DEAS 455 :2021  
16 © EAC 2021  – All rights reserved  
 SA, calibration solution C B, sample solution S B, sample solution S B, calibration solution C A, and so on. 
Measure the relevant peak areas.   
B.3.3.6  Calculation of permethrin content    Calculate the m ean value of each pair of response factors 
bracketing the two injections of a sample and use this value for calculat ing the permethrin contents of the  
 
 
where;  
fi  is the individual response factor;  
f  is the mean response factor;  
Hs  is the total pea k area of permethrin (cis -permethrin + trans -permethrin) in the calibration solution;  
Hw  is the total peak area of permethrin (cis -permethrin + trans -permethrin) in the sample solution;  
Ir  is the peak area of the internal standard in the calibration s olution;  
Iq  is the peak area of the internal standard in the sample solution;  
s  is the mass, in milligrams, of permethrin working standard in the calibration solution;  
w  is the mass, in milligrams, of sample taken; and  
 P  is the purity, in grams pe r kilograms, of permethrin working standard.  
Repeatability, r =   1.6 g/kg at 20.3 g/kg active ingredient content  
        1.3 g/kg at 20.0 g/kg active ingredient content  
        0.9 g/kg at 18.7 g/kg active ingredient content  
Reproducibility, R =  1.9 g/kg at 20.3 g/kg active ingredient content  
        1.5 g/kg at 20.0 g/kg active ingredient content  
        1.5 g/kg at 18.7 g/kg active ingredient content  DEAS 455 :2021  
© EAC 2021  – All rights reserved  17 
 
 
Figure B.1 ― Example of gas chromatogram of permethrin LN  
 
Figure B.2 ― Infrared spectrum of permethrin  
 DEAS 455 :2021  
18 © EAC 2021  – All rights reserved  
 Annex  C 
(normative)  
 
Determination of Alphacypermethrin  content in long lasting insecticide 
treated mosquito nets  
C.1 Sampling  
Take net specimens.  
C.2 Identity test  
GLC capable of operating over a range 100 ºC to 300 ºC, fitted with a flame ionization detector  
C.3 Alphacypermethrin  
Alphacypermethrin 454/TC/(M)3 is dissolved in tetrahydrofuran and determined by capillary gas 
chromatography in split injection mode using flame ionization and internal standardization.  
C.4 Reagents   
C.4.1  Tetrahydrofuran  
C.4.2  Aphacypermethrin  standard of known purity, Di(2 -ethylhexyl)phthalate(dioctyl phthalate, DOP), 
internal standard, purity at least 980 g/kg and giving no peaks with similar retention times to alphcypermethrin.  
C.4.3  Citric acid  5 % solution, dissolve citric acid (25 g) in water (500 ml).  
C.4.4  Internal standard solution , dissolve dioctyl phthalate (5.0 g) intetrahydrofuran (500 ml). Ensure 
sufficient quantity of this solution is prepared for all samples and calibration solutions to be analysed.  
C.5 Calibration solutions  
C.5.1  Preparation of calibration solutions  
Weigh 50 mg alpha cypermethrin (to the nearest 0.1 mg) in a volumetric flask (25 -ml). Fill to the mark with 
THF. Place the flask in an ultrasonic bath for 10 min. After temperature equilibrium pipette 1.50 ml, 4.50 ml of 
this solution into three volumetric flaks (50 ml). Add 0.5 ml of internal standard solution (dioctyl phthalate, 1 % 
in acetone) and fill up each to the mark with THF.  
These solutions are used as calibration solutions A (C A), B (C B) and C (C C). Transfer 200 µl out of each flask 
into separate GC vials. Add one drop of citric acid in each case and seal the vials. Place the  vials into the 
sample tray (cooled down to 15 ºC) of the GC apparatus.  
NOTE  Citric acid is added to stop epimerization of alphacypermethrin in solution.  DEAS 455 :2021  
© EAC 2021  – All rights reserved  19 
 C.5.2  Description of calibration solutions  
The calibration solutions are described as follows:  
• CA: concentration of approximately 3.0 mg alphacypermethrin in 50 ml THF;   
• CB: concentration of approximately 6.0 mg alphacypermethrin in 50 ml THF; and  
• CC: concentration of approximately 9.0 mg alphacypermethrin in 50 ml THF.  
C.5.3  Apparatus  
C.5.3.1  Gas chromatograph  with flame ionization detector (for example, HP6890 Plus)  
C.5.3.2  Automatic sample injector (for example, HP series 7683) equipped with a sample which is 
cooled down to 15 ºC  
C.5.3.3  Capillary column fused silica (for example, DB -1) 30 m x  0.32 mm, film thickness of 0.25 µm  
C.5.3.4  Electronic data evaluation system  (for example, HP ChemStation)  
C.5.3.5  Ultrasonic bath  
C.5.3.6  Electronic balance  
C.5.3.7  Laboratory glassware  
C.6 Procedure  
C.6.1  Operating conditions  
As per alphacypermet hrin 454/TC/(M)3   
C.6.2  Preparation of the samples  
C.6.2.1  Determination via the water/detergent extraction process  
C.6.2.1.1  First step: Quantification of the adherent contents of alphacypermethrin on surface fibres  
a) Procedure done by manufacturer  
Place 2 g impregnated net in a beaker (one -litre). Add soap (commercially available bar soap or as flakes, 
2g/l) and water (500 ml). The washing is done for 10 min at 30 ºC on a shaker with 155 movements/min. 
Directly after the washing, the wash liquor is acidified with 10 ml/l acetic acid 30% in order to prevent 
hydrolysis of the extracted alphacypermethrin (there is no difference in hydrolysis in neutral water compared 
to wash liquor after 10 min at 30 ºC). Transfer 150 ml of the washing liquid into a sep aration funnel (500 -ml). 
The extraction procedure is done twice with 100 ml ethyl acetate each by shaking twice for 30 s. Both portions 
of ethyl acetate are combined together in a flask (250ml). Ethyl acetate is evaporated in a rotary evaporator. 
The flask  is stoppered and sent to the analytical laboratory.  
b) Procedure done by analytical laboratory  
Fill up the flask with THF (50 ml). Add 0.5 ml of internal standard solution (dioctyl phthalate, 1 % in acetone). 
Transfer 200 µl of sample out of the flask into  a separate GC vial. Add one drop of citric acid into the vial.  DEAS 455 :2021  
20 © EAC 2021  – All rights reserved  
 C.6.2.1.2  Second step: Quantification of the total contents of alphacypermethrin  
Weigh (to the nearest 0.1 mg) 1 g of the impregnated net into a volumetric flask (100 ml) and add THF (50 
ml). Place this flask in a refluxing apparatus. Heat up the flask in the apparatus and reflux at approximately 90 
ºC (oil bath temperature). Sampling will be done after 5 min refluxing. Add 0.5 ml of internal standard solution 
(dioctyl phthalate, 1 % in acet one). Transfer 200 µl of the sample into separate GC vial. Add one drop of citric 
acid into the vial .  
C.6.2.2  Determination via the n -hexane extraction process  
C.6.2.2.1  First step: Quantification of the adherent contents of alphacypermethrin on the sur face of 
the fibers  
Weigh (to the nearest adherent drops of n -hexane) out of the flask into another volumetric flask (100 -ml) and 
add THF (50 ml). Place this flask in a refluxing apparatus. Heat up the flask in the apparatus and reflux at 
approximately 90 ºC. Sampling will be done after 5 min refluxing. Add 0.5 ml of internal standard solution 
(dioctyl phthalate, 1 % in acetone). Transfer 200 µl of the sample into a separate GC vial. Add one drop of 
citric acid into the vial.  
C.6.2.2.2  Second step: Quantif ication of the total contents of alpha -cypermethrin  
Transfer the net (without adherent drops of n -hexane) out of the flask in to another volumetric flask (100 -ml) 
and add THF (50 ml). Place this flask in a refluxing apparatus. Heat up the flask in the app aratus and reflux at 
approximately 90 ºC. Sampling will be done after 5 min refluxing. Add 0.5 ml of internal standard solution 
(dioctyl phthalate, 1 % in acetone). Transfer 200 µl of the same into a separate GC vial. Add one drop of citric 
acid into the v ial.  
C.6.2.3  System calibration  
As for alphacypermethrin 454/TC/(M3)   
C.6.2.4  Determination  
Each calibration solution C i and each sample solution S J is injected twice. The following sequence is advised:  
CA , CA,, CB, CB,CC, CC, SA, SA,SB, SB,SC,SC,…  
C.6.2.5  Calculation  
As for alphacypermethrin 454/TC/(M)3 and see test of linearity  
 
Where; 
 f  is the response factor  
Hw is the total peak area of alphacypermethrin (cis +ll) in the sample solution  
Lq  s the peak area of internal standard in the sampl e solution  
w is the mass of sample taken  
C.6.2.6  Surface concentration and release index  
a) Determination  DEAS 455 :2021  
© EAC 2021  – All rights reserved  21 
 The determination of alphacypermethrin content is done via the n -hexane extraction process from fibres.  
Each calibration solution Cj and each sam ple solution Sj ai are injected twice. The following sequence is 
advised: C A, CA,CB,CB,CB,CC,CC,SA1,SA1,SA2,SA2,SA3,SA3,SB1,SB1,...  
• SA  is the first rinse; S A mean value of S A1, SA2, SA3  
• SB  is the second rinse; S B mean value of S B1, SB2, SB3  
• Sc   is the third rinse; S C mean value of S C1, SC2, SC3  
where 1,2,3 are net samples  
b) Calculation of the release index  
Calculate the mean value of sample solutions S C and S B by the equations described in C.6.2.5 and the 
release index for each piece of netting.  
 
Where;  
SB refers to second rinse; S B mean S B1, SB2, SB3  
SC refers to third rinse; S C mean value of S C1, SC2, SC3  DEAS 455 :2021  
22 © EAC 2021  – All rights reserved  
 Annex  D 
(normative)  
 
Determination of Piperonyl butoxide in polyethylene matrix in long 
lasting insecticide treated mosquito nets by Gas Ch romatography  
D.1 Scope  
The method is suitable for the determination of piperonyl butoxide in polyethylene matrix.  
D.2 Outline of method  
The sample is extracted by refluxing with xylene. The piperonyl butoxide content is determined by capillary 
gas chroma tography using flame ionisation detection and internal standard.   
D.3 Reagents  
D.3.1  Xylene  
D.3.2  Piperonyl butoxide standard  of known purity. Store below 0 °C.  
D.3.3 Octadecane internal standard: Internal standard solution . Weigh (to the nearest 0.1 mg) into a 
volumetric flask (50 ml) octadecane (0.4 g). Fill to the mark with xylene and mix well.   
Calibration solutions: Allow piperonyl butoxide to equilibrate to ambient temperature. Then weigh (to the 
nearest 0.1 mg) into a volumetric flask (50 ml) 0 .25 g. Fill to the mark with xylene and mix well. To pipette 0.50 
ml, 1.50 ml, 2.00 ml, 3.00 ml and 4.00 ml of this solution into five volumetric flasks (25 ml). Add 2 ml of internal 
standard solution and fill up each to the mark with xylene and mix well.  
i. Five solutions are used as calibration solutions A (CA), B (CB), C (CC), D (CD), E (CE). Transfer 
200 ml out of each flask into separate GC vials. Place the vial into the sample tray of GC 
apparatus.  
ii. Description of the calibration solutions:  
• CA: concent ration of approximately 2.5 mg piperonyl butoxide in 25 ml xylene  
• CB: concentration of approximately 7.5 mg piperonyl butoxide in 25 ml xylene  
• CC: concentration of approximately 10.0 mg piperonyl butoxide in 25 ml xylene  
• CD: concentration of approximate ly 15.0 mg piperonyl butoxide in 25 ml xylene  
• CE: concentration of approximately 20.0 mg piperonyl butoxide in 25 ml xylene  DEAS 455 :2021  
© EAC 2021  – All rights reserved  23 
 D.4 Apparatus  
D.4.1  Gas chromatograph  capable of operating over the range 180 °C to 250 °C fitted with a flame 
ionisation detecto r, a split injector, and an auto sampler  
D.4.2  Capillary column fused silica , 30 m x 0.32 mm (i.d.) with 100% methyl polysiloxane, cross -linked, 
surface bonded stationary phase and 0.25 µm film thickness (Durabond -1 or equivalent).   
D.4.3  Electronic integ rator or data system.  
D.5 Operating Procedure  
D.5.1  Operating conditions (typical)  
a) Column: Fused silica, 30 m x 0.32 mm (i.d.) with 100 % methyl polysiloxane, cross -linked, surface 
bonded stationary phase and 0.25 µm film thickness (Durabond -1 or equiva lent);  
b) Injection system: Injector split injection;  
c) Injector temperature 250 °C;  
d) Split ratio 20:1;  
e) Purge flow 1 ml/min;  
f) Injection volume 1 µl;  
g) Detector system: Type; Flame ionisation;  
h) Temperature 300 °C;  
i) Oven temperatures: Initial 180 °C;  
j) Program;  
 180 °C hold for 11 min  
 200 °C at 10 °C/min, hold for 8 min  
 210 °C at 10 °C/min, hold for 18 min  
 245 °C at 30 °C/min, hold for 4 min  
 Total run time 45 min  
k) Gas flow rates;  
 Helium (carrier) linear velocity: 39 cm/min at 180 °C  
 Helium (make up) 30 ml/m in  
 Hydrogen 40 ml/min  
 Air 400 ml/min  
l) Total flow 35 ml/min; and  DEAS 455 :2021  
24 © EAC 2021  – All rights reserved  
 m) Retention time  
 octadecane: about 6 min  
 Piperonyl butoxide: about 23 min  
D.5.2  Preparation of sample  
Cut the sample with scissors into 1 cm to 2 cm squares and thoroughly mixed. Weigh (to  the nearest 0.1 mg) 
sufficient sample to contain 12.5 mg of piperonyl butoxide into a 250 -ml reflux flask. Add 23 ml xylene and 2 
ml internal standard solution. Reflux the sample about 30 min. Cool down the sample to room temperature. 
Filter the solution through a 0.45 -µm Teflon filter membrane. Transfer into a separate GC vial.   
D.5.3  System equilibration  
Inject into the gas chromatograph a 1 -µl portion of the sample solution to condition the column and to check 
for the appropriate flow rates and integr ation events.  
D.5.4  Determination   
Inject in duplicate into the gas chromatograph 1 -µl portions of the calibration and sample solutions in the 
following sequence; CA, CA, CB, CB, CC, CC, CD, CD, CE, CE, S1, S1, S2, S2, etc.  
D.6 Calculation   
The piperon yl butoxide content, shall be calculated as follows :  
Concentration = R/w (g/kg)  
Where;  
R  is the Piperonyl butoxide reading, in milligrams, from the analysis, and  
w  is the mass, in grams, of sample taken.  
 DEAS 455 :2021  
© EAC 2021  – All rights reserved  25 
 Annex  E 
(normative)  
 
Measurement of mosquito n et dimensions  
E.1 Rectangular nets: Length, width and height  
E.1.1  Apparatus  
E.1.1.1  Flat table  
E.1.1.2  Measuring tape or steel rule  
E.1.2  Conditioning  
Condition the net samples in accordance with ISO 139.  
E.1.3  Procedure  
Lay the conditioned net sam ple on a flat table (E.1.1.1), and take measurements of height, width and 
diameter.  
E.1.4  Calculation  
If more than one net sample is tested, take the average measurement for each dimension .  
E.1.5  Report  
Report the value of the net dimension as the aver age calculated in E.1.4 in centimetres .  
E.2 Circular nets: Top ring diameter, bottom circumference and conical height  
E.2.1  Apparatus  
E.2.1.1  Hook  supported at a vertical distance of at least more than the height of the net sample to be 
tested  
E.2.1.2  Measuring tape or steel rule  
E.2.1.3  Twine , of measuring at least 10 m  
E.2.1.4  Felt pen marker  
E.2.2  Conditioning  
Condition the net sample in accordance with ISO 139.  DEAS 455 :2021  
26 © EAC 2021  – All rights reserved  
 E 2.3  Procedure  
E.2.3.1  Top ring diameter  
E.2.3.1.1  Procedure  
Place the top portio n of the net sample on a flat table (E.1.1.1) and put the twine (E.2.1.3) around the 
circumference of the top ring of the net sample, identifying the two ends with a marker (E 2.1.4) which 
represent the dimension of the top ring. Using a measuring tape (E. 2.1.2) determine the top ring 
circumference (s) of the net as the distance between the two points marked on the twines. Repeat the test on 
each of the other net samples.  
E.2.3.1.2  Calculation  
Take the average of the individual measurements as the top cir cumference of the conical nets.  
E.2.3.1.3  Report  
Report the top ring circumference as the value(S) calculated in E.2.3.1.2 in centimetres.  
E.2.3.2  Bottom circumference  
E.2.3.2.1  Procedure  
Lay the bottom part of the net on a flat table removing any cu rls and take the measurement (N) from one end 
of the flattened net to the other using a twine. Repeat the procedure for other net samples.  
E.2.3.2.2  Calculation  
Take the average of the measurements (N) taken in E.2.3.2.1.  
Calculate the bottom circumfer ence as N x 2.  
E.2.3.2.3  Report  
Report the value of bottom circumference of the net as the value (N x 2) calculated in E.2.3.2.2 in centimetres.  
E.2.3.3  Conical net height   
E.2.3.3.1  Procedure  
Hang the net with the loop from a hook. Take measurements  of height along all the vertical seams.  
E.2.3.3.2  Report  
Report the least measurement taken as the conical net height.  DEAS 455 :2021  
© EAC 2021  – All rights reserved  27 
 Annex  F 
(normative)  
 
Determination of mesh count  
F.1 Principle  
Mesh size is determined by counting the number of holes in a square o f the fabric.  Counting may be done 
directly on the fabric or indirectly by scanning/photocopying the fabric. Indirect methods may ease counting 
and provide a permanent record. Before counting, the fabric should be conditioned according to ISO 139 (4 h, 
20 ºC, 65 % relative humidity).   
F.2 Procedure  
Use a template to define the square of netting, taking care not to stretch or distort the fabric.  The template 
should be a rigid sheet, 1 mm - 2 mm thick, in or on which an accurately calibrated (±1 % in each  dimension) 
square (for example, 2 cm x 2 cm or 5 cm x 5 cm) has been cut or marked.  If a template is not available and 
a ruler shall be used, great care is required to ensure that the area counted is square.  If possible, at least one 
edge of the square to be counted should be aligned with a row of complete holes in the fabric.  Count replicate 
squares in pieces selected and calculate the average and note the lowest value  
 
Figure 1 — Typical illustration of a rectang ular mosquito net  
 DEAS 455 :2021  
28 © EAC 2021  – All rights reserved  
 
 
Figure 2 — Typic al illustration of a c onical mosquito net  
 DEAS 455 :2021  
© EAC 2021  – All rights reserved  29 
 Bibliography  
[1] EAS 455:2019, Long lasting insecticide treated mosquito nets — Specification  
[2] WHO Interim specification 333/LN/1 (July 2019)  
[3] WHO Interim specification 333/LN/2 (January 2019)  
[4] WHO Interim specification  333+33/LN/1 (NETTING) (April 2019)  
[5] WHO Interim specification 333+33/LN/1 (NET) (April 2019)  
[6] WHO Interim specification 333+33/LN/2 (NETTING) (January 2019)  
[7] WHO Interim specification 333+33/LN/2 (NET) (January 2019)  
 DEAS 455: 2021   
 
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