seventh commiss direct ec juli relat method analysi check composit cosmet product text eea relev commiss european commun regard treati establish european commun regard council direct eec juli approxim law member state relat cosmet product amend commiss direct ec articl thereof direct eec offici test cosmet product aim ensur condit laid commun provis composit cosmet product satisfi method analysi laid quickli method adopt commiss direct eec amend direct eec eec amend direct eec commiss direct eec eec eec ec identif determin phenoxyethanol phenoxypropan ol methyl ethyl propyl butyl benzyl hydroxybenzo cosmet product constitut seventh step measur provid direct accord opinion committe adapt direct eec technic progress adopt decis articl member state step ensur offici test cosmet product identif determin phenoxyethanol phenoxypropan ol methyl ethyl propyl butyl benzyl hydroxybenzo carri accord method annex articl member state bring forc law regul administr provis need compli direct septemb forthwith inform commiss thereof member state adopt provis refer direct accompani refer time offici public procedur refer adopt member state member state commun commiss provis nation law adopt field cover direct articl direct enter forc dai public offici journal european commun articl direct address member state brussel juli commiss emma bonino member commiss oj oj oj oj oj oj oj oj oj oj annex identif determin phenoxyethanol phenoxypropan ol methyl ethyl propyl butyl benzyl hydroxybenzo cosmet product identif scope field applic method specifi tlc procedur combin determin method section identif phenoxyethanol phenoxypropan ol methyl hydroxybenzo ethyl hydroxybenzo propyl hydroxybenzo butyl hydroxybenzo benzyl hydroxybenzo cosmet product principl preserv extract acidifi cosmet sampl aceton filtrat aceton solut mix water alkalin medium fatti acid precipit calcium salt alkalin aceton water mixtur extract diethyleth remov lipophil substanc acidif preserv extract diethyleth aliquot diethyleth extract spot silica gel coat thin layer plate develop plate chromatogram obtain observ uv light visual millon reagent reagent gener reagent analyt puriti water distil water water equal puriti aceton diethyleth pentan methanol acet acid glacial hydrochlor acid solut hcl mol potassium hydroxid solut koh mol calcium chlorid dihydr cacl detect reagent millon reagent millon reagent mercuri ii nitrat readi made solut commerci fluka phenoxyethanol phenoxypropan ol methyl hydroxybenzo methylparaben ethyl hydroxybenzo ethylparaben propyl hydroxybenzo propylparaben butyl hydroxybenzo butylparaben benzyl hydroxybenzo benzylparaben refer solut prepar solut refer substanc methanol develop solvent mix volum pentan volum glacial acet acid apparatu normal laboratori equip waterbath capabl maintain temperatur develop tank line filter paper ultraviolet light sourc nm thin layer plate cm cm precoat mm silica gel concentr zone merck darmstadt equival oven capabl maintain hot air hair dryer woollen paint roller length approxim cm diamet approxim cm thick wool layer mm trim wool note ml glass tube screw cap electr heat plate thermostat temperatur control temperatur set hot plate cover aluminium plate cm cm thick mm obtain uniform heat distribut procedur sampl prepar weigh approxim sampl ml glass tube screw cap add drop hydrochlor acid solut ml aceton strongli basic cosmet product toilet soap drop hydrochlor acid solut ad close tube gentli heat mixtur approxim facilit extract preserv aceton phase shake vigour minut measur ph solut ph indic paper adjust ph solut amp le hydrochlor acid solut shake vigor minut cool solut room temperatur filter filter paper conic flask transfer ml filtrat ml conic flask add ml water mix adjust ph mixtur approxim potassium hydroxid ph indic paper add calcium chlorid dihydr shake vigor filter solut filter paper ml separ funnel ml diethyleth shake vigor minut phase separ collect aqueou layer ml conic flask adjust ph solut approxim hydrochlor acid solut ph indic paper subsequ add ml diethyleth shake vigor minut phase separ transfer approxim ml diethyleth layer ml sampl vial thin layer chromatographi tlc place tlc plate heat aluminium plate appli ìl refer solut ìl sampl solut start line concentr zone tlc plate desir stream air facilit evapor solvent remov tlc plate heat plate cool room temperatur transfer ml develop solvent develop tank place tlc plate immedi unsatur chamber develop room temperatur solvent front run cm base line remov plate develop tank dry stream hot air mean hot air hair dryer examin plate uv light mark posit spot heat plate minut oven remov excess acet acid visual preserv chromatogram millon reagent dip paint roller reagent roll tlc plate evenli wet note altern spot visual care applic drop millon reagent spot mark uv light ester hydroxybenzo acid red spot phenoxyethanol phenoxypropan ol yellow spot note hydroxybenzo acid present sampl preserv decomposit product paraben red spot identif calcul rf spot compar spot obtain sampl solut refer solut respect rf valu behaviour uv radiat colour visual draw preliminari conclus ident preserv paraben present hplc procedur section perform combin result tlc high perform liquid chromatographi hplc confirm presenc phenoxyethanol phenoxypropan ol paraben remark toxic millon reagent reagent appli procedur sprai recommend compound hydroxyl group give colour millon reagent tabl colour rf valu obtain number preserv tlc procedur found de kruijf rijk pranato soetardhi schouten determin preserv cosmet product thin layer chromatograph procedur identif preserv cosmet product chomatographi rf valu list tabl serv indic valu obtain gt tabl gt separ obtain hydroxybenzo acid methylparaben benzylparaben ethylparaben identif compound confirm perform hplc method section compar retent time obtain sampl standard determin scope field applic method specifi procedur determin phenoxyethanol phenoxypropan ol methyl hydroxybenzo ethyl hydroxybenzo propyl hydroxybenzo butyl hydroxybnenzo benzyl hydroxybenzo cosmet product definit amount preserv determin method express percentag mass principl sampl acidifi ad sulfur acid suspend mixtur ethanol water gentli heat mixtur melt lipid phase promot quantit extract mixtur filter preserv filtrat determin revers phase hplc isopropyl hydroxybenzo intern standard reagent gener reagent analyt puriti suitabl hplc water distil water water equal puriti ethanol absolut phenoxyethanol phenoxypropan ol methyl hydroxybenzo methylparaben ethyl hydroxybenzo ethylparaben propyl hydroxybenzo propylparaben isopropyl hydroxybenzo isopropylparaben butyl hydroxybenzo butylparaben benzyl hydroxybenzo benzylparaben tetrahydrofuran methanol acetonitril sulfur acid solut mol ethanol water mixtur mix volum ethanol volum water intern standard solut accur weigh approxim isopropylparaben transfer ml volumetr flask dissolv make volum ethanol water mixtur mobil phase tetrahydrofuran water methanol acetonitril mixtur mix volum tetrahydrofuran volum water volum methanol volum acetonitril preserv stock solut accur weigh approxim phenoxyethanol phenoxypropan ol methylparaben ethylparaben propylparaben butylparaben benzylparaben ml volumetr flask dissolv make volum ethanol water mixtur refriger solut stabl week standard preserv solut stock solut transfer ml ml ml ml ml ml volumetr flask flask add ml intern standard solut ml sulfur acid solut make volum ethanol water mixtur solut freshli prepar apparatu normal laboratori equip waterbath capabl maintain temperatur high perform liquid chromatograph uv detector wavelength nm analyt column stainless steel cm mm cm mm pack nucleosil equival ml glass tube screw cap boil chip carborundum size mm equival procedur sampl prepar sampl prepar addit intern standard weigh approxim sampl ml glass tube screw cap pipett ml sulfur acid solut ml ethanol water mixtur tube add approxim boil chip close tube shake vigor homogen suspens obtain shake minut place tube minut waterbath facilit extract preserv ethanol phase immedi cool tube stream cold water store extract refriger hour filter extract filter paper transfer approxim ml filtrat ml sampl vial store extract refriger perform hplc determin hour sampl prepar includ addit intern standard weigh decim place sampl ml glass tube screw cap pipett ml sulfur acid solut ml ethanol water mixtur tube add approxim boil chip ml intern standard solut close tube shake vigor homogen suspens obtain shake minut place tube minut waterbath facilit extract preserv ethanol phase immedi cool tube stream cold tap water store extract refriger hour filter extract filter paper transfer approxim ml filtrat ml sampl vial test solut store extract refriger perform hplc determin hour high perform liquid chromatographi hplc chromatograph condit mobil phase tetrahydrofuran water methanol acetonitril mixtur flow rate ml minut detect wavelength nm calibr inject ìl standard preserv solut chromatogram obtain determin ratio peak height standard preserv solut peak height intern standard plot curv preserv relat ratio concentr standard solut determin inject ìl sampl solut intern standard chromatograph record chromatogram inject ìl standard preserv solut record chromatogram compar chromatogram obtain chromatogram sampl extract peak present approxim retent time isopropylparaben recommend intern standard continu inject ìl sampl solut intern standard record chromatogram measur peak height interf peak observ chromatogram sampl solut approxim retent time isopropylparaben intern standard select preserv examin absent chromatogram sampl preserv altern intern standard calcul ratio peak height investig preserv peak height intern standard ascertain standard solut calibr procedur linear respons obtain ascertain chromatogram obtain standard solut sampl solut meet requir peak separ worst separ pair definit peak separ figur gt refer film gt peak separ figur peak separ requir separ achiev effici column mobil phase composit adjust requir met asymmetri factor peak obtain rang definit peak asymmetri factor figur record chromatogram determin asymmetri factor chart speed cm minut recommend gt refer film gt asymmetri factor figur peak asymmetri factor steadi baselin obtain calcul calibr curv ratio peak height investig preserv peak height intern standard calcul concentr preserv sampl solut calcul phenoxyethanol phenoxypropan ol methyl hydroxybenzo ethyl hydroxybenzo propyl hydroxybenzo butyl hydroxybenzo benzyl hydroxybenzo content wi percentag weight formula wi gt num gt bi gt den gt bi concentr ìg ml preserv test solut read calibr curv mass test posit repeat remark reproduc remark remark stationari phase retent behaviour solut hplc determin strongli depend type brand histori stationari phase column separ preserv examin conclud result obtain standard solut remark addit propos column pack materi hypersil od zorbax od found suitabl altern recommend mobil phase composit optim order obtain requir separ detect wavelength rugged test method shown slight chang detect wavelength signific effect result determin paramet control carefulli analysi interfer condit method compound preserv cosmet addit elut retent time larg number preserv mention annex vi council direct cosmet product list de kruijf rijk pranato soetardhi schouten determin preserv cosmet product ii high perform liquid chromatograph identif chromatographi project analyt column guard column method investig collabor trial laboratori particip sampl analyz tabl list sampl mean repeat reproduc found analyt contain gt tabl gt iso