embodiments of the present invention will be described below with reference to accompanying drawings . fig1 is a schematic diagram of a configuration of a liquid chromatography apparatus including a loop injection automatic sample introduction device , which is an embodiment of the present invention . a sample retaining container 1 is arranged on a sample rack 14 . a needle 2 is moved among the sample retaining container 1 , a cleaning tank 10 , a sample inlet 3 of a 6 - port 2 - position injection valve 8 by a needle moving mechanism , not shown . the 6 - port 2 - position injection valve 8 includes six ports , and a flow path allowing two adjoining ports thereamong to communicate with each other . in an injection position , the port p 1 communicates with the port p 6 , the port p 2 communicates with the port p 3 , and the port p 4 communicates with the port p 5 , as shown in the drawing . furthermore , the port p 1 is connected with a pump 7 . the port p 2 is connected with a column 6 . the port p 3 and the port p 6 are connected with each other through a sample storage loop 5 . the port p 4 is connected with the sample inlet 3 . the port p 5 is connected with a drain 22 for discharging waste fluid . moreover , the column 6 is connected to a detector 30 via a tube . the detector 30 detects a separated sample supplied from the column 6 , and transmits a detection signal to a data processor , not shown . the 6 - port 2 - position injection valve 8 can take another position by being turned by 60 degrees . as shown by broken lines in fig1 , in a load position , the port p 1 communicates with the port p 2 , the port p 3 communicates with the port p 4 , and the port p 5 communicates with the port p 6 . in the load position , the pump 7 , the port p 1 , the port p 2 and the column 6 communicate with each other in this order . the sample is not injected into a mobile phase transferred from the pump 7 , and the mobile phase flows to the column . the needle 2 , the sample inlet 3 , the port p 4 , the port p 3 , the sample storage loop 5 , the port p 6 , the port p 5 and the drain 22 communicate with each other in this order . the sample sucked from the sample retaining container 1 by the needle 2 is injected through the sample inlet 3 , and the sample storage loop 5 is filled with the sample . in the injection position , the sample retained in the sample storage loop 5 is flushed to the column 6 by the mobile phase transferred from the pump 7 . in the case where the sample is changed , the needle 2 is positioned at the cleaning tank 10 to clean the needle 2 , and a cleaning solution is caused to flow from the cleaning pump 15 to the needle 2 via a syringe valve 16 . the needle 2 is positioned at the sample inlet 3 , thereby cleaning the injection valve 8 . the cleaning pump 15 , the syringe valve 16 , a plunger cleaning flow path 17 , a three - way valve 18 , a cleaning solution container 20 , a cleaning solution container 21 , a deaerator 24 and a deaerator 25 are collectively referred to as a cleaning unit . the 5 - port 4 - position syringe valve 16 has five ports , and is provided with passages including four positions indicated by solid lines and broken lines in the diagram . the passage allows two of the ports to communicate with each other . the port p 1 communicates with the cleaning tank 10 . the port p 2 communicates with the needle 2 . the port p 3 communicates with a syringe 11 for measuring the sample . the port p 4 communicates with the plunger cleaning flow path 17 for cleaning the plunger of the pump 7 . the port p 5 communicates with the cleaning pump 15 . the four positions can be taken by turning by 45 degrees . in the first position , the port p 5 communicates with the port p 1 , and the port p 2 communicates with the port p 3 . in the second position , the port p 5 communicates with the port p 2 and the port p 3 communicates with the port p 4 . the third position , which is indicated by the solid line in the diagram , only allows the port p 5 to communicate with the port p 3 . the fourth position only allows the port p 5 to communicate with the port p 4 . two types of cleaning solutions are prepared according to the usage . the cleaning solution a is retained in the cleaning solution container 20 . the cleaning solution b is retained in the cleaning solution container 21 . any one of the cleaning solutions a and b according to the three - way valve 18 is sucked by the cleaning pump 15 via deaerators 24 and 25 , and transferred through the syringe valve 16 and a buffer tube 13 to the needle 2 . communication between the plunger cleaning flow path 17 and the pump 7 allows salts that are included in the mobile phase and deposited on the surface of the plunger of the pump 7 to be cleaned . during the syringe valve 16 being in the position where the port p 1 communicates with the port p 5 and the port p 2 communicates with the port p 3 , the needle 2 is connected with the syringe 11 for measuring the sample , via the buffer tube 13 . the liquid in the tube between the needle 2 and the syringe 11 is sucked and discharged by operating the syringe 11 upward and downward . fig2 is a functional diagram showing control targets of an operation controller 201 that controls movable mechanisms , such as valves of the liquid chromatography apparatus . the operation controller 201 includes a processor executing a control program preliminarily held in a memory , not shown , and transmits operation instructions to a needle moving mechanism 202 , a syringe operation mechanism 203 , a cleaning unit operation mechanism 204 , a syringe valve operation mechanism 205 , a three - way valve operation mechanism 206 , and an injection valve operation mechanism 207 . the movement , sucking and discharging operations of the syringe 11 are controlled by the syringe operation mechanism 203 . the cleaning unit is operated by the cleaning unit operation mechanism 204 . the syringe valve 16 is operated by the syringe valve operation mechanism 205 . the three - way valve 18 is operated by the three - way valve operation mechanism 206 . the injection valve 8 is operated by the injection valve operation mechanism 207 . next , a sample injection process will be described . the loop injection scheme in this embodiment transfers the total amount of the sample sucked from the needle 2 to the sample storage loop 5 of the injection valve 8 , and causes the sample to reach the column 6 for separating the sample . accordingly , this scheme is also referred to as the total amount injection scheme . here , terms are defined as follows . vi : injection volume , which is a net volume of sample introduction to the mobile phase flow path . vd : dead volume , which ranges from the sample inlet to the injection valve . va : air volume , which is a volume of an air layer before and after the sample . here , the setting of whether the sample is sandwiched before and after va or not can be selected by the automatic sample introduction device . the aforementioned fig1 shows the flow path where the automatic sample introduction device is initialized and in an idle state . the mobile phase into which no sample has been injected flows from the pump 7 to the column 6 via the sample storage loop 5 of the injection valve 8 . meanwhile , the cleaning solution container 20 for retaining the cleaning solution a is connected with the syringe 11 via the port p 3 , which communicates with the three - way valve 18 , the cleaning pump 15 and the port p 5 of the syringe valve 16 , thereby cleaning the inside of the syringe 11 with the cleaning solution a . the needle 2 is positioned above the cleaning tank 10 , and liquid dropping from the needle 2 is received by the cleaning tank 10 . fig3 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a state where the contents of the buffer tube 13 and the needle 2 are replaced with the cleaning solution b retained in the cleaning solution container 21 , thereby cleaning the tube and the needle . the needle 2 is moved to the sample inlet 3 to communicate with the port p 4 of the injection valve 8 . the syringe valve 16 is turned clockwise by 45 degrees from the state of fig1 . the turn switches the position to that where the port p 5 communicates with the port p 2 and the port p 3 communicates with the port p 4 . furthermore , the three - way valve 18 is switched to the cleaning solution container 21 retaining the cleaning solution b . the cleaning pump 15 transfers the cleaning solution b to the syringe valve 16 , the buffer tube 13 , the needle 2 and the injection valve 8 , thereby cleaning the inside of the port p 5 communicating with the port p 4 of the injection valve 8 . the cleaning solution b is then discharged from the drain 22 . fig4 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a state where the outside of the needle 2 is cleaned with the cleaning solution a in the cleaning tank 10 . the positions of the ports of the injection valve 8 are not changed , and the syringe valve 16 is turned clockwise by 45 degrees from the state in fig3 , thereby switching the position to that where the port p 5 communicates with the port p 1 and the port p 2 communicates with the port p 3 . the cleaning pump 15 transfers the cleaning solution a in the cleaning solution container 20 to the cleaning tank 10 via the syringe valve 16 , thereby soaking the needle 2 in the cleaning solution a in the cleaning tank 10 . the cleaning solution a is sucked by the syringe 11 , thereby filling the tube including the syringe valve 16 and the needle 2 with this solution . the amount of suction is vf + vd , i . e ., the sum of the feed volume and the dead volume . the needle 2 is soaked in the cleaning tank 10 , thereby cleaning the outside of the needle 2 . fig5 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a process of sucking the sample . as shown in fig5 , the positions of the ports of the syringe valve 16 and the injection valve 8 are not changed , and the needle 2 is moved from the cleaning tank 10 to the sample retaining container 1 . in the process of the movement , air is sucked by the syringe 11 . the amount of suction is half an air volume va . next , the needle 2 is moved to the sample retaining container 1 , and the sample is sucked by the syringe 11 . the amount of suction is the injection volume vi . fig6 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a state where the outside of the needle 2 is cleaned with the cleaning solution a after the sample is sucked . as shown in fig6 , the positions of the syringe valve 16 and the injection valve 8 are not changed , and the needle 2 is moved from the sample retaining container 1 to the cleaning tank 10 . in the process of the movement , air having an amount half as large as the air volume va is sucked by the syringe 11 . after the needle 2 is moved to the cleaning tank 10 , the cleaning pump 15 transfers the cleaning solution a to the cleaning tank 10 to clean the outside of the needle 2 . the cleaning solution a overflown from the cleaning tank 10 is discharged from the drain 23 . fig7 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a state where the needle 2 is moved to the sample inlet 3 of the injection valve 8 . as shown in fig7 , the positions of the ports of the syringe valve 16 and the injection valve 8 are not changed , and the needle 2 is moved to the sample inlet 3 of the injection valve 8 , thus preparing injection of the sample from the port p 4 to the injection valve 8 . fig8 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a state where the pressure in the sample storage loop 5 is reduced . in the states up to the state shown in fig7 , the sample storage loop 5 is connected with the pump 7 to allow the inside of this loop to serve as the mobile phase flow path . accordingly , the pressure is higher than atmospheric pressure . as shown in fig8 , the positions of the ports of the syringe valve 16 are not changed , and the injection valve 8 is turned counterclockwise by 60 degrees . the turn separates the sample storage loop 5 of the injection valve 8 from the mobile phase flow path of the pump 7 , thus separating the sample storage loop 5 at high pressure from the mobile phase flow path . this separation allows the pressure in the sample storage loop 5 to be released to atmospheric pressure through the drain 22 . fig9 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a process of transferring the sample sucked by the needle 2 to the injection valve 8 . as shown in fig9 , the positions of the ports of the syringe valve 16 and the injection valve 8 are not changed , and the cleaning solution a and air in the syringe 11 are flushed , thereby transferring the sample in the needle 2 to the sample storage loop 5 in the injection valve 8 through the port p 4 of the injection valve 8 . the amount flushed by the syringe 11 is the sum of the feed volume , the injection volume , the dead volume and the air volume , i . e ., vf + vi + vd + va . after the sample with the volume vi sucked by the process in fig5 is transferred , the cleaning solution a with the volume of sucked by the process in fig4 is transferred to the injection valve 8 . accordingly , the sample storage loop 5 can be filled with the total amount of the sample . fig1 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a process of introducing the sample retained in the sample storage loop 5 to the mobile phase flow path . as shown in fig1 , the positions of the ports of the syringe valve 16 are not changed , and the injection valve 8 is turned clockwise by 60 degrees , thereby causing the port p 3 of the sample storage loop 5 to communicate with the port p 2 connected with the column 6 , causing the port p 6 of the sample storage loop 5 to communicate with the port p 1 connected with the pump 7 . with the communication , the pump 7 causes the mobile phase to flow to the sample storage loop 5 , and transfers the mobile phase to the column 6 together with the sample . meanwhile , for preparation for the next process , the syringe 11 is moved to the top dead center . this movement discharges the liquid in which the cleaning solution a in the needle 2 and the residue of the sample are mixed , from the sample inlet 3 to the drain 22 through the ports p 4 and p 5 of the injection valve 8 . fig1 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a process of cleaning the inside of the needle 2 with the cleaning solution a . as shown in fig1 , the positions of the ports of the injection valve 8 are not changed , and the syringe valve 16 is turned counterclockwise by 45 degrees , thereby switching the position to that where the port p 5 communicates with the port p 2 and the port p 3 communicates with the port p 4 . the cleaning pump 15 transfers the cleaning solution a retained in the cleaning solution container 20 to the needle 2 via the syringe valve 16 , and the inside of the needle 2 is cleaned with the cleaning solution a . the cleaning solution a is then discharged from the drain 22 . after cleaning of the needle 2 shown in fig1 is completed , the syringe valve 16 is turned counterclockwise by 45 degrees . the turn causes the port p 5 of the syringe valve 16 to communicate with the port p 3 , thereby causing the state to transition to the idle state shown in fig1 . the needle 2 is moved above the cleaning tank 10 . fig1 is a schematic diagram of a configuration of a liquid chromatography apparatus , as with fig1 , and shows a process performed after cleaning of the needle 2 shown in fig1 in the case where cleaning of the plunger of the pump 7 is preset . the syringe valve 16 is turned counterclockwise by 90 degrees , thereby switching the position to that where the port p 5 communicates with the port p 4 . in the case of cleaning the plunger with the cleaning solution b instead of the cleaning solution a , the three - way valve 18 is switched to be connected to the cleaning solution container 21 , and the cleaning solution b is sucked by the cleaning pump 15 and transferred from the plunger cleaning flow path 17 to the plunger of the pump 7 , not shown . the cleaning time is preset . after completion , the syringe valve 16 is turned clockwise by 45 degrees , thereby causing the state to transition to the idle state shown in fig1 . fig1 a , 13 b , 14 a and 14 b are graphs showing examples of chromatograms . fig1 a shows a result of a conventional device configuration . fig1 b shows a result of the device configuration of the present invention . analysis conditions are set such that the sample is 60 ppm methylparaben , the sample solution is methanol , the mobile phase is 60 % methanol aqueous solution , the cleaning solution a is methanol , the cleaning solution b is 60 % methanol aqueous solution , the flow rate of the mobile phase is 1 milliliter / min ., the column is ods , the dimensions are 4 . 6 mmid × 150 mml , the particle diameter is 5 μm , the column temperature is 40 ° c ., the absorbance detection wavelength is 265 nm , and the injection volume is 10 microliters . fig1 a shows a chromatogram in the case where the process shown in fig3 is not performed . fig1 b shows a chromatogram in the case where the process shown in fig3 is performed . in the chromatogram shown in fig1 a , a ghost peak , which is caused by difference in absorbance between the mobile phase of 60 % methanol aqueous solution and the cleaning solution a of methanol and is due to the cleaning solution a of methanol , is detected , before the peak of methylparaben as the target component . in contrast , in fig1 b , the ghost peak is completely eliminated in the chromatogram shown in fig1 b , because the content in the tube including the buffer tube 13 and the needle 2 is replaced with the cleaning solution b of 60 % methanol aqueous solution in the process shown in fig3 . fig1 a shows a result of the conventional device configuration . fig1 b shows a result of the device configuration of the present invention . the analysis conditions are set such that the sample is 60 ppm methylparaben , the sample solution is 60 % methanol aqueous solution , the mobile phase is 60 % methanol aqueous solution , the cleaning solution a is 60 % methanol aqueous solution , the cleaning solution b is distilled water , the flow rate of the mobile phase is 1 milliliter / min ., the column is ods , the dimensions are 4 . 6 mmid × 150 mml , the particle diameter is 5 μm , the column temperature is 40 ° c ., the absorbance detection wavelength is 265 nm , and the injection volume is 10 microliters . fig1 a is a chromatogram in the case where the process shown in fig3 is not performed . fig1 b shows a chromatogram in the case where the process shown in fig3 is performed . in the chromatogram of fig1 a , the sample solution of methylparaben as the target component easily dissolves in the cleaning solution a of 60 % methanol aqueous solution . accordingly , the solution is diluted in the sample introduction process , and reaches the column while having a wide bandwidth in the analysis flow path . as a result , the peak width of methylparaben detected by the detector is increased . the peak height of methylparaben is reduced . in contrast , in the chromatogram of fig1 b where the process shown in fig3 is performed , the content in the tube including the buffer tube 13 and the needle 2 is replaced with the cleaning solution b of distilled water . as a result , the peak width of methylparaben is reduced , and the peak height is increased by approximately 17 %, thus allowing the sensitivity of the liquid chromatograph to be improved . as described above , in the loop injection scheme , for introducing the total amount of the sample into the column without waste , in the process of temporarily storing the sample to be introduced into the column in the sample storage loop , not only the actual sample solution but also the cleaning solution is also stored in the sample storage loop at the same time . however , according to the embodiment of the present invention , the amount of storage of the cleaning solution can be reduced . accordingly , the ghost peak on the chromatogram can be eliminated , the peak width can be prevented from being increased , and the degree of separation of the chromatogram is not degraded or the degree of separation is improved , thereby allowing high sensitivity to be achieved . as described above , the present invention provides a liquid chromatograph and a sample introduction device for a liquid chromatograph that have a high sensitivity and can prevent analysis time from being increased . the above description has been made on the embodiment . however , the present invention is not limited thereto . instead , it is apparent for those skilled in the art that various changes and modifications may be made within the scope of the spirit of the present invention and attached claims .