Simultaneous Determination of Insect Repellent by HPLC

Abstract

       Determination of ethyl butylacetylaminopropionate, dimethyl phthalate (DMP) and N, N-diethyl-m-toluamide (DEET) in insect repellent products was developed to analyse simultaneously by High Performance Liquid Chromatography (HPLC) technique. The separation was achieved on a XTerra RP C8, 5μm, 4.6 mm × 150 mm column. Mixture of acetonitrile and water (25:75 v/v) was used as a mobile phase at flow rate of 1.0 mL per minute and with UV detection at 220 nm. Under the HPLC conditions, ethyl butylacetylaminopropionate, DMP and DEET were simultaneous separated without interference of other peaks with the retention time of 8.86, 11.6 and 14.2 minutes, respectively. The method validation was performed in samples of light lotion and cream. The validation showed the linear relationship between their concentration and peak area cover the range of 0.1 - 3 mg/mL with correlation coefficient (r) of 0.99995, 0.99998 and 0.99998 for ethyl butylacetylaminopropionate, DMP and DEET respectively. Repeatability was tested by replicate analysis of ethyl butylacetylaminopropionate, DMP and DEET in lotion and cream samples % RSD of three substances in both sample matrices were in the range 0.06 - 0.12%, 0.04% and 0.03 - 0.19%. There is no different of the results analysed for five days with p-value of 0.35 - 0.80, 0.06 and 0.13 - 0.996, respectively. Test results from different analyst were not different with p-value in the range of 0.22, 0.40 and 0.18 - 0.92. Analysis of spiked samples showed percent recovery of 99.7 - 104.6%, 94.6 - 98.9 and 97.5 - 101.6%, respectively. Limit of detection (LOD) is 0.08%w/w, 0.05%w/w and 0.05%w/w, respectively. Limit of quantitation (LOQ) is 0.30 %w/w, 0.20%w/w and 0.20%w/w, respectively. The relative expanded uncertainty are 0.027, 0.041 and 0.024, respectively. The developed methods with acceptable validation results could be routinely used to analyse the ethyl butylacetylaminopropionate, DMP และ DEET in insect repellent samples.