Determination of some insect repellents in cosmetic products by high-performance thin-layer chromatography

Quantitative and qualitative determination of dimethyl phthalate and N, N-diethyl-m-toluamide in repellents commercial formulations by high performance thin layer chromatography

In this study HPTLC was used for simultaneous quantitative and qualitative determination of N, N-diethyl meta toluamide (DEET) and dimethyl phthalate (DMP), which are the main elements and active ingredients in current chemical repellents. Some defined amounts of commercial form of 3 repellents included trench pomade, stick insect repellent (SIR), which is containing 33% of DEET and DMP60 (dimethyl phthalate 60%) dissolved in ethyl acetate solvent, separately. The method employed TLC aluminum plate precoated with silica gel plates (SiO4) 60F245 as the stationary phase. The solvent system consisted of benzene-diethyl etherhexane (5:3:2, v/v/v) as mobile phase. The multiple level method used for spotting. Densitometric analysis of repellents was carried out using TLC scanner 3 and CATS4 software in the absorption/reflection mode at 230 nm. According to the results, the type and amount of active ingredients in DMP60 lotion was 61.8 g (SE = +/-1.6) per 100 cc and in SIR, 31.3 g (SE = +/-0.8) diethyl meta toluamide per 100 g of repellents raw materials. Also the active ingredients in trench pomade were determined as a combination of DMP and DEET by rates of 5.5 g (SE = +/-0.2) and 25 g (SE = +/-l) per 100 g repellents commercial formulations, respectively. In this study, the value of Rf for DMP and DEET was calculated 0.71 +/- 0.2 and 0.32 +/- 0.2, respectively. HPTLC is a suitable method to quantitatively and quantitatively determine repellents which have DMP and DEET active ingredients. Since most of commercial chemical repellents have this active ingredient, adjusting and setting HPTLC up can be important.

Development of a high-performance liquid chromatographic method for the quantification of chlorpyrifos, pyridostigmine bromide, N,N-diethyl-m-toluamide and their metabolites in rat plasma and urine

A method was developed for the separation and quantification of the insecticide chlorpyrifos (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphorothioate), its metabolites chlorpyrifos-oxon (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphate) and TCP (3,5,6-trichloro-2-pyridinol), the anti-nerve agent drug pyridostigmine bromide (PB; 3-dimethylaminocarbonyloxy-N-methyl pyridinium bromide), its metabolite N-methyl-3-hydroxypyridinium bromide, the insect repellent DEET (N,N-diethyl-m-toluamide), and its metabolites m-toluamide and m-toluic acid in rat plasma and urine. The method is based on using solid-phase extraction and high-performance liquid chromatography (HPLC) with reversed-phase C18 column, and gradient UV detection ranging between 210 and 280 nm. The compounds were separated using a gradient of 1-85% acetonitrile in water (pH 3.20) at a flow-rate ranging between 1 and 1.7 ml/min over a period of 15 min. The retention times ranged from 5.4 to 13.2 min. The limits of detection ranged between 20 and 150 ng/ml, while the limits of quantitation were between 150 and 200 ng/ml. Average percentage recovery of five spiked plasma samples was 80.2+/-7.9, 74.9+/-8.5, 81.7+/-6.9, 73.1+/-7.8, 74.3+/-8.3, 80.8+/-6.6, 81.6+/-7.3 and 81.4+/-6.5, and from urine 79.4+/-6.9, 77.8+/-8.4, 83.3+/-6.6, 72.8+/-9.0, 76.3+/-7.7, 83.4+/-7.9, 81.6+/-7.9 and 81.8+/-6.8 for chlorpyrifos, chlorpyrifos-oxon, TCP, pyridostigmine bromide, N-methyl-3-hydroxypyridinium bromide, DEET, m-toluamide and m-toluic acid, respectively. The relationship between peak areas and concentration was linear over a range between 200 and 2000 ng/ml.

Simultaneous determination of pyridostigmine bromide, N,N-diethyl-m-toluamide, permethrin, and their metabolites in rat plasma and urine by high-performance liquid chromatography

A rapid and simple method was developed for the separation and quantification of the anti nerve agent drug pyridostignmine bromide (PB; 3-dimethylaminocarbonyloxy-N-methyl pyridinium bromide) its metabolite N-methyl-3-hydroxypyridinium bromide, the insect repellent DEET (N,N-diethyl-m-toluamide), its metabolites m-toluamide and m-toluic acid, the insecticide permethrin (3-(2,2-dichloro-ethenyl)-2,2-dimethylcyclopropanecarboxylic acid(3-phenoxyphenyl)methylester), and two of its metabolites m-phenoxybenzyl alcohol, and m-phenoxybenzoic acid in rat plasma and urine. The method is based on using C18 Sep-Pak cartridges for solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with reversed-phase C18 column, and gradient UV detection ranging between 208 and 230 nm. The compounds were separated using gradient of 1 to 99% acetonitrile in water (pH 3.20) at a flow-rate ranging between 0.5 and 1.7 ml/min in a period of 17 min. The retention times ranged from 5.7 to 14.5 min. The limits of detection were ranged between 20 and 100 ng/ml, while limits of quantitation were 150-200 ng/ml. Average percentage recovery of five spiked plasma samples were 51.4+/-10.6, 71.1+/-11.0, 82.3+/-6.7, 60.4+/-11.8, 63.6+/-10.1, 69.3+/-8.5, 68.3+/-12.0, 82.6+/-8.1, and from urine 55.9+/-9.8, 60.3+/-7.4, 77.9+/-9.1, 61.7+/-13.5, 68.6+/-8.9, 62.0+/-9.5, 72.9+/-9.1, and 72.1+/-8.0, for pyridostigmine bromide, DEET, permethrin, N-methyl-3-hydroxypyridinium bromide, m-toluamide, m-toluic acid, m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, respectively. The relationship between peak areas and concentration was linear over the range between 100 and 5000 ng/ml. This method was applied to analyze the above chemicals and metabolites following their administration in rats.