The liquid chromatographic separation of permethrin enantiomers on chiral beta-cyclodextrin-based stationary phase has been investigated. All four enantiomers are obtained by using simple methanol and water mobile phase, under gradient mode. The method was optimized and validated. The relationship between temperature and chromatographic parameters: k' (capacity factor), alpha (separation factor) and Rs (resolution factor) was studied. Van't Hoff's curves for each enantiomer were plotted for temperature range 288-318 K. It was noticed that the response factor ratio of permethrin isomers differ and calculated value is found to be 1.66 (cis/trans, for n = 5). This method has been used for determining permethrin enantiomer ratio for a few samples of working standards and one formulation.
Asolid-phase extraction (SPE) method, coupled with HPLC/DAD and GC/FID
analysis has been developed for the simultaneous determination of simazine,
atrazine and propazine in water samples. The compounds of interest were
enriched on Envi-carb SPE tubes. The recoveries for simazine, atrazine and
propazine from spiked Nanopure water were 101 5.6 %, 99 4.9 % and 96
5.7 %, respectively. The detection limits were 4.00, 8.00 and 10.00 ng
absolute samplemass in the column for simazine, atrazine and propazine,
respectively. Standard curve r2 values of 0.9828-0.9988 for the analyzed
compounds were consistently obtained.
An isocratic High Performance Liquid Chromatographic (HPLC) method was optimized for 3-phenoxybenzyl (1RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylate (permethrin) residues identification and quantification in wine matrix. Analytical reverse phase (RP) C-18 column was used (25 cm × 4 mm i.d., 5 μ m) with mobile phase consisting of acetonitrile and water in ratio 70 %/30 % (v v(-1)), flow-rate 2.0 mL min(-1), UV-detection at 215 nm and controlled oven temperature at 25°C. The peaks of isomers were identified with the retention times as compared to standard cis-/trans- mixture and confirmed with characteristic spectra using photodiode array detector. Under these conditions, permethrin isomers were well separated with resolution 2.8 and no interference with the naturally present wine compounds was observed. The method was validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). Linear regression analysis data proved a good linear relationship (correlation coefficients, r(2), for cis- and trans-isomer are: 0.9995 and 0.9997, respectively) between response of the detector and concentration of permethrin isomers over a wide concentration range for both isomers (0.55 mg L(-1) -4.40 mg L(-1)). Experimental data showed mean recoveries between 93.95% and 96.58% with RSD values in range: 0.89% -3.69%. The effect of ethanol content in the solvent on permethrin isomers peak areas was also studied and 60% v v(-1) ethanol was found to be optimal for sample preparation. The method was successfully tested on 20 commercial wine samples from the market in which no permethrin was detected. Thus, it was proved that it is suitable for routine permethrin residues analysis. The proposed method is suitable for routine analysis because of the simple sample preparation, acceptable run-time, low cost and its applicability with conventional instruments.
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