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.

An HPLC method has been developed for the fast separation and quantification of permethrin using C18 column packed with 1.8 µm particles. The method is specific with good resolution to degradation products and to other present components. It has acceptable validation results. The run time is 4.5 min (or may be within 1.6 min is rapid resolution mode) with an organic solvent consumption of 3.6 mL per run. The method has been applied to samples of formulations for various uses: mattress cleaner, shampoo, and veterinary powder. The performance of the applied column is compared with other common column types. The relationships between linear velocity of the mobile phase (u) and resolution factor (Rs), back-pressure (ΔP), and efficiency (H) are presented. The experimental data shows the advantages of 1.8-µm particle columns to be a significant reduction in solvent consumption (by factor of 4.4 and 1.5) and a reduction in run-time (by factor 4.7 and 1.5), and the weaknesses are a high back-pressure and lower efficiency. Finally, it has been shown that use of 1.8-µm particle packed columns with conventional HPLC systems is possible, but with limitations in mobile phase flow-rate.

Abstract:The Tribulus terrestris L. (Zygophyllaceae) is a known medical plant used in traditional and folk medicine worldwide. The steroid saponine protodioscin, an active component found in this plant, serves as a marker for quality control of plant raw materials. In this study, we developed a simple and selective method for determination of protodioscin using convenient High-Performance Liquid Chromatographic (HPLC) laboratory equipment. The detection was performed by Diode-Array Detector (DAD). The proposed method was fully validated and according to the validation results, it was accurate and precise. It was proven to be linear over a protodioscin concentration range of 10,9 to 544.9 µg/mL. The low values of limit of detection (LOD) and limit of quantitation (LOQ) demonstrated adequate sensitivity (16.0 µg and 48.6 µg protodioscin per g plant material, respectively). The proposed method was successfully applied for quality control of a raw plant material intended for use in pharmaceutical industry, as well as for determination of protodioscin in a commercially available pharmaceutical formulation. The positive identification of protodioscin in analyzed samples was done by comparison of retention times of chromatographic peaks and their UV spectra. The content of protodioscin in analyzed samples was: 0.65 -0.73 % in a raw plant material, and 0.38 % in tablets, respectively.

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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