Suitable conditions for liquid-phase microextraction using solidification of a floating drop for extraction of fat-soluble vitamins established using an orthogonal array experimental design.

A simple, rapid and efficient microextraction method for the extraction and determination of some fat-soluble vitamins (A, D2, D3) in aqueous samples was developed. For the first time orthogonal array designs (OADs) were employed to screen the liquid-phase microextraction (LPME) method in which few microliters of 1-undecanol were delivered to the surface of the aqueous sample and it was agitated for a selected time. Then sample vial was cooled by inserting it into an ice bath for 5 min. The solidified solvent was transferred into a suitable vial and immediately melted. Then, the extract was directly injected into a high-performance liquid chromatography (HPLC) for analysis. Several factors affecting the microextraction efficiency such as sample solution temperature, stirring speed, volume of the organic solvent, ionic strength and extraction time were investigated and screened using an OA16 (4(5)) matrix. Under the best conditions (temperature, 55 degrees C; stirring speed, 1000 rpm; the volume of extracting solvent, 15.0 microL; no salt addition and extraction time, 60 min), detection limits of the method were in the range of 1.0-3.5 microgL(-1). The relative standard deviations (RSDs) to determine the vitamins at microg L(-1) levels by applying the proposed method varied in the range of 5.1-10.7%. Dynamic linear ranges of 5-500 mugL(-1) with good correlation coefficients (0.9984

Extraction and determination of trace amounts of chlorpromazine in biological fluids using hollow fiber liquid phase microextraction followed by high-performance liquid chromatography.

In the present work, hollow fiber liquid phase microextraction (HF-LPME) in conjunction with reversed-phase HPLC/UV was developed for extraction and determination of trace amounts of chlorpromazine in biological fluids. The drug was extracted from an 11 ml aqueous sample (source phase; SP) into an organic phase impregnated in the pores of the hollow fiber (membrane phase; MP) followed by the back-extraction into a second aqueous solution (receiving phase; RP) located in the lumen of the hollow fiber. The effects of several factors such as the nature of organic solvent, compositions of SP and RP solutions, extraction time, ionic strength and stirring rate on the extraction efficiency of the drug were examined and optimized. Under the optimal conditions, enrichment factor of 250, dynamic linear range of 1-500 microgl(-1), and limit of detection of 0.5 microgl(-1) were obtained for the drug. The percent relative intra-day and inter-day standard deviation (R.S.D.%) based on three replicate determinations were 6.7 and 10.3%, respectively. The method was applied to drug level monitoring in the biological fluids and satisfactory results were obtained.

Analysis of free nucleotide pools of mouse liver tissue by high-pressure liquid chromatography (HPLC).

In this paper, analysis of free nucleotides from mouseliver tissue during different day times has been described. Perchloric acid extract of mouse liver tissue was neutralized with tri-N-octylamine in trichlorotriflouroethane and after removal of ClO4(-), subjected to preliminary purification on a Cu(2+)-loaded column of Chelex 100. A high-pressure liquid chromatographic (HPLC) anion-exchange procedure used in the study gave a good resolution of free nucleotides on a single column.