Gas chromatography–mass spectrometry determination of pharmacologically active substances in urine and blood samples by use of a continuous solid-phase extraction system and microwave-assisted derivatization

Multiresidue method for the determination of pharmacologically active substances in egg and honey using a continuous solid-phase extraction system and gas chromatography–mass spectrometry

“…As previously found by our group in the SPE of PASs in blood, the presence of acetonitrile at concentrations above 15% in the aqueous solution seriously impaired retention of the analytes on the sorbent column (Azzouz & Ballesteros, 2012). This led us to evaporate the supernatant obtained by centrifuging the egg samples to a final volume of about 200 ll under a stream of ultra-pure N 2 and to dilute it with 10 ml of purified water at pH 7 prior to introduction into the continuous SPE system.…”

“…The optimum conditions for which are summarized in Table 2. Subsequently, the method was optimized to reduce the derivatization time of PASs of our previous study (Azzouz & Ballesteros, 2012) by heating in a microwave oven.…”

“…For this purpose, samples of 2 g of uncontaminated eggs spiked with a 500 ng/kg concentration of each analyte were mixed with 10 ml of solvent and centrifuged at 4500 rpm for 10 min, after which the supernatant was filtered, evaporated to near-dryness (final volume of 200 ll) under an N 2 stream, redissolved to 10 ml with purified water and adjusted to pH 7 with dilute HCl. Finally, the pretreated sample was introduced into the continuous SPE system (Azzouz & Ballesteros, 2012;Azzouz et al, 2010) and processed as described in Section 2.5. The highest extraction efficiency for all PASs ($95%) was obtained with a 3:2 (v/v) acetonitrile-water mixture, which facilitated precipitation of proteins and lipids, and their subsequent separation by centrifugation.…”

Preparation and characterization of a composite based on polyaniline, polypyrrole and cigarette filters: adsorption studies and kinetics of phenylbutazone in aqueous media

“…In humans, the pharmacokinetic is characterized by a slow release and the absorption is almost complete after oral dosing. 6,7 There are some studies to determine PBZ in various matrices such as bovine, equine and porcine muscle tissues using SPE cartridge packed with magnesium-silica gel, 8 animal urine using liquid extraction with chloroform, 9 urine and blood using continuous solid-phase extraction in a sorbent column (Oasis HLB), 10 equine plasma using molecularly imprinted solid-phase extraction, 11 aqueous medium using C8 stationary phase and phosphatidylcholine-modified microemulsion mobile phase. However, after repeated dosing, plasma concentration of PBZ is from 95 µg mL -1 to 45 µg mL -1 for its metabolite oxyphenbutazone.…”

Densitometric and Ratio Spectra Methods for Simultaneous Determination of Sulfaquinoxaline Sodium and Pyrimethamine in Binary Mixture

“…Several analytical methods have been reported for the determination of either sulfaquinoxaline-Na or pyrimethamine in their pharmaceutical formulations and/or in biological fluids. The literature comprises spectrophotometric [4][5][6][7][8] , electrochemical [9][10][11][12] , biochemical [13][14][15] and chromatographic techniques namely, densitometry [16][17][18][19] , GC [20][21][22] and HPLC [23][24][25][26][27][28][29] . Also, capillary electrophoresis [30][31][32] was revealed for sulfaquinoxaline-Na determination.…”