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At least 685 records · Page 38Linked to original sources
PubMed1985

A rapid sample preparation method for the determination of sulfamethazine in swine tissues by high-performance liquid chromatography.

A rapid procedure for the determination of sulfamethazine in swine muscle and kidney is described. The method comprises sonication-aided extraction with dichloromethane, cleaning-up of the extract on a combination of silica and reversed-phase C18 Sep-Pak cartridges and analysis by high-performance liquid chromatography on a Hypersil ODS column using acetonitrile/ammonium acetate solution (10 mmol X 1(-1), pH 6.8) 1 + 3 v/v as the mobile phase. Detection was performed at 254 nm. Mean recoveries of added sulfamethazine from swine muscle and kidney, at levels of 0.05 to 0.5 micrograms X g-1, were 89.5 and 80.5%, respectively. After intramuscular injection of sulfamethazine into swine, residues in tissues were also determined. The application of ultrasonic energy for the extraction of sulfamethazine residues from animal tissues is also discussed.

Animals↗
PubMed2003

New methods for acceleration of meat sample preparation prior to determination of the metal content by atomic absorption spectrometry.

Focused microwave-assisted digestion and ultrasound leaching have been applied for the extraction of Pb, Cd, Cr, Cu, Fe, Zn, Ca, and Mg from raw meat. Semimembranous muscle (SM) of raw pig ham was used for optimizing both the digestion and extraction steps by multivariate approaches. The detection and quantification limits were 0.5 and 0.9 microg kg(-1) for Pb, 0.06 and 0.1 microg kg(-1) for Cd, 0.2 and 1.2 microg kg(-1) for Cr, 0.4 and 3 microg kg(-1) for Cu, 0.04 and 0.1 mg kg(-1) for Fe, 0.012 and 0.017 mg kg(-1) for Zn, 0.3 and 0.4 mg kg(-1) for Ca, and 0.01 and 0.03 mg kg(-1) for Mg. The precision, expressed as relative standard deviation (RSD), ranged between 2.5 and 9.6% for focused microwave-assisted digestion and between 3.5 and 10.6% for ultrasound leaching. The methods were then compared with a reference method and applied to a certified reference material (bovine muscle 184, from the BCR). The t-test, applied to the results obtained from focused microwave-assisted digestion, revealed that they are in agreement (p>0.01) with the certified and estimated values in the case of Pb, Cd, Cr, Cu, Fe, Ca, Mg, and Zn but not in that of Fe. In the case of ultrasound leaching, only the extraction of Pb, Cu, and Ca was quantitative. The method based on microwave digestion provides more accurate and precise results than ultrasound leaching. These new procedures have many advantages with regards to conventional methods, namely, reduction of the extraction time, simplification of the process, avoidance of chemical emissions to the atmosphere, and no losses of metals by volatilization.

Animals↗
PubMed2000

Trace analysis of pentachlorophenol (PCP) in wood and wood-based products--comparison of sample preparation procedures.

The main problem with routine analyses of pentachlorophenol (PCP) and sodium pentachlorophenolate (Na-PCP) in wood and wood-based products is to determine critical PCP-contents. This task requires a reliable analytical method and statistical testing. An analytical procedure is described, which permits the determination of PCP and Na-PCP with sufficient sensitivity and accuracy. A medium size sieve (4 x 4 mm quadratic mesh) was found suitable for the grinding step. Different extraction techniques and solvents were tested systematically. Extraction by a combination of ultrasonication and shaking in the solvent mixture toluene/sulfuric acid showed best recoveries. The eluted PCP and Na-PCP were derivatized with acetic anhydride and determined by GC/ECD. The limits of detection and determination were 0.14 mg/kg and 0.40 mg/kg, respectively.

Acetic Anhydrides↗
PubMed1987

Comparison of sample preparation methods for the high-performance liquid chromatographic analysis of cell culture extracts for triphosphate ribonucleosides and deoxyribonucleosides.

We compared four different procedures for the purification and concentration of nucleoside triphosphates in cell extracts prior to HPLC analysis. Two methods involved precipitation, with either acetonitrile or calcium fluoride. The acetonitrile procedure yielded reasonable recovery and sufficient purity for the subsequent HPLC analysis. The calcium fluoride coprecipitation procedure gave both good recovery and purity; but the recovery was shown to be dependent on the concentration of the nucleoside triphosphates. The other two methods involved small Sep-Pak cartridges. The silica cartridge procedure yielded unfavorable recoveries in periodate-treated cell extracts, apparently due to poor solubility of nucleoside triphosphates in the requisite solvents. The strong anion exchange cartridge procedure yielded both good recovery and purity. This procedure was found to be fast, efficient, and reliable for purifying and concentrating nucleotides in cell extracts.

Acetonitriles↗