PubMed · 3046429
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H G Barth, W E Barber, C H Lochmüller, R E Majors, F E Regnier. 1988-06-15. Column liquid chromatography.. https://doi.org/10.1021/ac00163a025
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Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants, and a number of them are carcinogenic. One approach for measuring exposure to them is to determine the concentrations of metabolites in urine. The pyrene metabolite 1-hydroxypyrene has been used as a biomarker for exposure in numerous studies. However, determination of exposure to several PAHs may be advantageous, since the relative amounts may vary depending upon the exposure source. We developed a liquid chromatography-tandem mass spectrometry method for the determination of phenolic metabolites of naphthalene, fluorene, phenanthrene, and pyrene in human urine. Following enzymatic cleavage of the glucuronide and sulfate conjugates, the phenolic metabolites are extracted from urine and converted to pentafluorobenzyl ethers. These derivatives greatly enhance the sensitivity of detection by atmospheric pressure chemical ionization in the negative ion mode. Lower limits of quantitation range from 0.01 to 0.5 ng/mL. Stable isotope-labeled internal standards were synthesized or obtained commercially. Data on urinary excretion of several PAH metabolites in urine of smokers and nonsmokers are presented.
Silica-based monolithic capillary columns (25 cm x 10 microm i.d.) with integrated nanoESI emitters have been developed to provide high-quality and robust microSPE-nanoLC-ESI-MS analyses. The integrated nanoESI emitter adds no dead volume to the LC separation, allowing stable electrospray operation at flow rates of approximately 10 nL/min. In an initial application with a linear ion trap MS, we identified 5510 unique peptides that covered 1443 distinct Shewanella oneidensis proteins from a 300-ng tryptic digest sample in a single 4-h LC-MS/MS analysis. The use of an integrated monolithic ESI emitter provided enhanced resistance to clogging and provided good run-to-run reproducibility.
Part of a comprehensive study on the comparison of different extraction methods, GC-MS(/MS) and LC-MS/MS detection methods and modes, for the analysis of soya samples is described in this paper. The validation of an acetone-based extraction method for analysis of 169 pesticides in soya, using LC-MS/MS positive and negative electrospray ionisation (ESI) mode, is reported. Samples (5 g) were soaked with 10 g water and subsequently extracted with 100 mL of a mixture of acetone, dichloromethane and light petroleum (1:1:1), in the presence of 15 g anhydrous sodium sulphate. After centrifugation, aliquots of the extract were evaporated and reconstituted in 1.0 mL of methanol, before direct injection of the final extract (corresponding with 0.05 g soya mL(-1)) into the LC-MS/MS system. Linearity, r(2) of calibration curves, instrument limit of detection/quantitation (LOD/LOQ) and matrix effect were evaluated, based on seven concentrations measured in 6-fold. Good linearity (at least r(2)> or =0.99) of the calibration curves was obtained over the range from 0.1 or 0.25 to 10.0 ng mL(-1), corresponding with pesticide concentrations in soya bean extract of 2 or 5-200 microg kg(-1). Instrument LOD values generally were 0.1 or 0.25 ng mL(-1). Matrix effects were negligible for approximately 90% of the pesticides. The accuracy, precision and method LOQ were determined via recovery experiments, spiking soya at 10, 50, 100 microg kg(-1), six replicates per level. In both ESI modes, method LOQ values were mostly 10 or 50 microg kg(-1) and more than 70% of pesticides analysed by each mode met the acceptability criteria of recovery (70-120%) and RSD (< or =20%), at one or more of the three levels studied. A fast, easy and efficient method with acceptable performance was achieved for a difficult matrix as soya, without cleanup.