PubMed · 8865597
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W Q Sun. 1996. Regarding calibration.. https://pubmed.ncbi.nlm.nih.gov/8865597/
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Mass spectrometry has become an increasingly important tool of high accuracy, efficiency, and speed for the routine analysis of nucleic acids. To make it useful for large-scale sequencing of genomic material as required for example in genotyping and clinical diagnosis, it is necessary to find approaches that allow the analysis of sequences much larger than the 100 nucleotides currently possible. Matrix-assisted laser desorption/ionization (MALDI) mass spectra of synthetic DNA, restriction enzyme fragments of plasmid DNA, and RNA transcripts up to a size of 2180 nucleotides are reported. The demonstrated mass accuracy of 1 percent or better and the sample requirement of a few femtomoles or less surpass all currently available techniques for the analysis of large nucleic acids. DNA and RNA can be analyzed with only a limited investment in sample purification.
A method was developed for the determination of human hemoglobin (Hb) adducts from hexahydrophthalic anhydride (HHPA) and methylhexahydrophthalic anhydride (MHHPA). The procedure includes lysis of erythrocytes, dialysis of the Hb-solution followed by acid hydrolysis. The released hexahydrophthalic (HHP) acid and methylhexahydrophthalic (MHHP) acid were purified using a combined liquid-liquid and solid-phase extraction procedure followed by derivatization with pentafluorobenzyl bromide. The derivatives were analyzed using GC-MS in negative ion chemical ionization mode with ammonia as moderating gas. As internal standards, deuterium-labeled HHP and MHHP acids were used. The detection limits were 0.3 pmol/g Hb for HHP acid and 0.9 pmol/g Hb for MHHP acid. The between-day precisions for HHP acid were 18% at 2 pmol/g Hb and 10% at 13 pmol/g Hb. For MHHP acid, the precision was 27% at 2 pmol/g Hb and 14% at 22 pmol/g Hb. The method was applicable for analysis of Hb adducts from workers occupationally exposed to HHPA and MHHPA.
A new method is described for the solid-phase extraction of 18beta-glycyrrhetinic acid from plasma or serum, with subsequent analysis by HPLC. New aspects of the method include the use of commercially available 18alpha-glycyrrhetinic acid as the internal standard and the use of a Bond Elut C2 (ethyl) extraction column, to avoid the need to use large volumes of organic solvent to elute the isolates from the columns. Separation was achieved on a Shandon Hypersil BDS C18 analytical column, with a mobile phase consisting of acetonitrile-0.02 M phosphate buffer, pH 5.7 (55:45, v/v). The column effluent was monitored at 248 nm. Compared with previous methods, the procedure is much easier to carry out, whereas the sensitivity (limit of detection, 10 ng/ml, and limit of quantitation, 50 ng/ml), the precision (0.3-6.2%) and the accuracy (97.2-101.9%) are of the same order of magnitude.