Trace determination of peptides in water samples using packed capillary liquid chromatography with UV and MS detection and characterization of peptide oxidation products by MS |
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Authors: | Thomas?Bjellaas Anders?Holm Paal?Molander John?Aasulf?T?rnes Tyge?Greibrokk Email author" target="_blank">Elsa?LundanesEmail author |
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Institution: | (1) Department of Chemistry, University of Oslo, P.O. Box 1033, 0315 Blindern, Norway;(2) National Institute of Occupational Health, P.O. Box 8149 Dep., 0033 Oslo, Norway;(3) Norwegian Defence Research Establishment, P.O. Box 25, 2027 Kjeller, Norway |
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Abstract: | A capillary liquid chromatographic column switching method has been developed for fast and sensitive determination of peptides in water samples. Sample volumes of 1 mL were loaded onto a (320 m I.D. ×30 mm) 10 m Kromasil C18 pre-column, providing on-line analyte enrichment, prior to back-flushed elution onto a (320 m I.D. ×150 mm) 3.5 m Kromasil C18 analytical column. Loading flow rates of 250 L/min and a mobile phase composition of acetonitrile/water/trifluoroacetic acid (22/77.9/0.1, v/v) provided a total analysis time of less than 25 minutes for the test peptides angiotensin II, bombesin, bradykinin, corazonin, neurotensin and substance P, using temperature programmed elution. In addition, solvent gradient elution and combined solvent gradient elution and temperature programming were explored. Using on-capillary UV detection at 210 nm resulted in a concentration limit of detection (cLOD) of about 1 ng/mL. The method was validated over the concentration range 1–100 ng/mL, yielding a coefficient of correlation of 0.997 or better. The within-assay (n=6) and between-assay (n=6) precisions of peak areas were on average 6% RSD and 5% RSD, respectively.When the method was applied to spiked chlorinated tap water samples, it was found that peptides containing methionine, tryptophan and cystine were oxidized. Identification of the oxidation products of the peptides in hypochlorite-treated water was done with positive electrospray ionization time-of-flight mass spectrometric detection. |
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Keywords: | Capillary liquid chromatography Mass spectrometry Peptides Hypochlorite-treated water Oxidation |
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