Attomole amino acid determination by capillary zone electrophoresis with thermooptical absorbance detection.
Attomole quantities of 4-(dimethylamino)azobenzene-4'-sulfonyl chloride derivatized amino acids are separated by using capillary zone electrophoresis in a mixed acetonitrile/aqueous buffer system. Detection is performed with an on-column thermooptical absorbance detection technique based on a 130-mW argon ion pump laser. Detection limits for the concentration of analyte injected onto the column range from 5 x 10(-8) M for methionine to 5 x 10(-7) M for aspartic acid. Only 37 amol of methionine and 450 amol of aspartic acid are contained within the subnanoliter injection volume. It is interesting to note that these limits are a factor of 4 superior to the best fluorescence detection limit reported for chromatographic separation of amino acids. A subnanoliter sample of derivatized human urine was analyzed with this technique; quantities of amino acids contained within the sample are 3 orders of magnitude greater than the detection limit.
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Dovichi
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D000596:Amino Acids / Q000032:analysis*; D004586:Electrophoresis; D007202:Indicators and Reagents; D004124:p-Dimethylaminoazobenzene / Q000031:analogs & derivatives
D000596:Amino Acids; D007202:Indicators and Reagents; C010572:4-N,N-dimethylaminoazobenzene-4'-sulfonyl chloride; D004124:p-Dimethylaminoazobenzene