Jam. Vanriel et C. Olieman, SELECTIVE DETECTION IN RB HPLC OF TYR, TRP, AND SULFUR-CONTAINING PEPTIDES BY PULSED AMPEROMETRY AT PLATINUM, Analytical chemistry, 67(21), 1995, pp. 3911-3915
A technique for electrochemical detection of Trp-, Tyr-, and sulfur-co
ntaining peptides, using a two-step potential waveform at a platinum w
all-jet electrode, has been developed. The detection is fully compatib
le with reversed-phase HPLC employing gradients of acetonitrile in wat
er/trifluoroacetic acid, At similar to + 1.2 V (first potential) versu
s Ag/AgCl, Trp-, Tyr-, and Cys-containing peptides are predominantly d
etected, while at + 1.4-1.6 V, Met- and (Cys)(2)-containing peptides a
re additionally detected. The electrode surface is cleaned by the seco
nd potential (+ 2.0 V). The linearity is at least 2 orders of magnitud
e. The sensitivity is in the picomole range. By using postcolumn elect
rochemical conversion, the selectivity toward Met- and Cys-containing
peptides can be enhanced. Applications are shown for the determination
of caseinomacropeptide (6.6 kDa) and a tryptic map of beta-casein.