Integrated square-wave electrochemical detection of biogenic amines in soybean seeds following their separations by liquid chromatography

A strategy for electrochemical detection (ED), based on digital integration of the current response at a An electrode resulting from a square potentia l-time waveform, is applied for the direct detection of organic polyamines in complex samples following their separations using cation-exchange liquid chromatography (CELC). The samples consist of soybean extracts and are inj ected in acidic media to facilitate adsorption on the cation-exchange chrom atographic phase. Alkaline buffer is mixed with the chromatographic effluen t to facilitate ED. Whereas emphasis is given to the CELC-ED methodology, c omparison is made with the more traditional application of photometric dete ction (PD) of the derivatized amines following their separation by reversed phase liquid chromatography (RPLC). Estimated detection limits are signifi cantly lower for CELC-ED in comparison with RPLC-PD. For example, detection limits (25 mul injections) for 1,4-diaminopropane (putrescine) are 200 and 8000 pmoles for CELC-ED and RPLC-PD, respectively. Detection limits for 1, 5-diaminopentane (cadavarine) are 190 and 9000 pmoles for CELC-ED and RPLC- PD, respectively. Furthermore, baseline drift under the associated gradient elution programs, is significantly less for CELC-ED in comparison to RPLC- PD. (C) 2001 Elsevier Science B.V. All rights reserved.