Derivatization reactions for the determination of aflatoxins by liquid chromatography with fluorescence detection

Abstract

Various derivatization methods for the fluorometric detection of aflatoxins after separation by HPLC are reviewed. In normal-phase chromatography the sensitivity for aflatoxins B, and B, was improved by using special mobile phases or a flow cell packed with silica-gel particles. In the nowadays more popular reversed-phase methods, the fluorescence intensity of B, and G, can be increased by precolumn derivatization with trifluoroacetic acid or by postcolumn derivatization with iodine or bromine. Optimum conditions for the reactions are discussed. In terms of sensitivity, the three derivatization schemes give similar results. The methods are compared with respect to experimental convenience, selectivity, reproducibility and suitability for automation.

Validation of a UHPLC-FLD method for the simultaneous quantification of aflatoxins, ochratoxin A and zearalenone in barley

“…In this study, the method chosen has been the photoderivatization, which was adopted as an official AOAC method 2005.08 (Waltking & Wilson, 2006), because of the advantages that it presents. On the one hand, the photochemical reaction allows the simultaneous determination of aflatoxins, and OTA and ZEA, while post-column iodine derivatization decrease the OTA peak and make the ZEA peak disappear completely; and bromine derivatization (Kobra cell) prevents the zearalenone analysis (Kok, 1994). In addition, the photo-derivatization does not require chemical reagents, pumps or other manipulations (Joshua, 1993).…”

Validation of a UHPLC-FLD analytical method for the simultaneous quantification of aflatoxin B1 and ochratoxin a in rat plasma, liver and kidney

“…However, it is well known than AFB1 suffers quenching in aqueous solvents; therefore, derivatization reactions would be necessary to quantify low levels. Either pre-column or post-column derivatization could be possible [38,40,41]. Pre-column derivatization was initially discarded in order to obtain a simple and quick method.…”

“…In addition, post-column iodine or bromine (Kobra cell) derivatization was also discarded because both reagents need to add extra pumps and chemical reactors to the UHPLC system. Furthermore, iodine derivatization decreases OTA peak intensity [38]. The derivatization was performed with a photo-chemical reactor made with a knitted coil and a mercury lamp placed in line just after the column [41].…”

“…OTA was extracted from the matrix with an organic solvent (ethanol) in very acid conditions using trichloroacetic acid (TCA). Unfortunately, this extraction process was not suitable for the simultaneous extraction of AFB1 and OTA because the pH conditions were too low for the AFB1 stability and because TCA, a trihaloacetic acid such as TFA (used for AFB1 derivatization [32,38]), gives undesired chemical reactions.…”

Identification and HPLC Quantification of Aflatoxins in Dried Chili Peppers (Capsicum annum L.) in Mexico and Other Countries

“…The vials were then placed in a 65°C water bath for 10 min. The dried samples were dissolved in 100 µL of ACN and 400 µL of derivatizing solution to increase the fluorescence, as previously reported [69,70].…”