Fluorescent reagents, derivatization with carbamate

Since BAs occurring in food do not exhibit satisfactory absorbance or fluorescence in the visible or ultraviolet range, chemical derivatization, either pre- (35-37) or postcolumn (38), is usually used for their detection in HPLC. The most frequently employed reagents for precolumn derivatization are fluorescamine, aminoquinolyl-lV-hydroxysuccinimidyl carbamate (AQC) (39, 40), 9-fluorenylmethyl chloroformate (FMOC) (41-43), 4-dimethylaminoazobenzene-4 -sul-fonyl chloride (dabsylchloride, DBS) (44), N-acetylcysteine (NAC) (45,46), and 5-dimethyl-amino-1-naphthalene-1-sulfonyl chloride (dansylchloride, DNS) (47,48), phthalaldehyde (PA), and orf/to-phthaldialdehyde (OPA) (49-51), together with thiols such as 3-mercaptopropionic acid (MPA) (37) and 2-mercaptoethanol (ME) (35,49). 

A Note on Post-Column Reaction Techniques A post-column reaction unit is an online derivatization system that supplies reagents to the column eluent into a heated chamber to convert the analytes into more chromophoric forms for higher sensitivity detection. Some common applications of post-column reaction systems are amino acid analysis using ninhydrin (with visible detection), and carbamate pesticide analysis using o-phthaldehyde (with fluorescence detection).]... 

The UV detector has been the most widely used in the LC determination of pesticides [59,63,69,71,77,106,107,109,111,122,147,148]. However, at present, the diode array detector is usually preferred to obtain the UV spectrum for each individual compound and confirm e presence of target analytes [35 8,45,48,50,71,74,76,108,149]. Carbamate pesticides are usually determined with fluorescence detector, following LC-postcolumn derivatization of methylamine (formed in the previous hydrolysis of pesticide) with OPA reagent [68,74]. Recently, a postcolumn detection system was used for the... 

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