Page 141 - Modern Derivatization Methods for Separation Sciences

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Glyphosate

For determining glyphosate (GP) herbicide and its decomposition products, aminomethyl phosphoric
acids (APA) are usually used in the post-column methods with o-phthalaldehyde/mercaptoethanol
[37,38]. However, pre-column methods have been reported which are intended for simpler and more
highly sensitive detection.

Several applications have been reported which use 9-fluorenylmethyl chloro formate (FMOC-C1) to
apply the fluorescent label to the secondary amine of glyphosate [39-41]. Fig. 1.3.13 shows the flow of
the determination method from water and soil performed by Glass and others [39]. The detection limit
was 10 ppb in the water sample and 5-50 ppm in the soil sample. Gauch and others [41] determined GP
and APA in drinking water by HPLC-FL using direct derivatization with FMOCCl at the detection limit
of 0.02 µg/l.

As an alternative application to FMOC-Cl, recently Sen and others [42] developed the HPLC-CL
method which can determine GP in water at the recovery of 67-100% and at the detection limit of
0.005-1µg/g. This method is the combination of the following: clean-up and concentration of the
sample solution by the anion exchange resin mini-columns, nitrosation, separation using amine phase-
bonded column-HPLC, production of nitric oxide by the post-column denitrosating reaction, and the CL
detection of the liberated nitric oxide.

Phenoxy Acid Herbicides

In the LC methods for analysis of phenoxy acid herbicides, investigations have been focused on the
application of relatively strong UV absorption properties naturally accompanying these compounds.
Application of the 'HPLC with derivatization' methods was reported by Suzuki and others [43] which
applies 9-anthryldiazonethane (ADAM) to carboxyl residues to obtain anthrylmethyl ester derivatives
(Fig. 1.3.14). They adjusted water samples to be acidic, extracted the components in hexane-ethyl
acetate mixture, concentrated the solution, derivatized the concentrate with ADAM, and conducted
separation and detection by HPLC-FL (Fig. 1.3.15). The recovery

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