1. Introduction
Carbamate and carbamoyloxime pesticides are being increasingly
used in crop protection over the last three decades, mainly because of
their broad spectrum of activity, high pesticide efficiency and relatively
lower environmental half life. However their use in vegetables, fruits
and cereal crop protection poses serious risk to humans, as they are
often used near the maturing stages of the crops [1–3]. Carbamates
bind with the active sites in acetylcholinesterase (AChE), an important
enzyme in nerve conduction leading to accumulation of acetycholine
(ACh) at cholinergic nerve terminals. This leads to excessive stimulation
of the cholinergic receptors throughout the central and peripheral nervous
systems. Chronic overexposure to carbamates leads to weakness,
excessive secretions, nausea, vomiting and diarrhea [4,5]. Thus many
countries have established maximum permissible limits for their residues
in food products and drinking water [6].
The need for rapid monitoring of carbamate pesticides in food
samples has risen in past few years [7–10] and building local capabilities
for their rapid detection at trace levels is a serious challenge, particularly
in the small island countries because of high capital cost in instrumentation
and low volume of samples. The analytical challenge is
further compounded by two factors that there exist a range of carbamate
pesticides and secondly that fruits, vegetables and grains are
being marketed globally. Although numerous methods for the detection
of individual carbamates and their metabolites have been reported in