Agriculture Reference
In-Depth Information
There are several analytical methods currently available for the
determination of nitrofurans either in pure form or in pharmaceutical
formulations. The United States Pharmacopeia (USP) methods recommend
direct spectrophotometric measurements for furazolidone and nitrofurazone,
while HPLC is suggested for the determination of nitrofurantoin (USP
Convention, 2007). However, the British Pharmacopoeia (BP) methods
recommend only spectrometric procedure for quantifying these nitrofurans
[147].
Other accepted analytical procedures had been proposed for the assays of
these nitrofurans in pharmaceutical formulations including colorimetry,
cathodic stripping voltammetry [148], liquid chromatography,
spectrophotometry [149] and liquid chromatography-mass spectrometry [118].
However, the colorimetric methods often lack the speed and the experimental
conditions are cumbersome and were thus prone to errors. Thus, the
spectrometric methods are rather insensitive and subject to interferences from
other excipients. Several analytical methods for the determination of
nitrofurans residues in various sample matrices have been developed such as
honey, muscle tissue, chicken meat and animal feeds [147].
For screening, ELISA tests can be applied because specifically tailored
antibodies are capable of detecting nitrofuran metabolites through the use of
an enlarged target molecule, which can be formed by a simple derivatisation
step [125, 127]. The first ELISA screening test was developed for the
detection of AOZ in biologic samples such as shrimps [127, 128] with a limit
of detection (LOD) of 0.05 µg kg
-1
.
More recently, the first antibodie specific for derivatised SEM were
produced in two laboratories. The polyclonal antibodies developed [124] using
3-carboxyphenyl SEM were incorporated into a competitive direct ELISA
providing a detection capability for SEM in chicken muscle at 0.25 µg kg
−1
.
Nowadays the development of a chemiluminescence-based biochip array
permit the screening for the presence of AHD, AOZ, AMOZ and SEM
residues in biological samples [129] .
For nitrofuran parent compounds HPLC with UV detection are applied
with success. Examples are the ISO method 14797:1999, described for the
determination of FZD content in animal feedingstuffs and the multi-analyte
detection in animal feeds wich includ FZD, FTD, NFT and NFZ with the use
of nifuroxazide (NXZ) as internal standard [8].
HPLC with UV detection at 275 nm was first applied for the detection of
nitrofurans metabolites after derivatization with nitrobenzaldehyde wich yields
a nitrophenyl chromophore derivative with intense UV absortion. But this
