Maximum allowable residue analysis technology of nitrofuran metabolites-determination method (2)

(3) Liquid chromatography-mass spectrometry (LC-MS)

The LC-MS tandem technology has high-efficiency separation ability, excellent detection sensitivity and strong ability to overcome impurity interference.
It is currently the most important technical means for the determination of NFs metabolites, and LC-MS/MS is the most commonly used method
.

1) Liquid chromatography-single-stage mass spectrometry (LC-MS)

LC-MS connects a single quadrupole mass spectrometer as a detector to the LC, and is an early product of the LC-MS instrument
.

Compared with LC-MS/MS, there is a lot of difference in sensitivity and selectivity.

In 1996 Horne et al.
developed LC-MS detection methods for AOZ and AMOZ
.

Derived with o-nitrobenzaldehyde, after LLP, measured by LC-MS, the detection limit of liver samples is 10μg/kg

2) Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS)

Due to its excellent sensitivity, selectivity, and the ability to provide structural information required for the confirmation of banned drugs, LC-MS/MS has become the most commonly used method for the detection of NFs metabolites, and it is also a method recognized by most countries and organizations
.

A.
Tissue sample analysis

Alexander et al.
reported for the first time a method for simultaneous analysis of four NFs metabolites in animal muscle tissue by LC-MS/MS
.

The analyte is acidic hydrolyzed and then released from the tissue, derivatized with 2-nitrobenzaldehyde, purified by SPE, and detected by LC-MS/MS in ESI positive ion and MRM mode

B.
Bee product analysis

Ding Tao et al.
reported a method for the determination of furazolidone, nitrofurazone, nitrofurantoin and furantoin in royal jelly by LC-MS/MS
.

Trichloroacetic acid is used as the protein precipitant of royal jelly, while providing the acidic environment required for the derivatization reaction; the use of 4 isotopic internal standards compensates for the effects of derivatization efficiency, pH of the sample solution after derivatization and light on the quantitative results , Which greatly improves the accuracy of quantification

C.
Milk and egg analysis

Peng Tao et al.
simultaneously determined the metabolites of furazolidone, furazolidone, nitrofurazone and nitrofurantoin in milk powder by LC-MS/MS
.

Hydrochloric acid was used to hydrolyze the protein-bound metabolites in the milk powder, and 2-nitrobenzaldehyde was added at the same time, and derivatized overnight at 37°C

Cao Wenqing et al.
established an LC-MS/MS method for the determination of NFs metabolites such as furantone, nitrofurazone, nitrofurantoin and furazolidone in egg yolk powder
.

Use diatomaceous earth as the matrix dispersant to disperse the egg yolk powder, the trichloroacetic acid solution precipitates the protein and provides a hydrolysis environment, 2-nitrobenzaldehyde derivatization, ethyl acetate liquid-liquid extraction and other pre-treatment methods Nitrofuran metabolites were extracted and purified, and detected by LC-MS/MS

D.
Analysis of plasma and serum

Radovnikovic et al.
established a UHPLC-MS/MS method for the confirmatory detection of 4 NFs metabolites (AHD, AOZ, SEM, AMOZ) in animal plasma (cattle, sheep, horse and pig)
.

Plasma samples were derivatized with 2-nitrobenzaldehyde, then extracted with organic solvents, the extracts were concentrated, and then analyzed by UHPLC-MS/MS