Determination of zearalenol, zearalenone, diethylstilbestrol, diethylstilbestrol and diethylstilbestrol residues in milk and milk powder

9.

(1) Liquid chromatography conditions

Column: ZORBAX Eclipse SB-C ₈ , 3.

(2) Mass spectrometry conditions

Ionization method: electrospray ionization; scanning method: negative ion scanning; detection method: multiple reaction monitoring (MRM); ion source temperature: 350℃; atomizing gas pressure: 0.

Table 9-20 Qualitative ion pairs, quantitative ion pairs, collision energy and declustering voltage of 5 hormones and metabolites

9.

(1) Extraction of the test substance

Milk has a complex composition, in addition to water, it also contains protein , fat and a variety of trace elements.

(2) Solid phase extraction purification

In this method, the OasisHLB column was first used for purification, but the sensitivity was low, and then the Oasis AX column (60 mg) was used for SPE purification treatment from Waters Corporation, the sensitivity and recovery rate were relatively high

Table 9-21 The influence of eluent ratio on recovery rate (the amount of eluent is 2mL)

Table 9-22 The influence of the ratio of eluent on the recovery rate (first rinse with 1mL ammonia-water [5+95], rinse with 0.

Table 9-23 The influence of the amount of eluent on the recovery rate (three times elution, 3mL each time)

The targets tested in the experiment are two types, zearalenol and its metabolites, and stilbene hormones

(3) Optimization of mass spectrometry conditions

Using a syringe pump direct injection mode, at 5μL / min to zeranol, Zearalanone , diethylstilbestrol , hexoestrol standard solution of phenol and dienes female tandem mass spectrometry were injected into the ion source

(4) Optimization of HPLC conditions

This method has tried several C18 and C8 columns of Waters, Agilent, Merck and other brands.