Determination of chloramphenicol, thiamphenicol and florfenicol residues in edible animal muscles, liver and aquatic products-selection of analytical conditions

4.
2.
2.
6 Determination

(1) Liquid chromatography conditions

Chromatographic column: Discovery C ₁₈ chromatographic column, 5μm, 150mm×2.
1mm (inner diameter) or equivalent; column temperature: 40℃; mobile phase: methanol + water (40+60, v/v); flow rate: 0.
30mL/min ; Injection volume: 20μL
.

(2) Mass spectrometry conditions

Ion source: electrospray ion source; scanning method: negative ion scanning; detection method: multiple reaction monitoring (MRM); electrospray voltage:-1750V; atomization gas, curtain gas, auxiliary heating gas, and collision gas are all high-purity nitrogen and Other suitable gases; each gas flow rate should be adjusted to make the mass spectrometer sensitivity meet the detection requirements before use; auxiliary gas temperature: 500℃; qualitative ion pair, quantitative ion pair, acquisition time, declustering voltage and collision energy are shown in Table 4-7
.

(3) Qualitative determination

Choose 1 parent ion and 2 or more product ions for each tested component.
Under the same experimental conditions, the ratio of the retention time of the analyte and the internal standard in the sample, that is, the relative retention time, corresponds to the standard solution The deviation of the relative retention time is within ±2.
5%; and the relative abundance of the qualitative ions of each component in the sample is compared with the relative abundance of the corresponding qualitative ions in the standard solution with close concentrations, and the deviation does not exceed the requirements in Table 1-5 Within the range, it can be determined that there is a corresponding analyte in the sample
.

(4) Quantitative determination

Under the best working conditions of the instrument, sample the matrix mixed standard working solution, and take the ratio of the peak area of ​​the measured component in the standard solution to the peak area of ​​deuterated chloramphenicol (d5-chloramphenicol) as the ordinate, the standard solution The ratio of the measured component concentration to the concentration of deuterated chloramphenicol (d5-chloramphenicol) is the abscissa to draw a standard working curve.
Use the standard working curve to quantify the sample.
The response value of the analyte in the sample solution should be Within the linear range measured by the instrument
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4.
2.
2.
7 Selection of analysis conditions

(1) Selection of extraction and purification conditions

1) Selection of sample extract

Thiamphenicol and Florfenicol are easily soluble in ethyl acetate and acetonitrile
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2) Selection of purification conditions

The ethyl acetate extract of the sample contains lipids and needs to be purified
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3) Residue solubility test

After the ethyl acetate extract of the sample was concentrated, the residue was dissolved in water
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(2) Optimization of instrument conditions

1) Optimization of mass spectrometry conditions

The peristaltic pump continuously injects 0.
1 mg/L chloramphenicol standard solution into the TurbolonSpray ionization source at a flow rate of 10uL/min, and performs primary mass spectrometry (Q1 scan) on the three chloramphenicols in the negative ion detection mode.
For molecular ion peaks, perform secondary mass spectrometry (product ion scan) on each quasi-molecular ion peak to obtain fragment ion information
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2) Optimization of chromatographic conditions

The "T" three-way method is adopted, that is, the peristaltic pump continuously injects 0.
1 mg/L chloramphenicol standard solution at a flow rate of 10μuL/min, and the mobile phase is mixed with the chloramphenicol standard solution at a flow rate of 300uL/min and then enters Ion source for optimization
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Related links: Determination of chloramphenicol, thiamphenicol and florfenicol residues in edible animal muscle, liver and aquatic products-scope of application and principle of the method