Procedures for determination of 7 quinolones residues in milk and milk powder

11.
2.
3.
6 Determination

(1) Liquid chromatography conditions

Chromatographic column: C ₁₈ , 5μm, 150mm×2.
1mm (inner diameter) or equivalent: Column temperature: 30°C; injection volume: 15μL; mobile phase gradient and flow rate are shown in Table 11-19
.

Table 11-19 Liquid chromatography gradient elution conditions

(2) Mass spectrometry conditions

Ionization mode: electrospray positive ion mode (ESI+); mass spectrometry scan mode: multiple reaction monitoring (MRM); sheath gas pressure: 15unit; auxiliary gas pressure: 20unit; positive ion mode electrospray voltage (IS): 4000V; capillary temperature : 320℃; Induced dissociation voltage in the source: 10V; Q1, Q3 resolution: Q1 is 0.
4, Q3 is 0.
7; Collision gas: high-purity argon; Collision gas pressure: 1.
5mTorr; See Table 11 for other mass spectrometric parameters and retention times -20
.

Table 11-207 Species quinolone drugs retention time qualifier ion for quantitative cleavage energy ion pair and

(3) Qualitative determination

Choose one parent ion and two or more product ions for each tested component.

(4) Quantitative determination

Under the best working conditions of the instrument, sample the mixed matrix standard calibration solution.
Use the peak area as the ordinate and the concentration of the mixed matrix calibration solution as the abscissa to draw a standard working curve.
Use the standard working curve to quantify the sample.
The response value of the measured object should be within the linear range measured by the instrument
.

Figure 11-4 seven kinds of a quinolone Standards multiple reaction monitoring (MRM) chromatogram