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11.
2.
3.
8 Linearity range and lower limit of determination
According to the sensitivity of 7 kinds of quinolone drugs, a series of matrix standard working solutions were prepared with sample blank solution and measured under selected chromatographic conditions and mass spectrometry conditions.
The injection volume was 15uL, and the peak area was used to measure the matrix standard working solution.
The concentration of the components is plotted, and the linear range, linear equation and linear correlation coefficient are shown in Table 11-21
.
This method uses matrix addition standards to calibrate the content of the sample to eliminate matrix interference
Table 11-2 The linear ranges, linear equations and correlation coefficients of 17 quinolones
Thus, in the process operating conditions, marbofloxacin , ciprofloxacin , enrofloxacin , danofloxacin , orbifloxacin , difloxacin and the quinolone seven sarafloxacin 1 ~ 50ng/mL (corresponding to the quinolone drug residue in milk within the range of 0.
5-25.
0μg/kg, corresponding to the quinolone drug residue in the milk powder within the range of 2.
0-100.
0μg/kg), the response values are all within the linear range of the instrument
.
At the same time, the limit of detection (LOD) of 7 quinolones in milk is 0.
11.
2.
3.
9 Method recovery and precision
Use milk and milk powder samples that do not contain the 7 quinolones to be tested for addition recovery and precision experiments.
After adding different concentration standards to the samples, they are placed for 1 hour to allow the standards to be fully absorbed by the sample, and then extraction and purification are carried out according to this method.
Measured by liquid chromatography-tandem quadrupole mass spectrometry, the recovery and precision results are shown in Table 11-22 and Table 11-23
.
The recovery rate of milk in this method is between 83.
Table 11-22 The recovery rate and precision experimental data of 7 quinolones in milk
Table 11-23 The recovery rate and precision experimental data of 7 quinolones in milk powder
11.
2.
Under repeatability test conditions, the absolute difference between the two independent test results obtained does not exceed the repeatability limit (r).
If the difference exceeds the repeatability limit (r), the test results should be discarded and the two individual tests should be completed again.
Determination
.
Under the reproducibility test conditions, the absolute difference between the two independent test results obtained does not exceed the reproducibility limit (R)
Table 11-24 Content range and repeatability and reproducibility equation of 7 quinolones in milk
Table 11-25 Content range and repeatability and reproducibility equation of 7 quinolones in milk powder