Determination of Streptomycin Residues in Aquatic Products - High Performance Liquid Chromatography (2)

7 How to operate

1 Specimen Preparation

Prepare the sample according to the requirements of SC/T 3016.

2 Extraction

Weigh (5±02) g of the sample into a 50mL centrifuge tube, add 10mL trichloroacetic acid solution, homogenize at 10000r/min for 1min, shake for 5min, centrifuge at 4500r/min for 15min, transfer the supernatant to a beaker, and use 10mL for the residu.

3 SPE cleanup

The C18 solid phase extraction cartridge was pre-washed with 5 mL of methanol and 10 mL of water in tur.

NOTE: The pretreatment and cleanup process of the SPE column keeps the column we.

4 Preparation of standard working curve

Accurately take the standard stock solution (18) and dilute it with sodium heptane sulfonate solution (17) into a series of standard work with concentrations of 1μg/mL, 5μg/mL, 0μg/mL, 5μg/mL, 0μg/mL liquid for analysis by high performance liquid chromatograph.

5 Chromatographic analysis

Inject 50 μL of standard working solution and sample extraction solution into high performance liquid chromatograph respectively, carry out chromatographic analysis according to the above chromatographic conditions, record the peak area, and the response value should be within the linear range detected by the instrumen.

6 Blank test

Except that no sample was added, all were carried out according to the above-mentioned measurement conditions and step.

8 Calculation

The content of streptomycin in the sample is calculated according to formula (1.

where:

X—streptomycin content in the sample, in micrograms per kilogram (μg/kg);

Cs—streptomycin content in standard solution, in micrograms per milliliter (μg/mL);

A - the peak area of ​​streptomycin in the sample solution;

V——The final volume of the sample extraction solution, in milliliters (mL);

As - the peak area of ​​streptomycin in the standard solution;

m—the mass of the sample, in grams (g.

9 Method Sensitivity, Accuracy and Precision

1 Sensitivity

The minimum quantification limit of this method is 100 μg/kg, and the minimum detection limit is 20 μg/k.

2 Accuracy

When the standard addition concentration of this method is 100 μg/kg~5000 μg/kg, the recovery rate is 70%~120.

3 Precision

The relative standard deviation within and between batches of this method is less than or equal to 15.