Determination of metal elements in solid waste by inductively coupled plasma mass spectrometry (4)

(8) Quality assurance and quality control

(1) At least 2 blank samples should be analyzed for each batch of samples

① The blank value should be lower than the detection limit of the method;

②Below 10% of the standard limit;

③Below 10% of the lowest measured value of each batch of samples

(2) A standard curve should be established for each analysis, and the correlation coefficient of the curve should be greater than 0.

(3) For every 10 samples analyzed, the middle mass concentration point of the calibration curve should be analyzed, and the relative deviation between the measurement result and the actual mass concentration value should not exceed 10%, otherwise the cause should be found or the calibration curve should be re-established

(4) In each analysis, the response value of the internal standard in the sample should be between 70% and 130% of the response value of the calibration curve.

(5) In each batch of samples, at least one reagent blank (2% nitric acid ) for standard addition should be analyzed , and the standard addition recovery rate should be between 80% and 120%

(6) At least one matrix spike and one matrix repeat spike should be measured for each batch of samples.

(9) Matters needing attention

(1) All the utensils used for analysis need to be soaked in HNO ₃ (1+1) solution for 24 hours, and then washed with deionized water before use

(2) When adding acid solution to the digestion tank, observe the reaction in the tank.

(3) For solid wastes suspected of serious pollution, first scan the sample with semi-quantitative analysis to determine the mass concentration of the metal element to be measured, so as to avoid contamination of the instrument by samples with high mass concentrations

(4) When using microwave to digest samples, pay attention to the temperature and pressure limits of the digestion tank, and check the tightness of the digestion tank before and after digestion

(5) The waste liquid and waste generated during the experiment should be placed in airtight containers for classified storage, and entrusted to a qualified unit for disposal

(6) For special matrix samples, if the digestion method described in this article is not complete, the amount of acid can be appropriately increased

(7) If the verification can meet the quality control and quality assurance requirements, the sample digestion can also use other digestion methods such as electric heating plates