Determination of 22 metal elements in solid waste by inductively coupled plasma emission spectrometry (4)

(7) Result expression and calculation

(1) The content of metal elements in solid waste is expressed in mg/kg

(2) The metal element content in liquid or semi-solid solid waste that does not need to be dried is expressed in mg/kg

(3) The mass concentration of metal elements in the solid waste leachate is expressed in mg/L

(4) The number of decimal places of the measurement result is consistent with the detection limit of the method, and up to three significant digits are reserved

(5) The content w (mg/kg) of the metal element to be tested in the solid waste is calculated according to formula (2):

Liquid and semi-solid solid waste w (mg/kg) without drying is calculated according to formula (3):

The determination result p(ug/L) of solid waste leachate is calculated according to formula (4):

In the formula, p ₁ ——The mass concentration of the metal element to be measured in the test sample is calculated from the calibration curve, ug/L;

P ₀ ——The mass concentration of the metal element to be tested in the blank sample, ug/L;

V————Sampling volume of solid waste leachate, mL;

V ₀ ——The constant volume of the sample after digestion, mL;

m ₁ ——the weight of the sample, g;

m ₂ ——the mass of the sample after drying, g;

m ₃ ——the weighed amount of solid waste sample after grinding and sieving/the weighed amount of sample, g

(8) Quality assurance and quality control

(1) Make at least one laboratory blank for each batch of samples, and the blank value of the measured element shall not exceed the lower limit of the method

(2) A calibration curve must be drawn for the analysis of each batch of samples, and the correlation coefficient of the calibration curve should not be less than 0.

(3) Make one parallel double sample for every 10 samples analyzed.

(4) When the actual samples are measured in full, each batch of samples shall be accompanied by certified reference materials for solid waste, and the measurement results shall be within the given uncertainty range

(9) Matters needing attention

(1) The crucibles and glass containers used in the experiment must be soaked in nitric acid solution for more than 12 hours, rinsed with tap water and experiment water in turn, and placed in a clean environment to dry

(2) After the instrument is ignited, it should be preheated for more than 30 minutes to prevent wavelength drift

(3) For elements with lower content, you can appropriately increase the sample weighing or reduce the volume of the constant volume, or you can concentrate the digestion solution and determine it

(4) The waste and liquid waste generated in the experiment should be collected and stored separately, and sent to a qualified unit for disposal