Determination of Soil Elements by Inductively Coupled Plasma Atomic Emission Spectrometry (2)

(5) Instruments and equipment

(1) For qualified inductively coupled plasma emission spectrometers, before calibrating every day, check the sampling system, including the atomizer, torch, sampling tube and riser for obstruction and dust, because they will affect the sampling And instrument operation; if necessary, these parts should be cleaned or cleaned every day

(2) Microwave digestion instrument: with program temperature control function, the maximum power range is 600~1500W

(3) Temperature control electric heating plate: control accuracy ±2.

(4) Analytical balance: accuracy ±0.

(5) PTFE crucible: 100mL, 50mL

(6) Sieve: non-metallic sieve, 100 mesh

(7) Commonly used instruments and equipment in general laboratories

(6) Sample analysis

(1) Adjust the instrument to the selected power and operating conditions

(2) In accordance with the steps required by the instrument manufacturer, use the mixed calibration standard and calibration blank to calibrate the instrument for daily analysis

(3) After completing the initial test according to the requirements of this method, the samples can be analyzed in accordance with the steps of the calibration curve.

(4) If the measured mass concentration of the sample reaches 90% or even higher of its linear dynamic range, the sample needs to be diluted with reagent water and analyzed again

(7) Result expression and calculation

(1) The data of water samples are reported in mg/L, and the data of solid samples are reported in mg/kg on a dry basis

(2) For the test substance whose detection limit is lower than 0.

(3) For the fully recoverable test substance in the soil sample, its dry basis content w (mg/kg) is calculated by formula (1):

In the formula, P——-the mass concentration in the digestion solution, mg/L;

V——The volume of digestion solution, L;

f——Dilution factor (undiluted=1);

m——The quality of the digested sample

(8) Quality assurance and quality control

(1) A calibration curve must be drawn for the analysis of each batch of samples.

(2) Make at least 2 laboratory blanks for each batch of samples, and the blank value of the measured element shall not exceed the lower limit of the method
.

(3) Make 1 parallel double sample for every 10 samples analyzed.
When the number of samples is less than 10, at least one parallel double sample should be measured
.

(9) Matters needing attention

(1) For the soluble test substance in the aqueous solution, the result given by the instrument can be directly reported, and the dilution of the sample should be taken into consideration
.

(2) For the fully recoverable test substance in the water sample, the corresponding dilution factor must be adjusted
.
In addition, consider additional dilutions for samples whose mass concentration exceeds the upper limit of the linear dynamic range by 90% or more
.

(3) After the instrument is ignited, there should be a long enough warm-up time to prevent wavelength drift
.

(4) 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 measure it
.

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