Soil and Sediment Wavelength Dispersive X-ray Fluorescence Spectrometry (3)

(8) Result calculation and expression

The aluminum, iron, silicon, potassium, sodium, calcium, and magnesium in the sample are expressed as oxides and the unit is %; the others are all expressed as elements and the unit is mg/kg

The mass fraction wi (mg/kg or %) of the inorganic element (or oxide) to be tested in the soil and sediment samples is calculated according to formula (1):

w _i =k×(I _i +β _ij ×I _k )×(1+∑α _ij ×w _j )+b (1)

Where w _j —— content or mass fraction of interfering elements, mg/kg or %;

k——The slope of the calibration curve;

b——The intercept of the calibration curve;

I _i ——Measure the X-ray fluorescence intensity of the element (or oxide), keps;

β _{ij ——spectral} line overlap correction coefficient;

I _k ——theoretical calculated intensity of spectral line overlap;

α _{ij ——The} α influence coefficient of the interfering element on the measured element (or oxide)

(9) Precision and accuracy

1.

The six laboratories respectively analyzed and determined the national certified standard samples (soil, water system sediments) and actual samples (soil and sediment).

2.

The six laboratories respectively analyzed and determined the national certified standard samples (soil, water system sediments) and actual samples (soil and sediment), and the relative error of the certified standard materials analysis was -70.

(10) Quality assurance and quality control

(1) The measuring instrument should be periodically corrected for drift, such as replacing argon-methane gas, large changes in ambient temperature and humidity, and turning on the instrument after a long time of shutdown

(2) When analyzing each batch of samples, at least one nationally certified reference material of soil or sediment shall be determined.

(3) Each batch of samples should be tested in 20% parallel samples.

(11) Matters needing attention

(1) After replacing the oxygen-methane gas, drift correction should be performed or the calibration curve should be re-established

(2) When the sample matrix obviously exceeds the range of the soil and sediment calibration curve specified in this method, or when the element content exceeds the measurement range, other national standard methods should be used for verification

(3) Sulfur and chlorine are unstable and easily polluted.

(4) When the mass fraction of silica in the sample is greater than 80.

(5) After replacing the X-ray tube, when adjusting the voltage and current, gradually adjust from low voltage and current to working voltage and current