Abstract:The main factors affecting the accuracy of high-precision portable X-ray fluorescence spectrometry (HDXRF) for the determination of total cadmium concentration (CdT) in soil were screened with the heavy metal contaminated farmland soil in a sewage irrigation area of Baiyin City, Gansu Province as the object of the research. The influences of moisture, organic matter type and content, and soil type on the determination results of CdT by HDXRF were studied, respectively. The relative error (RE), relative standard deviation (RSD) and determination coefficient (R2) were used to evaluate the accuracy and precision of HDXRF method. The results showed that the RE and RSD of HDXRF were ≤ 10%, R2>0.99, which met the accuracy and precision requirements of farmland soil environmental quality monitoring technical specifications and US Environmental Protection Agency standards. The determination results of CdT by HDXRF method was exponentially decayed with the increase of moisture, and the attenuation equation was y=0.412e-1.3284xwith an attenuation coefficient (μω) of -1.328 4 and a coefficient of determination (R2) of 0.984 5. There was a significant negative correlation between CdTby HDXRF method and organic matter content (r=-0.955), and humic acid (HA) had a much stronger influence on determination results by HDXRF method than that of peat (Peat). The correction equation of HA was y=-1.555x + 0.780 with a R2 of 0.934 4. The influence of soil type on the determination results of CdTby HDXRF method was limited, and the determination results of CdT in sierozem by HDXRF method were closer to the determination results by traditional laboratory analysis method than that of red soil and paddy soil. In conclusion, although the determination results of HDXRF are affected by many factors, the reliability of the correction results can meet the needs of accurate investigation of cadmium contaminated farmland soils through model correction.