Comparative study of two common methods for the determination of total mercury in soil

Cold atomic absorption spectrophotometry and atomic fluorescence methods were employed to ascertain the total mercury concentration in soil samples. A systematic comparison and analysis were conducted on the operational procedures, precision and detection limits of these methodologies. The standard curve for total mercury determination in soil using the atomic fluorescence method is <i>y</i> = 851.98<i>x</i>+16.771 (<i>R</i> ² = 0.9996, 0-2.5 µg l^-1), with a detection limit of 0.0006 mg kg^-1. This method demonstrates superior precision and accuracy not only for samples with high and medium concentrations but also for those with low concentrations. For the cold atomic absorption spectrophotometry method, the standard curve for total mercury determination is <i>y</i> = 0.0547<i>x</i> + 0.0047 (<i>R</i> ² = 0.9998, 0-15 µg l^-1). For high-concentration samples, the curve is <i>y</i> = 0.0007<i>x</i> - 0.0003 (<i>R</i> ² = 0.9998, 0-600 µg l^-1). The detection limit for this method is 0.06 μg kg^-1, indicating better sensitivity and accuracy compared with the atomic fluorescence method. While the precision for low-concentration (0.017 ± 0.003 mg kg^-1) samples is moderate, it is higher for medium (0.030 ± 0.003 mg kg^-1) and high-concentration (0.590 ± 0.05 mg kg^-1) samples. Overall, there is no significant difference between the two detection methods. However, the cold atomic absorption spectrophotometry method has the advantage of not requiring pre-treatment, making it more convenient and environment friendly.