固相萃取-钨丝电热原子吸收光谱分析法测定水样中的银

Determination of Trace Silver in Water Samples by Solid Phase Extraction Portable Tungsten-Coil Electrothermal Atomic Absorption Spectrometry

建立了基于固相萃取和便携式钨丝电热原子吸收光谱仪的测定环境水样中痕量银的新方法。样品流经以硅胶作为吸附剂的固相萃取小柱,银离子被吸附于柱上,用硫脲和硝酸混合液将其洗脱,洗脱液用便携式钨丝电热原子吸收光谱仪进行检测。考察了各种实验参数及共存离子对测定的干扰情况,最终选择样品pH值为6.0、流速为4.0 mL.min-1;洗脱剂为4%（m/v）硫脲和2%（φ）硝酸混合溶液、流速为0.5 mL.min-1。在最优实验条件下,该方法的线性范围是0.20-4.00 ng.mL-1,检出限（3σ）为0.03 ng.mL-1,富集倍数为94。采用建立的方法测定了三个环境水样中的痕量银,结果令人满意。

A simple method has been developed for the determination of silver in environmental water samples using solid phase extraction with tungsten-coil electrothermal atomic absorption spectrometry.Silica gel was used as an adsorbent and packed into a syringe barrel for solid phase extraction of silver prior to its determination by using a portable tungsten-coil electrothermal atomic absorption spectrometer.Optimum conditions for adsorption and desorption of silver ion,as well as interferences from co-existing ions,were investigated.A sample pH value of 6.0,a sample loading flow rate of 4.0 mL·min-1,and the mixture of 4%（m/v） thiourea and 2%（φ） nitrate acid with the eluent flow rate of 0.5 mL·min-1 for desorption were selected for further studies.Under optimal conditions,a linear range of 0.20~4.00 ng·mL-1,a limit of detection（3σ） of 0.03 ng·mL-1 and a preconcentration factor of 94 were achieved.The proposed method was validated by testing three environmental water samples with satisfactory results.