将憎水性的聚氯乙烯(PVC)四氢呋喃溶液,借助模具在切割成一定形状的滤纸上制成一环形栏线,此环形栏线环绕部分为硫化物检测区,其中预先加入含硫氰酸汞和硝酸铁的检测试剂溶液1 μL,由此制成了一个具有固定尺寸和形状的硫化物检测装置。该装置能接受的试样量为10 μL。试样溶液经进样过道引入装置与PVC栏环接触时,只有硫离子能渗透进入检测区与硫氰酸汞反应生成硫化汞并定量释出硫氰酸根,所释出的硫氰酸根与检测试剂溶液中的铁(Ⅲ)离子生成红色络合物,用扫描仪将显色结果转换成数字信号并通过软件功能再转换成像素密度平均值。试验结果表明:硫化物浓度在65~2 000 μmol·L-1范围内呈线性关系,检出限(3S/N)为36 μmol·L-1。应用该装置分析河水和污泥,所测得硫化物含量与国标方法的测定值相符。

The hydrophobic tetrahydrofuran solution of PVC was introduced onto a specially shaped filter paper with the help of a mould to fabricate a barrier ring, in which 1 μL of a reagent solution, containing HgSCN and Fe(NO3)3, was added to form a detection zone, thus forming a selective S2--ion detector with definite size and shape. The volume of sample introduction was set at 10 μL. When the sample solution comes in contact with the barrier ring, only S2- ion can osmosed through the barrier into the detection zone, and reacts with HgSCN to form HgS and liberates SCN- ion quantitatively, which in turn reacts with Fe3+ ion to form a red colored complex, the intensity of which is transformed into digital signal and pixel density by the scanner and software of the computer in succession. It was found that linearity range for S2- was kept between 65 to 2 000 μmol·L-1, and detection limit (3S/N) found was 36 μmol·L-1. The detector was used in analysis of samples of river water and sludge, values of S2- content found were in consistency with the results obtained by the method of GB standard.