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N,N’-二(2-羟基-5-磺基苯基)-C-氰基甲(月朁)(简称 DSPCF)及 N,N’-二(2-羟基苯基)-C-氰基甲(月朁)(DPCF)已用于镓等元素的比色测定。作者等实验确定,此二试剂在稀盐酸介质中与铌形成绿色络合物,试剂本身均为红色。如加入亚硝酸钠,则试剂被氧化为颜色极浅之氧化型,而铌络合物遇氧化剂稳定不变。故在含铌的盐酸试液中加入上述二试剂的任一种使与铌络合后,滴入亚硝酸钠,过量试剂的红色立即隐褪,而显出铌络合物的翠绿色。此反应对铌的灵敏度与择选性甚高,可用于微量铌的检出或目视比色。DPCF 及与铌的络合物在水溶液中溶解度较小,可用异戊醇等有机溶剂萃取,惜常温时萃取速度过于缓慢。具磺酸基的 DSPCF 及其
N, N’-bis (2-hydroxy-5-sulfophenyl) -C- cyanocarban (abbreviation DSPCF) and N, Choke (lunar) (DPCF) has been used for gallium and other elements of the colorimetric determination. The authors experimentally determined that the two reagents form a green complex with niobium in a dilute hydrochloric acid medium and the reagents themselves are red. When sodium nitrite is added, the reagent is oxidized to a very light-colored oxidized form, whereas the niobium complex is stable to oxidising agents. Therefore, niobium-containing hydrochloric acid test solution by adding any one of these two reagents to niobium complexed, dropping sodium nitrite, excess reagent red immediately fading, showing the niobium complex emerald. The reaction of niobium sensitivity and selectivity is very high, can be used for the detection of micro niobium or visual colorimetric. DPCF and niobium complex in aqueous solution less solubility, available isoamyl alcohol and other organic solvents extraction, but at room temperature extraction speed is too slow. Sulfonic acid-based DSPCF and its