Shiobara T, Teshima N, Kurihara M, Nakano S, Kawashima T
Laboratory of Analytical Chemistry, Department of Chemistry, University of Tsukuba, Tsukuba 305-8571, Japan.
Talanta. 1999 Aug 9;49(5):1083-9. doi: 10.1016/s0039-9140(99)00020-x.
A catalytic flow-injection (FI) method was developed for the determination of 10(-9) mol l(-1) levels of vanadium(IV, V). The method is based on the catalytic effect of vanadium(V) on oxidation of N-(3-sulfopropyl)-3,3',5,5'-tetramethylbenzidine (TMBZ.PS) using bromate as oxidant to form a yellow dye (lambda(max)=460 nm). The use of 5-sulfosalicylic acid (SSA) as an activator enhanced the sensitivity of the method. The calibration graphs with a working range 0.05-8.0 ng ml(-1) were obtained for vanadium(V). Vanadium(IV) was also determined, being oxidized by bromate. The detection limit (signal/noise, S/N=3) was 0.01 ng ml(-1) (ca. 2x10(-10) mol l(-1)) vanadium. The relative standard deviations (R.S.D.) for 15 determinations of 0.5 ng ml(-1) vanadium, and for ten determinations of 0.1 and 1.0 ng ml(-1) vanadium were 0.41, 2.6 and 0.25%, respectively, with a sampling rate of 15 samples h(-1). The proposed method was successfully applied to the determination of vanadium in natural waters.
开发了一种催化流动注射（FI）法用于测定10⁻⁹ mol·L⁻¹水平的钒（IV、V）。该方法基于钒（V）对以溴酸盐为氧化剂氧化N-（3-磺丙基）-3,3',5,5'-四甲基联苯胺（TMBZ.PS）形成黄色染料（λmax = 460 nm）的催化作用。使用5-磺基水杨酸（SSA）作为活化剂提高了该方法的灵敏度。得到了钒（V）的工作范围为0.05 - 8.0 ng·ml⁻¹的校准曲线。钒（IV）也可通过溴酸盐氧化进行测定。钒的检测限（信号/噪声，S/N = 3）为0.01 ng·ml⁻¹（约2×10⁻¹⁰ mol·L⁻¹）。在进样速率为15个样品·h⁻¹时，对0.5 ng·ml⁻¹钒进行15次测定、对0.1和1.0 ng·ml⁻¹钒进行10次测定的相对标准偏差（R.S.D.）分别为0.41%、2.6%和0.25%。所提出的方法成功应用于天然水中钒的测定。
