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微量的比色测定,最常用的是碘鉀法、硫脲法及打薩宗法。硫脲法的灵敏度較低,而打薩宗法操作較繁复。因此碘化鉀法虽然是較老的方法,但在鉍的比色測定中还佔据着重要的地位。 鉍的碘化鉀法是基于在酸性溶液中碘化物与鉍組成黄色[Bil_4]~-絡合物。此法最早系Stone(1)提出,起先藉濁度法測定,后經改用比色法进行,Sproull及Cettler(2);Wiegaud、Lann及Kalich(3)等对此法进行了較詳細的研究,并并分別提出用亞硫酸、次亞磷酸作为还原剂以还原析出的碘。Haddock
Trace colorimetric determination, the most commonly used is the iodine and potassium method, thiourea method and fight Sazong law. The sensitivity of thiourea method is lower, while playing Sazan method is complicated. Therefore, although potassium iodide is an older method, it still plays an important role in the colorimetric determination of bismuth. The bismuth potassium iodide method is based on the yellow [Bil_4] ~ - complex of iodide and bismuth in acidic solutions. This method was first proposed by Stone (1), first by turbidimetry and then by colorimetry. Sproull and Cettler (2); Wiegaud, Lann and Kalich (3) Research, and also proposed to use sulfite, hypophosphorous acid as a reducing agent to restore the precipitation of iodine. Haddock