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甲基百里酚蓝(MTB)光度法测定铝时酸度的影响小,在pH3.5～6.5显色液内吸光度稳定,络合物不被EDTA分解,因此可以用EDTA作掩蔽剂。络合物组成为A1:MTB=1:2,摩尔吸光系数为1.22×10~4;铝量0～50微克/50毫升符合比尔定律。显色液中其它元素的允许量:Mn(Ⅱ)、Mo(Ⅵ)、Zn(Ⅱ)、Si(Ⅳ)、∑RE、Ba(Ⅱ)、Sr(Ⅱ)、Cd(Ⅱ)为0.2毫克,Bi(Ⅲ)、Pb(Ⅱ)、Co(Ⅱ)、As(Ⅲ)、Fe(Ⅲ)、Pt(Ⅱ)、Cu(Ⅱ)、Ag(Ⅰ)、Hg(Ⅱ)、Cr(Ⅲ)(加热一分钟)为0.1毫克,Ca(Ⅱ)、Mg(Ⅱ)为5毫克,V(Ⅴ)、Ni(Ⅱ)、Sb(Ⅴ)、Zr(Ⅳ)为50微克,Ti(Ⅳ)、W(Ⅵ)为30微克,Nb(Ⅴ)、Ta(Ⅴ)、Sn(Ⅳ)、Ga(Ⅲ)、Be(Ⅱ)为10微克,F~-、草酸根、柠檬酸根、酒石酸根、大量ClO_4~-PO_4~(3-)有干扰。本法可用于白云石、铁矿中铝的测定。
Methyl thymol blue (MTB) spectrophotometric determination of aluminum when the acidity of the small, pH 3.5 ~ 6.5 color liquid absorbance stability, the complex is not EDTA decomposition, it can be used as a masking agent EDTA. Complex composition of A1: MTB = 1: 2, the molar absorption coefficient of 1.22 × 10 ~ 4; aluminum amount of 0 to 50 micrograms / 50 ml in line with Beer’s law. The allowable amount of other elements in the color developing solution is 0.2 mg (mg / L) of Mn (Ⅱ), Mo (Ⅵ), Zn (Ⅲ), Pt (Ⅱ), Cu (Ⅱ), Ag (Ⅰ), Hg (Ⅱ), Cr (Ⅲ) (Heating for one minute) is 0.1 mg, and Ca (II), Mg (II) is 5 mg, V (V), Ni (W) is 30 micrograms, Nb (Ⅴ), Ta (Ⅴ), Sn (Ⅳ), Ga (Ⅲ) and Be ClO_4 ~ -PO_4 ~ (3-) interference. This method can be used for the determination of aluminum in dolomite and iron ore.