Ultramicro Analysis by Higher-Order Derivative Spectrophotometry Application to the Determination of Ultramicro Amounts of Copper with α, β, γ, δ, -Tetrakis(1-methylpyridinium-3-yl)porphine-

Abstract

Sensitivity in spectrophotometry can be extremely enhanced by measuring the higher-order derivative value, instead of the absorbance, by using an automatic recording spectrophotometer and analogue differentiation amplifiers. Sensitivities obtained for α, β, γ, δ, -tetrakis (1-methylpyri-dinium-3-yl)porphine [T(3-MPy)P] and its copper(II) complex in n'th-order derivative spectrophotometry (n=1-4) are about 4.5ⁿ times that in the ordinary spectrophotometry. Fundamental studies for the determination of copper at ppb level or lower have been carried out from the viewpoint of application of the derivative spectrophotometry to ultramicro analysis. As a result, a sensitive, simple and practical determination method based on measurement of the 2nd-order derivative value of the Soret band of the copper (II)-T(3-MPy)P complex is developed. According to the proposed method, as low as 1 ppb of copper in drinking water can be determined with satisfactory accuracy and precision without any preconcentration treatment.