Highly Sensitive Spectrophotometric Determination of Human Serum Albumin with 3', 4', 5', 6'-Tetrachlorogallein-Molybdenum(VI) Complex

Abstract

A highly sensitive spectrophotometric determination of human serum albumin (HSA) with 3', 4', 5', 6'-tetrachlorogal-lein (T.Cl.Gall)-Mo(VI) complex in a Triton X-100+polyvinyl alcohol micellar medium is proposed. This method can be used to determine up to ca. 150μg/10ml of HSA from the optical absorbance at 640nm, and is superior in sensitivity to the other extremely sensitive spectrophotometric methods. The great sensitivity of this method results from the use of third-derivative spectrophotometry. The binding parameters of T.Cl.Gall-Mo(VI) complex to HSA are n=77.3 and K=1.05×10⁴ M^-1 as determined from dual double-reciprocal plots. It is suggested that the colored complex in this system may be the association complex between [HSA]^m+ and [Mo^VI(T.Cl.Gall)₂]^n- involving hydrophobic interaction between HSA and T.Cl.Gall. The proposed method should also be useful for the detection and determination of some peptides (e.g. low molecular weight peptides containing gasic amino acids), as well as proteins.