Direct Determination of Zinc in Human Serum by Flow-Injection Spectrophotometric Analysis

Abstract

Flow-injection spectrophotometric analysis has been established for the determination of zinc at 1μg ml-1 level in serum using 5-Br-PAPS(2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol, disodium salt) as a chromogenic reagent. A 100μl portion of serum is directly injected into the carrier stream containing 5%(v/v) TMAH (tetramethylammonium hydroxide) and 0.5M trisodium citrate. After mixing with 0.01%(w/v) 5-Br-PAPS-0.5M ammonium acetate-7.2×10-3M salicylaldehyde oxime-1%(v/v) Triton X-100-0.5M hydrochloric acid solution, the absorbance of Zn-5-Br-PAPS complex is measured at 560nm. The proposed flow-injection system is fully controlled with a personal computer and permits 60 samples to be measured per hour. The relative standard deviation (n=50) for 1.2μgZn ml-1 solution is 3.3%.