DIRECT DETERMINATION OF ZINC IN HUMAN SERUM BY FLOW-INJECTION SPECTROPHOTOMETRIC ANALYSIS

Flow-injection spectrophotometric analysis has been established for th e determination of zinc at 1 mu g ml(-1) level in serum using 5-Br-PAP S lazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol, disodium salt) as a chromogenic reagent. A 100 mu l portion of serum is directly inject ed into the carrier stream containing 5%(v/v) TMAH (tetramethylammoniu m hydroxide) and 0.5 M trisodium citrate. After mixing with 0.01%(w/v) 5-Br-PAPS-0.5 M ammonium acetate-7.2X10(-3) M salicylaldehyde oxime-1 %(v/v) Triton X-100-0.5 M hydrochloric acid solution, the absorbance o f Zn-5-Br-PAPS complex is measured at 560 nm. The proposed flow-inject ion system is fully controlled with a personal computer and permits 60 samples to be measured per hour. The relative standard deviation (n=5 0) for 1.2 mu gZn ml(-1) solution is 3.3%.