DETERMINATION OF TRACE METAL IONS USING PORPHYRINS AS CHELATING AGENTS BY HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY-DENSITOMETRY

A method was developed for separation and quantitative determination of mercury, copper, cobalt, and zinc as porphyrin complexes using newly synthesized tetra-(3-bromo-4-hydroxyphenyl) porphyrin (TBHPP), tetra-(4-phenoxyphenyl) porphyrin (TPPP) and tetra-p-chloromethylphenyl porphyrin (CMPP) in aqueous medium by HPTLC densitometry. The method involves enrichment of metal ions as metal complexes with octadecyl cartridges and elution using tetrahydrofuran. The analysis was performed on HPTLC silica gel plates with acetone-chloroform (2:8, v/v) as the mobile phase for TBHPP and TPPP quantification and dichloromethane-chloroform-hexane (1:1:3, v/v) for CMPP quantification. Quality parameters were confirmed and detection limits were ranged from 0.16 to 0.92ngL-1. Detection was performed densitometrically in absorption-reflection mode around 420nm. The method was found to be simple, precise and accurate for the determination of these metal ions in water and food sample.