EVALUATION OF BENZOYLACETONE AS A CHELATING AGENT FOR MULTIELEMENT ANALYSIS BY REVERSED-PHASE HPLC WITH PHOTOMETRIC DETECTION

In order to evaluate benzoylacetone (BA) as a chelating agent for multielement analysis by reversed-phase high-performance liquid chromatography (RP-HPLC), various metal-BA chelates are separated on silica-based tetramethylsilane (TMS), phenyl (Ph), C8, and C18 columns with a methanol-water-chloroform-BA mixture as the mobile phase. The metal chelates examined are V, Cu, Be, Al, Ga, Pd, Fe, and In. Four C18 columns are also tested to examine the effects of residual silanol groups and carbon percentage on elution behaviors of BA chelates. Calibration curves are prepared with the Ph column from which the best separation chromatogram was obtained. The metal ions, except for V and Pd, are extracted into chloroform from weak alkaline solution as BA chelates, and then separated on the Ph column and monitored at 375 nm. Log-log plots of each metal concentration vs. peak area show good linearity with a correlation coefficient of more than 0.9995. Linear ranges of the calibration curves are 60 ng/mL (ppb) to 20 μg/mL (ppm) for Cu, 100 ppb to 1 ppm for Be, 100 ppb to 10 ppm for Al, 100 ppb to 10 ppm for Ga, 5 ppb to 6 ppm for Fe, and 200 ppb to 10 ppm for In.