PREPARATION AND DETERMINATION OF ZINC(II) CHLOROPHYLLS BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A preparative method for zinc(II) chlorophyll a and b [Zn(Il)-chl-a and -b] was developed on the basis of their purification by semi-preparative high-performance liquid chromatography. Zn(II)-chl-a and -b and the corresponding epimers were separated and determined with an ODS (C18 chemically bonded silica gel) column using methanol-acetone (75:25, v/v) as mobile phase. Linear calibration graphs were obtained over the concentration range 0-50 mug cm-3 of each zinc(II) chlorophyll with photometric detection at 425 nm. The present HPLC determination provides an accurate and conventional method with a detection limit of 3.5 ng cm-3 for Zn(II)-chl-a, 2.5 ng cm-3 for Zn(II)-chl-a' and 3.0 ng cm-3 for Zn(II)-chl-b with a relative standard deviation of less than 2.3% (n = 10). The analytical values obtained for synthetic samples by a spectrophotometric method were confirmed to be high compared with those determined by the proposed HPLC method.