Control of the contaminant level for determination of Al3+ using 8-quinolinol by high-performance liquid chromatography with fluorescence detection.

We developed a technique controlling contaminant Al3+ level using a combination of kinetics and thermodynamics at a pre-column derivatizing step in HPLC. The technique involves modifying a conventional HPLC of 8-quinolinol (Ox) complex with Al3+. The contaminant suppressing reagents, dihydroxyazobenzene (DHAB) and 1,2,3-trihydroxybenzene (pyrogallol) were added to the Ox and pH buffer solutions to convert contaminant Al3+ in these solutions to inactive complexes. The Al3+ in the sample selectively formed Ox complexes with fast kinetics. After that, the labeled fluorescent complexes in the resultant metastable state were separated in the HPLC. This technique successfully suppressed contamination by a factor of 17. This method allowed for an improvement in the detection limits and also provided a stable blank.