Fluorospectrophotometric Determination of Trace Amount of Cobalt in TCM

In a PBS of pH 7.4 and in the presence of CTMAB, reaction of energy transfer between rhodamine B and calcein occurred as observed by the enhancement of fluorescence intensity at the λem of 581 nm. When microamount of Co2+ was added to this reaction system, significant decrease in fluorescence intensity at this wavelength was observed. Based on these facts, a method for the determination of trace amount of Co2+ by fluorospectrophotometry was proposed. Linear relationship between the magnitude of decrease in fluorescence intensity and mass concentration of Co2+ was obtained in the range of 4.0×10-4-1.35×10-2g·L-1, with detection limit (3S/N) of 1.8×10-7g·L-1. The proposed method was used to the analysis of TCM, giving values of recovery and RSD′s (n=6) in ranges of 97.6%-102% and 0.98%-1.5% respectively.