Fluorometric determination of proteins using the terbium (III)-2-thenoyltrifluoroacetone-sodium dodecyl benzene sulfonate-protein system

It is found that in hexamethylene tetramine (HMTA)-HCl buffer of pH=8.00, proteins can enhance the fluorescence of terbium (III) (Tb3+)-2-thenoyltrifluoroacetone (TTA)-sodium dodecyl benzene sulfonate (SDBS) system. Based on this, a sensitive method for the determination of proteins is proposed. The experiments indicate that under the optimum conditions, the enhanced fluorescence intensity is in proportion to the concentration of proteins in the range of 4.0×10−9-7.5×10−6 g/mL for bovine serum albumin (BSA), 5.0×10−9-1.5×10−5 g/mL for human serum albumin (HSA), 1.0×10−8-7.5×10−6 g/mL for egg albumin (EA). Their detection limits (S/N=3) are 0.5, 0.8 and 2.0 ng/mL, respectively. The interaction mechanism is also studied.