Binding reaction of methylene blue (MB) with human serum albumin (HSA) in the presence of sodium dodecyl sulfate (SDS) was studied. It was found that at pH = 2.87 positively charged MB bound firstly to HSA via hydro.-en and hydrophobic bonds to form MB-HSA aggregate. The aggregate contained many positive charges and attracted negatively charged SDS to form macromolecules, which induced a great enhancement of RLS intensity. RLS intensity was directly proportional to the concentration of HSA. This phenomenon was utilised in a new method for quantitative determination of HSA protein.

In this article a sensitive differential pulse stripping voltammetry technique on Nafion-coated bismuth-film electrode (NCBFE) was studied for the simultaneous determination of zinc, cadmium, and lead ions in blood samples at ultra trace levels. The measurement results were in excellent agreement with those obtained from atomic absorption spectroscopy. Various operational parameters were investigated and discussed in terms of their effect on the measurement signals. Under optimal conditions, calibration curves for the simultaneous determination of zinc, cadmium, and lead ions were achieved, based on three times the standard deviation of the baseline, the limits of detection were 0.09 mu g L-1 for Cd(II), 0.13 mu g L-1 for Pb(II), and 0.97 mu g L-1 for Zn(II) respectively.

A nanostructured gold modified glassy carbon electrode (Au nano /GCE) was employed for the determination of trace chromium(VI). To prepare Au nano /GCE, the GCE was immersed into KAuCl 4 solution and electrodeposition was conducted at the potential of −0·4 V (vs Ag/AgCl) for 600 s. Scanning electron microscopy measurements show that the electrochemically synthesized gold nanoparticles were deposited in aggregated form. Any undue effects caused by the presence of foreign ions in the solution were also analysed to ensure that common interference in the determination of chromium(VI) by square wave voltammetry, do not influence the electrochemical response of the latter element. The results show that this method allows for Cr(VI) determinations with a much lower detection limit (0·01 µg L −1 ) in the presence of excess of Cr(III) than the commonly used diethylenetriammine pentaacetic acid (DTPA) method. The method was applied to determine levels of chromium(VI) in tap water and sewage water.