Piezoelectric quartz crystal impedance study of the Pb2+-induced precipitation of bovine serum albumin and its dissolution with EDTA in an aqueous solution.
The piezoelectric quartz crystal impedance technique (QCI) was employed to monitor in situ the Pb2+-induced precipitation of BSA onto a gold electrode and the precipitate dissolution with EDTA in an aqueous solution. The critical precipitation concentration of Pb2+, at which the resonant frequency decreased significantly, was estimated to be 4.78 x 10(-4) mol/L. The saturated adherence of the precipitate on the electrode was observed when the concentration of Pb2+ was greater than 7.53 x 10(-2) mol/L. The frequency response was mainly caused by the mass effect of the precipitate adherence to the electrode, rather than the changes in the physico-chemical properties of the contacting liquid. An excess addition of Na2EDTA after the Pb2+-BSA dissolution led to new precipitation, probably due to the formation of an EDTA precipitate in this medium (pH approximately 3). The pH effect on the response of the resonant frequency was analyzed by using the sum of two exponential functions. A larger frequency response occurred at a pH greater than pI. These findings have been reasonably explained. Also, a decrease in the concentration of the background electrolyte increased the frequency response.
Yuan
Yu
Y
yuyuan7604@163.com
Cai
Yan
Y
Xie
Qingji
Q
Yao
Shouzhuo
S
D000818:Animals; D002417:Cattle; D011232:Chemical Precipitation; D004492:Edetic Acid / Q000737:chemistry* / Q000378:metabolism*; D017097:Electric Impedance; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000494:pharmacology*; D016015:Logistic Models; D011485:Protein Binding / Q000187:drug effects; D011791:Quartz; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D012996:Solutions; D013997:Time Factors
D012996:Solutions; D011791:Quartz; D012710:Serum Albumin, Bovine; D007854:Lead; D004492:Edetic Acid