pH and buffering in the bicinchoninic acid (4,4'-dicarboxy-2,2'-biquinoline) protein assay.
The HCO3/CO3(2-) buffer used in the bicinchoninic acid (BCA) protein assay has only weak buffering capacity at the recommended pH (11.25). Consequently the assay is rather sensitive to interference from effectively acid or alkaline samples, particularly in the micro method. Adjustment of pH in these alkaline solutions of high [Na+] is complicated by Na+ errors on the pH electrode. Hence it is recommended to prepare the buffers from known amounts of NaHCO3 and Na2CO3, and to reduce the pH to around 10.7; this offers much better buffering capacity with only a limited reduction in color development.
Zhang
J X
JX
Department of Bioscience & Biotechnology, University of Strathclyde, Glasgow, United Kingdom.
Halling
P J
PJ
D001639:Bicarbonates; D002021:Buffers; D002254:Carbonates; D055598:Chemical Phenomena; D002621:Chemistry; D006863:Hydrogen-Ion Concentration; D011506:Proteins / Q000032:analysis*; D011804:Quinolines; D012972:Sodium Hydroxide
D001639:Bicarbonates; D002021:Buffers; D002254:Carbonates; D011506:Proteins; D011804:Quinolines; C005686:sodium carbonate; D012972:Sodium Hydroxide; C047117:bicinchoninic acid