Perchloric Acid Precipitation of Interfering Protein
Material
In order to avoid laborious digestion of the protein
samples, e.g., with wet ashing, precipitation with 10%
perchloric was tested for removing interfering protein
from the sample while leaving the metal in solution
(see Fig. 5). Perchloric acid precipitation is a common
method to remove proteins form, e.g., human serum
(17). Measurement of 8 nM Mo and W in the presence
of 3.6 mg/ml BSA resulted in 98% reduction of the
tungsten response and 60% reduction of the molybdenum
response. Precipitation of protein in the same
sample with 10% perchloric acid prior to measurement
resulted in a recovery of 92% of the tungsten and 93%
of the molybdenum. The AdSV method of Wang and Lu
(11) is thus applicable to crude protein samples after
precipitation with perchloric acid.