Table I. Yield of protein extraction methods.

The percent yield was calculated as the percentage of total urine protein that was recovered by the extraction method. Protein concentration was measured in the urine sample and the resulting protein extract by the Bradford assay. Each protein extraction method was tested 10–12 times with similar results. The ranges shown are representative of the observed values.

Protein extraction method	Yield
	%
Organic solvent precipitation	60–70
Methanol	60–70
Ethanol	30–40
Acetonitrile	<30
TCA
Ultrafiltration	25–30
Dialysis, lyophilization	70–80