Preliminary investigations on the standardization and quality control for the determination of acid phosphatase activity in seminal plasma

BACKGROUND: The determination of ACP in seminal plasma was considered as an appropriate biochemical marker to evaluate prostate function, as recommended by the WHO manual. However, few reports on the standardization and quality control for the determination of biochemical markers in seminal plasma have been documented. METHODS: Two frozen samples of seminal plasma with or without phenylmethylsulfonyl fluoride were determined for their acid phosphatase (ACP) levels. The ACP level and sperm concentration of each of 72 samples of seminal plasma obtained at 1000xg for 10 min or 3000xg for 15 min centrifugation were assayed. ACP activity in 10 samples of seminal plasma was measured immediately or standing for 30 min after dilution. The ACP levels in seminal plasma with or without chymotrypsin were also assayed. RESULTS: There was no significant difference of ACP levels (P=0.166) but of sperm concentrations (P=0.000) in seminal plasma obtained by centrifugation at different velocity. ACP activities in seminal plasma measured when standing for 30 min after dilution were significantly lower than those measured immediately after dilution (P=0.001). Both chymotrypsin and freezing-thawing had no apparent effect on the determination of ACP in seminal plasma. CONCLUSION: The results indicated that standing time after dilution and centrifugation velocity should be standardized, and frozen seminal plasma could serve as the quality control products for the determination of ACP activity among different laboratories.