Preparation of home-made lyophilized human serum for quality control in clinical chemistry.

ABSTRACT

Tested serum of donors from the Blood Bank unit of Siriraj Hospital was collected. Only negative hepatitis B-antigen determined by RPHA (reverse passive haemagglutination) method was selected. The sera were pooled as one pooled serum. Filtrations were performed after adjusting some biochemical constituents. To obtain lyophilized serum, the pooled serum was subjected to freeze-dry process. It was divided into aliquot of 5.0 ml in each vial, then quick freezed and dried in the lyophilizer. Precision of between-vial filling volume was studied. We found that the coefficient if variation was 0.01%. Reconstitution of the lyophilized serum before use was performed by adding 5.0 ml of distilled water to each vial. The coefficient variation of between-vial biochemical constituents was found to be less than 0.5%. The precision of 19 routine biochemical tests in these Home-Made lyophilized human serum were compared to those of 3 batches of well-known commercial control materials (ORTHO, MONITROL, VALIDATE). By F-test analysis, the coefficient variation of most biochemical tests in the Home-Made lyophilized human serum was not significant different from those of the commercial ones (P>0.05). The long-term consistency of the biochemical constituents was studied. In a duration of one year, from March 1985 to February 1986, three-month periods means and standard deviations were analyzed. The results showed no significant difference for these period of study (P>0.05). Since 1985, the Home-Made lyophilized serum has been used as internal control material in our Central Clinical Chemistry Laboratory, Faculty of Medicine Technology, Mahidol University in place of imported control serum. The external control evaluation was successfully reported by the International External Quality Control Assessment Scheme. (Birmingham UK) and the improvement of Overall Mean Running Variance Index Score (OMRVIS) is obviously seen in the graphic curve.