Stability of lyophilized human serum for use as quality control material in bhutan

Bovine Serum as an Alternative to Control Serum for Total Protein Levels

Total protein describes the liver's ability to synthesize proteins and metabolize substances in the blood. Bovine serum can be used as a control material because the total protein analyte in bovine blood serum is almost identical to the analyte in human serum. The researchers intend to determine the homogeneity and stability of bovine serum with the addition of 7,5% ethylene glycol preservative after being stored for 12 weeks at -20°C as an alternative to control serum for total protein levels. This research used survey analytics using a one-group pretest-posttest research design.  Data analysis used ISO 13528 2005 calculations. From the examination of the total protein level in the serum, the value of Xr – Yr = 0.23817, which is where the value meets the test criteria according to |  Xr - Yr |  <0.36, that is 0.23817 <0.91585. The total protein content of bovine serum was homogeneous and stable with the addition of 7.5% ethylene glycol stored at -20oC for 12 weeks.

Efficacy of Pooled Serum Internal Quality Control in Comparison with Commercial Internal Quality Control in Clinical Biochemistry Laboratory

Introduction  With increasing automation in clinical laboratories, the requirements for quality control (QC) material have greatly increased in order to monitor performance. The constant use of commercial control material is not economically feasible for many countries because of nonavailability or the high-cost of those materials. Therefore, preparation and use of in-house QC serum will be a very cost-effective measure with respect to laboratory needs. Materials and Methods  In-house internal quality control from leftover serum samples of master health checkup subjects, which have been screened negative for HIV, HCV and HBsAg antibodies was pooled in a glass jar with ethanediol as preservative and kept in deep freezer at - 20°C. From the pooled serum, 100 microliter thirty aliquots were prepared. Every day along with commercial internal QC (IQC), one aliquot of pooled serum was analyzed for 30 days for the following parameters: plasma glucose, blood urea, serum creatinine, total cholesterol, triglycerides (TGL), high-density lipoprotein, calcium, total protein, albumin, total bilirubin, AST, ALT, ALP, amylase. After getting 30 values for each parameter, mean, standard deviation (SD) and CV% were calculated for both IQC commercial sample and pooled serum sample. Results  The mean, SD, and CV% of glucose, cholesterol, TGL, calcium, alanine aminotransaminase (ALT), aspartate aminotransferase (AST), amylase, and alkaline phosphatase (ALP) were statistically significant between pooled serum and commercial QC. Conclusion  In-house QC prepared from pooled serum is better than commercial internal QC. The biochemical parameters were stable in pooled serum due to less matrix effect; also, variation was less in pooled serum IQC.

Stability of lyophilized pooled sera as quality control materials for tumor marker assays in external quality assessment

BACKGROUND

External quality assessment (EQA) requires stable quality control (QC) materials. We evaluated the stability of QC materials made of lyophilized and liquid pooled sera for the tumor markers α-fetoprotein, carcinoembryonic antigen, carbohydrate antigen 125, and carbohydrate antigen 19-9.

METHODS

Specimens of the 4 tumor markers were collected from the sera of patients and stored at -20°C. After sera collection and pooling, liquid or lyophilized samples were stored at -20°C, 5°C, or room temperature. Tumor markers were quantified on days 0, 1, 4, 7, 14, 30, and 90 of storage. Internal QC results were analyzed, and the effects of heat inactivation and sucrose addition were assessed.

RESULTS

Heat inactivation lowered tumor marker levels in lyophilized pooled sera, whereas sucrose addition had no effect. The coefficients of variation of the internal QC results were stable, whereas those of lyophilized samples were higher than those of liquid samples. Tumor marker levels were significantly lower in lyophilized samples (p<0.05) and did not significantly differ according to storage temperature. A declining trend over time was observed for all tumor markers.

CONCLUSIONS

Lyophilized QC materials are insufficiently stable for use in EQA among clinical laboratories.