Quality control in the microbiological serum folate assay

Low values obtained in the microbiological assay of serum folate are often due to the presence of antibiotics in the test serum. The assay has been modified to permit consistent recognition of the presence and extent of such contamination. Other assay variables have been investigated and a quality control system devised which rapidly identifies the presence of inconsistencies in any one assay batch. The system further allows for the reporting of some clinically useful results from an imperfect assay batch thus reducing the necessity for reassay of some test sera.