AWWA WQTC63968

A method was developed to monitor precision for heterotrophic plate count (HPC) usingboth blind duplicates and lab replicates as part of a project looking at pilot drinking waterdistribution systems. Precision control charts were used to monitor for changes in assayvariability with time just as they are used for chemical assays. In adapting these controlcharts for the HPC assay, it was determined that only plate counts ¿¿¿¿¿¿¿ 30 cfu per plate couldbe used for Quality Assurance (QA) purposes. In addition, four dilutions were used for allknown Quality Control (QC) samples to insure counts usable for QC purposes would beobtained. The method worked well for HPC but resulted in a 50% increase in the requiredlabor for a given number of samples when blind duplicates and lab replicates were run inparallel with the samples. The methodology developed for HPC can be adapted to otherbiological assays for precision (for example, assimilable organic carbon - AOC). Includes reference, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2006

Number of Pages:

12

File Size:

1 file , 390 KB