OWML: QA/QC

Quality Assurance/Quality Control Manual: Ohio Water Microbiology Laboratory
 

Coliphage
The method currently in use for quantitative coliphage analysis by the Ohio Water Microbiology Laboratory (OWML) is the USEPA Method 1602, single-agar layer (SAL) procedure (USEPA, 2001b) (Appendix O). This method is generally most suitable for quantification of coliphage in surface-water samples. Antibiotic-resistant E. coli CN-13 (resistant to nalidixic acid) and E. coli F-amp (resistant to streptomycin and ampicillin) are used as bacterial hosts for somatic and F-specific coliphage, respectively. Procedures for quality-control samples are described in Appendix O. Results are recorded on a QC log form (Appendix P).

The method currently in use for qualitative determination of coliphage in larger sample volumes at the OWML is the USEPA Method 1601, two-step enrichment method (USEPA, 2001a). Sample volumes of 1 L are recommended for detec¬tion of coliphage using this method. Because the SAL method is impractical for sample volumes above 100 mL, the two-step enrichment method is often used for ground-water sample analysis. A summary of Method 1601 can be found in Appendix Q. Results from quality-control samples are recorded on a QC log form (Appendix R).

Results from coliphage QC samples are recorded in the LIMS. Coliphage QC log forms are kept in the Sample Logbook with the Service Request Forms. A second book, coliphage QC log book, contains information on media sterility, additional quality-control samples, and coliphage stock enumeration results. Information on host culture strains is maintained in LIMS.