Glossary - M

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"Macro analysis" means the determination of parameters at concentrations in the high part per million or percent range.

"Manual" means "Manual for the Certification of Laboratories Analyzing Drinking Water, Criteria and Procedures Quality Assurance," USEPA/570/9-90/008, USEPA, Office of Water (WH-550D), Washington, DC 20460, as updated or supplemented. This reference is the federal training and standard operating procedures manual for federal, state, and local certification officers of drinking water laboratories for microbiological, chemical, and radiochemical testing.

"Maximum contaminant level (MCL)" means the maximum permissible level of a contaminant allowed in drinking water under the National Primary Drinking Water Regulations.

"Membrane filtration (MF) method" means a method for determining the bacterial count in a water sample. In this method, a known volume of water is filtered through a membrane filter of optimum pore size for full bacterial retention. The filter is incubated in contact with culture medium to provide nutrients for bacterial growth. After incubation at a prescribed time and temperature, the cultures are examined for bacterial colonies that are counted and recorded per 100 mL of water sample.

"Method detection limit" (MDL) means the minimum concentration of a substance that can be measured and reported with 99 percent confidence that the analyte concentration is greater than zero and is determined from analysis of a sample in a given matrix type containing the analyte according to the Guidelines Establishing Test Procedures for the Analysis of Pollutants, 40 CFR 136, Appendix B.

"Method reference" means the name, abbreviation or acronym (e.g. USEPA, ASTM, USGS) of the organization that has developed an approved method or of the publication containing an approved method. The method reference, together with the method number, specifically identifies a method.

"Methods for Measuring Acute Toxicity - EPA" means "Methods for Measuring Acute Toxicity of Effluents to Aquatic Organisms," USEPA, Environmental Monitoring and Support Laboratory, Cincinnati, Ohio, EPA-600/4-78-012.

"Micro analysis" means the determination of trace quantities of parameters at concentrations in the low and sub part per million range.

"Modified static toxicity test" means, for Acute Toxicity Testing, the "Renewal Toxicity Test."

"Most probable number (MPN)" means a quantitative designation of microbial population which is determined by a statistical method. In this method, a multiple dilution tube technique is used with a standard culture medium. The tubes are incubated and observed for gas production. Results of these tubes are translated by mathematical probability tables into population numbers.

"MS" means mass spectrometry.

"mv" means millivolt or 1/1000 of a volt.