Louisiana Administrative Code
Title 48 - PUBLIC HEALTH-GENERAL
Part V - Preventive Health Services
Subpart 28 - Drinking Water Laboratories
Chapter 80 - Certification of Laboratories Performing Drinking Water Analyses
Subchapter D - Criteria and Procedures for Radiological/Radiochemical Testing and Analysis
Section V-8081 - General Laboratory Practices [Formerly Section 8079]

A. Chemicals/Reagents. Chemicals and reagents used must meet the specifications in the referenced method. If not specified therein, then analytical reagent (AR) grade or American Chemical Society (ACS) grade chemicals or better shall be used for analyses in certified laboratories.

B. Reagent Water. The laboratory shall have a source of reagent water meeting the requirements of being an American Society of Testing Materials (ASTM) Type 1, 2, or 3 reagent water, having a minimum resistivity of 10 megohms-cm (conductivity less than 0.1 microhoms/cm) at 25°C. It shall be monitored daily by measuring the reagent water's conductivity or resistivity and documented. Radioactive components have been known to break through reagent water manufacturing units before an increase in resistivity is noted. To monitor the background radioactivity of the reagent water, it is to be screened for radioactivity each time the treatment unit is serviced, and periodically thereafter depending on the volume of reagent water use at the laboratory between servicing units.

C. Glassware Preparation. Specific requirements in the methods for the cleaning of glassware must be followed. The purpose of these requirements are to minimize the possibility that glassware can contaminate samples, and should include acid rinsing. Acid rinsing not only mobilizes any metals remaining adhering to their surfaces, but also hydrates the outer silica layer on the glassware which inhibits contamination with radioactive materials. If there are no specifications for cleaning glassware in the method, then the glassware should first be washed in detergent solution, then thoroughly rinsed in tap water followed by a second rinse in a dilute acid solution, and finally rinsed with reagent water and dried.

D. Distilled and deionized water shall have at a minimum, resistivity values between 0.5 to 2.0 megohms-cm (2.0 to 0.5 micromhos/cm.) at 25° C. Preferably, distilled and deionized water should have resistivity values greater than 1.0 megohms-cm (less than 1.0 micromhos/cm) at 25°C. When purchasing distilled or deionized water, laboratories should request a list of quality specifications for the water purchased. Containers of distilled or deionized water should be capped when not in use and should be capped immediately after each use.

E. All solutions shall be properly labeled with identification of the compound, concentration, solvent, date, and analyst who prepared the solution.

F. All chemicals, solutions, and standards, shall be dated upon receipt by the laboratory; and the date opened by the laboratory shall also be noted.

G. Compositing of Samples. If deemed acceptable by the department, samples may be composited by the utility or the laboratory, provided that all the sample aliquots are properly preserved at the time of collection. Since the required compliance protocol monitoring measurements is "total activity" (i.e., the composited sample is required to represent the maximum potential exposure from drinking water), samples shall not to be filtered before preservation. Samples must be drawn on a quarterly basis and where compositing is not done by the laboratory, there shall be documentation submitted with the composited sample detailing on what particular day(s) each aliquot was obtained, its volume, and when it was preserved. A sample of the preservative itself shall accompany the composited sample to the laboratory to determine the contribution of radioactivity, if any, from the addition of the preservative to the sample. Analysis of the composited sample shall be completed within 1 year after the first sample is collected or within normal holding times if the compositing period is less than 90 days. Wherever possible, the laboratory should be responsible for managing the compositing of samples.