2011-04-04_REVISION - M1987143 - Laserfiche WebLink

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• Requested analyte(s) • Type or acid preservation • Field filtered or not Sample Containers: Operator must be cognizant of the appropriate type and number of containers needed for the sampling objectives. Different containers are needed for: • Dissolved metals • Total (or total recoverable) metals • Anions (Alkalinity, Chloride, Fluoride, Sulfate) • Mercury • Nitrate, Nitrite, or Nitrate + Nitrite • Ammonia • Cyanide If the laboratory supplying the containers is made aware of the sampling objectives and the desired analytes, then it should be able to provide the correct number, type and size of containers needed for the job. Acid preservation: Samples for dissolved and total recoverable metals must be acidified to pH -.!?2.0 before or immediately after collection. Acid preservation is necessary to inhibit bacterial growth and to prevent chemical changes in the water sample that can alter the concentration of dissolved metals. Many laboratories will pre-acidify empty sample bottles before providing them to the client for the sampling program. Operators should use laboratories that employ this practice if at all possible, because this will greatly reduce the risk of injury and the probability of error introduced by the wrong type or quantity of acid added to the bottles. If necessary, the Division geochemist can provide guidelines for addition of the appropriate acid in the field, but this practice is not recommended, as the acids are very strong and hazardous and require special handling. Acids typically used for preservation include: Sulfuric acid for mercury Nitric acid for all other metals • Sulfuric acid for nitrogen compounds (nitrate, nitrite, ammonia) If the operator or DRMS staff choose to conduct the acid preservation, then appropriate Personal Protective Equipment is required, including nitrile or latex gloves, protective eyewear, and clothing that covers exposed skin, preferably clothing to which the person is not emotionally attached. Cyanide preservation with NaOH: Samples collected for analysis of cyanide compounds, such as free cyanide, are preserved differently than metals. Cyanide compounds are unstable at acidic pH, so the preservation media is sodium hydroxide. Refrigeration: Refrigeration helps inhibit bacterial growth and off-gassing. Most labs will provide coolers and usually blue ice so that samples can be stored and delivered to the lab cold. This is more critical for samples of organic constituents than for inorganic, but is still a wise protocol to follow. Filtration: Samples for dissolved metals must be filtered in the field during sampling. Filter pore size must be 0.45 micron (µm) or smaller. It is not acceptable to ship the samples to the laboratory for 4