USGS


Water Resources--Office of Water Quality

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PREPARATORY PROCEDURES   5.0.1

Use of the procedures described in this section will help to avoid mistakes and preserve sample integrity. Protocols that are applicable to most sampling efforts for surface water are described in detail in Horowitz and others (1994). Koterba and others (1995) describe the protocols for ground-water sampling that were designed for the National Water-Quality Assessment (NAWQA) Program; these protocols are generally applicable to the routine collection of ground-water samples. Field personnel are responsible for being familiar with any specific sampling protocols that might be required for their studies and programs, especially those that differ from the routine procedures covered by this field manual. For example, field procedures, bottle type, and sample preservation requirements differ for samples collected as part of the USEPA Drinking Water Program (National Water Quality Laboratory Technical Memorandum 97.054).

To minimize delays in sample processing, calibrate field instruments (NFM 6), and set up processing equipment and supplies in the work area before collecting the sample.
Clean-sampling procedures are recommended as a general practice when processing raw samples, particularly those for analysis of trace levels of inorganic and organic analytes.
Clean-sampling procedures such as Clean Hands/Dirty Hands techniques (NFM 4) are required when collecting samples to be filtered for analysis of trace elements (Office of Water Quality Technical Memorandum 94.09; Horowitz and others, 1994; Koterba and others, 1995).
When using Clean Hands/Dirty Hands techniques:
  -- Designate the Clean Hands (CH) person and the Dirty Hands (DH) person before field work begins (table 4-2 in NFM 4) .
  -- CH duties: Has the only contact with the sample bottle; transfers sample from sampler to splitter; filters, extracts, and preserves sample.
  -- DH duties: Operates sampling equipment and manages any contact with potential sources of contamination (for example, the churn carrier and pumps).
  -- CH and DH: Both must wear appropriate disposable, powderless gloves (vinyl, latex, or nitrile for inorganic work; latex or nitrile for organic work).
Check sample-designation codes and processing requirements for each sample. Requirements depend on program and laboratory protocols, study objectives, and data-quality requirements. Laboratory codes and processing requirements are summarized in Appendixes A5-A, B, and C.
  -- Organic analytes. Identify the bottle requirement by checking the sample designation code (see in-text table below and Appendix A5-A). Use only containers that arrive clean, baked, and capped. Discard any bottles that arrive uncapped.
  -- Inorganic and radiochemical analytes. Identify the bottle requirement by checking the sample designation code (see in-text table below and Appendixes A5-B and A5-C). For example, samples to be acidified must be collected in bottles that arrive from the laboratory acid rinsed and capped; discard any acid-rinsed bottles that arrive uncapped. Prerinse all bottles used for nutrients, major-ion, and trace-element samples with deionized water (DIW) before sampling. Field rinse bottles with the water to be sampled, if a field rinse is specified (section 5.0.3 and Appendixes A5-B and A5-C).

5.0.1.TABLE1

5.0.1.TABLE2

Clean equipment and supplies as directed in NFM 3.

  -- Organic analytes. All containers arrive precleaned and baked from the laboratory. Do not prerinse or field rinse these glass bottles or vials. Samples to be analyzed for organic compounds are hereafter referred to as organic-compound samples.
  -- Inorganic analytes. Prerinse bottles with DIW and store half filled with DIW. This procedure is required for all FA samples with target analytes at parts-per-billion (ppb) concentrations, and is recommended for all samples to be analyzed for inorganic constituents (hereafter referred to as inorganic-constituent samples) that also require field-rinsed bottles.
Set up a clean work area at the field site for sample processing. (An appropriate area includes, for example, a mobile laboratory, a water-quality field vehicle (NFM 2), or clean space in a building near the sampling site.)
  -- Protect the area from airborne sources of contamination such as dust, vehicle emissions, and vapors from inorganic chemicals and organic solvents.
  -- Spread sheeting over the area where samples are to be processed. For inorganic-constituent samples, use plastic sheeting. For organic-compound samples, use aluminum foil.
Prevent direct contact with potential source(s) of contamination.
  -- Exclude airborne particulates by processing samples onsite in processing and preservation chambers.
  -- Handle anoxic samples rapidly and under an inert gas atmosphere (NFM 4.0.3).
  -- Keep hands gloved and away from potential sources of contamination while processing samples. While filling the sample bottle, the sample must not come in contact with gloved hands.
Keep sample-processing equipment covered with a clean, noncontaminating material when not in use; keep sample bottles capped and covered or bagged.

 


4The technical memorandums referenced in this manual are available on the Word Wide Web; see "Selected References and Internal Documents" for memorandum titles, dates, and the Web Site address.


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