Laboratory Analyses
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times prior to sample analysis are not exceeded. The chemical analyses must
focus on adherence to the quality assurance/quality control (QA/QC) plan, outlined in Chapter 4, and the data quality objectives (DQOs) applicable to the
particular investigation in question.
Details of the laboratory analyses must also be documented and closely followed. These should be compiled and presented in a standard operating procedure (SOP). Detailed analysis plans should be constructed for each instrument
and analyte.
To produce high-quality data, a laboratory should have effective procedures
in place for each of the following elements:
• bottle cleaning
• sample processing
• chemical analysis
Each of these elements is described in the sections that follow. In addition,
the laboratory should follow effective procedures for documentation of method
implementation and method changes. This chapter provides information on
all major aspects of successfully operating a low-nutrient, low-ionic-strength
water analysis laboratory.
3.2 LABORATORY PREPARATION PRIOR TO
SAMPLE ANALYSIS
3.2.1 Bottle Cleaning
All bottles used for sample collection and for partitioning the sample into
aliquots for transport to the laboratory must be clean and free of any contamination. Generally, it is the responsibility of the laboratory to provide
clean bottles to the field crew in advance of initiating field sampling. Lownutrient, low-ionic-strength samples can be more easily contaminated by
improperly washed bottles than most other types of water samples because
their low concentrations can be measurably altered by trace amounts
of contaminants. Therefore, rigorous cleaning procedures must be used,
which are often specific to the intended use of each size and type of bottle. Laboratories experienced with low-nutrient, low-ionic-strength surface
water samples have adopted various methods for cleaning laboratory plasticware and glassware. Dilute acid (usually 1% or 2%) washing is often preferred for some analytes to solubilize potential contaminants that can then
be removed with multiple deionized water (DIW) rinses. If acid washing is
done, it should be carried out in a separate room with a negative-pressure
ventilation system.
82
times prior to sample analysis are not exceeded. The chemical analyses must
focus on adherence to the quality assurance/quality control (QA/QC) plan, outlined in Chapter 4, and the data quality objectives (DQOs) applicable to the
particular investigation in question.
Details of the laboratory analyses must also be documented and closely followed. These should be compiled and presented in a standard operating procedure (SOP). Detailed analysis plans should be constructed for each instrument
and analyte.
To produce high-quality data, a laboratory should have effective procedures
in place for each of the following elements:
• bottle cleaning
• sample processing
• chemical analysis
Each of these elements is described in the sections that follow. In addition,
the laboratory should follow effective procedures for documentation of method
implementation and method changes. This chapter provides information on
all major aspects of successfully operating a low-nutrient, low-ionic-strength
water analysis laboratory.
3.2 LABORATORY PREPARATION PRIOR TO
SAMPLE ANALYSIS
3.2.1 Bottle Cleaning
All bottles used for sample collection and for partitioning the sample into
aliquots for transport to the laboratory must be clean and free of any contamination. Generally, it is the responsibility of the laboratory to provide
clean bottles to the field crew in advance of initiating field sampling. Lownutrient, low-ionic-strength samples can be more easily contaminated by
improperly washed bottles than most other types of water samples because
their low concentrations can be measurably altered by trace amounts
of contaminants. Therefore, rigorous cleaning procedures must be used,
which are often specific to the intended use of each size and type of bottle. Laboratories experienced with low-nutrient, low-ionic-strength surface
water samples have adopted various methods for cleaning laboratory plasticware and glassware. Dilute acid (usually 1% or 2%) washing is often preferred for some analytes to solubilize potential contaminants that can then
be removed with multiple deionized water (DIW) rinses. If acid washing is
done, it should be carried out in a separate room with a negative-pressure
ventilation system.