USGS: TWRI BK 9 CH A5.3.2: Spike Solutions for Organic-Analyte Samples in Water Sample Processing
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Official Method Name
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Section 5.3.2: Instructions for Field Use of Spike Solutions for Organic-Analyte Samples (of USGS National Field Manual for the Collection of Water-Quality Data) |
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Current Revision
| June 2009 |
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Media
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WATER |
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Instrumentation
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Matrix Spike Kit |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Protocol
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TWRI Book 9, Ch. A5 - National Field Manual for the Collection of Water-Quality Data: USGS Techniques of Water-Resources Investigations Book 9, Ch. A5: Processing of Water Samples. |
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Brief Method Summary
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A matrix spike is a type of quality-control sample used to evaluate the effects of sample matrices on the performance of an analytical method. Matrix spikes are used most often for quality control of organic-analyte samples because the analytical methods for organic-analyte samples involve extraction and analysis steps that can be affected by other chemicals in the sample (referred to as the sample matrix). Matrix spikes can be prepared at the sampling site or in the laboratory. If spiked at the sampling site, matrix spikes are called field matrix spikes. If spiked at the USGS National Water-Quality Laboratory (NWQL), matrix spikes are called laboratory matrix spikes. Field matrix spikes are used to monitor the stability of the organic analytes in the sample bottles, from the time of collection at the site to the time of extraction and analysis at the laboratory, in addition to determining potential bias from the sample matrix. This method will describe supplies and materials, unpacking equipment and spike preparations, sample coding and bottle labeling, analytical service requests, field spiking instructions, disposal, and shipping. |
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Scope and Application
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This method pertains to Chapter A5: "Processing of Water Samples" from the USGS National Field Manual (NFM) for the Collection of Water-Quality Data (TWRI Book 9). This section of NFM provides detailed instructions for using organic-analyte spike solutions that meet the criteria for NWQL methods as part of the USGS quality-assurance and quality-control (QA/QC) protocol for incorporating field spikes into water-quality investigations. Organic analytes can be degraded by microorganisms in the sample, or undergo chemical reactions such as oxidation or hydrolysis. Many organic-analyte sampling methods do not use a preservative to prevent sample degradation and loss because the preservatives can negatively affect some (although not all) of the analytes. Instead, samples are shipped to the laboratory and extracted within a short time period. This time period is called the sample holding time, and is determined by the laboratory to represent a reasonable time for samples to be shipped and stored until analysis, with minimal change in analyte concentration. Field matrix spikes can be used to verify that the sample holding times were sufficient for the sites sampled during the course of a project. |
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Applicable Concentration Range
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Interferences
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Quality Control Requirements
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Method describes details of QA/QC. |
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Sample Handling
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Chill and maintain the sample at <6oC at all times. |
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Maximum Holding Time
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Use the spike solutions as soon as possible after opening to prevent changes in concentration caused by evaporation of the solvent. Do not save an unused portion of the spike solution for re-use. |
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Relative Cost
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Unknown |
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Sample Preparation Methods
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CAUTION: Organic-analyte spike solutions contain toxic compounds. Perform spiking in a well-ventilated area; avoid inhaling the fumes, and wear gloves at all times. Take adequate precautions to prevent contact with eyes and skin. |
