The greatest challenge in collecting a sample for Ultra-Trace Metals Analysis is minimizing contributions from extraneous sources. The sampling containers provided, along with the acid and filters used for preservation and filtering of the samples upon receipt of the samples back at the laboratory have been tested and confirmed to be contaminant-free. If other containers are used, or if samples are filtered and/or preserved in the field, the laboratory may not be able to confirm the origin of any reported concentrations.
Please review the following prior to going on-site. Contact your Project Manager if you have any questions.
Sample Suitability
- Only pristine samples with a turbidity <1 NTU are suitable for analysis. Samples with a turbidity of <1 NTU are visually clear, typically colourless and contain no sediment. If samples are determined to have a turbidity >1 NTU, they with be processed using a less sensitive method.
- High-salinity samples cannot be analyzed using this method.
Container Considerations
- Only use sample containers supplied by the laboratory specifically for this analysis. These are soaked for a minimum of 48 hours in 2% Nitric Acid, and then washed 3X with Ultra-Pure Deionized Water within our Class 100 fume hood to remove any trace metals associated with the container material.
- If laboratory supplied containers are not used, a note will qualify the data reported.
- Each container is double-bagged. Do not open either bag until you are ready to collect.
Contamination Control
Atmospheric Sources
- If possible, avoid sampling during periods of moderate to high wind.
- Orientate sampler, additional personnel and any sampling materials downwind (coolers, truck, tables).
- Identify and take note of any potential fixed upwind sources (infrastructure).
- Avoid sampling if raining, or snowing. Record a field note if unavoidable.
Sampler Sources
- Gloves must be powder-free and not contaminated. It is advisable for the “Clean Hands” sampler to replace their gloves prior to each sampling event (discussed below). Wearing two pairs of gloves is also recommended to facilitate removal of the outer pair should it become contaminated.
- Ensure clothing worn is clean and unlikely to shed particulates. As mentioned above, orientation of the sampler downwind minimizes this risk.
- Cigarette smoke and smoke residue is a well-documented trace-metal contaminant source.
- Amalgam Fillings are a source of Mercury. Avoid breathing near/into the sample container.
- Cosmetics contain a variety of metallic compounds. Avoid applying makeup on the day of sampling.
Equipment Sources
- The use of sampling equipment such as a bailer, or a Van Dorn bottle is not recommended. If unavoidable, it is strongly recommended to submit an Equipment Blank sample for analysis (refer to QC section below).
- When collecting samples from a boat, collect from the bow while slowly drifting forward to reduce potential cross-contamination from the hull and motor.
Clean Hands / Dirty Hands (Split Duties)
In response to widespread issues concerning sample contamination during collection, the EPA released Method 1669; commonly referred to as the Clean Hands/Dirty Hands protocol. This method is "performance-based" meaning alternate sampling procedures or techniques can be used as long the suitability of the procedure can be demonstrated through the collection and analysis of uncontaminated blank samples. Review the document linked below (particularly Section 8), and confirm/practice roles prior to arrival on-site. Where the EPA Protocol procedure deviates from the Sampling Procedure outlined below, the Sampling Procedure is to be followed.
https://www.epa.gov/sites/default/files/2015-10/documents/method_1669_1996.pdf
Sampling Procedure
- If approximate concentrations are known, start at the site with the lowest concentration and proceed stepwise up to the highest.
- Samples containers (50ml tubes) must be rinsed with sample three (3) times prior to collection. Ensure the tube is capped, shaken, and the contents discarded each time.
- Samples are not to be preserved. This is completed upon receipt at the laboratory.
- Do not field-filter for dissolved metals. This is completed upon receipt at the laboratory.
- If samples are filtered and/or preserved in the field, data will be qualified with a note.
Quality Control Considerations
Incorporation of Field Quality Control (QC) samples into the site-sampling plan is essential to validate the sampling procedure, ensure the suitability of any equipment used, and to confirm an acceptably low extraneous background concentration existed at the time of sampling. If unexpected sample results were received from the laboratory, a review of the Field QC data would be an essential first step in confirming the source of the data. Refer to Section 9.0 of EPA Method 1669 (link above), and Section 3.2 of the British Columbia Field Sampling Manual (BCFSM) – Part E (link below) for in-depth information. Consult your Project Manager for your QC supplies.
Equipment Blanks
If equipment is used, the generation of an Equipment Blank is necessary to demonstrate that the equipment is free from contamination. Reagent water provided by the laboratory is treated as a sample source. This is passed through the same equipment following the same sampling and pre-sampling equipment-cleaning procedures.
Field Blanks
Required to demonstrate the suitability of the ambient conditions at the time of sampling. Reagent water provided by the laboratory in a separate container is transferred (poured) into a sample tube and capped.
Trip Blanks
Used to monitor potential sources of contamination during transportation to and from the sampling site. Reagent water supplied in a sample container (tube) which is not to be opened at any time following receipt. Return along with the other collected samples.