In our blog posts Lessons From the Lab we answer frequently asked questions from clients. Find all installments of Lessons From the Lab here.
What is Trace Metals Analysis?
Trace Metals analysis may be performed on a variety of aqueous matrices. Depending on the objective of your sampling, WETLAB can perform total recoverable or dissolved metals analysis. For total recoverable or total metals analysis, the sample must be preserved with the addition of nitric acid (HNO3) to lower the pH of the sample to <2. Dissolved metals require an additional step prior to the addition of HNO3. Samples for dissolved metals must be filtered using a 0.45 µm filter, after the sample has passed through the filter, the sample must be preserved with HNO3. In SW-846, the EPA recommends that samples are field filtered. If field filtration is not possible, clients may submit an unpreserved sample to WETLAB and we can filter the sample using 0.45 µm filters and preserve with HNO3. If field preservation is not possible, the EPA recommends in EPA 200.2, “Preservation may be done at the time of sample collection, however, to avoid the hazards of strong acids in the field, transport restrictions, and possible contamination it is recommended that the samples be returned to the laboratory within two weeks of collection and acid preserved upon receipt in the laboratory. Following acidification, the sample should be mixed and held for 16 hours.” Aqueous samples that have been properly preserved for trace metals analysis by EPA 200.7 and/or EPA 200.8 may be held and analyzed up to six months after collection date.