Sample containers for ultratrace metals analyses should be inert to the metals of interest. Metals should not leach from the container, nor should any metals “stick” to the container walls. Sample containers are “proofed” to ensure that they are not a source of metals themselves.
For ultra-trace testing of waters, containers and preservatives are proven free of metals to the part per trillion range. Glass is not used for water samples because it contains significant levels of many metals. Similarly, acid preservatives can contain significant levels of metals. High Density Polyethylene (HDPE) is a common choice for sampling waters for trace metals. It is light, impermeable to water and resistant to breaking. Different brands can contain some metals, however.
Bureau Veritas Laboratories has exhaustively researched to find the cleanest HDPE containers and preservatives available.
Sample Collection – Ultra Trace Metals and Mercury
Sampling Element | Groundwater | Surface Water | Drinking Water |
Sample Container | 50 mL HDPE | 50 mL HDPE | 50 mL HDPE |
Field Filtered | Yes | No | No |
Preservative | HNO3 (to pH <2) | HNO3 (to pH <2) | HNO3 (to pH <2) |
Min. Sample Size | 20mL | 20 mL | 20 mL |
Recommended Sample Size | 50 mL | 50 mL | 50 mL |
Hold Time | days | 60 days | 60 days |
Sample Container | 50 mL HDPE | 50 mL HDPE | 50 mL HDPE |
Dissolved Metals (filtered) | Yes | No | No |
Preservative | HCl (to pH <2) | HCl (to pH <2) | HCl (to pH <2) |
Min. Sample Size | 50mL | 50 mL | 50 mL |
Recommended Sample Size | 100 ml | 100 ml | 100 ml |
Hold Time | 28 days | 28 days | 28 days |