The CAS metals lab analyzes drinking and nonpotable water, soil, solid, organic and miscellaneous samples. Analytical capabilities include over 20 metallic elements, such as mercury, lead, and arsenic.
Often, metal samples must first be prepared before analysis can begin. Preparation includes digesting "or heating" the samples in differing acid solutions for specified periods of time at 95° C in order to dissolve the metals. Once dissolved, the metals are contained in solution where they can more easily be analyzed.
Samples are analyzed using three different technologies:
- Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)
ICP-OES uses a plasma (ionized argon gas) to produce excited atoms in the sample that emit electromagnetic radiation having distinct wavelengths characteristic of each particular element.
The human eye can detect many different wavelengths within the spectrum of visible light. Instrumentation used in the metals laboratory also uses visble light wavelengths and, in addition, goes well beyond those wavelengths to detect and quantify metals contained in samples.
The intensity of this emission is indicative of the concentration of the element within the sample.
- ICP-Mass Spectrometry (ICP-MS)
ICP-MS uses the plasma to produce the ions in the sample that are separated and detected using a mass spectrometer.
ICP-MS is used for the determination of a wide range of metals at low concentrations, generally below 5 parts per billion.
- Flow Injection Mercury System (FIMS)
- FIMS uses cold-vapor atomic absorption spectrometry for detection of total Hg (mercury).
- Hg(II) is converted to elemental Hg and transported to the spectrometer for detection.
Data generated by these techniques must be interpreted, reviewed, and processed by the analyst using appropriate software and method. The data is then arranged into a detailed report for database entry and further reviews.