Trace metal analysis identifies and quantifies very small amounts of metals and heavy metals in a sample. Although having some trace metals in our diet is essential for our well-being, many metals can be toxic and can negatively impact human, animal and plant health, as well the environment. Trace metal analysis is used to ensure compliance with legal requirements and regulations. In pharmaceutical, chemical and petrochemical industries, trace metal analysis is used in quality control to identify and measure metal contaminants in products such as drugs, fertilizers, cosmetics, packaging, medical devices, lubricants and catalysts. Due to the influence metals may have on different chemical reactions, trace metal analysis is also used in chemical formulation research and for improving manufacturing processes.
Determining very small quantities of potentially toxic elemental impurities such as lead (Pb), mercury (Hg), arsenic (As), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn) etc. requires highly sensitive analytical equipment. The metals in a sample are typically measured in parts per million (ppm), parts per billion (ppb) or even parts per trillion (ppt), depending on the complexity of the sample (i.e. the sample matrix) and the analytical technique used. Common analytical methods used for trace metal analysis include atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS).
Why Accurate Weighing Is Important
The analysis of trace metals by ICP is a highly sensitive procedure. It is therefore essential that samples, reference standards and calibration standards are weighed, dosed and diluted carefully and very accurately. There are always some inherent errors in volumetric preparation of solutions and dilution series associated with both pipetting and volumetric glassware, such as Erlenmeyer flasks. Gravimetric preparation of solutions and dilutions provides a much higher degree of accuracy.