Andrew Ryan Varian Australia Pty. Ltd., Mulgrave, 3170, Victoria, Australia
The role of major, minor and trace levels of elements in human health has been an important area of scientific research. In particular, research on the value of trace elements to the diagnosis, treatment and prevention of diseases has been vast.
The advent of atomic absorption (AA) techniques and the development of the graphite tube atomizer (GTA) has provided the means for accurate determination of all levels of many elements in human body fluids. An advantage of the graphite furnace is the small sample consumption in the determination of trace levels. Disadvantages of flame AA are that releasing agents or modifiers are necessary and careful control of the flame stoichiometry is important to overcome chemical interferences1. While the atomic absorption technique offers adequate performance, in most cases it is a single element technique and is therefore slow.
The inductively coupled plasma mass spectrometer (ICP-MS) offers rapid, highly sensitive, multielement determinations. The high sensitivity of ICPMS means that samples can be diluted to give a reasonable working volume. Dilution is also required for ICP-MS because of limitations imposed by the sample matrix. Typically with ICP-MS, an upper total dissolved solids (TDS) limit of 0.2% in the solution should not be exceeded to ensure continuous operation for an extended period2. At TDS levels in excess of this limit, unacceptable levels of signal instability are commonly experienced.
Inductively coupled plasma atomic emission spectrometry (ICP-AES) also offers rapid, multielement determinations. The sensitivity of ICP-AES is lower than that of either ICP-MS or AA-GTA, but ICP-AES can handle higher levels of TDS than ICPMS and is much faster than AA-GTA. Since ICPAES is able to analyze samples with high