04/12/2017
Preparing Biological Samples for Elemental Analysis by ICP-MS
Andrew Ryan , Analytik Jena GmbH+Co. KG
The transition from Atomic Absorption Spectroscopy (AAS) to Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) has been gradual for the clinical industry over the past two decades. Both flame AAS and graphite furnace AAS techniques have served the industry well in hospitals, clinical institutes, universities, health organizations and general industry for research, diagnostic and monitoring purposes. The strength of Atomic Absorption lies in its ability to accurately and precisely measure the major, minor, essential and toxic elements in various biological samples, from % levels down to sub parts-per-billion (<ppb).
Although, the ability of ICP-MS to measure more elements in less time has seen the technique become the preferred choice in the clinical industry for elemental analysis. With a large dynamic range and ultra-low detection limits, ICP-MS is able to meet the growing demands for more information in less time and with less complexity.
In replacing flame and furnace AAS systems, the Inductively Coupled Plasma provides a significantly hotter heat source in decomposing the sample into its individual atoms (and ions), offering reduced matrix effects in comparison and true multi-element analysis. And while graphite furnace AAS offers the advantage of low volume handling at microliter volumes, the lower detection limits of ICP-MS allows for greater dilution volumes. Although, the demand for better handling of low-volume samples has seen the introduction of more efficient sample loading accessories in ICP-MS.
Before samples can be analyzed, whether they be whole blood, blood serum, blood plasma, urine or some other biological material, they first must be prepared for analysis. The simplest preparation is to analyze directly, although the high matrix of biological samples usually exceeds the total dissolved solids (TDS) limit that an ICP-MS can routinely analyze long term. While the variable matrix of biological samples can influence the accuracy of results if not accounted for. Even the pH of the final sample to be analyzed is important in determining which elements can be precisely measured. Therefore, the question often asked "What is the best way to prepare biological samples for analysis by ICP-MS".