9: Which Technique to Use? Check Access

This final chapter attempts to assist the reader in choosing the best technique for their application. There may be Hobson’s choice in that only one technique is available. However, if a laboratory is fortunate enough to have a full suite of analytical instrumentation, then the choice may be governed by how many samples there are, how many analytes require determination, the concentration range of the analytes and whether or not the instrumentation is already in use. If only one analyte requires determination and is present at the mg L⁻¹ level, then a flame AAS instrument could complete the job quickly and efficiently. If the determination of several analytes is required and the concentration range expected is the tens of µg L⁻¹ to mg L⁻¹, then ICP–OES is likely to be more suitable. Trace and ultra-trace levels may require ICP–MS (if there are numerous analytes) or even ETAAS if there are only one or two. The application itself can be a decisive factor. If isotope ratios need to be measured, then ICP–MS is the logical choice, with high precision being obtained by multicollector instruments. A table of the attributes of all of the techniques discussed is provided.