Analytical standards are compounds of known concentration with suitable purity for instrument calibration and/or experiment validation. Say you routinely investigate the composition of analytes via inductively coupled plasma optical emission spectroscopy (ICP-OES), you likely run periodic diagnostic assessments using analytical standards to correct for drift induced by low-frequency noise.
There is some argument about the difference between analytical standards and certified reference materials (CRMs), but for the purposes of this discussion, it is enough to define both as reagents of unambiguous composition and purity that assist with quality assurance and control (QA/QC) in the lab. The main difference to be aware of is analytical standards that are mixed in-house versus those that are custom designed by specialist CRM suppliers.
Preparing Analytical Standards 101
The preparation of analytical standards focuses on converting solids to liquids. Directly analyzing solids poses various challenges, including inhomogeneity, matrix complications, and operational difficulties associated with sample transportation. It is simpler to break the solid down and disperse it in an aqueous media. This is also the format required for ICP and AAS instrumentation.
Preparing Different Elements
Approaches to preparing analytical standards vary from element to element. Alkali metals like sodium (Na) and potassium (K) are commonly prepared by dissolving them in a mixture of strong mineral acid. Various silicates and phosphates are prepared using lithium tetraborate fusion fluxes.
Refer to our individual sample preparation guides for different group elements for more details.
Choosing a Solvent
Different matrices will also offer different results, and chemists have their preferred solutions. Be sure to use a matrix with good compatibility to your analyte and negligible chemical or spectral interferences – which might otherwise affect the quality of your results.
Using Analytical Standards
When you receive or have mixed your chosen analytical standard, it is important to follow the correct procedure to ensure the quality of your results. If you have purchased solutions from a certified supplier, check the integrity of the storage materials and validate all paperwork. Of course, you should also be sure to store standards in the stated conditions and use any CRMs/analytical standards before their expiry date.
For more practical insights into the step-by-step use of analytical standards in different ICP and AAS workflows, refer to our series of trace analysis guides.
Analytical Standards from Inorganic Ventures
At Inorganic Ventures, we specialize in synthesizing custom reagents for use as analytical standards in the lab. We offer a wide range of NIST-traceable solutions for experiment validation and instrument calibration, with a broad selection of elements and matrices at varying concentrations to suit your individual needs.
Interested in learning more? Contact a member of the Inorganic Ventures team today.