What is a Conductivity Standard Solution?
The science of measurement is principally the realm of physicists concerned with measuring physical quantities: length, mass, time, and so on. Metrology was applied to the field of chemistry relatively recently, and as such, has not been adopted so easily. Many analytical chemists are yet to be convinced of the value of standardized chemical measurements, with poor cross-fertilization failing to put an end to the debate. Standards solutions aim to bridge this cultural gap by laying out a clear framework for traceability and quality assurance in wet chemistry and analysis.
Certified reference materials (CRMs) for elemental analysis and wet chemistry applications are formulated to strict regulatory standards for a range of downstream applications. Conductivity standards, for instance, can be used to calibrate electrochemical sensors or to assist with conductivity detection in ion-exchange chromatography (IEC).
Understanding Conductivity Standard Solutions
We are going to use conductivity standard solutions as a brief case study to try and justify the presence of metrology in analytical chemistry. Many sample preparation reagents use water as a primary material as it has a known theoretical conductivity of 18.2 megohms at 25°C. In reality, this value fluctuates and is almost never achievable in the presence of carbon dioxide (CO2), which is difficult to eliminate from working environments unless the water is handled in a cleanroom. Additionally, it is not uncommon for leachable elements from containers to contaminate reagent-grade water at the sub-parts per billion (ppb) range. Further still, it is impossible to tell that your water is pure from conductivity measurements alone as they do not account for non-ionized contaminants.
In short, you cannot reliably assume that your analyses offer a truly representative insight into trace level sample composition under these conditions. Conductivity standard solutions can be used as calibrators for guaranteed water quality, using aqueous matrices to eliminate mismatch errors and high purity starter materials – typically potassium salt (KCl). As most trace metal labs use ion-exchange purification to generate conductivity water, calibrating the chromatograph with a conductivity standard first could dramatically improve the quality of your primary reagents, thus the quality of your results.
Conductivity Standard Solutions from Inorganic Ventures
Inorganic Ventures supplies a range of conductivity standard solutions that are accredited, certified, and fully traceable to NIST standards. If you are curious about using CRMs in your trace analysis workflow, why not contact a member of the team today?