Difference between reference standard and working standard in analytical lab?

Answer 1

A reference standard is the traceable, raw material standard (usually in crystallized form) that you dissolve and volumetrically dilute to make your working standard. The working standard is what you use to "do your work."

Let's say you are performing an HPLC purity and degradation assay on aspirin tablets for your client. The client corporation would supply the reference standard(s) (or in this case could be purchased from the US Pharmacopeia) with a lot number, purity coefficient and expiration date (among other things like storage requirements). This information makes it traceable and is recorded in the preparation notebook. Then per the assay method the working standard is dissolved in a volumetric flask and diluted to volume (with subsequent dilutions if necessary) to make the working standard. The working standard is then used to make calibration curve injections on the HPLC to estimate the quantities of your aspirin tablets being analyzed.

Note: In the above example, reference standards are also used to make a system suitability solution. This would contain the A) reference standard material used for the calibration curve and B) another reference standard of at least one possible degradant to show peak separation.

Answer 2

A reference standard is a highly purified compound with a known purity and identity used to calibrate instruments and validate methods. A working standard is a solution or sample of known concentration prepared from the reference standard and used as a control in routine analysis for quantification and quality control purposes.