Small supplement and nutraceutical producers often need assay testing to verify that a product contains what the label says it contains, but the route to getting that testing done is not always obvious. Large contract research organisations typically require minimum batch commitments and long lead times. This is a guide to what assay testing involves and what to look for in a laboratory.
What assay testing measures ¶
An assay measures the concentration of an active ingredient in a finished product or raw material. For a supplement tablet, this means extracting the active from the tablet matrix, separating it from other components using HPLC, and quantifying it against a reference standard of known purity. The result is expressed as a percentage of the labelled amount. A result of 95 to 105 percent of label claim is generally considered acceptable for most supplement categories, though the acceptable range depends on the product type and any applicable monograph.
Content uniformity and why it matters ¶
Assay on a composite sample tells you the average content across the batch. Content uniformity testing measures the variation between individual units. A batch can have an acceptable average assay result while individual tablets vary widely, which is a manufacturing quality problem. For products where dose consistency matters, content uniformity testing on a sample of ten units is a more informative test than a single composite assay. We offer both, and we can advise on which is appropriate for your product and intended market.
Method development for novel actives ¶
If your active ingredient does not have a published pharmacopoeial method, a bespoke HPLC method needs to be developed and validated before routine testing can begin. This involves selecting the appropriate column chemistry and mobile phase, optimising the gradient, demonstrating specificity, linearity, accuracy, and precision, and documenting the validation in a report. For a straightforward small molecule, this typically takes three to four weeks. We have developed methods for marine-derived actives, novel botanical extracts, and synthetic peptides.
What to send and what to expect ¶
Send a representative sample of the finished product (typically ten units for content uniformity, or a 10g composite for assay), the product specification including the labelled amount of active, and the reference standard if you have one. If you do not have a reference standard, we can source one from a certified supplier and include the cost in the quote. Results are reported as a percentage of label claim with the uncertainty of measurement included.
If you are a supplement producer who needs assay testing without a large minimum commitment, get in touch to discuss what you need. The scoping call is free and we can usually give an indicative quote within the same conversation.