Proficiency testing in the phytochemical industry – development of the PHYTAS scheme

The quality of botanical products is a great uncertainty faced by many consumers, analysts and regulators. In many sectors proficiency testing (PT) provides an independent quality assurance tool, enabling laboratories to assess the quality of their analytical measurements. Regular PT participation facilitates the implementation of improvement measures, thereby improving the quality of analytical measurements made and reducing the risks associated with poor measurement results. Despite the increasing use of botanical materials in health care products and food supplements, and the number of analytical measurements made on such materials, PT is not well established in the phytochemical industry.

A new phytochemical PT scheme, PHYTAS, was recently launched with a trial round. This consisted of two test materials, one for confirmatory analysis of an extract of milk thistle, and one for the quantification of total Silybin A & B, Taxifolin and Silychristin in an extract from an unknown material. Participation in the PT was international with results submitted from laboratories in eleven different countries.

Laboratory performance for the confirmatory analysis was excellent with most participants positively confirming the material to be an extract of milk thistle. A range of different methods was employed by the laboratories. Performance for the quantitative analysis was varied, both in terms of laboratories and the specific analyte. Overall performance scores were similar for Taxifolin and total Silybin A & B, but those for Silychristin were poorer.

This trial round of PHYTAS has provided important feedback on their performance to the participating laboratories. However, this only provides a single indication and ongoing participation is required for laboratories to monitor their performance over time. Based on these results, and to facilitate ongoing and regular monitoring of performance, the future direction of PHYTAS is discussed.