Feasibility of a portable, low-cost near-infrared spectrophotometer for the quality screening of omega-3 dietary supplements.

The quality of omega-3 supplements, commercialized at substantial high prices and supplied by several manufacturers, must be assessed. The existing reference methods to attest the quality of omega-3 supplements are based on chromatography, which requires expensive equipment, a cumbersome analytical protocol to determine the contents of the active components, and operates ex-situ. This work evaluates, comprehensively, the feasibility of a low-cost near-infrared spectrophotometer and simple chemometrics to achieve fast and robust characterization of omega-3 supplements. The necessary attention, very often neglected, to the performance of the low-cost portable equipment is highlighted, and an appropriate sample measurement protocol is established. A non-conventional way to construct multivariate regression models based on partial least square regression to evaluated the omega-3 content in the supplements was proposed using few references values and completing the data set with the label values selected using the X-Y relation outliers plots. The results showed that the simple, fast and inexpensive approach proposed could deliver in situ relevant information related to the quality of the supplements such as identification several raw materials employed in its fabrication, screening for the content of the active components, identify frauds/non-conformities, and report on unscrupulous marketing practices.