Proposal for the Updating of the ISO 29841 Liquid Chromatographic Method for the Determination of Chlorophyll a and a′ Degradation Products in Virgin Olive Oil

Pyropheophytin a (PPPa) found in minute amounts in virgin olive oil under good manufacturing practice conditions and increasing as a function of storage temperature and length, has attracted the interest of scientists as a marker of quality. Certain bodies developing olive oil standards have adopted its content (% PPPaₘₐₓ < 17 throughout the shelf‐life of a product) as a quality criterion. The analytical protocol to examine product compliance is the ISO 29841 method. In the present work, green improvements are proposed through the use of a short column and vacuum in the solid‐phase sample extraction step. The preparation of handmade cartridges that can be reused without pretreatment at least six times reduces further the cost of analysis. The proposed protocol is repeatable and robust. In case fluorescence detection is used, selection of λₑₓ = 407 nm/λₑₘ = 672 nm instead of λₑₓ = 430 nm/λₑₘ = 670 nm increases detection sensitivity of the target compounds by 1.5‐ to 2.6‐fold. Fluorescence detection results in higher %PPPa values by 2% on average compared to those obtained with a diode array detector set at 410 nm. Present proposals and observations are expected to be of interest for the next edition of the ISO 29841:2009/AMD1:2016. Practical applications: The proposals made in the present study expedite significantly the analysis, thus, increasing the sample throughput even compared to other alternative fast approaches in the literature. The reduction of the use of chemicals adds to the modification of the ISO 29841 method to an analytical tool that abides by green and sustainable chemistry which is considered critical for “beyond the 2020 process.” The proposed chromatographic column updates the method as its effective use in an HPLC instrument provides comparable efficiency to a UHPLC one, and makes method transfer to the latter without adjustments. In this way, method adoption may be wider by analytical laboratories involved in virgin olive oil quality control. Finally, the identification of quantitative differences using different detection means (visible, fluorescence) for the first time, when addressed by the ISO committee, may assist the effective quality control and facilitate the virgin olive oil international trade.