Quantifying Illegal Additives in Fruit and Vegetable Plums Using UHPLC-Based Technique

Scientists from the Hubei Provincial Institute for Food Supervision and Test in Wuhan, China, created a new approach for detecting dicyclohexylformyl oxyphenisatin, an illegal chemical that can be added to health-care foods, in fruit and vegetable plums. Their findings were published in the Journal of Chromatography Open (1).

plums | Image Credit: © Sea Wave - stock.adobe.com

As material living standards improve, there is a higher demand for fitness and health management. In recent years, due to an increase in work and life pressures, it has become popular to achieve weight loss by taking in various foods or health-care foods (which can include almonds, fruits, and vegetables) made from natural plants, medicine- and food-derived traditional Chinese medicinal materials (2). Some may take advantage of this market by illegally adding fast-acting chemicals to health-care foods that explicitly or implicitly indicate weight loss effects. The types and dosages of illegally added medicines are often unclear in food labels, meaning that long-term consumption without physician guidance can seriously threaten consumer health.

In this study, the scientists aimed to create an effective approach for separating, identifying, and quantifying suspected illegal additives from fruit and vegetable plums. They used ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) to perform non-targeted screening of illegal additives from over 10 batches of fruit and vegetable plums. With this, they identified a diesterified oxyphenisatin analog that is believed to have never been detected before in foodstuffs. This analog was separated and purified using column chromatography; its molecular structure was analyzed and identified using one-dimensional and two dimension-nuclear magnetic resonance spectra (1D and 2D NMR). After obtaining the synthesized reference standard, a UHPLC-photodiode array detector (PDA) detection method for quantitatively analyzing the analog in real samples was established.

The data showed that the characteristic fragment ions with mass/charge ratios (m/z) of 224.07 and 196.07 appeared in the MS² spectrum. This indicated that the analog had the skeleton of oxyphenisatin. The scientists also combined the fitted molecular formula of the suspected compound, its degree of unsaturation, and the fragment ions with m/z ratios of 428.18, 334.14, and 83.08 in the secondary mass spectrum. With this, they speculate that the anhydride of esterified oxyphenisatin might be cyclohexanecarboxylic anhydride, which does prove consistent with NMR spectroscopic analysis. The analog was eventually named dicyclohexylformyl oxyphenisatin. UHPLC–PDA test results showed that the content of this analog in 10 batches of fruit and vegetable plum samples was 614.0 mg/kg.

The toxicological and pharmacological status of dicyclohexylformyl oxyphenisatin is still unknown, and due to this, overconsumption will bring unknown harm to uninformed consumers. As far as the scientists know, dicyclohexylformyl oxyphenisatin is not a food additive, as it is structurally the product of dicyclohexylformylation of oxyphenisatin. There have been increasing cases of oxyphenisatin and its derivatives, including diesterified oxyphenisatin compounds, being detected in weight-loss health-care foods. As such, the scientists concluded their research by pushing for more effort and financial support to be put towards creating non-targeted screening strategies for these analogs. With this type of support, the scientists can prepare standard samples of the new illegal additives and develop detection methods for these substances.

References

(1) Wu, W.; Zhu, S.; Xia, J.; Jiang, F.; Fan, X.; et al. Separation, Identification, and Quantification of Dicyclohexylformyl Oxyphenisatin, An Illegal Additive, From a Fruit and Vegetable Plum. J. Chromatogr. Open 2025, 7, 100214. DOI: 10.1016/j.jcoa.2025.100214

(2) 10 Great Health Foods. Mayo Clinic 2024. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/10-great-health-foods/art-20546837 (accessed 2025-5-14)