Rapid and accurate identification of Illicium verum and its poisonous adulterant Illicium lanceolatum based on high-sensitivity VUV photoionization mass spectrometry

Abstract

The occasional mix of the poisonous adulterant Illicium lanceolatum fruits in the Illicium verum fruits (Chinese star anise) sold in the agricultural market causes a food safety concern. Therefore, rapid differentiation between the fruits of these two species is essential for food safety. This paper reports a mass spectrometric recognition method between the Illicium verum and Illicium lanceolatum fruits. A high-sensitivity VUV photoionization time-of-flight mass spectrometer (PI-MS) directly sampled the volatile organics emitted from these two fruits via dynamic headspace. The assay results show that the mass peak of trans-anethole (m/z = 148) is predominant in the mass spectrum of Illicium verum, whereas no significant peak is observed at m/z 148 in the mass spectrum of Illicium lanceolatum. In contrast, the mass peak at m/z 154 with moderate intensity, associated with oxygenated monoterpenes, is detected in Illicium lanceolatum but not detected in Illicium verum. A developed chemical pattern recognition method achieved recognition with 100 % confidence between the Illicium verum and Illicium lanceolatum fruits. This study provides a new identification method using PI-MS to rapidly differentiate the Illicium verum and poisonous adulterant Illicium lanceolatum fruits. The advantages of soft ionization in PI-MS, coupled with its capability to detect volatile gases and the avoidance of complex sample pre-treatment steps, facilitate rapid and easily interpretable mass spectral detection.