Rapid and simple neurotoxin-based distinction of Chinese and Japanese star anise by direct plant spray mass spectrometry.

Abstract Ingestion of products containing Chinese star anise ( Illicium verum ) fruits contaminated or adulterated with Japanese star anise ( Illicium anisatum ) fruits can cause poisoning due to the neurotoxin anisatin that is present in Japanese star anise. Thus a rapid, simple and unambiguous distinction between the morphologically similar Chinese star anise and toxic Japanese star anise fruits is important for guaranteeing food safety. After adding ∼200 μL of methanol to one star anise carpel placed at 7–10 mm from the inlet of a mass spectrometer and applying a potential of ∼5 kV to the carpel, an electrospray is created. The formation of the electrospray is immediate, robust and stable and lasts for at least a minute. The presence or absence of anisatin could be monitored by orbitrap high resolution mass spectrometry (HRMS) in negative mode by observing the [M−H] − ion at m / z 327.1074 (C 15 H 19 O 8 ) or in positive mode the [M+K] + ion at m / z 367.079 (C 15 H 20 KO 8 ). Several parameters like wetting solvent, voltage, distance and set-up were optimised. The anisatin signal was ∼250 times higher in Japanese than in Chinese star anise. An existing Direct Analysis in Real Time (DART) HRMS for anisatin was used for benchmarking. Alternatively a linear ion trap mass spectrometer could be used in negative selective reaction monitoring (SRM) mode albeit with lower selectivity than the HRMS method. The transition of the [M−H] − ion at m / z 327 to the fragment at m / z 265 was monitored. Direct plant spray and DART ionisation are both robust and provided the same yes/no answer in seconds without any prior sample preparation. Compared with the DART-HRMS procedure, the direct plant spray method is simpler in terms of equipment, yields a more stable signal, does not require heating of the sample but is slightly less selective and requires working with high voltages.