Spectral and theoretical analysis of derivatives of 1,2,3,3-tetramethyl-3H-indolium iodide (TMI), a highly selective derivatization reagent of cyanide, and their utility for the analysis of cyanide concentrations in beverages.

We develop a specific derivatization gas chromatography-mass spectrometry (GC-MS) method for cyanide using 1,2,3,3-tetramethyl-3H-indium iodide as the derivatization reagent. The derivative compounds were synthesized and characterized using 1H nuclear magnetic resonance (NMR), 13C NMR, and Fourier transform infrared (FT-IR) spectroscopy. The high selectivity of this derivatization for cyanide is supported by calculations and activation energy comparisons. We applied this method to pure water, green tea, orange juice, coffee cafe au lait, and milk. Derivatization was performed by diluting 20 μL of sample solution with 0.1 M NaOH and adding 100 μL of saturated borax solution and 100 μL of 8 mM TMI solution, each drink was completed in 5 min at room temperature, and selected ion (m/z = 200) monitoring analysis was linear (R2 > 0.998) at 0.15 to 15 μM, with detection limits of 4-11 μM were shown. This method is expected to be widely used in forensic toxicology analysis and can be applied to beverages, which are forensically important field samples.