New Determination Methods of Halides and Cyanide Ions by Electrospray Ionization Mass Spectrometry Based on Ternary Complex Formation

Abstract

Determination methods of halide ions (X⁻ = F⁻, Cl⁻, Br⁻ and I⁻) by electrospray ionization mass spectrometry (ESIMS) were developed, where negative ions of the ternary complexes of group-13 elements, nitrilotriacetic acid (NTA), and halides were measured. In particular, these halides were simultaneously determined by measuring [InX(nta)]⁻, and the limits of detection (LODs) were 1.1 μmol dm⁻³ for F⁻, 0.32 μmol dm⁻³ for Cl⁻, 3.8 nmol dm⁻³ for Br⁻, and 1.6 nmol dm⁻³ for I⁻, respectively. This approach was extended to the determination of CN⁻, where the ternary complex of Cu^II, CN⁻ and 4-(2-pyridylazo)resorcinol (PAR), i.e., [⁶³Cu^II(CN)(par)]⁻ (m/z 302) was measured. The LOD for CN⁻ was 20 nmol dm⁻³.