Flow injection chemiluminescence determination of N-tetrahydrobenzothiazolyl imines

Abstract

A flow injection chemiluminescence (CL) method is described for the determination of five newly synthesized N-tetrahydrobenzothiazolyl imines (N-THBTIs) based on their sensitizing effect on the CL reaction of cerium(IV) and sulfite. The fluorescence, CL and absorption spectra are studied. The CL is deduced to originate from the excited sulfur dioxide, which is formed in a free radical reaction initiated by the free radical of N-THBTI. The relationship between the CL intensity and the concentration of N-THBTI is linear in the range of 2.0 × 10⁻⁷ to 8.0 × 10⁻⁵ mol l⁻¹ with a detection limit of 8.0 × 10⁻⁸ mol l⁻¹. The relative standard deviation (RSD) for seven independent determinations of N-THBTI (1.0 × 10⁻⁶ mol l⁻¹) is 1.2%. Most metal ions and some organic compounds do not interfere with the determination, except for Fe(III), Fe(II), Mn(II), Tl(I) and Bi(III). The method has been successfully applied to the determination of N-THBTI in synthetic samples.