Simple detector for oral malodour based on spectrofluorimetric measurements of hydrogen sulphide in mouth air

A sensing phase for spectrofluorimetric determination of hydrogen sulphide in mouth air, by immobilizing in a silica gel support the complex formed between Hg(II) and 2,2'-Pyridylbenzimidazole, has been developed. The sensing scheme is based on the fluorescence intensity increase of the solid phase upon reaction of hydrogen sulphide with the Hg(II), present in the non-fluorescent binary complex, with release of the fluorescent reagents. The developed sensing phase exhibits a response time of less than 2 min for hydrogen sulphide concentrations in the linear range. The 3 sigma detection limit is 4 ppb (v/v) of hydrogen sulphide and the linear range extends up to 200 ppb. The system has been successfully assayed for the measurement of human oral malodour and the results validated by comparison with those obtained for the same patients using a commercially available instrument based on electrochemical measurements. (C) 1999 Elsevier Science B.V. All rights reserved.