Preparation and characterization of some novel metal complexes and their applications to chemical sensors

Abstract

In this chapter, a simple spectrophotometric method with good selectivity and high sensitivity towards sulfide ions is introduced. The method is based on the replacement of the axial water molecule of the aquacyanocobyrinic acid heptamethyl ester (ACCbs) reagent after the reaction with HS- ions, and forming stable complex. ACCbs reagent is characterized with three distinguishable absorption bands with absorption maxima at 353, 497 and 527 nm. After adding HS-, a new absorption band at 582 nm has been obtained. The decrease of the absorption bands of the reaction product at 353, 497 and 527 nm and the enhancement of the band at 582 nm are quantitatively linear to HS- concentration over the concentration range 0.02-1.543 µg mL-1 with lower limit of detection 0.019 µg mL-1. No noticeable interferences are caused by most common ions. Suitability for the assessment of HS- in complex matrices without prior treatment was shown after validation of the method according to the standards of quality assurance. The method has the advantage of high stability of the reagent and reaction product and absorbance measurements at four different wavelengths in the same run. The method is successfully applied to monitor the hydrosulfide contents in water samples. The results compare fairly well with data obtained using the standard method.