New fiber optic competible chromoionophore/matrix combinations for hco3- analysis in real groundwater samples

Dissolved and gaseous carbon dioxide is an important parameter in water samples, industrial, biochemical and medical applications. Mostly, correct analysis of gaseous and dissolved carbon dioxide is difficult due to the matrix effects. Here we intended to investigate new approaches for optical analysis of dissolved carbon dioxide in groundwater samples. Our investigations focused on newly synthesized choromoionphores or their combination with new matrix materials. We performed their spectral chacterization in transperent polymers and tested their compatibility to solid state optics.In this work, the ion pair form of pH indicator dye, 8-hydroxypyrene-1,3,6-trisulfonicacidtrisodiumsalt was used for the gaseous CO2 detection. Poly (methyl methacrylate) and ethyl cellulose were used as polymeric materials. Sensing slides were fabricated by electrospinning technique. In this sensor design, the response time, reversibility, linear concentration range and repeatability characteristics also have been studied. Similarly newly synthesized dyes N'-[(E)-(9-methyl-9H-carbazol-3-yl) methylidene] pyridine-4-carbohydrazide and N'-{(1E, 2E)-3-[4-(dimethylamino) phenyl] prop-2-en-1-ylidene} pyridine-4-carbohydrazide were characterized by spectroscopic ways in thin film or nanofiber form in the ethyl cellulose and poly (methyl methacrylate) polymers. Acidity constant and quantum yield calculations of the employed dyes were performed in the conventional solvents and/or in the solid matrices. Their fluorescence based response to dissolved CO2 were examined both in thin film and nanofiber form. Their cross sensitivities to anions, metal cations were tested.The indicator dyes namely N'-[(E)-(2-hydroxyphenyl) methylidene] pyridine-4-carbohydrazide (MY2), N'-[(E)-(3-hydroxyphenyl) methylidene] pyridine-4-carbohydrazide (MY4), N'-[(E)-(4-nitrophenyl) methylidene] pyridine-4-carbohydrazide (MY5), were spectroscopically chacterized and offered for emission based analysis of bicarbonate anion. Acidity constant values of three indicator dyes were calculated and cross sensitivities to other cations and anions were also tested and evaluated.Bicarbonate analysis in groundwater samples was performed by spectrophotometric and volumetric (indicator and potentiometric) methods. Obtained results were compared with proposed method.