Zusammenfassung
An absorbance based calcium ion sensor is presented which applies a new immobilized chromogenic calix[4]arene. The membrane consists of a hydrogel/1,3-pentanedial mixture and the 1,3-bis(indoaniline)-derived 2,4-bis-[(ethylcarbonyl)methoxy]-calix[4]arene as calcium receptor. The indicator entrapped within the gel was not rapidly washed out. Upon calcium complexation a batho-chromic shift up to 70 ...
Zusammenfassung
An absorbance based calcium ion sensor is presented which applies a new immobilized chromogenic calix[4]arene. The membrane consists of a hydrogel/1,3-pentanedial mixture and the 1,3-bis(indoaniline)-derived 2,4-bis-[(ethylcarbonyl)methoxy]-calix[4]arene as calcium receptor. The indicator entrapped within the gel was not rapidly washed out. Upon calcium complexation a batho-chromic shift up to 70 nm was observed along with an increase of the absorption coefficient. The dynamic range of calcium measurements is from 3 to 10 mM with a point of inflection of the calibration curve at a calcium concentration of about 7 mM. The concentration of calcium ions can be calculated from either absorbance at a distinct wavelength or - preferably when indicator leaching occurs - from the wavelength shift of the absorbance occurring when calcium levels are increased.
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