AI Article Synopsis
- The study focuses on developing disposable probes for measuring urea by covalently binding urease to ammonium-selective membranes.
- Two types of membranes were tested: type 1 used thin layers of cellulose acetate coated on PVC membranes, while type 2 used a blend of PVC and cellulose acetate.
- Type 1 membranes showed better performance, with a detection range for urea from 2 x 10(-5) to 0.01 M and a sensitivity of 50 mV/decade, compared to type 2 which was negatively affected by sodium periodate treatment.
Article Abstract
As part of the development of disposable urea bioselective probes, the covalent binding of urease on ammonium-selective potentiometric membranes has been assessed. Nonactin/bis(1-butylpentyl)adipate/poly(vinylchloride) (PVC) membranes, directly applied to an internal solid contact (conductive epoxy-graphite composite), has been used as a support for covalent immobilization of urease. Two types of all-solid-state construction process have been assayed: thin layers of cellulose acetate (CA) were coated on the PVC ammonium-selective membranes (type 1) and blends of PVC and CA at various ratios were used as ammonium-selective membrane matrices (type 2). Urease was covalently attached to CA via aldehyde groups. These groups were created on the polysaccharide with sodium periodate to which the enzyme was immobilized through a spacer (hexamethylenediamine). The viability of both types of probe for the determination of ammonium ions was assessed after each step of the activation process. Results indicated that type 2 potentiometric probes are altered after the treatment with sodium periodate. Good results were obtained with type 1 probes. Their dynamic concentration range of response to urea was from 2 x 10(-5) to 0.01 M with a sensibility of 50 mV/decade.
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| http://dx.doi.org/10.1016/0956-5663(92)85022-3 | DOI Listing |
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