Home
Resources
Publications
Determination of Water Uptake of Polymeric Ion-Selective Membranes With the Coulometric Karl Fischer and FT-IR-attenuated Total Reflection Techniques

Determination of Water Uptake of Polymeric Ion-Selective Membranes With the Coulometric Karl Fischer and FT-IR-attenuated Total Reflection Techniques

Ning He, Tom Lindfors

Anal Chem. 2013 Jan 15;85(2):1006-12.

PMID: 23249325

Abstract:

The water uptake of plasticized poly(vinyl chloride) (PVC) and silicone rubber (SR) based calcium-selective membranes which are commonly used in solid-contact and coated-wire ion-selective electrodes (SC-ISEs and CWEs) was quantified with the oven based coulometric Karl Fischer (KF) technique. Two different membrane types were studied: (1) the plasticized PVC or SR (RTV 3140) membrane matrix without other added membrane components and (2) the full Ca(2+)-selective membrane formulation consisting of the membrane matrixes, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate and calcium ionophore IV (ETH 5234) or calcium ionophore I (ETH 1001). The membranes were contacted for 24 h either asymmetrically from one side or symmetrically from both sides with deionized water (DIW) or 0.1 M solutions of CaCl(2), KCl, or NaCl. It was found that the water uptake was higher for symmetrically contacted membranes. The highest water uptake (0.15-0.17 wt %) was obtained for the plasticized PVC based Ca(2+)-selective membranes in DIW, whereas the water uptake was lower in 0.1 M electrolyte solutions. Symmetrically contacted Ca(2+)-selective SR membranes had much lower water uptake in 0.1 M CaCl(2) (0.03 wt %) than their plasticized PVC counterparts (0.1 wt %). However, the (noncontacted) SR membranes contained initially much more water (0.09-0.15 wt %) than the PVC membranes (0.04-0.07 wt %). Furthermore, in good accordance with the KF measurements, it was verified with FT-IR-attenuated total reflection (ATR) spectroscopy that the water content at the substrate/membrane interface and consequently in the whole membrane was influenced by the electrolyte solution.

Chemicals Related in the Paper:

Catalog Number	Product Name	CAS Number	Price
AP126572745	Calcium ionophore IV	126572-74-5	Price
AP135463068	Potassium ionophore IV	135463-06-8	Price
AP187404677	Chloride ionophore IV	187404-67-7	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: