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. Author manuscript; available in PMC: 2008 Apr 28.
Published in final edited form as: Anal Chem. 2002 Aug 1;74(15):420A–426A. doi: 10.1016/j.trac.2006.10.006

Figure 1.

Figure 1

Calibration curves for two types of a Ca2+-selective membrane electrode, each with two different inner solutions, as indicated. Left: ISE based on a monolithic capillary (200 μm i.d.) and a membrane solution without PVC [50]. Right: ISE with conventional plasticized PVC membrane (5 mm o.d., ca. 150 μm thickness) [50]. The EMF responses were recorded in CaCl2 solutions at pH 6.2 (successive dilutions) with 10−4 M NaCl as background electrolyte. With the conventional PVC membrane, because of ion fluxes from the membrane into the sample (inner solution 10−1 M CaCl2) or in the case of 5 × 10−2 M Na2EDTA (pH 9.0) from the sample into the membrane, LODs are less than optimal. With the monolith ISE, the composition of the inner solution has virtually no effect on the response.