TABLE 18.1

Selectivities, Concentration-Dependent Slopes and Response Times for the LIXs Used in a Self-Referencing Mode

Calcium
Fluka calcium ionophore I-Cocktail A. It has the following selectivity values determined by the fixed interference method:
log KCaNaPot−5.5
log KCaKPot−5.4
log KCaMgPot−4.9
Electrode function: Slope of the linear regression is 28.1 +/− 1.8mV (10−2 to10−7 CaCl2 determined in calcium buffered solutions at a constant background of 125mM K+). With a tip diameter between 1–2μm the expected resistance is in the range of 2×1010 Ω. Data from Fluka (1996). In our applications with larger tips(2–4μm) and short column lengths (30μm) we record a resistance of 2 3×109 Ω . Response times evaluated at the BRC give a mean value of 48ms to 90% response (see below)
Chloride
Fluka chloride ionophore 1-Cocktail A. It has the followings electivity factors as determined by the separate solution method:
log KClHCO3Pot−1.5[31]
−0.9[32]
log KClAcetatePot−1.3[31]
−1.2[32]
log KCIGlutamatePot−3.2[32]
log KCIGlutamatePot−3.0[32]
log KClCitratePot−1.6[32]
log KClThiosulfatePot−0.8[32]
log KClSO4Pot−2.6[31]
log KClSCNPot3.4[31]
log KClSalicylatePot3.0[31]
Electrode function: Slope of the linear regression is 57.5+/−0.5 mV (0.001–0.5 M NaCl on 0.01M Tris/H2SO4, pH 7.4). The resistance for an approximately 1 μm tip will be in the region of 7×1010 Ω. These data are taken from [31]. The 90% response time is given as 1.8s [32]
Hydrogen
Fluka hydrogen ionophore 1-Cocktail B. It has the followings electivity factors determined by the fixed interference method:
log KHNaPot−10.4
log KHKPot−9.8
log KHCaPot< −11.1
Electrode function: Slope of the linear regression is 58.0+/−0.4mV pH range5.5–12.0. The resistance for an approximately1 μm tip will be in the region of 1×1011Ω. These data are taken from [31]
Response times evaluated at the BRC give a mean value of 88ms to90%.
Potassium
This cocktail has the following selectivity values based on the separate solution method:
log KKLiPot−4.2
log KKNaPot−3.9
log KKMgPot−4.6
log KKCaPot−4.9
log KKAcetylcholinePot−4.9
Electrode function: Slope of the linear regression is 58.8 +/− 1.2 mV (20°C:10−4 to10−1). The detection limit of this ionophore is given as log aK = −5.0 against 140 mM Na+. These data are from [31]. The response time to 95% is 41 77 ms depending on the change in concentration [14]
Cadmium
These data are taken from Pineros et al. (1996). Reference should be made to this paper for ISE preparation and testing. Selectivity based on the separate solutions method:
log KCdZnPot−2.9
log KCsPbPot−4.6
log KCdCuPot−4.8
log KCdMnPot−5.2
log KCdFePot−8.6
log KCdNiPot−10.4
log KCdCaPot−10.8
log KCdMgPot−12.2
log KCdNH4Pot−6.2
log KCsNaPot−7.1
log KCdKPot−7.9

From: Chapter 18, Principles, Development and Applications of Self-Referencing Electrochemical Microelectrodes to the Determination of Fluxes at Cell Membranes

Cover of Electrochemical Methods for Neuroscience
Electrochemical Methods for Neuroscience.
Michael AC, Borland LM, editors.
Boca Raton (FL): CRC Press/Taylor & Francis; 2007.
Copyright © 2007, Taylor & Francis Group, LLC.

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