IONIC MOBILITY TABLES

For general information about the liquid junction potential calculator and LJP calculations, or for other information about such calculations and mobility values, click here

 

Please Note:  In the original printed article on Liquid Junction Potential Corrections in AxoBits 39, there was a sign error in our article for some of the examples of the correction BEFORE an experiment.  These were later corrected in the downloadable pdf version of the article and have been available on the Axon website ( http://www.axon.com/axobits/AxoBits39.pdf or click on  AxoBits39New.pdf.)Also, click on above link (Application .....) to see the principles involved.

 

N.B.   The tables below went through a major update on Oct. 23, with further additions on Oct. 29, 2003 and May 2012.

 

Some additional comments were also added in August 2005

 

LISTING OF SUPPLIED IONIC MOBILITIES WITH FULL ION NAMES FOR THE PROGRAM JPCalc/JPCalcW

 The following table of relative (generalised) mobility values (relative to K+; see Appendix below for more information and relationship to limiting equivalent conductivities) was extracted from Table 1 of Barry & Lynch1, with a slightly amended value for choline following later direct measurements (Ng & Barry4).  A supplementary list of other ionic mobilities is given in Table 2.

For information about what ion concentrations or activities to use in calculations click on Ion Concentrations etc.

Note that a number of values in the tables of Lange (2) and CRC (7) have been updated in their most recent editions,  currently listed in the references.  Where these differ from the values previously listed and incorporated in JPCalc, the new updated values are now listed below in blue. These differences are invariably small.

TABLE 1.  THESE IONS ARE CURRENTLY INCLUDED IN THE JPCalc/JPCalcW AND JUNCTION POTENTIAL CALCULATOR (in AXON'S pCLAMP) PROGRAMS

Symbolic Ion Name

 Full Ion Name/Formula

 Valency

Relative Mobility

Updated

value

Ref. for new value

Chol

Choline

1

0.51

   

Cs

Cesium

1

1.050

   

K

Potassium

1

1.000

   

Li

Lithium

1

0.525

0.526

2,7

NH4

Ammonium

1

1.000

1.001 2,7 (avr)

Na

Sodium

1

0.682

   

Rb

Rubidium

1

1.059

   

TEA

TetraethylAmmonium

1

0.444

   

TMA

TetramethylAmmonium

1

0.611

   

Acet

Acetate

-1

0.556

   

Benz

Benzoate

-1

0.441

   

Br

Bromide

-1

1.063

   

Cl

Chloride

-1

1.0388

1.0382 2,7

ClO4

Perchlorate

-1

0.916

   

F

Fluoride

-1

0.753

   

H2PO

H2PO4

-1

0.450

   

HCO3

HCO3

-1

0.605

   

I

Iodide

-1

1.0450

1.0456 2,7 (avr)

NO3

Nitrate

-1

0.972

   

Picr

Picrate

-1

0.411

   

Prop

Propionate

-1

0.487

   

SCN

Thiocyanate

-1

0.900

0.901 2,7 (avr)

Sulf

Sulfonate

-1

0.586

now deleted 2

Ba

Barium

2

0.433

0.434 2,7 (avr)

Ca

Calcium

2

0.4048

   

Co

Cobalt

2

0.370

0.367 2,7 (avr)

Mg

Magnesium

2

0.361

   

Sr

Strontium

2

0.404

   

Zn

Zinc

2

0.359

   

HPO4

HPO4

-2

0.390

   

SO4

Sulphate

-2

0.544

   

For values of some other ions, see Table 1 of Barry & Lynch1 and Table 2 following and Refs. 2, 6 and 7.

 

 TABLE 2: SUPPLEMENTARY LISTING OF MOBILITIES WITH FULL ION NAMES FOR THE PROGRAM JPCalc/JPCalcW

 The following table of relative mobility values was extracted from Ng and Barry4 and Keramidas et al.3

Symbolic Ion Name

 Full Ion Name/Formula

 Valency

Relative mobility

NMDG

NMDG

+1

0.33

Tris

Tris

+1

0.40

Asp

Aspartate

-1

0.30

gluc

Gluconate

-1

0.33

Glu

Glutamate

-1

0.26

HEPE

HEPES

-1

0.30

ise

Isethionate

-1

0.52

MES

MES

-1

0.37

MOPS

MOPS

-1

0.35

EGT2

EGTA(2-)

-2

0.24

EGT3

EGTA(3-)

-3

0.25

where the following standard abbreviations apply: NMDG, N-methyl-D-glucamine; Tris, tris[hydroxymethyl]aminomethane; HEPES, N-[2-hydroxyethyl]piperazine-N’-[2-ethanesulfonic acid]; MOPS, 3-[N-morpholino]propanesulfonic acid; MES, 2-[N-morpholino]ethanesulfonic acid.  The estimated error in the measurements from Ng and Barry4 was considered to be less than about 0.005.  EGTA(2-) and EGTA(3-) are from Keramidas et al.3

 

TABLE 3.  ADDITIONAL LISTING OF MOBILITIES WITH FULL ION NAMES FOR THE PROGRAM JPCalc/JPCalcW

 The following table of relative mobility values was calculated from limiting equivalent conductivities in the references below. 

Symbolic Ion Name

 Full Ion Name/Formula

 Valency

Relative mobility

Reference

Tl

Thallium

+1

1.02

7

Butr Butyrate -1 0.44 7
Citr Citrate (3-) -3 0.318 2
2MAEth 2-(Methyl-Amino) Ethanol  (or N-Methylethanolamine) +1 0.490 ± 0.018 8

 

TABLE 4.  FURTHER LISTING OF RELATIVE ION MOBILITIES  (ADDED IN OCTOBER 2003)

Symbolic ion name

Full ion name / formula

Valency

Relative mobility

Ref

Ag

Silver

+1

0.842

2,7

 

Diethylammonium

+1

0.57

2,7

 

Dimethylammonium

+1

0.701, 0.705

2,7

 

Ethyltrimethylammonium

+1

0.551

2,7

H

Hydrogen

+1

4.763, 4.757

2,7

 

Piperidinium

+1

0.506

2,7

 

Tetrabutylammonium

+1

0.265

2,7

 

Tetrapropylammonium

+1

0.320, 0.318

2,7

 

Triethylammonium

+1

0.467

7

 

Trimethylammonium

+1

0.642, 0.643

2,7

 

Bromoacetate

-1

0.533

2,7

 

Bromobenzoate

-1

0.41

2,7

 

Chloroacetate

-1

0.574, 0.541

2,7

C N O

Cyanate

-1

0.879

7

 

Cyanoacetate

-1

0.590

2,7

 

Dichloroacetate

-1

0.521

2,7

 

Ethylsulfate

-1

0.539*

7

 

Ethylsulfonate

-1

0.539*

2

 

Fluoroacetate

-1

0.604

2,7

 

Fluorobenzoate

-1

0.45

2,7

 

Formate

-1

0.743

2,7

 

Iodoacetate

-1

0.552

2,7

 

Lactate

-1

0.528

2,7

 

Methylsulfate

-1

0.664*

7

 

Methylsulfonate

(pseudonym = methanesulfonate)

-1

0.664*

2

OH

Hydroxide

-1

2.69

2,7

ReO4

Rhenate

-1

0.747

2,7

 

Salicylate

-1

0.49

2,7

 

Trichloroacetate

-1

0.498, 0.476

2,7

Cd

Cadmium

+2

0.37

2,7

Cu

Copper

+2

0.385, 0.365

2,7

Fe

Iron

+2

0.36, 0.37

2,7

Hg

mercury

+2

0.433

2,7

Mn

Manganese

+2

0.364

2,7

Ni

Nickel

+2

0.340, 0.337

2,7

Pb

Lead

+2

0.48

2,7

 

Malate

-2

0.400

2,7

 

Maleate

-2

0.421

7

 

Oxalate

-2

0.504

2,7

 

Succinate

-2

0.400

2,7

Gd Gadolinium +3 0.306, 0.305 2,7
Fe Iron +3 0.313, 0.308 2,7
La Lanthanum +3

0.316

2,7
Citr Citrate -3

0.318

2,7
ATP Adenosine 5'-Triphosphate -2, -3 or -4**

0.15***

9

*Note that both  methylsulfate ( Ref. 7) and methylsulfonate (Ref. 2) had identical limiting equivalent conductances. 

 The same was also true of ethylsulfate ( Ref. 7) and ethylsulfonate (Ref. 2).  This may mean that, in each case, one of

 the values was incorrectly copied from the other and is wrong.

**The relative proportions of each valency species depends on pH and the ionic composition of the solution.

***uATP/uK was calculated from the value of 3.0x10-6 cm2.s-1 for the diffusion coefficient of ATP in free solution (Ref. 9). 

 

TABLE 5  LISTING OF RELATIVE ION MOBILITIES OF AMINOPYRIDINES (ADDED MAY 2012)

Symbolic ion name

Full ion name / formula

Valency

Relative mobility

Ref

 

 

 

 

 

2-AP

2-aminopyridine

+1

0.45

10,11*

3-AP

3-aminopyridine

+1

0.46

10,11*

4-AP

4-aminopyridine

+2

0.29

11**

*Calculated from the relative limiting equivalent conductivities of 2-AP and 3-AP to that of K+ in both the paper (Ref 10) and  PhD thesis (Ref 11), where both are in agreement.

**Calculated only from the relative limiting equivalent conductivity value in the thesis (Ref. 11), which the author considered to be more correct, in contrast to multiple errors in the paper (R. Foley,  personal communication), which in this case a simple transposition error would have reduced the relative mobility of 4-AP right down to 0.17.

 

REFERENCES FOR MOBILITY AND LIMITING EQUIVALENT CONDUCTIVITY DATA

1. Barry, P.H. and Lynch, J.W. (1991).  Topical Review.  Liquid junction potentials and small cell effects in patch clamp analysis.  J. Membrane Biol.  121: 101-117.

2.  Dean, J.A.. (1999). Lange’s Handbook of Chemistry, 15th Edition, McGraw-Hill, New York.

3.  Keramidas, A., Kuhlmann, L., Moorhouse, A.J. and Barry, P.H. (1999). Measurement of the limiting equivalent conductivities and mobilities of the most prevalent ionic species of EGTA (EGTA2- and EGTA3-) for use in electrophysiological experiments.  J. Neurosci. Method., 89: 41-47.

4. Ng, B. and Barry, P.H. (1995).  The measurement of ionic conductivities and mobilities of certain less common organic anions needed for junction potential corrections in electrophysiology. J. Neurosci. Method., 56: 37-41.

5. Robinson, R.A. and Stokes, R.H. (1965).  Electrolyte Solutions. (2nd ed.revised), Butterworth's, London.

6. Zuidema, T., Dekker, K. and Siegenbeek van Heukelom, J. (1985).  The influence of organic counterions on junction potentials and measured membrane potentials. Bioelectrochem. Bioenerget., 14: 479-494.

7. Vanysek, P. (2002).  Ionic conductivity and diffusion at infinite dilution.  In: CRC Handbook of Chemistry and Physics (83rd  Edn; ed. D.R. Lide), CRC Press, Boca Raton.

8. Shapovalov, G. and Lester, H. (Division of Biology, Caltech, Pasadena, CA, USA). Personal communication (2001). Average of 4 measurements at pH 7.0.  Ion information: MW 75.11, Molecular Formula: C3H9NO, Structural Formula:  HOCH2CH2NHCH3, CAS: 109-83-1, MDL Number: MFCD00002839, pKa = 9.40.

9. Diehl, H., Ihlefeld, H., and Schwegler, H. (1991).  Physik fur Biologen.  Springer-Verlag, Berlin, p. 391 (also available at WWW site: http://ishtar.df.unibo.it/cgi-def/Ever?tabelle), quoted by Rostovtseva, T.K. and Bezrukov, S.M. (1998), Biophys. J., 74: 2365-2373.

10. Haddad, P.R. and Foley R.C. (1989).  Aromatic bases as eluent components for conductivity and indirect ultraviolet absorption detection of inorganic cations in nonsuppressed ion chromatography.  Anal. Chem. 61: 1435-1441.

11. Foley, R. (1990).  Studies on detection and retention characteristics of ionorganic cations in non-suppressed ion chromatography.  PhD Thesis, 1990, The University of New South Wales, Sydney, Australia (Chapter 6, P. 126).

 

 

Acknowledgement

The assistance of Jennifer Anderson in sourcing the new reference editions and in compiling the new mobility data for the 2003 update has been greatly appreciated.

 

Application of Junction Potential Corrections before an experiment.  

Although we prefer to recommend applying liquid junction potential corrections after an experiment, another option that some people prefer is to do it at the beginning of the experiment.  This is OK provided there are no solution changes during the experiment and the correction is applied correctly.  The way this is done can be a bit confusing. Click on the above link (Application .....) to see how these corrections should be applied.  Please also note link to updated (corrected) version of the junction potential calculations article in AxoBits 39 ( http://www.axon.com/axobits/AxoBits39.pdf or click  AxoBits39New.pdf.).

 

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P. H. Barry, May, 2012