Determination of sodium and potassium with ion-selective electrodes.

Abstract We compared different sample-handling techniques for measurement of Na+ and K+ with ion-selective electrodes (ISE). Imprecision was less for venous blood (with a minimum of heparin) than for plasma, serum, or capillary blood. The results for K+ were higher for serum than for whole blood, and higher for whole blood than for plasma. The latter difference was apparently due to release of K+ during the analysis. Values were more stable for whole blood stored at 20 degrees C than at 4 degrees C or 37 degrees C. The molality of Na+ in the plasma of mixed whole blood changed by -10.5 mmol/kg per unit change in blood pH. This could be explained by the different H+ buffering capacities of plasma and erythrocyte fluid, because when the pH is changed, the concentration of small anions in erythrocytes changes more than it does in plasma, with a consequent osmotic movement of water across the erythrocyte membrane. When we took into account the residual liquid-junction potential and the mass concentration of water in each of 65 patients' sera, the molality determined for Na+ was 1% lower and that of K+ 3% lower by ISE than by flame photometry--differences that may be related to ionic binding or to a lower molal activity coefficient in serum than in the calibrator.

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Influence of Erythrocytes on Direct Potentiometric Determination of Sodium and Potassium

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1177/000456328302000211 ◽

1983 ◽

Vol 20 (2) ◽

pp. 116-120 ◽

Cited By ~ 8

Author(s):

P Bijster ◽

H L Vader ◽

C L J Vink

Keyword(s):

Whole Blood ◽

Potassium Concentration ◽

Reference Electrode ◽

Sodium Concentration ◽

General Phenomenon ◽

Liquid Junction ◽

Direct Potentiometry ◽

The Difference ◽

Sodium And Potassium

We have shown that the sodium concentration in whole blood measured by direct potentiometry is higher than in plasma. The ‘erythrocyte-effect’, already described by Siggaard Andersen, is most pronounced for instruments equipped with a reference electrode with an open static liquid junction and is thus a general phenomenon. Instruments with a modified liquid junction show less interference. The same phenomenon appears for the determination of the potassium concentration, although the difference between whole blood and plasma, when measured with instruments equipped with a modified liquid junction, can be neglected in practice.

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Ion-selective electrodes for sodium and potassium: a new problem of what is measured and what should be reported.

Clinical Chemistry ◽

10.1093/clinchem/31.3.482 ◽

1985 ◽

Vol 31 (3) ◽

pp. 482-485 ◽

Cited By ~ 58

Author(s):

A H Maas ◽

O Siggaard-Andersen ◽

H F Weisberg ◽

W G Zijlstra

Keyword(s):

Activity Coefficient ◽

Theoretical Calculations ◽

Pair Formation ◽

Ion Selective Electrodes ◽

Residual Liquid ◽

Liquid Junction Potential ◽

Liquid Junction ◽

Normal Plasma ◽

Sodium And Potassium ◽

Junction Potential

Abstract For clinical purposes the activities of Na+ and K+ obtained with ion-selective electrodes in undiluted whole blood or serum should be multiplied by an appropriate factor to obtain the same values as the substance concentrations obtained by flame photometry. The factor is primarily dependent on the mass concentration of water in normal plasma divided by the molal activity coefficient of Na+ (or K+) of normal plasma. We discuss the value of the molal activity coefficient of Na+ obtained by theoretical calculations and by direct measurement. The discrepancies between theory and measurement (gamma Na+ of 0.747 and 0.73, respectively) may be due to some binding of Na+ (protein binding or ion pair formation), a small and variable residual liquid-junction potential, or certainty about the appropriate value for the ionic strength of normal plasma (0.16 mol/kg or somewhat higher).

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Direct potentiometric measurement of sodium and potassium in whole blood.

Clinical Chemistry ◽

10.1093/clinchem/23.10.1912 ◽

1977 ◽

Vol 23 (10) ◽

pp. 1912-1916 ◽

Cited By ~ 11

Author(s):

J H Ladenson

Keyword(s):

Whole Blood ◽

Potassium Concentration ◽

Residual Liquid ◽

Liquid Junction Potential ◽

Liquid Junction ◽

Significant Difference ◽

Potentiometric Measurement ◽

Capillary Liquid ◽

Sodium And Potassium ◽

Junction Potential

Abstract I compared results for sodium and potassium in whole blood and plasma as measured with a newly available potentiometric analyzer, the "Orion SS-30". No significant difference was found for either sodium or potassium in 207 such comparisons. With use of the flowing, high mixing-velocity liquid junction of the Orion SS-30, the residual liquid junction potential due to blood cells was found to be less than 0.1 mV and to be independent of the hematocrit. This is in contrast to the hematocrit-dependent residual liquid junction potential of approximately 0.6 mV noted by others at normal hematocrit values with the open capillary liquid junctions now commonly used in pH instruments. I also found that the potassium concentration can increase significantly during the mixing of whole blood, and such samples should be mixed gently, if at all. Evidently sodium and potassium can be accutately and easily measured directly in heparinized blood.

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DETERMINATION OF ALKALINITY AND DISSOCIATION CONSTANTS OF HIGH SALINITY WATERS: USE OF F5BC TITRATION FUNCTION

Eclética Química Journal ◽

10.26850/1678-4618eqj.v35.2.2010.p79-87 ◽

2018 ◽

Vol 35 (2) ◽

pp. 79

Author(s):

Bernadete F. Cavalcanti ◽

Lourdes Cristina Lucena Agostinho ◽

Luciano Nascimento

Keyword(s):

Natural Waters ◽

Dissociation Constants ◽

A Priori ◽

Linear Regression Analysis ◽

Liquid Junction ◽

Carbonate System ◽

Ph Measurements ◽

Apparent Dissociation Constant ◽

Junction Potential

Measurements of parameters expressed in terms of carbonic species such as Alkalinity and Acidity of saline waters do not analyze the influence of external parameters to the titration such as Total free and associated Carbonic Species Concentration, activity coefficient, ion pairing formation and Residual Liquid Junction Potential in pH measurements. This paper shows the development of F5BC titration function based on the titrations developed by Gran (1952) for the carbonate system of natural waters. For practical use, samples of saline watersfrom Pocinhos reservoir in Paraiba were submitted to titration and linear regression analysis. Results showed that F5BC involves F1x and F2x Gran functions determination, respectively, for Alkalinity and Acidity calculations without knowing “a priori” the endpoint of the titration. F5BC also allows the determination of the First and Second Apparent Dissociation Constant of the carbonate system of saline and high ionic strength waters.

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Lithium determinations evaluated in eight analyzers

Clinical Chemistry ◽

10.1093/clinchem/40.6.869 ◽

1994 ◽

Vol 40 (6) ◽

pp. 869-872 ◽

Cited By ~ 20

Author(s):

M Sampson ◽

M Ruddel ◽

R J Elin

Keyword(s):

Colorimetric Method ◽

Atomic Emission ◽

Ion Selective Electrodes ◽

Drug Interference ◽

Flame Atomic Absorption ◽

Analytical Recovery ◽

And Performance ◽

Mean Differences ◽

Sodium And Potassium

Abstract We compared five ion-selective electrodes (ISEs; AVL 985S, Baxter Lytening 2Z, Beckman EL-ISE, Ciba-Corning 654 Na/K/Li, and Nova CRT 11) and a colorimetric method (Ektachem) for determination of lithium with flame atomic absorption and atomic emission spectroscopy. We evaluated precision, recovery, interference by drugs (procainamide, N-acetylprocainamide, quinidine, lidocaine, carbamazepine, and valproic acid) and inorganic analytes (Na, K, Ca, Mg, and Br), and performance with sera from patients receiving lithium. Imprecision was < 5% (CV) for all analyzers except Ektachem and Beckman. Analytical recovery was 100% +/- 5% for all analyzers except Ektachem and Baxter. Some drug interference was seen with all analyzers except AVL and Corning. Calcium caused interference with AVL, Corning, and Ektachem analyzers, and sodium and potassium interfered with the Ektachem analyzer. The results with the Baxter, Beckman, and Corning analyzers were closest to those by flame atomic emission (mean differences, 0.01 to 0.02 mmol/L); the AVL and Nova analyzers gave lower results (mean differences, -0.11 to -0.13 mmol/L) and the Ektachem gave higher results (mean difference, 0.08 mmol/L).

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Determination of Total Interleukin-8 in Whole Blood after Cell Lysis

Clinical Chemistry ◽

10.1093/clinchem/46.9.1387 ◽

2000 ◽

Vol 46 (9) ◽

pp. 1387-1394 ◽

Cited By ~ 20

Author(s):

Jochen Reinsberg ◽

Jörg Dembinski ◽

Christoph Dorn ◽

Daniela Behrendt ◽

Peter Bartmann ◽

...

Keyword(s):

Whole Blood ◽

Healthy Subjects ◽

Room Temperature ◽

Sample Pretreatment ◽

Cell Lysis ◽

Interleukin 8 ◽

Simple Method ◽

Sample Handling ◽

A Cell

Abstract Background: It has been shown that a high percentage of interleukin-8 (IL-8) in blood is cell associated. Recently, a simple method for determination of cell-associated IL-8 in whole blood after cell lysis has been described. The purpose of this study was to evaluate this method, to examine the influence of preanalytic sample handling, and to establish the concentration range of total IL-8 and its relation to age and sex in healthy subjects. Methods: Total IL-8 content of whole blood was determined after lysing blood cells with Milenia® cell lysis solution. IL-8 in the resulting blood lysate was measured with the IMMULITE® IL-8 immunoassay. Results: When freshly drawn blood was stored up to 48 h on ice, no significant changes in total IL-8 were measured in the subsequently prepared lysate, whereas with storage at room temperature, total IL-8 increased after 3 h from 94 ± 13 ng/L to 114 ± 16 ng/L (n = 10). In lysate stored for 48 h at 4 °C, marginal changes of the IL-8 concentration were noted, with storage at room temperature, only 76% ± 5% (n = 12) of initial concentration was recovered. From lysate frozen at −20 and −80 °C, respectively, 84% ± 4% and 93% ± 2% of initial IL-8 was recovered after 70 days (n = 10). IL-8 was measured with comparable precision in plasma (CV, 3.2–4.2%) and blood lysate (CV, 3.7–4.1%). When plasma was diluted with cell lysis solution, a slightly overestimated recovery (125% ± 3%) was observed; for lysate specimens with a cell lysis solution content ≥75%, the recovery after dilution was 98% ± 2%. In lysate prepared from 12 blood samples with exogenous IL-8 added, IL-8 recovery was 104% ± 2% (recovery from plasma <35%). The median total IL-8 in blood lysates from 103 healthy subjects (22–61 years) was 83 ng/L of blood (2.5–97.5 percentile range, 49–202 ng/L of blood). In females but not in males, total IL-8 increased significantly with advancing age (P <0.002). We found grossly increased total IL-8 in six pregnant women with amniotic infection syndrome. Conclusions: The evaluated method allows the assessment of total IL-8 in blood with good performance when appropriate conditions of sample pretreatment are considered. The values in healthy volunteers all were above the detection limit of the IL-8 assay; therefore, slight changes of total IL-8 could be noted. Thus, the present method is a suitable tool to study the diagnostic relevance of total IL-8 in blood.

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