Use of ion-selective electrodes for blood-electrolyte analysis. Recommendations for nomenclature, definitions and conventions. International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Scientific Division Working Group on Selective Electrodes.

This paper will familiarize the reader with the terms used to describe the behavior of ion-selective electrodes, particularly in relation to their use in clinical chemistry for determination of blood electrolyte cations. It serves as an introduction to a series of papers dealing with important cations in blood, namely calcium, sodium, and potassium. The detailed relationships between the ion activity determined by means of ion-selective electrode potentiometry in undiluted specimens, and the total substance concentration measured by flame atomic-emission spectrometry are described by flow chart and equations. Adoption of a convention for reporting results is recommended. The Working Group on Selective Electrodes has taken into account recent revisions of IUPAC recommendations on nomenclature and selectivity coefficient determinations for ion-selective electrodes, and benefited from the experience of a member of the WG, who was also involved in the IUPAC discussions. Nomenclature for determined quantities follows previous IUPAC/IFCC joint recommendations.

IFCC recommended reference method for the determination of the substance concentration of ionized calcium in undiluted serum, plasma or whole blood.

A reference method is described for the determination of the substance concentration of ionized calcium in plasma by which ionized calcium (free or unbound) may be reliably determined on the basis of calibration with aqueous solutions with known concentration of ionized calcium. The composition of the calibration solutions is chosen such that the activity coefficient of the calcium ion is assumed to be identical both in the calibration solutions and in "normal" plasma, i.e. by convention, the ionic strength (Im) is 0.160 mol/kg. The convention is adopted of reporting ionized calcium measurements as concentration expressed as mmol/l. The proposed reference method for ionized calcium measurement in plasma is based on the use of a cell consisting of an external reference electrode with a saturated potassium chloride liquid/liquid junction in combination with a calcium ion-selective membrane electrode of defined construction and performance. Procedures for using the reference cell and a protocol for sample measurement are described. The preparation of the calibration solutions to be used are described in detail in Appendix A, secondary calibration solutions and check standards in Appendix B, and reference cell vessel design in Appendix C.

Recommendations for measurement of and conventions for reporting sodium and potassium by ion-selective electrodes in undiluted serum, plasma or whole blood. International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). IFCC Scientific Division Working Group on Selective Electrodes.

Ion-selective electrodes (ISEs) respond to ion-activity and therefore do not sense substance concentration directly. However, it is recognized that sodium and potassium in plasma will continue to be expressed for clinical purposes in terms of substance concentration (mmol/l). A convention is proposed whereby for routine clinical purposes results of ISE measurements of sodium and potassium in undiluted plasma should be reported in terms of substance concentration (mmol/l). In specimens with normal concentrations of plasma water, total CO2, lipids, protein and pH, the values will concur with the total substance concentration as determined for example by flame atomic emission spectrometry (FAES) or ISE measurements on diluted samples. In specimens with abnormal concentrations of plasma water, the results will differ. However, under these circumstances, measurements of sodium and potassium by ISE in the undiluted sample will more appropriately reflect the activity of sodium and potassium and are therefore clinically more relevant than the determination in diluted samples. Detailed recommendations are made about practical procedures to achieve this. The recommended name for this quantity is the substance concentration of ionized sodium or ionized potassium in plasma, as opposed to total sodium or total potassium determined by, e.g. FAES, or ISE measurements on diluted samples.

International Federation of Clinical Chemistry (IFCC). Recommendation on mean molar activity coefficients and single ion activity coefficients of solutions for calibration of ion-selective electrodes for sodium, potassium and calcium determination.

In principle, flame photometry measures substance concentration, and ion-selective electrodes (ISEs) measure ion activity. However, the situation regarding the comparison of results from the two techniques when applied to blood plasma is complex. The problem can be approached experimentally from the point of view of calibration of ion-selective electrodes with concentration calibrators, and similar procedures are adopted for commercial ISE-based clinical analysers. Nevertheless, there is interest in the evaluation of single ion activities in blood plasma and solutions simulating its ionic composition. Solutions are proposed for calibrating ion-selective electrodes for the determination of sodium, potassium and calcium. It is recommended that the values for single ion activities derived from the Pitzer treatment of mixed electrolyte solutions be adopted, because, although this has some empirical features, it has a sounder theoretical basis than the previously used Stokes-Robinson-Bates hydration approach.

Recomendações para coleta, transporte e armazenamento de sangue total para determinações simultâneas de PH, gases e eletrólitos / Recommendations on whole blood sampling, transport and storage for simultaneous determination of PH, blood gases and electrolytes

As variáveis pré-analíticas: coleta, transporte e armazenamento, podem contribuir significativamente para a imprecisão dos valores de pH, gasometria e eletrólitos. A International Federation of Clinical chemistry (IFCC), através de seus comitês em pH, Gases Arteriais e eletrólitos, tem publicado recomendações específicas com o intuito de minimizar os efeitos indesejáveis das variáveis pré-analíticas. Estes comitês se basearam na experiências de seus próprios membros, como também em artigos publicados por outros. Especificamente, os comitês têm incluído rotinas e sugestões confeccionadas pelos: IFCC Working Group on Selective Electrodes (WGSE), National Committee on Clinical Laboratory Standards (NCCLS), Eletrolyte/Blood Gás Division of the American Association for Clinical Chemistry (AACC). Este artigo irá familiarizar o leitor com os efeitos de diferentes tipos de frascos e anticoagulantes. Também serão discutidos aspectos importantes dos procedimentos de coleta, incluindo o estado do paciente e as precauções especiais a serem tomadas quando utilizam-se catéteres ou cânulas para a coleta. Serão vistos também as diferentes normas para o armazenamento e tranporte das amostras, para as análises gasométrica e eletrolítica.

International Federation of Clinical Chemistry (IFCC), Committee on pH, Blood Gases and Electrolytes: approved IFCC recommendation on definitions of quantities and conventions related to blood gases and pH.

Terminology in blood pH and gas analysis can be confusing, both because more than one name has been used for the same quantity, and because the same name has been used for more than one quantity. In addition, several calculated quantities are commonly used, but in some cases many different algorithms have been published for a single quantity. This document contains definitions of the most useful quantities in blood pH and gas analysis, and presents algorithms for the most useful calculated quantities. Use of these should lessen confusion among users and should also result in data that are more comparable among laboratories.

International Federation of Clinical Chemistry (IFCC). Scientific Division. Committee on pH, Blood Gases and Electrolytes. Approved IFCC recommendations on whole blood sampling, transport and storage for simultaneous determination of pH, blood gases and electrolytes.

Pre-analytical variables, e.g., specimen collection, transport, and storage, can contribute significantly to inaccurate pH, blood gas, and electrolyte values. The International Federation of Clinical Chemistry (IFCC), through its Committee on pH, Blood Gases and Electrolytes, has developed specific recommendations to minimize the undesirable effects of pre-analytical variables. The Committee has drawn upon the experiences of its own members as well as published data by others. Specifically, the Committee has included pertinent guidelines and suggestions by the IFCC Working Group on Selective Electrodes (WGSE), the National Committee on Clinical Laboratory Standards (NCCLS), and the Electrolyte/Blood Gas Division of the American Association for Clinical Chemistry (AACC). This paper will familiarize the reader with the effect of different types of specimen containers and anticoagulants. It discusses important aspects of specimen collection procedures including patients status and special precautions during specimen collection from indwelling catheters or cannulae. The paper also identifies different requirements in storage and transport of specimens for blood gas and electrolyte analysis.

Recommendations on whole blood sampling, transport, and storage for simultaneous determination of pH, blood gases, and electrolytes. International Federation of Clinical Chemistry Scientific Division.

Pre-analytical variables, e.g., specimen collection, transport, and storage, can contribute significantly to inaccurate pH, blood gas, and electrolyte values. The International Federation of Clinical Chemistry (IFCC), through its Committee on pH, Blood Gases and Electrolytes, has developed specific recommendations to minimize the undesirable effects of pre-analytical variables. The Committee has drawn upon the experiences of its own members as well as published data by others. Specifically, the Committee has included pertinent guidelines and suggestions by the IFCC Working Group on Selective Electrodes (WGSE), the National Committee on Clinical Laboratory Standards (NCCLS), and the Electrolyte/Blood Gas Division of the American Association for Clinical Chemistry (AACC). This paper will familiarize the reader with the effect of different types of specimen containers and anticoagulants. It discusses important aspects of specimen collection procedures including patient status and special precautions during specimen collection from indwelling catheters or cannulae. The paper also identifies different requirements in storage and transport of specimens for blood gas and electrolyte analysis.

Recommendation on sampling, transport, and storage for the determination of the concentration of ionized calcium in whole blood, plasma, and serum. IFC Scientific Division, Working Group on Ion-Selective Electrodes (WGSE).

The substance concentration of ionized calcium (cCa 2+) in blood, plasma, or serum preanalytically may be affected by pH changes of the sample, calcium binding by heparin, and dilution by the anticoagulant solution. pH changes in whole blood can be minimized by anaerobic sampling to avoid loss of CO 2, by measuring as soon as possible, or by storing the sample in iced water to avoid lactic acid formation. cCa 2+ and pH should be determined simultaneously. Plasma or serum: If centrifuged in a closed tube and measured immediately, the pH of the sample will be close to the original value. If there has been a delay between centrifugation and measurement, causing substantial loss of CO 2, equilibration of the sample with a gas mixture corresponding to pCO 2 = 5.3 kPa prior to the measurement is recommended. Conversion of the measured values to cCa 2+ (7.4) is only valid if the pH is in the range 7.2-7.6. Ca 2+ binding by heparin can be minimized by using either of the following: 1) a final concentration of sodium or lithium heparinate of 15 IU/mL blood or less; or 2) calcium-titrated heparin with a final concentration of less than 50 IU/mL blood. Dilution effect can be avoided by use of dry heparin in capillaries or syringes.(ABSTRACT TRUNCATED AT 250 WORDS)

Dependence of measured ionized calcium on protein concentration as measured by three ion-selective electrodes.

A positive effect of protein on the measurement of ionized calcium in serum by ion-selective electrodes (ISEs) has been previously reported and the present study confirms this finding. Ionized calcium in serum was measured in the presence of increasing protein concentrations induced by venous stasis in 17 healthy volunteer subjects. Ionized calcium was measured using two commercial analysers, a Radiometer ICA2 analyser and a Baker Analyte+2 analyser, and a calcium cell devised by Covington for the calcium reference method (CRM). Both commercial analysers used charged ionophores and the CRM used a neutral carrier ionophore in the selective membrane. A small but significant rise in ionized calcium with increasing protein was measured on all analysers. Substitution of isotonic KCl for saturated KCl in the reference electrode of the CRM resulted in significantly reduced values for ionized calcium in paired serum samples when measured using the isotonic salt bridge. This study supports the premise that the positive effect of protein is related to the salt bridge concentration of the reference electrode rather than the ISE membrane composition.

International Federation of Clinical Chemistry (IFCC), scientific division: IFCC recommendation on sampling transport and storage for the determination of the concentration of ionized calcium in whole blood, plasma and serum.

The substance concentration of ionized calcium (cCa2+) in blood, plasma or serum preanalytically may be affected by pH changes of the sample, calcium binding by heparin, and dilution by the anticoagulant solution. pH changes in whole blood can be minimized by anaerobic sampling to avoid loss of CO2, by measuring as soon as possible or by storing the sample in iced water to avoid lactic acid formation. cCa2+ and pH should be determined simultaneously.

Guidelines for routine measurement of blood hemoglobin oxygen affinity. IFCC Scientific Division, Committee on pH, Blood Gases, and Electrolytes.

Two methods for the routine determination of blood hemoglobin oxygen affinity are described. Both methods use whole blood and do not require special equipment, tonometry, or special gas mixtures. The first method consists of a one-point determination of p 50, and requires only 200 muL to 400 muL of whole blood, therefore making it suitable for the pediatric population. The second method uses multiple points, thereby establishing both the shape and position of the hemoglobin oxygen equilibrium curve between 10 and 99% oxygen saturation. Interpretation of p 50 is discussed in relation to evaluation of patients with hemoglobinopathies and as a parameter in estimating availability of oxygen to the tissues.

Comparative performance of 14-crown-4 derivatives as lithium-selective electrodes.

A series of neutral ionophore-based lithium-selective liquid-membrane electrodes have been prepared and the electrode performance compared with similar electrodes based on the lithium ionophores ETH 1810-ortho-nitrophenyl octyl ether (oNPOE) and ETH 2137-bis(1-butylpentyl) adipate (BBPA). By using a diamide substituted 14-crown-4 macrocycle, selectivities for Li+ in the presence of Na+ of log kpotLi,Na = -3.25 and -2.92 were obtained for diisobutylamide-oNPOE and di-n-butylamide-oNPOE derivatives. The di-n-butylamide-oNPOE based electrode functioned satisfactorily in serum, exhibiting a fast response time (10-15 s), an acceptable lifetime of 50 d and minimal protein interference.

IFCC recommendation on sampling, transport and storage for the determination of the concentration of ionized calcium in whole blood, plasma and serum.

The substance concentration of ionized calcium (c(Ca) (2+)) in blood, plasma or serum preanalytically may be affected by pH changes of the sample, calcium binding by heparin, and dilution by the anticoagulant solution.pH changes in whole blood can be minimized by anaerobic sampling to avoid loss of Co(2), by measuring as soon as possible, or by storing the sample in iced water to avoid lactic acid formation. c(Ca) (2+) and pH should be determined simultaneously.PLASMA OR SERUM: If centrifuged in a closed tube, and measured immediately, the pH of the sample will be close to the original value. If a delay has occurred between centrifugation and the measurement, causing substantial loss of Co(2), equilibration of the sample with a gas mixture corresponding to pCO2= 5.3 kPa prior to the measurement is recommended. Conversion of the measured values to c(Ca) (2+) (7.4) is only valid if the pH is in the range 7.2-7.6.Ca(2+) binding by heparin can be minimized by using either of the following:(1) A final concentration of sodium or lithium heparinate of 15 IU/ml blood or less(2) Calcium titrated heparin with a final concentration of less than 50 IU/ml blood.Dilution effect can be avoided by use of dry heparin in capillaries or syringes. When heparin solutions are used, errors due to dilution or calcium binding can be reduced by using syringes with a heparin solution containing free calcium ions corresponding to the mean concentration of ionized calcium in normal plasma.Conditions for blood collection, storage, and transport to avoid preanalytical errors are described in this paper.

International Federation of Clinical Chemistry (IFCC) scientific division IFCC recommendation. Recommendation on sampling, transport and storage for the determination of the concentration of ionized calcium in whole blood, plasma and serum.

The substance concentration of ionized calcium (cCa2+) in blood, plasma or serum preanalytically may be affected by pH changes of the sample, calcium binding by heparin, and dilution by the anticoagulant solution. pH changes in whole blood can be minimized by anaerobic sampling to avoid loss of CO2, by measuring as soon as possible or by storing the sample in iced water to avoid lactic acid formation. cCa2+ and pH should be determined simultaneously. Plasma or serum: if centrifuged in a closed tube and measured immediately the pH of the sample will be close to the original value. If delay has occurred between centrifugation and the measurement, causing substantial loss of CO2, equilibration of the sample with a gas mixture corresponding to PCO2 = 5.3 kPa prior to the measurement is recommended. Conversion of the measured values to cCa2+ (7.4) is only valid if the pH is in the range 7.2-7.6 Ca2+ binding by heparin can be minimized by using either of the following: a final concentration of sodium or lithium heparinate of 15 IU/ml blood or less, by use of calcium titrated heparin with a final concentration less than 50 IU/ml blood. Dilution effect can be avoided by use of dry heparin in capillaries or syringes. When heparin solutions are used errors due to dilution or calcium binding can be reduced using syringes with a heparin solution containing free calcium ions corresponding to the mean concentration of ionized calcium in normal plasma. Conditions for blood collection, storage, and transport to avoid preanalytical errors are described.

International Federation of Clinical Chemistry (IFCC). Scientific Division. Committee on pH, Blood Gases and Electrolytes. Guidelines for transcutaneous pO2 and pCO2 measurement.

This document provides guidelines in the terminology, methodology, and in the interpretation of data obtained from the use of skin (transcutaneous) pO2 and pCO2 electrodes. The transcutaneous technique has found special application in newborn infants. The causes of analytical bias with respect to arterial blood gas values and imprecision obtained with transcutaneous pO2 and pCO2 electrodes are reviewed. Electrode temperatures above 44 degrees C should not be used routinely, and at a measuring temperature of 44 degrees C, the measuring site should be changed at least every 4 h to avoid skin burning.

Método IFCC (1988) para tonometria de sangre; materiales de referencia para Pco2 y Po2 / IFCC método (1988) from blood of tonometry; Pco2 and Po2 reference of material

Se describe un método de referencia para tonometría de la sangre. El documento abarca la teoria de la tonometría, los materiales y el equipo necesarios y los aspectos esenciales del procedimiento de tonometría para sangre. Las presiones parciales de oxígeno y dióxido de carbono en sangre tonometrada son conocidas exactamente y, por lo tanto, esta sangre se recomienda para evaluación de la exactitud de analizadores de gases sanguíneos. La tonometría de muestras de sangre de pacientes puede ser también usada en la determinación de cantidades ácido-base y de la afinidad hemoglobina-oxigeno e.g.Pso. (AU)