Evaluation of three first-generation ion-selective electrode analyzers for lithium

Systematic errors, frequency of random interferences, and recommendations based on comparison with flame atomic emission spectrometry

Anthony Okorodudu, Robert W. Burnett, Robert B. McComb, George N. Bowers

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Ion-selective electrode analyzers for measuring lithium (Li/ ISE) in serum became available in early 1987. We compared results for patients' samples from three of them vs results from flame atomic emission spectrometry (FAES). Within-run and day-to-day imprecision ranged from 0.01 to 0.03 mmol/L and 0.01 to 0.04 mmol/L, respectively. Comparing Li/ISE results (y) with the FAES results (x) gave the following equations: y = 1.063x - 0.035 for AMDEV's Lytening 2, y = 1.020x + 0.038 for NOVA's Model 11, and y = 1.030x - 0.027 for AVL's Model 985. Unexplained positive errors >0.2 mmol/L were observed for two of the 90 patients' samples, but only a few additional excessively high values were seen in 3000 patients' samples run subsequently (Lytening 2). Causes of error in clinical Li/ISE measurements are still unclear; simply characterizing them as "matrix effects" does not correct the underlying analytical problem. An increase in pH from loss of CO2 gave low results on two of the three Li/ISE analyzers but did not change FAES results. Trimethylammonium bicarbonate used in a reconstitution solution caused extremely high Li/ISE results but did not change FAES results. Performance specifications to help reduce and correct these errors are recommended.

Original languageEnglish (US)
Pages (from-to)104-110
Number of pages7
JournalClinical Chemistry
Volume36
Issue number1
StatePublished - 1990
Externally publishedYes

Fingerprint

Ion-Selective Electrodes
Systematic errors
Lithium
Spectrometry
Spectrum Analysis
Bicarbonates
Specifications
Serum

Keywords

  • Economics of laboratory operation
  • ISE liquid membranes
  • Lithium ionophores
  • pH
  • Variation, source of

ASJC Scopus subject areas

  • Clinical Biochemistry

Cite this

@article{5c755c07fe7541519c4e2e81e3286631,
title = "Evaluation of three first-generation ion-selective electrode analyzers for lithium: Systematic errors, frequency of random interferences, and recommendations based on comparison with flame atomic emission spectrometry",
abstract = "Ion-selective electrode analyzers for measuring lithium (Li/ ISE) in serum became available in early 1987. We compared results for patients' samples from three of them vs results from flame atomic emission spectrometry (FAES). Within-run and day-to-day imprecision ranged from 0.01 to 0.03 mmol/L and 0.01 to 0.04 mmol/L, respectively. Comparing Li/ISE results (y) with the FAES results (x) gave the following equations: y = 1.063x - 0.035 for AMDEV's Lytening 2, y = 1.020x + 0.038 for NOVA's Model 11, and y = 1.030x - 0.027 for AVL's Model 985. Unexplained positive errors >0.2 mmol/L were observed for two of the 90 patients' samples, but only a few additional excessively high values were seen in 3000 patients' samples run subsequently (Lytening 2). Causes of error in clinical Li/ISE measurements are still unclear; simply characterizing them as {"}matrix effects{"} does not correct the underlying analytical problem. An increase in pH from loss of CO2 gave low results on two of the three Li/ISE analyzers but did not change FAES results. Trimethylammonium bicarbonate used in a reconstitution solution caused extremely high Li/ISE results but did not change FAES results. Performance specifications to help reduce and correct these errors are recommended.",
keywords = "Economics of laboratory operation, ISE liquid membranes, Lithium ionophores, pH, Variation, source of",
author = "Anthony Okorodudu and Burnett, {Robert W.} and McComb, {Robert B.} and Bowers, {George N.}",
year = "1990",
language = "English (US)",
volume = "36",
pages = "104--110",
journal = "Clinical Chemistry",
issn = "0009-9147",
publisher = "American Association for Clinical Chemistry Inc.",
number = "1",

}

TY - JOUR

T1 - Evaluation of three first-generation ion-selective electrode analyzers for lithium

T2 - Systematic errors, frequency of random interferences, and recommendations based on comparison with flame atomic emission spectrometry

AU - Okorodudu, Anthony

AU - Burnett, Robert W.

AU - McComb, Robert B.

AU - Bowers, George N.

PY - 1990

Y1 - 1990

N2 - Ion-selective electrode analyzers for measuring lithium (Li/ ISE) in serum became available in early 1987. We compared results for patients' samples from three of them vs results from flame atomic emission spectrometry (FAES). Within-run and day-to-day imprecision ranged from 0.01 to 0.03 mmol/L and 0.01 to 0.04 mmol/L, respectively. Comparing Li/ISE results (y) with the FAES results (x) gave the following equations: y = 1.063x - 0.035 for AMDEV's Lytening 2, y = 1.020x + 0.038 for NOVA's Model 11, and y = 1.030x - 0.027 for AVL's Model 985. Unexplained positive errors >0.2 mmol/L were observed for two of the 90 patients' samples, but only a few additional excessively high values were seen in 3000 patients' samples run subsequently (Lytening 2). Causes of error in clinical Li/ISE measurements are still unclear; simply characterizing them as "matrix effects" does not correct the underlying analytical problem. An increase in pH from loss of CO2 gave low results on two of the three Li/ISE analyzers but did not change FAES results. Trimethylammonium bicarbonate used in a reconstitution solution caused extremely high Li/ISE results but did not change FAES results. Performance specifications to help reduce and correct these errors are recommended.

AB - Ion-selective electrode analyzers for measuring lithium (Li/ ISE) in serum became available in early 1987. We compared results for patients' samples from three of them vs results from flame atomic emission spectrometry (FAES). Within-run and day-to-day imprecision ranged from 0.01 to 0.03 mmol/L and 0.01 to 0.04 mmol/L, respectively. Comparing Li/ISE results (y) with the FAES results (x) gave the following equations: y = 1.063x - 0.035 for AMDEV's Lytening 2, y = 1.020x + 0.038 for NOVA's Model 11, and y = 1.030x - 0.027 for AVL's Model 985. Unexplained positive errors >0.2 mmol/L were observed for two of the 90 patients' samples, but only a few additional excessively high values were seen in 3000 patients' samples run subsequently (Lytening 2). Causes of error in clinical Li/ISE measurements are still unclear; simply characterizing them as "matrix effects" does not correct the underlying analytical problem. An increase in pH from loss of CO2 gave low results on two of the three Li/ISE analyzers but did not change FAES results. Trimethylammonium bicarbonate used in a reconstitution solution caused extremely high Li/ISE results but did not change FAES results. Performance specifications to help reduce and correct these errors are recommended.

KW - Economics of laboratory operation

KW - ISE liquid membranes

KW - Lithium ionophores

KW - pH

KW - Variation, source of

UR - http://www.scopus.com/inward/record.url?scp=0025190833&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025190833&partnerID=8YFLogxK

M3 - Article

VL - 36

SP - 104

EP - 110

JO - Clinical Chemistry

JF - Clinical Chemistry

SN - 0009-9147

IS - 1

ER -