title: Linearity and stability of the AVL and Nova magnesium and calcium ion-selective electrodes.
abstract: We studied the stability and linearity of the AVL and Nova Mg and Ca ion-selective electrodes and the relation between the ionized Ca and ionized Mg results reported by each analyzer. The response of the electrodes to different concentrations of Mg and Ca was determined for saline solutions, aqueous solutions, and serum samples. The electrodes from both manufacturers demonstrated acceptable stability for the time of the study. The response of the electrodes was linear within the range specified by each manufacturer, but relative nonlinearity and the values for the linear limits differed between the AVL and Nova analyzers. The ionized Mg results varied with the concentration of Ca. The relation between ionized Ca and ionized Mg results was nonlinear and differed between the AVL and Nova electrodes. Intermethod comparison between the electrodes showed poor agreement for ionized Mg results, especially at low and high concentrations of total Ca and total Mg.
authors.affiliation: Clinical Chemistry Service, Clinical Pathology Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA. nrehak@pop.cc.nih.gov
authors.forename: N N
authors.initials: NN
authors.lastname: Rehak
authors.forename: S A
authors.initials: SA
authors.lastname: Cecco
authors.forename: J E
authors.initials: JE
authors.lastname: Niemela
authors.forename: E N
authors.initials: EN
authors.lastname: Hristova
authors.forename: R J
authors.initials: RJ
authors.lastname: Elin
mesh_terms: D002118:Calcium / Q000032:analysis* / Q000097:blood; D002413:Cations, Divalent; D004563:Electrochemistry; D004566:Electrodes / Q000706:statistics & numerical data*; D006801:Humans; D008274:Magnesium / Q000032:analysis* / Q000097:blood; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D012965:Sodium Chloride; D012996:Solutions; D013997:Time Factors; D014867:Water
chemical_list: D002413:Cations, Divalent; D012996:Solutions; D014867:Water; D012965:Sodium Chloride; D008274:Magnesium; D002118:Calcium