title: Studies on measurement of plasma magnesium: application of the Magon dye method to the "Monarch" centrifugal analyzer.
abstract: The "Magnesium Liquid Stable Reagent Set" from Medical Analysis Systems, Inc., is evaluated. The method, which involves Magon dye binding and bichromatic absorbance measurements, was used in a Monarch centrifugal analyzer. Results were compared with those by atomic absorption spectrometry. The calibration curve for the Magon method is linear to 2.5 mmol/L, with a 2-microL sample volume. Analytical recovery of magnesium added to human plasma ranged from 95 to 102%. The working reagent is stable for at least five days at 15 degrees C. At concentrations of 0.54 and 1.20 mmol/L, the respective CVs were 2.15 and 3.60% within batch, and 3.13 and 3.24% between batch. We analyzed 150 clinical samples for magnesium by both methods. Absorbance readings at 520/600 nm rather than 520/690 nm improved the correlation (r = 0.9777 and r = 0.9428, respectively). Calcium, albumin, phosphate, or bilirubin did not significantly interfere.
authors.affiliation: Department of Clinical Chemistry, Western General Hospital, Edinburgh, U.K.
authors.forename: H M
authors.initials: HM
authors.lastname: Barbour
authors.forename: W
authors.initials: W
authors.lastname: Davidson
mesh_terms: D000818:Animals; D001663:Bilirubin / Q000097:blood; D002417:Cattle; D002498:Centrifugation; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood; D008274:Magnesium / Q000097:blood*; D011933:Reagent Kits, Diagnostic
chemical_list: D011933:Reagent Kits, Diagnostic; D008274:Magnesium; D001663:Bilirubin