ABSTRACT
We describe an automated, kinetic nephelometric method for fibronectin on the Multistat III F/LS Centrifugal Analyzer (Instrumentation Laboratory Inc., Lexington, MA 02173). Antiserum is diluted with polyethylene glycol. Calibrators and samples are prediluted with potassium phosphate buffer (10 mmol/L, pH 7.0) containing 8.5 g of NaCl per litre. Intensity (I) is read at 5 and 180 s and the resulting delta I plotted against concentration. A non-linear least squares curve fitting and interpolation of results is carried out automatically. Three controls, with values of between 190-370 gave coefficients of variation between 4 and 7 percent, and the sensitivity of the method is to 25 mg/L.
Subject(s)
Fibronectins/analysis , Adult , Autoanalysis/methods , Centrifugation/methods , Crohn Disease/blood , Humans , Indicators and Reagents , Infant, Newborn , Light , Male , Nephelometry and Turbidimetry/methods , Reference Values , Scattering, Radiation , Time FactorsABSTRACT
We developed a rapid fluorometric assay for measurement of serum magnesium using the ligand, 8-hydroxy-quinoline-5-sulfonate and adapted the procedure to the Multistat Fluorescence Light Scattering Centrifugal Analyzer. The standard curve extends from 0.26 to 4.11 mmol/l. There was no interference from calcium or inorganic phosphorus at concentrations of 4.95 and 5.0 mmol/l, lead, iron, zinc or copper at twice the normal levels found in serum, bilirubin at concentrations of 10 mg/dl, or lipemic samples with triglyceride concentrations of 2400 mg/dl. Citrate and EDTA lowered magnesium concentrations in serum. Analytical recovery of magnesium added to four serum specimens averaged 97%. Between-run and within-run precision of the assay gave CVs which ranged from 2.9 to 7.6%. Magnesium concentrations, measured by our fluorometric procedure, were compared with those obtained by atomic absorption and colorimetric procedures. Correlation coefficients of 0.91 and 0.88 were obtained.
Subject(s)
Fluorometry , Magnesium/blood , Autoanalysis/instrumentation , Colorimetry , Evaluation Studies as Topic , Fluorometry/instrumentation , Humans , Oxyquinoline/analogs & derivatives , Spectrophotometry, Atomic , Statistics as TopicSubject(s)
Blood Coagulation Tests/instrumentation , Centrifugation/instrumentation , Autoanalysis , Blood Coagulation Disorders/diagnosis , Blood Coagulation Disorders/drug therapy , Blood Coagulation Tests/methods , Chromogenic Compounds , Disseminated Intravascular Coagulation/diagnosis , Factor VII/analysis , Factor X/analysis , Fibrinogen/analysis , Heparin/administration & dosage , Heparin/blood , Humans , Prothrombin TimeABSTRACT
We have developed a centrifugal analyzer with both fluorescence/light-scatter and conventional absorbance optics. The instrument is used in this investigation to study the formation of antigen-antibody complexes by light scattering and turbidimetric measurements, and to develop assays for human immunoglobulins G, A, and M. Concentrations are calculated from a nonlinear least-squares fit of calibrators, and antigen excess is automatically detected from kinetic curve characteristics. Precisions and patients' results are presented, and assay sensitivity and reliability in the detection of antigen excess are compared. We also investigated the effects of centrifugal force on complex formation. Both nephelometry and turbidimetry can be very satisfactorily adapted to centrifugal analyzers. We present a model to describe the observed differences between the light-scatter and the turbidity data.
