Evaluation of a Direct α-Amylase Assay Using 2-Chloro-4-nitrophenyl-α-D-maltotrioside
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Klaus Lorentz
Abstract
We present the adaptation of an IFCC method for α-amylase using 2-chloro-4-nitro-phenyl-α-D-maltotrioside as substrate (1) suited for routine work at 37℃. In the assay, a constant proportion of substrate, i. e. 92%, is directly converted to 2-chloro-4-nitrophenol and maltotriose. The method is based on multi- and univariate optimization leading to following measurement conditions: substrate, 2.25 mmol/l; chloride, 310 mmol/l; calcium 5.0 mmol/l; 4-morpholinoethanesulphonic acid, 50 mmol/l; pH 6.28. The assay may be carried out manually or by mechanized procedures, with substrate or sample start, and it shows these analytical properties in measuring amylase activity of sera: no lag phase, detection limit 2.9 U/l, linear range ≤820 U/l (for 300 s) or ≤1450 U/l (for 120 s of measurement), and total manual imprecision 3.2% (CV) at 46 U/l. Bilirubin ≤630 μmol/l, haemoglobin ≤6 g/l, triacylglycerols ≤30 mmol/l, heparin ≤100 kU/l, and glucose ≤120 mmol/l do not interfere. For adults, we established a preliminary 0.95-reference interval of 30–90 U/l not dependent on sex or age. A close association with the IFCC method demonstrates the reliable transfer of its measurement conditions to a robust routine method with minimal changes.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
Artikel in diesem Heft
- Author Index
- Contents
- Subject Index
- Strategies for Cardiac Marker Measurement
- Statistical Techniques for Evaluating the Diagnostic Utility of Laboratory Tests
- Magnesium in Disease: a Review with Special Emphasis on the Serum Ionized Magnesium
- Methods for Improving Clinical Trials
- Infrared Analysis of Urinary Stones: a Trial of Automated Identification
- Evaluation of a Direct α-Amylase Assay Using 2-Chloro-4-nitrophenyl-α-D-maltotrioside
- Accurate Platelet Counting in an Insidious Case of Pseudothrombocytopenia
- A New Liquid Homogeneous Assay for HDL Cholesterol Determination Evaluated in Seven Laboratories in Europe and the United States
- Tissue Release of Cardiac Markers: from Physiology to Clinical Applications
- The Specificity of Biochemical Markers of Cardiac Damage: a Problem Solved
- Biochemical Factors Influencing Measurement of Cardiac Troponin I in Serum
- The Sensitivity of Cardiac Markers: an Evidence-based Approach
- Risk Stratification and Therapeutic Decision Making in Patients with Acute Coronary Syndromes the Role of Cardiac Troponin T
- Cardiac Markers: Centralized or Decentralized Testing?
- EC4 European Syllabus for Post-Graduate Training in Clinical Chemistry. Version 2 – 1999
- Plasma Malondialdehyde and Obesity: Is there a Relationship?
- Reference Intervals: Are Interlaboratory Differences Appropriate?
- Lipoprotein Protocols. By J.M. Ordovas, editor
- Tietz Textbook of Clinical Chemistry. By C.A. Burtis and E.R. Ashwood, editors
Artikel in diesem Heft
- Author Index
- Contents
- Subject Index
- Strategies for Cardiac Marker Measurement
- Statistical Techniques for Evaluating the Diagnostic Utility of Laboratory Tests
- Magnesium in Disease: a Review with Special Emphasis on the Serum Ionized Magnesium
- Methods for Improving Clinical Trials
- Infrared Analysis of Urinary Stones: a Trial of Automated Identification
- Evaluation of a Direct α-Amylase Assay Using 2-Chloro-4-nitrophenyl-α-D-maltotrioside
- Accurate Platelet Counting in an Insidious Case of Pseudothrombocytopenia
- A New Liquid Homogeneous Assay for HDL Cholesterol Determination Evaluated in Seven Laboratories in Europe and the United States
- Tissue Release of Cardiac Markers: from Physiology to Clinical Applications
- The Specificity of Biochemical Markers of Cardiac Damage: a Problem Solved
- Biochemical Factors Influencing Measurement of Cardiac Troponin I in Serum
- The Sensitivity of Cardiac Markers: an Evidence-based Approach
- Risk Stratification and Therapeutic Decision Making in Patients with Acute Coronary Syndromes the Role of Cardiac Troponin T
- Cardiac Markers: Centralized or Decentralized Testing?
- EC4 European Syllabus for Post-Graduate Training in Clinical Chemistry. Version 2 – 1999
- Plasma Malondialdehyde and Obesity: Is there a Relationship?
- Reference Intervals: Are Interlaboratory Differences Appropriate?
- Lipoprotein Protocols. By J.M. Ordovas, editor
- Tietz Textbook of Clinical Chemistry. By C.A. Burtis and E.R. Ashwood, editors
