'Carryback': effect of viscous liquid controls on the preceding sample analyzed with the SMA II continuous-flow analyzer

Autor:	M D Gallomore, R B Lepoff, M McAvoy, Cathel Kerr, C Smith, S D Winter
Rok vydání:	1985
Předmět:	Accuracy and precision Analyte Spectrum analyzer Chromatography Sample (material) Biochemistry (medical) Clinical Biochemistry Analytical chemistry Viscous liquid chemistry.chemical_compound chemistry Volume (thermodynamics) Sample preparation Ethylene glycol
Zdroj:	Clinical Chemistry. 31:1896-1899
ISSN:	1530-8561 0009-9147
DOI:	10.1093/clinchem/31.11.1896
Popis:	We systematically studied the "carryback" effect of ethylene glycol-based controls on the preceding sample on an SMA II continuous-flow analyzer. Including Beckman Level 1 unassayed liquid control material as a sample lowered the 12 analyte values of the preceding sample by an average of 2.7%, Level 2 (the most viscous) by an average of 4.4%, and Level 3 by 3.2%. Water-reconstituted lyophilized control material caused no carryback effect, but lyophilized control reconstituted with 330 mL/L ethylene glycol decreased the preceding sample's results by 4.1% (average carryback). We believe that carryback is caused by the drag placed on the sample line by a viscous sample, which decreases the volume of the preceding sample that is delivered to the reagent or pre-dilution mixing coils. Our findings were confirmed on another SMA II. Limited study of a SMAC analyzer gave inconclusive results, but further evaluation of continuous-flow systems for carryback is warranted. Carryback substantially increases total analytical variability.
Databáze:	OpenAIRE
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