Lab Med Online.  2021 Oct;11(4):254-266. 10.47429/lmo.2021.11.4.254.

Evaluation of Matrix Effect in Body Fluid Chemistry on Roche Cobas 8000 c702 System

• Seo JD
• Li C
• Kim S
• Nam Y
• Lee JH
• Lee K
• Song J
• Song SH

• KMID: 2526087
• DOI: http://doi.org/10.47429/lmo.2021.11.4.254

Abstract

Background
Analysis of body fluids aids in diagnosis and monitoring disease. However, only a few testing platforms and reagents have been validated for a range of body fluids or analytes. In this study, we evaluated a testing system, which has been approved for blood samples, in analyzing body fluid specimens upon matrix mixing.
Methods
Serum and body fluid samples, including cerebrospinal fluid (CSF), ascites, pleural fluid, amniotic fluid, and synovial fluid, were mixed, then the matrix effect and linearity for major analytes, namely amylase, chloride, glucose, LDH, and protein were evaluated (N = 30 serum-body fluid pairs) on the Cobas 8000 c702. The obtained data was compared with that of open reagents evaluated on the Architect c16000.
Results
For all analyte-body fluid pairs, the mean percent recovery ranged from 98.4% to 101.7%, and this was within the acceptable range for matrix effect. In the linearity test, maximum non-linearity for each analyte-body fluid pair ranged from -5.0% to +4.2%. In interference test, proteins showed positive hemolytic, icteric, and lipemic interference in CSF and hemolytic interference in amniotic fluid. There was no significant interference in the other analyte-body fluid pairs. Results were highly correlated between the Cobas 8000 c702 and the Architect c16000 system.
Conclusions
Our findings revealed that the matrix effect of major analytes in body fluid specimens can be excluded and they also validated the linearity of the analytes in the body fluid specimens. Therefore, reagents specified for blood samples can be readily adopted for the analysis of body fluids.

Keyword

Body fluid chemistry; Matrix effect; Test performance evaluation

Figure

• 

  Fig. 1 Percent recovery of each analyte, namely (A-E) Amylase, (F-J) chloride, (K-O) glucose. (P-T) LDH, and (U-Y) protein in five body-fluid specimen types (CSF, ascites, pleural fluid, amniotic fluid, and synovial fluid). Thirty values per analyte-body fluid pair are presented as dots. Dashed lines represent Westgard’s acceptable variation, while dotted lines represent mean percent recovery.

• 

  Fig. 2 Percent difference for measurement of each analyte in “high index” samples. (A) 135-216 mg/dL of hemoglobin, (B) 31-36 mg/dL of bilirubin, and (C) turbidity equivalent to 89-153 mg/dL of Intralipid solution were diluted using “low index” serum or body fluid specimens. The median and interquartile range of percent difference is presented as a box, and the range excludes the outlier, which is represented as a bar.

• 

  Fig. 3 The percent difference between the results obtained from the Roche Cobas 8000 c702 analyzer and the Abbott architect c16000 analyzer for each analyte-body fluid pair, except for protein in CSF specimens. Percent difference for five analytes, namely (A-E) Amylase, (F-J) chloride, (K-O) glucose. (P-T) LDH in five body-fluid specimen types (CSF, ascites, pleural fluid, amniotic fluid, and synovial fluid) and (U-X) protein in four body-fluid specimen types, excluding CSF. Twenty values per analyte-body fluid pair are presented as dots. Dashed lines represent Westgard’s acceptable variation, while dotted lines represent mean percent difference.

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