B-022 Technical Evaluation of Urine Chemistry Testing on the Beckman DxC700AU Chemistry Analyzer
Authors: Gea C , Wong F , Lim M , Quek B , Wong J , Yeo C 
Published: September 2023

Abstract

Background
The Singapore General Hospitals’ clinical biochemistry laboratory constantly reviews and optimizes its automated chemistry testing through workflow enhancements and advancement of technology. The laboratory had evaluated 11 urine chemistry analytes on a standalone Beckman Coulter DxC700AU in view of upgrading its existing Beckman Coulter AU680.

Methods
The laboratory evaluated the following urine chemistry analytes: urea, sodium, potassium, chloride, creatinine, total protein, calcium, inorganic phosphate, magnesium, amylase and uric acid. The parameters evaluated were: linearity, limit of detection (LOD), carryover, imprecision and patient comparison against the AU680. Linearity was verified by analyzing Validate-It linearity materials in triplicate, and assessed by generating linearity statistics using Analyze-It v2.03. LOD was verified by analyzing 20 replicates of a blank matrix (saline) and 20 replicates of a patient specimen with concentrations near the LOD. Carryover was verified by sequentially analyzing a low concentration sample in triplicates followed by a high concentration sample in duplicates and lastly the same low concentration sample in duplicates. Imprecision was performed in triplicates across 5 days using quality control material from Bio-Rad, and assessed against the vendor’s imprecision claims. Patient comparison was performed using 60 to 80 samples for each analyte between the DxC700AU and the AU680. Passing Bablok Regression, Spearman Correlation and Altman-Bland Bias Plots was generated using the Analyze-It program.

Results
All analytes were verified to be linear within their respective AMRs; all linearity material recovered within ±10% of its expected target value. LOD was assessed to be satisfactory and below the lower limit of measurement. No significant carryover was observed for any analyte. Total imprecision for all the analytes were generally &lt;4.8%. Passing Bablok Regressions, where X is the AU680 and Y is the DxC700AU, generated slopes ranging between 0.98X and 1.04X with constants ranging between -1.13 and 31.18. The large constants were partly due to analytes with large AMR (e.g. creatinine and uric acid urine). Altman-Bland Bias Plots presented bias ranging between −3.6% to 1.7% for different analytes. All analytes had excellent correlation between the 2 analyzers with R values of 1.0.

Conclusion
The performance characteristics of the DxC700AU in analyzing urine chemistries was found to be acceptable and highly comparable to the AU680. The upgrade of the AU680 to DxC700AU was seamless in view of excellent comparability in assay performances. Although the DxC700AU was expected to be the technological successor to the AU680, the quality-of-life improvements of the analyzer were the highlights of the DxC700AU. Improvements included a large clear LED indicator that highlights the status of the instrument and on-the-fly loading of reagent kits. Future improvements that the laboratory is looking forward to is the removal of the need to manually load specimens onto the instrument by connecting the standalone equipment onto its total laboratory automation track.