Systematic Quality Assurance/Quality Control Framework for a Volatile Organic Compound Real-Time Monitoring Instrument, Autonomous Rugged Optical Multigas Analyzer for VOCs

Abstract

This study presents a systematic quality assurance/quality control (QA/QC) framework for new technology adopters to validate environmental monitoring instruments when consistent, standardized validation and calibration procedures do not readily exist. This QA/QC framework is especially relevant for newly developed environmental monitoring instruments prior to deployment in field settings as part of environmental site investigations. Key QA/QC parameters used in the framework include repeatability, intermediate precision, reproducibility, linearity, limits of detection (LOD), limit of quantification (LOQ), trueness, and recovery. The QA/QC framework is demonstrated on the autonomous rugged optical multigas analyzer for VOCs (AROMA-VOC), a technology that employs cavity ring-down spectroscopy (CRDS) with preconcentration and chromatographic separation prior to CRDS detection. QA/QC protocols for nine VOCs, and results for AROMA-VOC were compared with laboratory-based gas chromatography/mass spectrometer (GC-MS). Results demonstrated high linearity (R2 > 0.95) and low LOQ values (0.0004 ± 0.0002-0.0455 ± 0.0192 μg/L). The instrument also exhibited ranges of LOD at least an order of magnitude lower than that of the referenced GC-MS. AROMA-VOC demonstrated acceptable precision [repeatability, intraday relative standard deviation (RSD %): 1.72-12.1%; intermediate, interday RSD %: 2.01-10.93%] and substantial recovery (104.8% to 212.4%). Interlaboratory testing also concluded that AROMA-VOC can produce consistent detections (R2 > 0.90). The z-score findings suggested that the performance of the instrument was satisfactory, with the exceptions of xylenes and 1,3-butadiene. Overall, using the systematic QA/QC framework presented in this study, AROMA-VOC is shown to be a robust method for volatile organic compound analysis.