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This device is intended for the quantitation of specific organophosphate metabolites by LC/MS/MS. The device system includes organophosphate metabolite calibrators to calibrate the system and organophosphate metabolite controls for quality control monitoring of the system. This device is intended for use in a single laboratory to detect and measure the concentration of specific organophosphate metabolites in human urine from individuals who have signs and symptoms consistent with cholinesterase poisoning. The data obtained by this device will be used following an exposure or suspected exposure event to confirm exposure, identify the causative agent, and distinguish exposed from the unexposed patients.

The device comprises internal standards which serve as the basis for the calibrators and quality control materials. A solid phase extraction cartridge is initially used to extract the metabolites for further separation and analysis on a tandem mass spectrometer and HPLC system.

This document describes CDC's Quantitation of Organophosphate Metabolites in Urine by LC/MS/MS device.

Acceptance Criteria and Device Performance Study

The study evaluates the analytical performance of the device, focusing on precision, linearity/reportable range, traceability, stability, detection limits, and analytical specificity.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the stated performance characteristics deemed sufficient by the FDA for classification. The reported device performance is directly from the provided tables.

Between-day (n=20, 14 days, 3 operators):
OP-1: 4.2% CV (15 ng/mL), 3.0% CV (75 ng/mL)
OP-2: 3.4% CV (15 ng/mL), 2.8% CV (75 ng/mL)
OP-3: 4.1% CV (15 ng/mL), 2.7% CV (75 ng/mL)
OP-4: 4.0% CV (15 ng/mL), 3.1% CV (75 ng/mL)
OP-5: 4.2% CV (15 ng/mL), 2.9% CV (75 ng/mL)
(All values reported for two concentrations (15 and 75 ng/mL) for five organophosphate metabolites (OP-1 to OP-5). The data "met the acceptance criteria" according to the section, implying these values are acceptable.) |
| Linearity/Reportable Range | Adequate accuracy across the measuring range. The claimed measuring range is 2 – 200 ng/mL. Recovery percentages are expected to be within an acceptable range, although specific percentage limits are not explicitly stated. | Claimed Measuring Range: 2 – 200 ng/mL
Recovery Studies: Spiked pooled urine samples analyzed in triplicate.
OP-1: % Recovery from 82.6% to 101.6% across reported concentrations (2-200 ng/mL).
OP-2: % Recovery from 92.6% to 99.9% across reported concentrations (2-200 ng/mL).
OP-3: % Recovery from 86.5% to 105.2% across reported concentrations (2-200 ng/mL).
OP-4: % Recovery from 81.1% to 96.0% across reported concentrations (2-200 ng/mL).
OP-5: % Recovery from 92.2% to 112.9% across reported concentrations (2-200 ng/mL).
(The full range of recovery data for various concentrations supports the claimed measuring range, implying accuracy within this range is acceptable.) |
| Traceability | Calibrator and quality control material values should be traceable. | Calibrators are prepared by a vendor using a dilution scheme and verified for precision, accuracy, and linear response. Values assigned to calibrators and quality control materials are traceable to internal standards synthesized by a vendor. No certified reference materials are available. (This fulfills the traceability requirement.) |
| Stability | Adequate stability for calibrators and quality control materials to support proposed shelf life. | Calibrator and quality control material storage stability was evaluated. All data met acceptance criteria and support a shelf life claim of 2 years at -70°C. (This fulfills the stability requirement.) |
| Detection Limits (LoQ) | Limit of Quantitation (LoQ) should be consistent with the claimed measuring range (2-200 ng/mL). | LoQ for all 5 metabolites (OP-1 to OP-5) is 2 ng/mL.
LoB: Ranged from 0.029 to 0.406 ng/mL.
LoD: Ranged from 0.13 to 0.69 ng/mL.
(The determined LoQ of 2 ng/mL aligns with the lower end of the claimed measuring range.) |
| Analytical Specificity | Demonstrate ability to detect specific organophosphate metabolites and absence of interference from other substances (e.g., related pesticides, naturally occurring compounds) to avoid false positives. | 200 individual unexposed urine samples: No peaks above LoQ were detected for all five metabolites. This indicates no false positives from naturally occurring compounds in unexposed urine.
Six non-specific pesticide metabolites (dialkylphosphates) spiked into samples: No interfering peaks associated with the organophosphates were detected. (This demonstrates specificity for organophosphate metabolites over similar compounds and in the absence of exposure.) |
| Clinical Cut-off | A defined clinical cut-off for determining exposure. | All values ≥ 2 ng/mL indicate exposure. Values

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