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.

Device Description

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.

AI/ML Overview

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.

Performance Characteristic	Acceptance Criteria (Implied)	Reported Device Performance and Fulfillment
Precision	Adequate precision across the measuring range. Specific criteria for %CV are not explicitly stated as acceptance criteria but are implied by the provided data being deemed "sufficient" by the FDA.	Within-day (n=4, 1 operator): OP-1: 5.4% CV (15 ng/mL), 2.9% CV (75 ng/mL) OP-2: 2.4% CV (15 ng/mL), 2.4% CV (75 ng/mL) OP-3: 2.7% CV (15 ng/mL), 4.1% CV (75 ng/mL) OP-4: 5.8% CV (15 ng/mL), 1.9% CV (75 ng/mL) OP-5: 3.1% CV (15 ng/mL), 4.0% CV (75 ng/mL) 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 < 2 ng/mL reported as "non-detectable". (This is a clear clinical cut-off.)
Expected Values/Reference Range	Clear understanding of expected values in exposed vs. unexposed subjects.	200 individual unexposed urine samples showed no positive peaks. Since organophosphate metabolites are not naturally occurring, 0 ng/mL is expected for an unexposed subject. (This confirms the expected values in a non-exposed population.)

2. Sample sizes used for the test set and the data provenance

Precision/Reproducibility:
- Within-day: n=4 per analyte (for each of 2 concentrations)
- Between-day: n=20 per analyte (for each of 2 concentrations) over 14 days.
- Data Provenance: The study was conducted using quality control materials in synthetic urine and spiked pooled urine samples. It is an analytical study, not involving human subjects or geographical data, therefore the provenance is the laboratory where the testing was performed (likely within the CDC). This is a prospective analytical study.
Linearity/Assay Reportable Range: Spiked pooled urine samples were prepared and analyzed in triplicate at various concentrations. The exact total number of individual urine samples used to form the "pooled urine" is not specified for the linearity study specifically, but the "unexposed urine samples" used for analytical specificity and expected values provides context.
Detection Limit: Spiked synthetic urine samples at 1, 2, and 5 ng/mL, as well as a blank synthetic urine sample. The exact number of replicates or distinct samples at each concentration is not specified beyond "measuring spiked synthetic urine samples".
Analytical Specificity: 200 individual unexposed urine samples.
Expected Values/Reference Range: 200 individual unexposed urine samples.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

Analytical Study: This is an analytical performance study for a quantitative LC/MS/MS assay establishing measurements of chemical analytes, not a diagnostic study requiring clinical ground truth established by experts interpreting images or patient data. The "ground truth" for the test set (e.g., known concentrations in spiked samples, absence of analytes in blank/unexposed samples) is established by the preparation methods of the samples themselves.
No clinical experts or their quantification were used to establish ground truth for this analytical test set.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set

None. This is an analytical study determining the performance of a quantitative chemical assay. Adjudication methods like 2+1 or 3+1 are typically used in clinical studies where human readers are making subjective interpretations (e.g., radiology reads) and a consensus among experts is needed to establish ground truth.

5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

Not applicable. This study is for a quantitative chemical assay (LC/MS/MS) and does not involve human readers interpreting cases or AI assistance in those interpretations. Therefore, an MRMC study or evaluation of human reader improvement with AI is not relevant.

6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done

Yes, this is a standalone analytical performance study. The device itself (LC/MS/MS system and associated method) is an "algorithm only" device in the sense that it performs a quantitative measurement on a biological sample to produce a numerical result. Its performance is evaluated independently of human interpretation of the result in a clinical context, though human operators are involved in running the assay. The study demonstrated the device's ability to accurately and precisely quantify organophosphate metabolites.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)

The ground truth used is primarily analytical ground truth based on:
- Known concentrations of organophosphate metabolites in spiked synthetic urine and pooled urine samples for linearity and detection limit studies.
- Absence of target analytes in synthetic urine blanks and individual unexposed human urine samples for detection limits and analytical specificity.
- Pre-defined concentrations in quality control materials for precision studies.

8. The sample size for the training set

Not applicable. This is an analytical device for quantitative measurement, not a machine learning or AI model that requires a "training set" in the conventional sense. The development of the LC/MS/MS method itself would involve optimization and calibration, but this is distinct from the statistical training of an AI algorithm.

9. How the ground truth for the training set was established

Not applicable for the same reason as above. The "ground truth" or reference for establishing the method's parameters would have been based on established analytical chemistry principles, known chemical standards, and optimized laboratory procedures.

Summary

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EVALUATION OF AUTOMATIC CLASS III DESIGNATION FOR QUANTITATION OF ORGANOPHOSPHATE METABOLITES IN URINE BY LC/MS/MS

DECISION SUMMARY

Correction Date: March 10, 2017 This Decision Summary contains corrections to the August 8, 2013 Decision Summary

A. 510(k) Number:	K122282
B. Purpose for Submission:	De novo request for evaluation of automatic classIII designation of the Quantitation ofOrganophosphate Metabolites in Urine byLC/MS/MS new assay
C. Measurand:	Selected Organophosphate Metabolites
D. Type of Test:	Quantitative LC/MS/MS
E. Applicant:	Centers for Disease Control and Prevention (CDC)

F. Proprietary and Established Names:

Quantitation of Organophosphate Metabolites in Urine by LC/MS/MS

G. Regulatory Information:

FDA identifies this type of device as: Organophosphate test system

An organophosphate test system is a device intended to measure organophosphate metabolites quantitatively in human urine from individuals who have signs and symptoms consistent with cholinesterase poisoning. The data obtained by this device is intended to aid in the confirmation and investigation of organophosphate exposure.

1. New Regulation Number:
  21 CFR 862.3652
1. Classification:
  Class II (special controls)
1. Product code:
  PDY

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4. Panel:

Clinical Chemistry and Clinical Toxicology Devices

H. Intended Use:

1. Intended use(s):
  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.
1. Indication(s) for use:
  Same as intended use.
1. Special conditions for use statement(s):
  For in vitro diagnostic use.

For prescription use only, in a single laboratory.

1. Special instrument requirements:
  AB Sciex Qtrap 5500 - Serial number (S/N) AU23771008

Agilent HPLC - (Degasser 1100 Series: S/N JP32750555: FC/ALS Therm Series: S/N DE60556845; HiP-ALS 1200 Series: S/N DE63055552; Bin Bump 1200 Series: S/N DE63057946; Degasser 1200 Series: S/N JP63705336)

Caliper Life Sciences - (Sciclone i1000 Workstation: S/N SS0712N0548 and SS739N0661; Twister II Microplate Handler: S/N T20838N0168)

Clearance of this assay is limited only to the instrument systems with the serial numbers as specified above. Any additional systems will require a validation panel to be reviewed and approved prior to use with the assay.

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I. Device Description:

J. Substantial Equivalence Information:

1. Predicate device name(s):
  No predicate device exists
1. Predicate 510(k) number(s):
  Not applicable
1. Comparison with predicate:
  Not applicable

K. Standard/Guidance Document Referenced (if applicable):

1. CLSI EP17-A, Protocol for Determination of Limits of Detection and Limits of Ouantitation: Approved Guideline, Vol. 24, No. 34, modified
1. CLSI EP6-A. Evaluation of the linearity of Quantitative Measurement Procedures: A Statistical approach; Approved Guideline, Vol. 23, No. 16

L. Test Principle:

This assay detects the presence of organophosphate metabolites in human urine. This is achieved through the separation, identification, and quantitation of the specific metabolites resulting from exposure to selected organophosphates by LC/MS/MS.

M. Performance Characteristics (if/when applicable):

1. Analytical performance:
- a. Precision/Reproducibility:

Precision and repeatability were both determined through analysis of quality control materials in synthetic urine at 15 and 75 ng/mL concentrations of five organophosphate metabolites (identified as OP-1, 2, 3, 4, 5). The samples were prepared, analyzed, and processed by three different operators over a

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period of 14 days, with no more than 4 QC samples prepared and analyzed in one 24-hour period. Within-day and between-day studies were performed on a single instruments. The data are summarized in the tables below.

		Within Day, n=4, operators = 1			Between Day, n=20, days = 14,operators = 3
Analyte	Concentration(ng/mL)	Mean	St. Dev.	%CV	Mean	St. Dev.	%CV
OP-1	15	15.2	0.8	5.4	14.9	0.6	4.2
	75	75.7	2.2	2.9	75.6	2.3	3.0
OP-2	15	15.0	0.4	2.4	15.0	0.5	3.4
	75	76.3	1.8	2.4	76.2	2.1	2.8
OP-3	15	15.4	0.4	2.7	15.0	0.6	4.1
	75	76.8	3.5	4.1	75.7	2.1	2.7
OP-4	15	15.5	0.9	5.8	15.0	0.6	4.0
	75	76.1	1.5	1.9	75.9	2.3	3.1
OP-5	15	14.9	0.5	3.1	14.8	0.6	4.2
	75	75.2	3.3	4.0	75.3	2.2	2.9

Instrument AU23771008

b. Linearity/assay reportable range:

The claimed measuring range is 2 – 200 ng/mL.

Recovery studies were conducted for each organophosphate metabolite. Spiked pooled urine samples at various concentrations were prepared and analyzed in triplicate.

Conc.ng/mL	OP-3		OP-4		OP-5
	Mean,ng/mL	%Recovery	Mean,ng/mL	%Recovery	Mean,ng/mL	%Recovery
2	1.7	86.5	1.9	96.0	1.9	94.0
3	2.8	92.3	2.4	81.1	3.4	112.9
7	6.8	96.4	6.3	90.1	7.2	103.1
9	7.9	87.6	8.5	94.5	8.3	92.2
22	20.2	92.0	20.4	92.9	20.4	92.6
30	n/a	n/a	n/a	n/a	n/a	n/a
45	40.7	90.5	40.5	90.1	42.3	94.0
65	60.5	93.0	59.5	91.5	60.4	93.0
80	72.9	91.2	71.2	89.0	74.5	93.2
95	86.7	91.3	87.5	92.1	90.1	94.9
115	106.3	92.5	103.7	90.1	107.5	93.5
130	120.0	92.3	118.2	90.9	123.2	94.7
145	n/a	n/a	n/a	n/a	n/a	n/a

Instrument AU23771008

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180	183.8	102.1	155.3	86.3	182.5	101.4
200	210.3	105.2	173.7	86.8	207.3	103.7

Conc.ng/mL	OP-1		OP-2
	Mean,ng/mL	%Recovery	Mean,ng/mL	%Recovery
2	1.9	93.0	1.9	95.5
3	2.5	82.6	2.9	97.3
7	6.7	95.2	6.8	96.6
9	8.4	93.2	8.9	98.9
22	21.2	96.3	20.8	94.6
30	28.6	95.4	n/a	n/a
45	42.9	95.5	43.7	97.1
65	63.1	97.1	n/a	n/a
80	n/a	n/a	74.8	93.5
95	90.2	95.0	88.0	92.6
115	n/a	n/a	107.3	93.3
130	125.8	96.8	122.3	94.1
145	140.2	96.7	136.3	94.0
180	177.7	98.3	173.8	96.6
200	203.2	101.6	199.8	99.9

Traceability, Stability, Expected values (controls, calibrators, or methods): C.

Traceability and Value assignment

Calibrators are prepared at the assigned levels by a vendor using a dilution scheme. Assigned values are verified according to precision, accuracy, and linear response.

Values assigned to the calibrators and quality control materials are traceable to the internal standards synthesized by a vendor. There are no certified reference materials available for these compounds.

Stability

Calibrator and quality control material storage stability was evaluated. All

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data met the acceptance criteria and support the shelf life claim of 2 years at -70 C.

d. Detection limit:
The LoD for the five metabolites were determined by measuring piked synthetic urine samples at 1, 2, and 5 ng/mL, as well as a blank synthetic urine sample. The LoB, LoD, and LoQ are summarized below. The claimed measuring range is 2 - 200 ng/mL.

	OP-1	OP-3	OP-2	OP-4	OP-5
LoB	0.229	0.192	0.029	0.090	0.406
LoD	0.40	0.35	0.13	0.20	0.69
LoQ	2	2	2	2	2

Instrument AU23771008

e. Analytical specificity:
200 individual unexposed urine samples were extracted for the presence of any peaks that would contribute to false positive results (i.e. the presence of any positive peaks). No peaks were detected in the samples that were above the LoQ for all five metabolites. Six non-specific pesticide metabolites, known as dialkylphosphates, were spiked into samples and the samples were analyzed for the presence of any positive peaks associated with the organophosphates. No interfering peaks were detected.
f. Assay cut-off:
Not applicable
1. Comparison studies:
- a. Method comparison with predicate device:

Not applicable

b. Matrix comparison:
Not applicable
1. Clinical studies:
- a. Clinical Sensitivity:

Not applicable

b. Clinical specificity:

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Not applicable

Other clinical supportive data (when a. and b. are not applicable): C.
Not applicable
1. Clinical cut-off:
  All values ≥ 2 ng/mL indicate exposure to an organophosphate metabolite. A value < 2 ng/mL will be reported as "non-detectable".
1. Expected values/Reference range:
  The sponsor tested 200 individual unexposed urine samples for the presence of any positive peaks associated with the organophosphates and their metabolites. No peaks were detected. These organophosphate metabolites are not naturally occurring, and as such, 0 ng/mL is expected for an unexposed subject.

N. Instrument Name:

AB Sciex QTrap 5500

O. System Descriptions:

1. Modes of Operation:
  Automated
1. Software:
  The software used with this assay is off-the-shelf (OTS) software to manage the LC/MS/MS system and the liquid handling system for the solid-phase extraction. FDA has reviewed applicant's Hazard Analysis and software development processes for this line of product types:

Yes x___ or No _________________________________________________________________________________________________________________________________________________________

1. Specimen Identification:
  Specimens are identified in a laboratory information management system and labeled/bar-coded with a traceable number. Final results are uploaded into the laboratory information management system to correspond with the label identified in the chain of custody form (refer to Section 4 below).
1. Specimen Sampling and Handling:

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Specimens are collected, frozen, and sent to the laboratory. The sample is thawed and processed for analysis.

1. Calibration:
  Instruments are calibrated on-site by the instrument manufacturer. Calibration curves for the assay are prepared as specified by the procedure.
1. Quality Control:
  Quality Control is ensured through the analysis of two positive quality control samples and one negative quality control sample.

P. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10 and 21 CFR 801.109.

Q. Other Supportive Instrument Characteristics Data Not Covered In The "Performance Characteristics" Section above:

None

Identified Potential Risk	Required Mitigation Measure
False Positive	1) The distribution of these devices is limited to laboratories withexperienced personnel who are trained to measure and evaluateorganophosphate exposure and guide public health response.2) Analytical testing must demonstrate the device has appropriateperformance characteristics, including adequate precision andaccuracy across the measuring range and near medical decisionpoints.
False Negative	1) The distribution of these devices is limited to laboratories withexperienced personnel who are trained to measure and evaluateorganophosphate exposure and guide public health response.2) Analytical testing must demonstrate the device has appropriateperformance characteristics, including adequate precision andaccuracy across the measuring range and near medical decisionpoints.
Public Health Risk fromIncorrect Test Results	1) The distribution of these devices is limited to laboratories withexperienced personnel who are trained to measure and evaluateorganophosphate exposure and guide public health response.2) Analytical testing must demonstrate the device has appropriateperformance characteristics, including adequate precision andaccuracy across the measuring range and near medical decision

R. Identified Potential Risks and Required Mitigation Measures:

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Identified Potential Risk	Required Mitigation Measure
	points.

S. Benefit/Risk Analysis:

Summary ofthe Benefit(s)	Summary
This is a public health tool whose primary utility is to identify exposure to selected organophosphate(s) and the metabolites to which the individual/individuals has/have been exposed. It would be highly valued for public health purposes in an effort to track and maintain epidemiologic data on exposures and potential exposures to organophosphate(s). No other tests are available for identification of organophosphate metabolites
Summary ofthe Risk(s)	Patients are subject to urine specimen collection, which is a standard procedure in clinical care and carries minimal risk. Risk is related to inaccurate test results as follows: False positive: The risks to the individual of a false positive result include unnecessary anxiety related to long term impact of such exposure and possible unnecessary medical work up, evaluation and follow-up for exposure-related complications. Since no treatment decisions will be initiated based on test results, a false positive result will not lead to risk of inappropriate treatment. Treatment is initiated based on signs and symptoms of possible exposure in the immediate setting, prior to obtaining results of medical diagnostic tests. False negative: The risk to the individual of a false negative result is missed identification of exposure to organophosphate(s). Since no treatment decisions are expected to be initiated based on test results, a false negative result will not lead to missed opportunity to initiate appropriate treatment in the immediate setting. A false negative result may lead to a missed opportunity for additional medical evaluation and follow-up for exposure-related complications. Public Health Risk from Incorrect Test Results: The consequences to public health for both false positive and false negative results are similar and are related to inaccurate epidemiologic data leading to long term misconceptions and inaccurate conclusions related to exposure event. Missed opportunities for valuable information gathering that could lead to significant benefits to public health may occur.
Summary ofOtherFactors	Not applicable
ConclusionsDo the probable benefits outweigh the probable risks?	Given robust analytical performance characteristics and risk mitigation (i.e. proper labeling and use in the Public Health response sector), the probable benefits to both the individual and public health outweigh the probable risks of this device.

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T. Conclusion:

The information provided in this de novo submission is sufficient to classify this device into class II under regulation 21 CFR 862.3652. FDA believes that special controls, along with the applicable general controls, provide reasonable assurance of the safety and effectiveness of the device type. This device, and similar devices, are classified under the following:

Product Code: PDY

Device Type:	Organophosphate Test System
Class:	II (special controls)
Regulation:	21 CFR 862.3652

(a) Identification. An organophosphate test system is a device intended to measure organophosphate metabolites quantitatively in human urine from individuals who have signs and symptoms consistent with cholinesterase poisoning. The data obtained by this device is intended to aid in the confirmation and investigation of organophosphate exposure.

(b) Classification. Class II (special controls). Organophosphate test systems must comply with the following special controls:

1. The distribution of these devices is limited to laboratories with experienced personnel who are trained to measure and evaluate organophosphate exposure and guide public health response.
1. Analytical testing must provide a reasonable assurance of safety and effectiveness demonstrate the device has appropriate performance characteristics, including adequate precision and accuracy across the measuring range and near medical decision points.

Regulation Number and Section

§ 862.3652 Organophosphate test system.

(a)
Identification. An organophosphate test system is a device intended to measure organophosphate metabolites quantitatively in human urine from individuals who have signs and symptoms consistent with cholinesterase poisoning. The data obtained by this device is intended to aid in the confirmation and investigation of organophosphate exposure.(b)
Classification. Class II (special controls). The special controls for this device are:(1) The distribution of these devices is limited to laboratories with experienced personnel who are trained to measure and evaluate organophosphate exposure and guide public health response.
(2) Analytical testing must demonstrate the device has appropriate performance characteristics, including adequate precision and accuracy across the measuring range and near medical decision points.