QNT Carryover

QNT Carryover

Quantitative Carryover (CRY)

Overview

Other Names - Contamination Study, Residual Effect Test, Cross-Contamination Assessment, Analyte Carryover Test, Sample Carryover Evaluation

A Carryover Experiment MV Experiment evaluates whether residual analytes from a high-concentration sample affect the results of subsequent lower-concentration samples.

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The Carryover Experiment does not need to be performed when the analyzer/test setup inherently prevents cross-contamination, such as when using disposable or single-use sample components, sealed reaction chambers, or methods where samples do not physically interact

Lab Juice

Definitions

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**Cualia Support Docs Definitions (Public)**

Name
Definition
Carryover

The effect of high concentration measurements on subsequent low concentration samples.

Carryover (%)

Measure of how much a high concentration sample influences the result of a subsequent low concentration sample. Carryover (%)=Low DiffHigh‾− Low-Low‾×100\text{Carryover (\%)} = \frac{\text{Low Diff}}{\overline{\text{High}} - \overline{\text{ Low-Low}}} \times 100 High‾{\overline{\text{High}}}: Average of High results Low-Low‾{\overline{\text{Low-Low}}}: Average of Low-Low results

Carryover Experiment

An MV experiment used to evaluate the effect of high concentration testing on subsequent low concentration samples.

Carryover High-Low

A result from a low sample tested directly after testing a high sample

Carryover Low Diff.

The subtracted difference between the first and last Low Concentration samples. Low Diff=Low Rep 1−Low Rep 3\text{Low Diff} = \text{Low Rep 1} - \text{Low Rep 3}

Carryover Low-Low

A result from a low sample tested directly after testing a low sample

Experiment

A sampling of results that are statistically analyzed and interpreted in the evaluation of testing performance.

Method Validation

A systematic process to evaluate whether the performance of a medical Test meets quality goals to be used for medical testing.

Method Verification

A systematic process to evaluate whether the performance of a medical Test meets quality goals set by a validation. Performance evaluations may usually be found in a manufacturer insert.

Result(s)

A value or determination collected by measurement or calculation.

Sample(s)

Individual specimens collected for testing representing the source. In MV experiments with Runs, this can refer to to the number of concentration levels used.

Standard Deviation (σ or StdDev)

Statistical measure of the amount of variation from the mean. σ=1n−1∑i=1n(xi−xˉ)2\sigma = \sqrt{\frac{1}{n-1} \sum_{i=1}^{n} (x_i - \bar{x})^2} σ = Standard Deviation n = Sample Size xix_i = Individual data point xˉ\bar{x} = Mean

What is the Carryover Experiment?

A Carryover Experiment is designed to assess whether analytes from high-concentration samples impact the measurement of subsequent lower-concentration samples, potentially affecting the accuracy of results. This evaluation is critical for ensuring the reliability and integrity of a testing method, particularly in automated laboratory systems where samples are processed sequentially. The experiment involves systematically testing a sequence of high and low analyte concentrations and analyzing whether the lower samples show elevated or altered values due to residual effects from the previous samples.

During this process, the experiment quantifies the extent of any carryover and determines whether it falls within acceptable limits defined by performance criteria. If carryover is detected, it may necessitate adjustments to the method, instrument cleaning protocols, or sample handling procedures. The goal is to ensure that results remain unaffected by prior sample concentrations, maintaining the method’s accuracy and precision across varying analyte levels. This experiment is vital in clinical and research settings where precise measurements are crucial for patient care and scientific validity.

Experiment Settings and Acceptance Criterias

In Cualia’s Carryover Experiment there is only 1 Acceptance Criteria:

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Error Allowance Type: Sets the Carryover to select a max % difference or Standard Deviation to determine if Carryover exceeds manufacturer claims.

The analyzer’s manufacturer insert for the test should indicate the maximum expected carryover for the test.

Options: Percent or Standard Deviation

Sample Selection

Select one sample at the higher end of the Test Range and one sample on the lower end of the Test Range

Testing Samples

Test the higher sample for 3 replicate results and then immediately test the lower sample for 3 replicate results.

Enter Results into Cualia

Set the Allowable % or SD (depending on you Acceptance Criterias) into the data table. Then enter the 3 high results and the 3 low results into the Cualia Carryover Experiment data table.

Preparation Checklist

Analyzer is set up in Cualia → AnalyzersAnalyzers
Tests are set up in the analyzer → Quantitative TestsQuantitative Tests and Qualitative TestsQualitative Tests
The initial MV details are prepared → MV Overview and DetailsMV Overview and Details

General Experiment Recommendations: Dos and Don’ts

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Don’t: Enter private patient information, identifiers or data into Cualia.
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Don’t: Rush Through an MV: Sometimes an MV can take months waiting for the right samples to come through. Based on our experience, the most time consuming part of an MV is finding out after days after measurements and painstakingly entering in the data to find that something was done incorrectly and the cycle must be repeated.
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Don’t: Rely too much on controls, calibrators and spiked samples: The goal of an MV is not to pass inspection but to truly evaluate that your instrumentation’s performance is up to clinical standards. Using samples that reflect the lab’s testing population will offer the best insights into the evaluation
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Do: Prepare your Cualia MV before taking measurements: Having a blueprint of work provides a smooth experience.
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Do: Enter Results Directly into Cualia: Taking down results to enter them into a spreadsheet just to copy them into Cualia will increase sources of error. When a result is returned, enter it directly into Cualia. You will be able to immediately have feedback into the success state of the experiment, identifying any missing variables that will hinder your MV.
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Do: Ask for clarification. Talk to regulators, auditor, consultants and don’t hesitate to reach out to support@cualia.io with questions.

Data Table

If the Error Allowance Type in the Acceptance Criteria is set to percent, the Allowable Error (%) may be set above the data table. If the Error Allowance Type is set to Standard Deviation it will be in the same position.

Allowable Error for Carryover - The max % or SD between the low concentration result (directly after a high concentration value) and the last low concentration result.

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Data Table Columns

Run Order | Read Only - The labels for samples used. The high and low replicate results should match the Run Order rows.

Result | Number only - Result value received from the sample tested.

Cualia’s Carryover testing follows the simple protocol which is 3 high concentration samples (High Rep 1,2,3) and 3 low concentration samples (Low Rep 1,2,3).

Low Rep 1 represents the low concentration sample that immediately followed the last High concentration sample (High Rep 3).

Low Rep 3 represents the expected result because it will not be affected by Carryover effects.

Results

🗣️
**Cualia Support Docs Definitions (Public)**

Name
Definition
Carryover (%)

Measure of how much a high concentration sample influences the result of a subsequent low concentration sample. Carryover (%)=Low DiffHigh‾− Low-Low‾×100\text{Carryover (\%)} = \frac{\text{Low Diff}}{\overline{\text{High}} - \overline{\text{ Low-Low}}} \times 100 High‾{\overline{\text{High}}}: Average of High results Low-Low‾{\overline{\text{Low-Low}}}: Average of Low-Low results

Carryover High-Low

A result from a low sample tested directly after testing a high sample

Carryover Low Diff.

The subtracted difference between the first and last Low Concentration samples. Low Diff=Low Rep 1−Low Rep 3\text{Low Diff} = \text{Low Rep 1} - \text{Low Rep 3}

Carryover Low-Low

A result from a low sample tested directly after testing a low sample

Standard Deviation (σ or StdDev)

Statistical measure of the amount of variation from the mean. σ=1n−1∑i=1n(xi−xˉ)2\sigma = \sqrt{\frac{1}{n-1} \sum_{i=1}^{n} (x_i - \bar{x})^2} σ = Standard Deviation n = Sample Size xix_i = Individual data point xˉ\bar{x} = Mean

Calculations

Percent Error Allowance

Low Diff

Low Diff - The difference between the first low concentration result following the high concentration samples and the the last low concentration sample.

Low Diff=Low Rep 1−Low Rep 3\text{Low Diff} = \text{Low Rep 1} - \text{Low Rep 3}Carryover (%)=Low DiffHigh Rep 3− Low Rep 3×100\text{Carryover (\%)} = \frac{\text{Low Diff}}{\text{High Rep 3} - \text{ Low Rep 3}} \times 100

Standard Deviation Error Allowance is Set

Standard Deviation is calculated for all low samples.

Standard Deviation (σ or StdDev)

Standard Deviation (σ or StdDev) - The statistical measure of the amount of variation from the mean.

σ=1n−1∑i=1n(xi−xˉ)2\sigma = \sqrt{\frac{1}{n-1} \sum_{i=1}^{n} (x_i - \bar{x})^2}

σ = Standard Deviation

n = Sample Size

xix_i = Individual data point

xˉ\bar{x} = Mean

Quantitative Carryover Acceptance

Percent Error Allowance is Set

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When all results are entered and the Carryover (%) is less than the Allowable Error (%) the experiment is considered passed.

Standard Deviation Error Allowance is Set

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When all results are entered and the Carryover SD is less than the Allowable Error (SD) the experiment is considered passed.