Sandwich injection and analyte protectants as a way to decrease the drift due to matrix effect between bracketing...

Area of Science:

• Analytical Chemistry
• Food Safety

Background:

• Calibration drift is a critical issue in pesticide residue analysis, potentially leading to inaccurate results and regulatory non-compliance.
• The SANTE/12682/2019 guideline mandates a ±30% drift criterion for bracketing calibrations, requiring reanalysis if unmet.

Purpose of the Study:

• To evaluate the efficacy of analyte protectants (Aps) and sandwich injection approach (SIA) in mitigating calibration drift.
• To assess the impact of Aps on the stability of matrix-matched calibrations using strawberry samples.

Main Methods:

• Strawberry samples were prepared using the citrate-buffered QuEChERS method followed by solvent exchange.
• Two GC-MS/MS batches were analyzed: one without Aps and one with Aps, using bracketing matrix-matched calibrations.
• Drift was assessed by comparing subsequent calibrations against the initial one, with 219 pesticides monitored.

Main Results:

• Without Aps, over 50% of pesticides exceeded the drift criteria after 20 injections, rising to 95% by the end of the batch.
• With Aps, only 8% of analytes were out of criteria after 20 injections, and 17% by the end of an 80-sample batch.
• The Aps batch showed significantly lower relative standard deviations (RSDs) and reduced negative drift compared to the non-protected batch.

Conclusions:

• Analyte protectants (Aps) are highly effective in minimizing calibration drift in pesticide residue analysis.
• The use of Aps improves the reliability and accuracy of matrix-matched calibrations, reducing the need for reanalysis.
• This approach offers a robust solution for pesticide residue monitoring, particularly in challenging matrices like strawberries.