QuEChERS is a Quick-Easy-Cheap-Effective-Rugged-Safe extraction method that has been developed for the determination of pesticide residues in agricultural commodities (1). The rise in popularity of the QuEChERS extraction has increased the demand for an automated workflow solution to this labor intensive technique. The AutoMate-Q40 fulfills this need by automating the process from the homogenate to the final extract, with or without sample clean-up.
The goal of this work is to utilize the AutoMate-Q40 for automating the QuEChERS extraction in a multi-lab validation study (Teledyne Tekmar and Pacific Agricultural Lab) for the determination of pesticides in apple juice. Pesticide residues were extracted from the apple juice by using the AutoMate-Q40 workflow solution. Quantification was based on matrix-matched calibration curves with the use of internal standard to ensure method accuracy. Quality control samples were evaluated at levels of 10, 50, and 100 ng/g to ensure the precision and accuracy of the AutoMate-Q40.
Figure 1 shows the flow chart for the AOAC QuEChERS extraction procedure for both analytical labs for the AutoMate-Q40.
Figure 1: Flow chart for the AOAC QuEChERS extraction procedure for both analytical labs for the AutoMate-Q40.
A precision and accuracy study was performed in both labs using the AutoMate-Q40. A 6 μg/mL stock pesticide solution was used to fortify the apple juice samples. Using the AutoMate-Q40, the system is able to spike the following samples with 25.0, 125.0, and 250.0 μL of the pesticide standard that yielded a 10.0, 50.0, and 100 μg/L check samples. Also, the AutoMate-Q40 spiked in 75.0 μL of the internal standard TPP in each sample that yielded a 100.0 μg/L of TPP. These QC samples were quantitated against their corresponding matrix matched calibration curve. Table I demonstrates the excellent recoveries achieved when using the AutoMate-Q40 and exceptional precision for the automated QuEChERS extraction.
Table I: Average LCâMS-MS recovery and %RSD for the AutoMate-Q40 (n = 7)
This study demonstrates the feasibility of automating the QuEChERS extraction method using the AutoMate-Q40. By automating the liquid handing, addition of salt/buffers, sample mixing, pipetting, and liquid level sensing using the patent pending VialVision™. The extraction process is more reliable, and easier. This enables time and labor savings, while improving consistency and repeatability of the extraction. As shown above in Table I the combined average pesticide spikes recovered at 100.17%, with an average RSD of 6.76%. These numbers indicate superb precision and accuracy from two independent testing sites validating the performance of the AutoMate-Q40 as an excellent analytical tool.
(1) AOAC Official Method 2007.07 Pesticide Residues in Food by Acetonitrile Extraction and Partitioning with Magnesium Sulfate. Gas Chromatography/Mass Spectrometry and Liquid Chromatography/Tandem Mass Spectrometry, First Action 2007
To view the full application note please visit http://info.teledynetekmar.com/pesticide_residue_apple_juice_lcgc
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