Using the iDQuant™ Standards Kit for Pesticide Analysis to Analyze Residues in Fruits and Vegetable Samples

The iDQuant™ Standards Kit for pesticide analysis of certified reference material (ISP Guide 34, IOS/IEC 17025, and ISO 9001:2008) includes 204 pesticides in 10 mixes at a concentration of 100 μg/mL. This kit has been designed to eliminate the need to source pesticides individually, and measure each one manually. This allows users to setup, verify, and validate the performance of pesticide screening methods faster.

Many recent developments such as generic extraction procedures, (like QuEChERS), generic LC separation methods, and highly selective and sensitive MS-MS detectors have established LC–MS-MS as a standard technique for the analysis of pesticide residues in food. Hundreds of targeted analytes can be detected in a single analytical run. Software designed for ease-of-use like Cliquid® software in conjunction with iMethod™ applications made the fast adaptation of LC–MS-MS in new routine testing laboratories possible. For a while, data processing was the bottleneck for most laboratories, but the development of fast and automatic data processing and reporting tools sped up the delivery of analytical results.

A major hurdle for each laboratory is method setup, verification, and validation. The newly available iDQuant™ kit can be used for the following tasks:

• Tune or verify MRM transitions for best selectivity and sensitivity of MS-MS detection

• Measure retention times to quickly update acquisition methods using the Scheduled MRM™ algorithm

• Investigate recovery and reproducibility of sample preparation procedures

• Validate the performance of the complete method procedure

Experimental

The iDQuant™ standards kit was used for method setup and preparation of calibration standards. Fruits and vegetables were extracted using a QuEChERS procedure and diluted 10× with water to optimize chromatographic peak shape and minimize possible matrix effects. LC separation was achieved on a Shimadzu UFLC_XR system with a Restek Ultra Aqueous C18 3 μm (100 × 2.1 mm) column and a 15 min gradient of water and methanol with ammonium formate buffer at a flow rate of 0.5 mL/min. The AB Sciex QTRAP® 5500 system was operated with Electrospray Ionization. 436 MRM transitions were monitored using the Scheduled MRM™ algorithm.

Results

The developed LC–MS-MS method was successfully applied to detect pesticides in food samples. Chromatograms were processed using the "multicomponent" query in MultiQuant™ software to automatically report concentrations above the threshold of 10 μg/kg and to compare MRM ratios for compound identification (Figure 1).

Figure 1: Pesticides above 10 μg/kg and with a positive identification based on their MRM ratio following guideline SANCO/10684/2009.

Summary

The iDQuant™ Standards Kit for pesticide analysis was used to successfully setup an LC–MS-MS method to identify and quantify pesticides in fruit and vegetable samples. This was accomplished in less time than it was previously possible when a standard kit was either unavailable or had to be created from individual standards.

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