An Automated Extraction Solution

Imidazolinone herbicides effectively control a wide-range of weed species. This group of herbicides is comprised of five main chemical compounds: imazamox, imazapic, imazapyr, imazaquin, and imazethapyr (1). Each compound has an identical imidazolinone ring structure with an attached carboxylic acid group. They only differ by the functional group attached to the Imidazolinone ring structure.

This project will evaluate the performance and versatility of the AutoMate-Q40 for the extraction of Imidazolinone herbicides. Liquid chromatography coupled to a triple-quadrupole mass spectrometer (LC–MS-MS) was employed for the detection of these herbicides in agricultural commodities. Quantification was based on matrix-matched calibration curves with the use of internal standard to ensure method accuracy. By using the AutoMate-Q40 to streamline this extraction, it provides us with appropriate analytical results falling in the established method guidelines (recovery range of 70–120% and an RSD <20%) for the target compounds.

Sample Preparation and Results

Figure 1 shows the sample preparation and extraction steps that are needed to extract imidazolinone herbicides from the carrot body and the carrot leafy stem.

Figure 1: Imidazolinone herbicide extraction.

Automating the imidazolinone herbicide extraction enables fast, easy, reliable, and highly reproducible extractions. The AutoMate-Q40 offers labor saving, and improves the repeatability and consistency between the extracted samples.

A precision and accuracy study was performed using the AutoMate-Q40. The system was able to fortify the carrots and the leafy stems, samples at 12.5 ng/g and 25.0 ng/g. This is accomplished through the systems automated standard addition feature. All control samples used for this study showed no significant residue of Imidazolinone herbicides.

Table I shows that when using the AutoMate-Q40 to extract imidazolinone herbicide residues from carrots recoveries ranging from 86.5% to 105.0%. Table I also shows that the results have excellent precision ranging from 2.4% to 10.4%.

Table I: Imidazolinone herbicides carrot results

Conclusion

Automation of this imidazolinone herbicide extraction method produced reliable results for the spiked samples. Automating this extraction shows the versatility of the AutoMate-Q40 and how it can be adapted to other extractions. The AutoMate-Q40 led to improved repeatability, a reduction in the likelihood of human error and the potential for significant labor savings.

Precision and accuracy were assessed for the carrots analyzed. Results for the automated procedure were well within the criteria set forth in this study: Average recoveries for the range of commodities were between 86.5% and 105.0% with good precision (ca. 6% RSD).

References

(1) R. Krieger, F.G. Hess, J.E. Harris, K. Pendino, and K. Ponnock, "Handbook of Pesticide Toxicology," Imidazolinones 1, 1641–1642, (2001).

(2) C. Lamberth, Bioactive Heterocyclic Compound Classes: Agrochemicals, 47–49 (2012).

(3) U. Schirmer, Modern Crop Protection Compounds: Herbicides 1, 88–91, (2012).

Acknowledgments

A special thanks to Rick Jordan and Pacific Agricultural Laboratory for their time and support. Without their help and knowledge, this project wouldn't have been possible.

Teledyne Tekmar
4736 Socialville Foster Rd., Mason, OH 45040
tel. (513) 229-7000
Website: www.teledynetekmar.com