Multi-residue Pesticide Analyses

Microchem offers pesticide residue analyses to the South African fresh fruits markets for fruit bound for the export market.  Process optimisation and high investment in state-of-the-art equipment allows for fast turn-around times and additional capacity needed to ensure customer satisfaction even during high season or for urgent testing.

Microchem uses the “QuEChERS” multi-residue analyses (MRAs). The “QuEChERS” MRA is a relatively new method developed by the USDA (United States Department of Agriculture), which can detect many of the newer pesticides.

Using this cutting-edge technology, we can identify and quantify a range of pesticide residues in fresh produce at parts per billion levels. Our method covers a wide range of pesticide classes, including many compounds and metabolites that traditionally have had to be analysed using separate targeted techniques to achieve the required level of detection.

Microchem also participates in proficiency testing programs including FAPAS (Food Analysis Performance Assessment Scheme) and other international laboratory testing schemes. Participation in these proficiency testing programs is a requirement of our ISO/IEC 17025:2017 accreditation and serves as an external quality measure of laboratory accuracy.

Microchem adheres to strict quality procedures to ensure accurate results. These include well defined areas where maximum safety and minimum chance of cross-contamination of samples prevail. Correct handling and storage procedures are in place to ensure that the integrity of the sample is maintained. We also make extensive use of matrix-matched standards, necessary sample clean-up procedures, spiked quality control samples for every batch of samples as well as internal standards to ensure consistent results.

Food Testing and Consulting

Partnering with Microchem gives you access to in-depth testing expertise, innovative testing techniques and world-class facilities and equipment, all designed to help you get your products to market faster, with the highest degree of confidence in the results.

Each technique has unique advantages and disadvantages, depending on the sample matrix and pesticides of interest. Pesticide polarity is an important consideration, as GC-MS is best suited to less polar compounds while LC-MS is best for highly polar compounds. For GC analysis, a pesticide must be volatile or undergo derivatization while LC enables the detection of a much wider range of pesticides. We use either GC or LC (or both) for all of our pesticide methods. LC extraction methods are typically easier and achieve lower detection limits, partially due to larger injection volumes. GC methods are rugged, reliable, and offer a different detection approach than LC. This can lead to identification of compounds LC may miss.

Detection methods are also an important consideration. Mass Spectrometry (MS) quantifies the mass-to-charge ratio of ions, while MS-MS (tandem MS) breaks precursor ions into fragments, which are then separated and detected in a second stage. MS-MS offers greater selectivity, which is beneficial for the detection of known compounds. The advantage of MS-MS is the high level of selectivity leading to lower method detection limits. The advantage of MS is the lack of selectivity, which can be useful in identifying compounds that we were not necessarily even looking for and is helpful in identifying ‘unknown’ compounds.

Older methods of measuring glyphosate residues tend to be more time- and solvent-intensive. For this reason, more routine testing labs are adopting simpler and greener methods of measuring glyphosate. The HILIC [hydrophilic interaction liquid chromatography] method targets metabolites to address pending changes to the regulated residue definitions.

Pesticides are still widely used to improve crop yields. Adherence to maximum residue limits, ongoing efforts to reduce the amount of pesticides applied, and sensitive testing techniques all serve to ensure consumer health and safety. As technology improves, we may further reduce our reliance on pesticides. In the meantime, vigilance is required to ensure environmental and human health.