Quadrupole GC-MS System for Pesticide Analysis in Tea

Pesticides are intended for use on food crops to prevent, destroy, and control pests, which can be chemical, biological (such as a virus or bacterium), antimicrobial, or disinfectant.1 As a result, pesticide residues can be found in agricultural products like tea leaves and, due to their potential toxicity, can be harmful to human health. Pesticide consumption can cause a wide range of long-term health problems, including damage to the nervous and reproductive systems, birth defects, and, in some cases, cancer. Short-term health effects include dizziness, headaches, fatigue, memory impairment, visual disorders, and vomiting, as well as skin, eye, and respiratory tract irritation.

To protect consumers and ensure product quality, multi-residue pesticide monitoring in complex matrices like tea leaves is an ongoing global requirement for regulatory agencies, contract laboratories, and industrial laboratories. It is important that the maximum residue limits (MRLs) of pesticides allowed in food and drink products are not exceeded.

Figure 1. These are the steps that are part of the solid phase micro extraction sample preparation. In this experiment 1g of homogenized sample is weighed into a vial and 3 mL of NaCl saturated water w/ 1% MeOH are added (1a, above left) and then placed on the autosampler (1b, above right).

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Figure 1. These are the steps that are part of the solid phase micro extraction sample preparation. In this experiment 1g of homogenized sample is weighed into a vial and 3 mL of NaCl saturated water w/ 1% MeOH are added (1a, above left) and then placed on the autosampler (1b, above right).

In the United States, the Environmental Protection Agency sets limits on the levels of pesticide residue that can remain in food and feed products without posing a risk to human health. These pesticide residue limits are known as tolerances and apply to both domestic and imported food.2 The U.S. Food and Drug Administration (FDA) is charged with enforcing regulations regarding imported and domestic foods shipped in interstate commerce in the United States. The FDA also carries out pesticide monitoring to gain an increased understanding of particular pesticide/commodity or food product combinations and, ultimately, to ensure consumer safety. The Office of Plant and Dairy Foods prepares an annual summary and detailed analysis of the residue data obtained. This information is made available to food producers and suppliers through the Center for Food Safety and Applied Nutrition.3 In the U.S., pesticides are also subject to the requirements of the Federal Insecticide, Fungicide, and Rodenticide Act and the Federal Food, Drug, and Cosmetic Act.

In addition, the World Health Organization (WHO) has developed the WHO Pesticide Evaluation to coordinate pesticide testing and evaluation, safeguarding public health.4 In March 2007, the WHO and the Food and Agriculture Organization of the United Nations (FAO) signed a Memorandum of Understanding to administer a joint program for pesticide management. The International Code of Conduct on the Distribution and Use of Pesticides, originally adopted by the FAO in 1985 and revised in 2002, promotes pesticide management practices that minimize potential health and environmental risks.1 This code gives a shared responsibility to governments, industry, trade, and international institutions.

Pesticide analysis poses a number of challenges for laboratories and operators due to the wide-ranging chemistries within the contaminants.

Regulations Vary

Despite the fact that food products are traded across international borders, pesticide regulations vary across countries. These differences led delegates at a conference of the FAO to adopt an International Code of Conduct on the Distribution and Use of Pesticides, establishing voluntary standards of pesticide regulation for different countries.5 In the United States, the FDA has since developed a number of guidelines to control and monitor the import of food and agricultural products, including the Automatic Detention of Raw Agricultural Products for Pesticides legislation, implemented in 2006.3

Pesticide analysis poses a number of challenges for laboratories and operators due to the wide-ranging chemistries within the contaminants. Multi-residue pesticide analysis methods are pushed to ever greater complexity as the number of regulated pesticides expands. Most analytical methodologies focus on improving the analytical method for enhanced analysis, which is a significant development given the growing need for robust analytical methods for multi-residue analysis. The bottleneck in such methods is the sample preparation stage, however, which can be lengthy, labor intensive, and error prone, limiting sample throughput. In addition, sample preparation can consume large amounts of solvent, increasing costs for analysis and disposal, generating considerable waste, and contaminating the sample. A key factor in improving sample throughput and providing a robust analysis begins with the sample extraction and concentration.

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