Providing Peace of Mind: Ultra Low-Level Detection of Pesticides in Baby Food

Pesticides are widely used to protect food crops from damage and consequently have the potential to end up in the food we eat. While pesticides help to protect crops, they can be detrimental to human health, even in trace amounts. Research has shown that exposure to pesticides can lead to a wide range of health issues both immediate and later in life, including cancer, allergies, reproductive problems, and endocrine or immune disorders.

Unfortunately, young children and babies can be particularly susceptible to pesticide residues in food. This is because, compared to adults, their digestive tracts are more sensitive and nervous systems are still developing. Changes in neurochemistry at this stage of life can result in long-term damage and behavioral disorders. Given their widespread use, and sometimes overuse, testing for pesticide residues in food, and baby food in particular, is therefore critical for the preservation of human health.

An important regulatory climate

Given the dangers of pesticide exposure, regulations such as the European Union (EU) Commission Directive 2006/125/EC have been put in place to control residues and ensure that the food put in front of infants is safe to eat. This directive has set very low maximum residue levels (MRL) for all pesticides, fixed at 10 µg/kg. This limit is suitable for most pesticide residues, however, a subset of pesticides and their metabolites require additional reduction of MRLs to 3-8 µg/kg. This is due to health concerns regarding their accumulation in the body, pushing the upper limits of a child’s acceptable daily intake (ADI) values.

These requirements create a need for highly sensitive and selective detection methods to ensure that all residues are properly measured. Not only do these analytical methods need to meet low-level detection requirements, they must also be capable of analyzing a variety of samples, that are often extremely complex considering their composition at the molecular level, in accordance with the SANTE/11813/2017 guidelines (which outlines acceptable approaches to achieve valid results in a quality controlled environment). 

Relying on analytical methods to keep food safe

With strict regulations in place, food safety laboratories are charged with the responsibility to make confident decisions about whether food has passed pesticide inspection. Particularly when it comes to safety in children, regulations are upheld to the strictest level. In order to investigate the most sensitive and reliable approach for the identification and quantitation of pesticide residues in baby food, a research team at Thermo Fisher Scientific evaluated the combination of QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation with advanced triple quadrupole gas chromatography-tandem mass spectrometry (GC-MS/MS). The study demonstrated that this method delivers robust quantitative results in accordance with SANTE guidelines for trace amounts of pesticide residues. 

Finding a sample preparation method that is compatible with difficult food samples can be daunting. Since the QuEChERS extraction method is known to work across a wide range of samples, is fast for improved productivity, and can be scaled for high throughput, the team used QuEChERS extraction for samples of carrot-potato and apple-pear-banana baby food. Each sample was then spiked with over 200 pesticides for matrix-matched calibration and analyzed. The observed recoveries of all pesticides in each sample were excellent and in accordance with SANTE/11813/2017 requirements.

The QuEChERS procedure has become a preferred sample preparation method in many food safety laboratories, having greatly simplified the analysis of multiple pesticide residues. The method includes sample extraction with acetonitrile and buffering salts, followed by dispersive solid-phase extraction (dSPE) clean-up. Though it is not the most specific sample preparation method available and clean-up with dSPE allows a significant amount of matrix components to remain in the final extract, using downstream analysis methods that are highly selective and sensitive enables the use of this more efficient approach.

A triple quadrupole GC-MS/MS system was chosen for sample analysis based on its reliability, specificity, and sensitivity to detect even the smallest amount of residue regardless of sample type. Data was acquired, processed, and reported using chromatography data system (CDS) software. Advances in GC-MS/MS enable consistent high-quality results, even when dealing with routinely encountered issues in extracted samples. 

As the QuEChERS approach can leave behind high concentrations of matrix components in the final acetonitrile extract, it can be a challenge for accurate and precise GC-MS analysis. Acetonitrile is a challenging GC solvent as it is insoluble in the low polarity phases typically used for pesticide analysis. Using an optimized programmable temperature vaporization injection helped overcome the challenges associated with acetonitrile as a GC solvent and aided in identifying the lowest detectable calibration standard, as well as indicating excellent linear response over a wide concentration range. The GC-MS/MS approach allows for the matrix components to be eliminated from the analytical signal, especially required in the most challenging sample matrices to reach the lowest detection levels.

During this study, the GC-MS/MS system demonstrated the sensitivity, linearity, and robustness needed to detect trace residues for identification within baby food samples. Over 90 percent of the compounds displayed a limit of identification (LOI) below 0.5 ug/kg and over 60 percent showed even lower LOIs (below 0.1 ug/kg), well below the MRLs set by Commission Directive 2006/125/EC. This confirms high system sensitivity with the capability to identify lower levels than required. The system displayed robustness over more than 400 sample injections while maintaining consistent sensitivity of detection. Samples could even be diluted to reduce matrix effects and achieve sensitive detection and identification for each residue. 

Food contamination even at low levels can be harmful, especially to children. Therefore, having advanced technologies that can detect damaging pesticides in food is vital. QuEChERS sample preparation and GC-MS/MS together enable the quick detection and identification of even low levels of residue in a broad range of sample types.