Young children and babies are most vulnerable to pesticides. While this seems like a strong generalization, given that pound for pound children breathe more air, drink more water, and eat more food than adults, it becomes obvious that the intake of potentially pesticide-ridden food and beverage is a higher risk for children. Not only can children accumulate more chemicals from their intake to size ratio, their still-developing digestive and nervous systems become easily affected by contaminants in food, causing neurological issues, behavioral problems, and other endocrine or immune system disorders.
If children and babies are known to be at a greater risk than adults, doesn’t it make sense that acceptable daily intake (ADI) values should reflect any risk to children when it comes to pesticides? Luckily, regulations support this argument, having established ultra-low maximum residue levels (MRL) for many pesticides. For example, European Union (EU) regulations specifically address the need for lower levels of pesticides in baby food. The European Union 2006/125/EC commission directive outlines required MRLs for pesticides in the majority of baby food products.
The MRL for the majority of pesticides in baby food products must be at, or less than 10 µg/kg. However, there are a handful of pesticides and their metabolites that can cause infants and young children to quickly exceed ADI values even at the standard required MRL of 10 µg/kg. EU regulations set an even lower MRL of 3-8 µg/kg exist for this group of pesticides.
In addition, the SANTE guidelines set forth method requirements to ensure that techniques used for the detection of pesticides in baby food are specific and reliable enough to detect these low levels of compounds on a consistent basis. These additional requirements are significant to the overall EU regulations given that the low levels of detection required can be missed by some methods.
Quantification methods must take into account the diverse composition of multi-ingredient baby foods and multiple pesticide identifications per sample, as well as the ability to robustly detect ultra-low levels of each pesticide regardless of sample contaminants. Advances in GC-MS/MS triple quadrupole instruments can help to overcome these obstacles, by providing high sensitivity and selectivity.
Applying GC-MS/MS to pesticide detection also offers the advantage of adopting faster, but less specific, sample extraction and clean-up procedures to improve productivity. Sample preparation methods such as QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) provide an efficient way to process samples for quantification. However, the extraction has low selectivity, leaving significant matrix components in the final acetonitrile extract. These can cause system contamination, potentially interfering with target compounds and affect sensitivity.
The newly launched Thermo Scientific TSQ 9000 GC-MS/MS triple quadrupole system can detect ultra-low levels of analytes while mitigating the effects of contaminants in the system. Optimized programmed temperature vaporization (PTV) injection addresses challenges using acetonitrile as a GC solvent by improving solvent focusing and effectively managing the expansion volume for each injection. The Thermo Scientific Advanced Electron Ionization (AEI) sourceovercomes matrix contamination issues by providing increased efficiency in the ionization of analytes and a tighter focus of the ion beam, reducing contamination of the ion source itself, and therefore extending maintenance intervals. Furthermore, the extremely high sensitivity of the AEI source allows for the potential to reduce the matrix load to the system (e.g. less sample taken, less concentration steps, less injected) and still maintain required levels of sensitivity for a number of applications, compounding robustness gains inherited from the source design.
The combined use of QuEChERS and the TSQ 9000 GC-MS/MS system has been validated by spiking two types of baby food, carrot/potato and apple/pear/banana, with 211 pesticides at 14 different concentrations to test sensitivity, consistency, and selectivity across the multiple ingredients and pesticides within a sample. You can read more about this study in this application note: Ultra low level quantification of pesticides in baby foods using an advanced triple quadrupole GC-MS/MS system. Overall, system enhancements allow detection of up to five orders of magnitude, from 0.025 µg/kg to 250 µg/kg, demonstrating accurate quantitative analysis and excellent limits of detection and linear response.
Source: Analyteguru.com by Paul Silcock