BACKGROUND
Deconstructing a BLT using pesticides In this latest in a series of advisory articles from ALS, Buddhi Dias - the company’s contaminants and pesticides laboratory manager, who heads their Contaminants and Pesticides Department to provide reliable testing, technical advice and training days – considers the rationale behind testing for pesticide residues in a sandwich product. DETECTION Because maximum residue levels (MRL) are applied to raw materials, the question of testing the final product for pesticides has been always debated. A frequently asked question is “what are the benefits of testing the final product for pesticides if there are no MRLs to compare the results against, and if we are to test a final product such as a sandwich, how could we make the results we find meaningful?” For the purpose of this article, we carried out a multi-residue screen on a supermarket bought BLT sandwich. The testing performed was a routine screen that we carry out daily, which covers 500 different pesticides. This process involves homogenising the sample and taking a portion to be extracted using QuEChER’s technique. Once the sample is extracted, a portion of this is then
run on a liquid chromatography (LC) and gas chromatography (GC) system, coupled with mass spectrometry (MS) to give us qualitative results. LC and GC systems are acting to separate out different pesticides, a bit like when you put an ink dot on paper and let the colours separate out, during the school science lessons. The MS system will then detect and identify the different pesticides. The pesticides that were detected above the 0.01mg/kg reporting limit (RL) on this sandwich were deltamethrin and piperonyl butoxide. The latter is not classed as a pesticide and there are no set MRLs for any raw material for this. Piperonyl butoxide is what known as a synergist. This is a part of the formulation of a pesticide makeup. It helps the pesticides to penetrate more easily to the plant and
50 November 2021 www.sandwichandfoodtogonews.co.uk
ALS Laboratories (UK) Ltd (www.als-testing.co.uk) is one of the UK’s leading providers of food and drink testing services. With six accredited laboratories located across the country, they offer a comprehensive range of high quality, analytical testing services, including microbiological, nutritional, vitamins and minerals, pesticides and contaminants, allergens and speciation. They also provide clients with a wide range of consultancy services and technical support on food safety, labelling requirements, allergens management and sensory testing. is commonly used with the pyrethroids class of pesticides. Apart from these, three other pesticides were detected well below the RL. These were boscalid, tebuconazole and pendimethalin. The reporting limit is also known as the limit of quantitation (LOQ). This is the limit at or above which a result can be accurately quantitated, and a value can be given. Below this limit, pesticides can be detected up until the limit of detection (LOD), however the values that are calculated would be qualitative only. SAFE? Now we have information regarding the pesticides that can be found in a sandwich, how can we say this is safe or it doesn’t breach any MRLs? One approach could be looking at using a consumer risk assessment model to
