F
Using multi-toxin analysis to overcome challenges in mycotoxin analysis
L
by R-Biopharm, UK
aboratories are typically presented with a wide variety of samples and include solid samples like cereals, which could be classified as an easy matrix. However, they may also consist of more complex samples like animal feed or spice mixtures. A number of samples may also be liquids like fruit juices and sauces. Regardless of the format of the sample, all will contain components other than the analyte of interest and may be a mix of carbohydrates, sugars, fats, salts, proteins and pigments. All of these components can result in what is referred to as sample matrix. The matrix can have a considerable effect on the way the analysis is conducted and the quality of the results obtained; such effects are called matrix effects. In order to obtain good, reliable results consistently the sample matrix should be removed. It is, therefore, necessary to ensure that a suitable sample extraction and clean-up method are employed. The removal of any sample matrix will reduce any issues with: • Blockages within the analytical detection system which can ultimately lead to downtime where no samples are analysed • False positives, as positive samples are normally required to be re-analysed in order to confirm results. This leads to an increase in analysis time and potentially a reduction in overall margin
64 | August 2020 - Milling and Grain
• Any results with high %RSD, which indicate poor accuracy and reproducibility and again would need to be re-analysed • Poor sensitivity. Sensitivity is important to ensure you are complying with legislative levels and to ensure that you are not reporting false negatives. There are several options available to laboratories analysing samples. The first is to use direct injection or dilute and shoot methods. These are typically used prior to LC-MS/MS detection, however, it should be noted that these methods are the most basic form of clean-up and, ultimately, will still result in some matrix effect being observed. These will need to be corrected for by using isotopic labelled standards and potentially also matrix matched standards. Solid phase columns are also typically used prior to LC-MS/MS detection, however, again are considered as a basic form of cleanup and, as a result, are most commonly used for the analysis of simple commodities like certain cereal samples. Alternatively, immunoaffinity clean-up is available. Although traditionally immunoaffinity columns were focused on single toxins, the market is changing and there are now various multitoxin options available which allow you to clean-up any sample type, effectively removing all matrix components. This ultimately means that you have a clean solvent-based eluate and removes the need for the use of isotopic labelled and matrix matched standards, resulting in quicker and more cost-effective analysis. Everyone is facing new challenges on a day to day occurrence and in general labs are facing the same challenges: