Exploring near-infrared spectroscopy and hyperspectral imaging as novel characterization methods for anaerobic gut fungi.

Neocallimastigomycota are a phylum of anaerobic gut fungi (AGF) that inhabit the gastrointestinal tract of herbivores and play a pivotal role in plant matter degradation. Their identification and characterization with marker gene regions has long been hampered due to the high inter- and intraspecies length variability in the commonly used fungal marker gene region internal transcribed spacer (ITS). While recent research has improved methodology (i.e. switch to LSU D2 as marker region), molecular methods will always introduce bias through nucleic acid extraction or PCR amplification. Here, near-infrared spectroscopy (NIRS) and hyperspectral imaging (HSI) are introduced as two nucleic acid sequence-independent tools for the characterization and identification of AGF strains. We present a proof-of-concept for both, achieving an independent prediction accuracy of above 95% for models based on discriminant analysis trained with samples of three different genera. We further demonstrated the robustness of the NIRS model by testing it on cultures of different growth times. Overall, NIRS provides a simple, reliable, and nondestructive approach for AGF classification, independent of molecular approaches. The HSI method provides further advantages by requiring less biomass and adding spatial information, a valuable feature if this method is extended to mixed cultures or environmental samples in the future.

Ambient mass spectrometry and near-infrared spectroscopy - a direct comparison of methods for the quantification of sucralose in e-liquids.

E-liquids have become increasingly popular in society in recent years. A wide variety of flavors and nicotine strengths make it possible for every user to get a product according to their wishes. Many of these e-liquids are marketed with countless different flavors, which are often characterized by a strong and sweet smell. Sweeteners, such as sucralose, are therefore commonly added as sugar substitutes. However, recent studies have shown the potential formation of highly toxic chlorinated compounds. This can be explained by the high temperatures (above 120 °C) within the heating coils and the used basic composition of these liquids. Nevertheless, the legal situation is composed of proposals without clear restrictions, only recommendations for tobacco products. For this reason, a high level of interest lies within the establishment of fast, reliable and cost-effective methods for the detection of sucralose in e-liquids. In this study, a number of 100 commercially available e-liquids was screened for sucralose in order to identify the suitability of ambient mass spectrometry and near-infrared spectroscopy for this application. A highly sensitive high-performance liquid chromatography coupled to a tandem mass spectrometer method was used as reference method. Furthermore, the advantages and limitations of the two mentioned methods are highlighted in order to provide a reliable quantification of sucralose. The results clearly revile the necessity for product quality due to the absence of declaration on many of the used products. Further on, it could be shown, that both methods are suitable for the quantification of sucralose in e-liquids, with beneficial economic and ecological aspects, over classical analytical tools including high-performance liquid chromatography. Clear correlations between the reference and novel developed methods are displayed. In summary, these methods enable an important contribution to ensure consumer protection and elimination of confuse package labelling.

Sulfonated halloysite nanotubes as a novel cation exchange material for solid phase extraction of toxic pyrrolizidine alkaloids.

Pyrrolizidine alkaloids are phytochemicals, which present a highly toxic class of compounds in multiple food resources and are therefore a late-breaking topic in food safety. This study describes the first use of modified halloysite nanotubes as a novel solid material for solid phase extraction. As a result of a fast one-pot sulfonation of the cheap and non-toxic halloysite nanotubes, an efficient cation exchange phase has been prepared. After optimization of the solid phase extraction protocol, high extraction efficiencies and overall recoveries were obtained for a mixture of four pyrrolizidine alkaloid structures through UHPLC-MS/MS analysis with caffeine as the internal standard. Furthermore, the novel solid phase was used for the selective binding of the toxic pyrrolizidine alkaloids in a real-life honey sample, which itself is often contaminated with these compounds. In-house validation showed great extraction efficiencies up to 99.9% for senecionine with a lower limit for lycopsamine with 59.3%, which indicated high selectivity even in the presence of potential interfering compounds. Subsequently, overall recoveries up to 91.5% could be obtained for senecionine while the lowest value was reached for lycopsamine with 55.1%. Comparison with a commercial strong cation exchange tube procedure showed the high competitiveness of the novel solid phase with respect to overall performance. Only slight disadvantages regarding precision and repeatability with values under 5.7% and 11.6% could be observed. Therefore, sulfonated halloysite nanotubes present themselves as an easy to prepare, cheap and highly efficient novel cation exchange material for the selective solid phase extraction of toxic pyrrolizidine alkaloids in frequently contaminated real-life samples like honey.