Development and application of ToF-SIMS within agrochemistry

This study is aimed at exploring the potential use of Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) for the detection and localization of agrochemicals in biological material. The first part focused on developing a method (from sample preparation to ToF-SIMS analysis) for the analysis of a selection of 44 commonly and commercially used agrochemicals. Based on the results of these analyses, a model compound was chosen for further investigation. The chosen compound was the fungicide fludioxonil and both limit of detection and quantification were calculated for its ToF-SIMS detection. Further experiments were performed on how endogenous molecules could affect the ToF-SIMS detection of fludioxonil and, in particular, the “matrix effect” of components typically present in biological matrices was studied. After proving the capabilities of the technique in a simplified experimental setting, ToF-SIMS was used to analyse real-life complex biological samples. The first targets of the analyses were nematodes, important agricultural pests. Extensive work focused on developing a reproducible sample preparation in order to obtain thin sections of nematodes. Unfortunately, none of the tried techniques gave good results. On top of this, fludioxonil was not detectable in any of the analysed nematodes. For this reason, another biological sample was explored for ToF-SIMS analyses: formulation coated wheat seeds. After developing a reproducible sample preparation method for sectioning the seeds, ToF-SIMS analyses were able to detect fludioxonil in all the sections. Overall, this study demonstrated the potential use of ToF-SIMS in the agrochemical industry. Its capability of obtaining visual information on the distribution of specific active ingredients in real-life biological samples at realistic concentrations makes this technique potentially valuable in agrochemical research, even though its limitations mean that its applications in the agrochemical industry are likely to be fairly specific and limited.Open Acces

Imaging of agrochemicals with ToF-SIMS

We evaluated the use of ToF-SIMS in the agrochemical field, which remains a largely unexplored area for this technique. In particular, we profiled a large number of biocidal active ingredients (herbicides, fungicides, and insecticides, selected based on their global importance); we then selected fludioxonil, a halogenated fungicide, as a model compound for more detailed study, including the effect of co-occurring biomolecules on detection limits. There was a wide range of sensitivity of the ToF-SIMS for the different active ingredient compounds, but fludioxonil was readily detected in real-world samples (wheat seeds coated with a commercial formulation). Fludioxonil did not penetrate the seed to any great depth, but was largely restricted to a layer coating the seed surface. ToF-SIMS has clear potential as a tool for not only detecting biocides in biological samples, but also mapping their distribution

Combining Thermal Desorption with Selected Ion Flow Tube Mass Spectrometry for Analyses of Breath Volatile Organic Compounds

An instrument integrating thermal desorption (TD) to selected ion flow tube mass spectrometry (SIFT-MS) is presented, and its application to analyze volatile organic compounds (VOCs) in human breath is demonstrated for the first time. The rationale behind this development is the need to analyze breath samples in large-scale multicenter clinical projects involving thousands of patients recruited in different hospitals. Following adapted guidelines for validating analytical techniques, we developed and validated a targeted analytical method for 21 compounds of diverse chemical class, chosen for their clinical and biological relevance. Validation has been carried out by two independent laboratories, using calibration standards and real breath samples from healthy volunteers. The merging of SIFT-MS and TD integrates the rapid analytical capabilities of SIFT-MS with the capacity to collect breath samples across multiple hospitals. Thanks to these features, the novel instrument has the potential to be easily employed in clinical practice

Tocilizumab for patients with COVID-19 pneumonia. The single-arm TOCIVID-19 prospective trial

BackgroundTocilizumab blocks pro-inflammatory activity of interleukin-6 (IL-6), involved in pathogenesis of pneumonia the most frequent cause of death in COVID-19 patients.MethodsA multicenter, single-arm, hypothesis-driven trial was planned, according to a phase 2 design, to study the effect of tocilizumab on lethality rates at 14 and 30 days (co-primary endpoints, a priori expected rates being 20 and 35%, respectively). A further prospective cohort of patients, consecutively enrolled after the first cohort was accomplished, was used as a secondary validation dataset. The two cohorts were evaluated jointly in an exploratory multivariable logistic regression model to assess prognostic variables on survival.ResultsIn the primary intention-to-treat (ITT) phase 2 population, 180/301 (59.8%) subjects received tocilizumab, and 67 deaths were observed overall. Lethality rates were equal to 18.4% (97.5% CI: 13.6-24.0, P=0.52) and 22.4% (97.5% CI: 17.2-28.3, P<0.001) at 14 and 30 days, respectively. Lethality rates were lower in the validation dataset, that included 920 patients. No signal of specific drug toxicity was reported. In the exploratory multivariable logistic regression analysis, older age and lower PaO2/FiO2 ratio negatively affected survival, while the concurrent use of steroids was associated with greater survival. A statistically significant interaction was found between tocilizumab and respiratory support, suggesting that tocilizumab might be more effective in patients not requiring mechanical respiratory support at baseline.ConclusionsTocilizumab reduced lethality rate at 30 days compared with null hypothesis, without significant toxicity. Possibly, this effect could be limited to patients not requiring mechanical respiratory support at baseline.Registration EudraCT (2020-001110-38); clinicaltrials.gov (NCT04317092)