Metabolomics is used to reduce the complexity of plants and to understand the underlying pathways of the plant phenotype. The metabolic profile of plants can be obtained by mass spectrometry or liquid-state NMR. The extraction of metabolites from the sample is necessary for both techniques to obtain the metabolic profile. This extraction step can be eliminated by making use of high-resolution magic angle spinning (HR-MAS) NMR. In this review, an HR-MAS NMR-based workflow is described in more detail, including used pulse sequences in metabolomics. The pre-processing steps of one-dimensional HR-MAS NMR spectra are presented, including spectral alignment, baseline correction, bucketing, normalisation and scaling procedures. We also highlight some of the models which can be used to perform multivariate analysis on the HR-MAS NMR spectra. Finally, applications of HR-MAS NMR in plant metabolomics are described and show that HR-MAS NMR is a powerful tool for plant metabolomics studies.

Background: Intentional sodium nitrite poisoning is an emerging trend worldwide, as it is promoted for its use in self-euthanasia. Nitrite dipstick urinalysis could potentially serve as a rapid-diagnostic tool. Urine dipstick analysis is a common point-of-care test (POCT) for the initial diagnosis of urinary tract infections. The aim of this study was to investigate nitrite dipstick urinalysis as a potential reliable POCT for the early detection of sodium nitrate poisoning. Methods: Postmortem urine samples, collected over 1 year, were prospectively analyzed for nitrite presence using a urine dipstick method. In addition, a retrospective search was conducted in the database to identify cases with suspected or confirmed sodium nitrite poisoning as the cause of death. Available urine samples from these cases were screened for the presence of nitrite. Results: Prospectively, 10 of the 420 urine samples tested positive for nitrite presence: 6 samples without any suspicion of sodium nitrite ingestion and 4 with confirmed sodium nitrite poisoning as the cause of death. In addition, in our retrospective study, 12 cases of suspected sodium nitrite poisoning were tested for nitrite presence in the urine using the dipstick. Of these, 8 tested positive for nitrite. Two of the 12 cases were later attributed to intoxication with other substances. As a control, urine samples spiked with sodium nitrite were tested using the dipstick; the pink color intensified with increasing sodium nitrite concentration. Conclusions: Nitrite dipstick urinalysis is a feasible approach for the early detection of nitrite poisoning in postmortem toxicological screening. In addition, this rapid POCT shows potential as a diagnostic tool for use in acute clinical settings in cases of suspected sodium nitrite poisoning or elevated methemoglobinemia with an unknown cause.