Mass Spectrometry Multiplexed Detection of SARS-CoV-2.

Testing of large populations for virus infection is now a reality worldwide due to the coronavirus (SARS-CoV-2) pandemic. The demand for SARS-CoV-2 testing using alternatives other than PCR led to the development of mass spectrometry (MS)-based assays. However, MS for SARS-CoV-2 large-scale testing have some downsides, including complex sample preparation and slow data analysis. Here, we describe a high-throughput targeted proteomics method to detect SARS-CoV-2 directly from nasopharyngeal and oropharyngeal swabs. This strategy employs fully automated sample preparation mediated by magnetic particles, followed by detection of SARS-CoV-2 nucleoprotein peptides by turbulent flow chromatography coupled with tandem mass spectrometry.

Establishing a mass spectrometry-based system for rapid detection of SARS-CoV-2 in large clinical sample cohorts.

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is pressing public health systems around the world, and large population testing is a key step to control this pandemic disease. Here, we develop a high-throughput targeted proteomics assay to detect SARS-CoV-2 nucleoprotein peptides directly from nasopharyngeal and oropharyngeal swabs. A modified magnetic particle-based proteomics approach implemented on a robotic liquid handler enables fully automated preparation of 96 samples within 4 hours. A TFC-MS system allows multiplexed analysis of 4 samples within 10 min, enabling the processing of more than 500 samples per day. We validate this method qualitatively (Tier 3) and quantitatively (Tier 1) using 985 specimens previously analyzed by real-time RT-PCR, and detect up to 84% of the positive cases with up to 97% specificity. The presented strategy has high sample stability and should be considered as an option for SARS-CoV-2 testing in large populations.

Analysis of cocaine and its adulterants in drugs for international trafficking seized by the Brazilian Federal Police.

Here, gas chromatography with nitrogen phosphorous detector (GC-NPD) method was developed and validated for the quantification of cocaine and adulterants (caffeine, 4-dimethylaminoantipyrine, levamisole, lidocaine and phenacetin) in illicit samples. The method was based on direct dilution of samples in methanol, sonication for 5 min and centrifugation. After appropriate dilution, an aliquot was injected into GC-MS in order to identify the active compounds and into GC-NPD for the analytes quantification. Bupivacaine was used as an internal standard. The method showed to be precise, accurate and linear over a range of 0.5-100% (weight/weight percentages) for all analytes, except phenacetin which showed a linear range between 2% and 100%. The method was successfully applied to 54 samples seized by the Brazilian Federal Police in the International Airport of Sao Paulo and mailing services during the year 2011. All the samples were associated with international trafficking and were apprehended while leaving the country. The purity of cocaine ranged from 16.5% to 91.4%. Cocaine was the only detected active compound in 29.6% of total samples. Among the identified cutting agents, levamisole was the most abundant (55.6% of the total samples) and relative concentrations (weight/weight percentages) ranged from 0.7% to 23%. Lidocaine, caffeine, phenacetin and 4-dimethylaminoantipyrine were also identified in these samples in minor concentrations. In contrast with what we initially hypothesized, drugs intended to international trafficking did not present high cocaine purity and most of the samples were laced with adulterants before leaving Brazil.

Determination of dimethyltryptamine and ß-carbolines (ayahuasca alkaloids) in plasma samples by LC-MS/MS.

BACKGROUND: Ayahuasca is a psychoactive plant beverage originally used by indigenous people throughout the Amazon Basin, long before its modern use by syncretic religious groups established in Brazil, the USA and European countries. The objective of this study was to develop a method for quantification of dimethyltryptamine and ß-carbolines in human plasma samples. RESULTS: The analytes were extracted by means of C18 cartridges and injected into LC-MS/MS, operated in positive ion mode and multiple reaction monitoring. The LOQs obtained for all analytes were below 0.5 ng/ml. By using the weighted least squares linear regression, the accuracy of the analytical method was improved at the lower end of the calibration curve (from 0.5 to 100 ng/ml; r(2)> 0.98). CONCLUSION: The method proved to be simple, rapid and useful to estimate administered doses for further pharmacological and toxicological investigations of ayahuasca exposure.