Algorithm of combining chromatography mass spectrometry-untargeted profiling and multivariate analysis for identification of marker-substances in samples of complex composition

2020 ◽  
Vol 86 (7) ◽  
pp. 12-19
Author(s):  
I. V. Plyushchenko ◽  
D. G. Shakhmatov ◽  
I. A. Rodin

A viral development of statistical data processing, computing capabilities, chromatography-mass spectrometry, and omics technologies (technologies based on the achievements of genomics, transcriptomics, proteomics, metabolomics) in recent decades has not led to formation of a unified protocol for untargeted profiling. Systematic errors reduce the reproducibility and reliability of the obtained results, and at the same time hinder consolidation and analysis of data gained in large-scale multi-day experiments. We propose an algorithm for conducting omics profiling to identify potential markers in the samples of complex composition and present the case study of urine samples obtained from different clinical groups of patients. Profiling was carried out by the method of liquid chromatography mass spectrometry. The markers were selected using methods of multivariate analysis including machine learning and feature selection. Testing of the approach was performed using an independent dataset by clustering and projection on principal components.

2020 ◽  
Vol 412 (27) ◽  
pp. 7469-7480
Author(s):  
Gustavo Henrique Bueno Duarte ◽  
Anna Maria Alves de Piloto Fernandes ◽  
Alex Aparecido Rosini Silva ◽  
Hans R. Zamora-Obando ◽  
Alan Gonçalves Amaral ◽  
...  

1997 ◽  
Vol 43 (1) ◽  
pp. 100-103 ◽  
Author(s):  
William E Wingert

Abstract A large-scale study was conducted to determine whether lowering the initial testing and confirmation testing cutoffs in urine would significantly affect the positive rates for cocaine (COC) and marijuana (THC). Customary cutoffs for COC are 300 μg/L and 150 μg/L for initial testing (screening) and gas chromatography–mass spectrometry (GC-MS; confirmation), respectively; for THC, the usual respective cutoffs are 50 μg/L and 10 μg/L. By applying a screening cutoff of 100 μg/L for COC and lowering the GC-MS cutoff to 50 μg/L, the COC-positive rate increased from 1.2% to 2.1%. For THC, lowering the screening cutoff to 20 μg/L while leaving the GC-MS cutoff at 10 μg/L increased the THC-positive rate from 2.8% to 4.1%. These increases appear noteworthy.


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