Reliable comparison of mass spectra recorded under identical conditions using principal component analysis

Рассмотрена возможность использования метода главных компонент для проведения надежного сопоставления масс-спектров, зарегистрированных в идентичных условиях и содержащих один и тот же набор значений m/z. Описанный в работе подход к сопоставлению масс-спектров основан на совместном использовании метода главных компонент и t-критерия Стьюдента. В качестве модельных соединений были рассмотрены алифатические спирты нормального строения (характеризующиеся весьма близкими масс-спектрами ионизации электронами).In this work, we considered the possibility of using principal component analysis for the reliable comparison of mass spectra recorded under identical conditions and containing the same set of m/z values. The described approach for mass spectra comparison was based on simultaneous use of principal component analysis and Student's t-test. Normal aliphatic alcohols (having very similar electron ionization mass spectra) were used as model compounds

Analysis of 4-Hydroxyphenyllactic Acid and Other Diagnostically Important Metabolites of α-Amino Acids in Human Blood Serum Using a Validated and Sensitive Ultra-High-Pressure Liquid Chromatography-Tandem Mass Spectrometry Method

The profile of and dynamic concentration changes in tyrosine, phenylalanine, and tryptophan metabolites in blood are of great interest since they could be considered potential biomarkers of different disorders. Some aromatic metabolites, such as 4-hydroxyphenyllactic, 4-hydroxyphenylacetic, phenyllactic, and 4-hydroxybenzoic acids have previously demonstrated their diagnostic significance in critically ill patients and patients with post-COVID-19 syndrome. In this study, a sensitive method, including serum protein precipitation with methanol and ultra-high-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection, was developed and validated for six phenyl- and five indole-containing acids in human serum. The liquid–liquid extraction was also examined, but it demonstrated unsatisfactory results based on analyte recoveries and the matrix effect. However, the recoveries for all analytes reached 100% and matrix effects were not observed using protein precipitation. This made it possible to use deionized water as a blank matrix. The lower limits of quantitation (LLOQs) were from 0.02 to 0.25 μmol/L. The validated method was used for the analysis of serum samples of healthy volunteers (n = 48) to reveal the reference values of the target analytes. The concentrations of the most clinically significant metabolite 4-hydroxyphenyllactic acid, which were revealed using UPLC-MS/MS and a previously developed gas chromatography-mass spectrometry method, were completely comparable. The proposed UPLC-MS/MS protocol can be used in the routine clinical practice of medical centers

Fast screening of hydro xymethylfurfural in honey using high-performance thin-layer chrometography

Впервые представлен способ быстрого определения (скрининга) оксиметилфурфурола в меде методом высокоэффективной тонкослойной хроматографии. Детектирование осуществляли методом денситометрического сканирования при измерении поглощения на длине волны 290 нм. При использовании предлагаемого подхода возможен одновременный анализ до 20 образцов, при этом длительность хроматографирования составляет около 5 минут.An approach for fast screening of hydroxymethylfurfural in honey by high-performance thin-layer chromatography is suggested for the first time. The detection was performed by densitometric scanning at 290 nm. Using this approach, it is possible to screen up to 20 samples simultaneously, and the separation takes just about 5 minutes