PTR-MS and GC-MS as complementary techniques for analysis of volatiles: A tutorial review

Majchrzak, Tomasz; Wojnowski, W.; Lubinska-Szczygeł, Martyna; Różańska, Anna; Dymerski, Tomasz

doi:10.1016/j.aca.2018.06.056

Cited by 119 publications

(76 citation statements)

References 89 publications

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“…Knowledge of fragmentation patterns of the volatiles is also crucial to get rid of incorrect attributions . Interestingly, the combined use of the two instrumental techniques, GC‐MS and PTR‐MS, has been recently reviewed with emphasis on their complementary utilization …”

Section: Introductionmentioning

confidence: 99%

Volatile compounds profiling by using proton transfer reaction‐time of flight‐mass spectrometry (PTR‐ToF‐MS). The case study of dark chocolates organoleptic differences

et al. 2019

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Direct‐injection mass spectrometry (DIMS) techniques have evolved into powerful methods to analyse volatile organic compounds (VOCs) without the need of chromatographic separation. Combined to chemometrics, they have been used in many domains to solve sample categorization issues based on volatilome determination. In this paper, different DIMS methods that have largely outperformed conventional electronic noses (e‐noses) in classification tasks are briefly reviewed, with an emphasis on food‐related applications. A particular attention is paid to proton transfer reaction mass spectrometry (PTR‐MS), and many results obtained using the powerful PTR‐time of flight‐MS (PTR‐ToF‐MS) instrument are reviewed. Data analysis and feature selection issues are also summarized and discussed. As a case study, a challenging problem of classification of dark chocolates that has been previously assessed by sensory evaluation in four distinct categories is presented. The VOC profiles of a set of 206 chocolate samples classified in the four sensory categories were analysed by PTR‐ToF‐MS. A supervised multivariate data analysis based on partial least squares regression‐discriminant analysis allowed the construction of a classification model that showed excellent prediction capability: 97% of a test set of 62 samples were correctly predicted in the sensory categories. Tentative identification of ions aided characterisation of chocolate classes. Variable selection using dedicated methods pinpointed some volatile compounds important for the discrimination of the chocolates. Among them, the CovSel method was used for the first time on PTR‐MS data resulting in a selection of 10 features that allowed a good prediction to be achieved. Finally, challenges and future needs in the field are discussed.

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Section: Introductionmentioning

confidence: 99%

Volatile compounds profiling by using proton transfer reaction‐time of flight‐mass spectrometry (PTR‐ToF‐MS). The case study of dark chocolates organoleptic differences

et al. 2019

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“…In spite of its popularity and its increasing economic relevance, the scientific literature does not report a characterization of Volatile Organic Compounds (VOCs) released by this peculiar dairy matrix. In order to characterize for the first time the VOCs associated with the headspace of mascarpone cheese, among various analytical techniques, we exploit the complementarity of Gas Chromatography-Mass Spectrometry (GC-MS) and Proton Transfer Reaction-Mass Spectrometry coupled to a Time of Flight mass analyzer (PTR-ToF-MS) [6]. Gas Chromatography-Mass Spectrometry (GC-MS) is the reference method in the analysis of VOCs in the field of environmental, food, flavour and fragrance, medical and forensic sciences [7].…”

Section: Introductionmentioning

confidence: 99%

“…These analytical approaches are complementary. In fact, PTR-MS provides analytical information that is mostly limited to concentration and m/z ratios, i.e., sum formula, while isobar separation and compound identification needs usually the support of GC analysis [6]. PTR-MS, however, guarantees rapid and direct analysis and high sensitivity [11].…”

Section: Introductionmentioning

confidence: 99%

Unveiling the Molecular Basis of Mascarpone Cheese Aroma: VOCs analysis by SPME-GC/MS and PTR-ToF-MS

Capozzi

Lonzarich²,

Khomenko

et al. 2020

Molecules

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Mascarpone, a soft-spread cheese, is an unripened dairy product manufactured by the thermal-acidic coagulation of milk cream. Due to the mild flavor and creamy consistency, it is a base ingredient in industrial, culinary, and homemade preparations (e.g., it is a key constituent of a widely appreciated Italian dessert ‘Tiramisù’). Probably due to this relevance as an ingredient rather than as directly consumed foodstuff, mascarpone has not been often the subject of detailed studies. To the best of our knowledge, no investigation has been carried out on the volatile compounds contributing to the mascarpone cheese aroma profile. In this study, we analyzed the Volatile Organic Compounds (VOCs) in the headspace of different commercial mascarpone cheeses by two different techniques: Headspace-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME GC-MS) and Proton-Transfer Reaction-Mass Spectrometry coupled to a Time of Flight mass analyzer (PTR-ToF-MS). We coupled these two approaches due to the complementarity of the analytical potential—efficient separation and identification of the analytes on the one side (HS-SPME GC-MS), and effective, fast quantitative analysis without any sample preparation on the other (PTR-ToF-MS). A total of 27 VOCs belonging to different chemical classes (9 ketones, 5 alcohols, 4 organic acids, 3 hydrocarbons, 2 furans, 1 ester, 1 lactone, 1 aldehyde, and 1 oxime) have been identified by HS-SPME GC-MS, while PTR-ToF-MS allowed a rapid snapshot of volatile diversity confirming the aptitude to rapid noninvasive quality control and the potential in commercial sample differentiation. Ketones (2-heptanone and 2-pentanone, in particular) are the most abundant compounds in mascarpone headspace, followed by 2-propanone, 2-nonanone, 2-butanone, 1-pentanol, 2-ethyl-1-hexanol, furfural and 2-furanmethanol. The study also provides preliminary information on the differentiation of the aroma of different brands and product types.

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“…Other active sampling techniques followed by ion chromatography are particularly suitable for the analysis of carboxylic acids such as formic and acetic acids . More exhaustive methods based on gas chromatography/mass spectrometry (GC/MS) techniques, such as solid‐phase microextraction on‐fibre derivatization with O ‐(2,3,4,5,6‐pentafluorobenzyl)hydroxylamine, allow the simultaneous measurement of aldehydes and other volatile organic compounds (VOCs) including carboxylic acids . In the food industry, gas chromatography coupled to olfactometry is a well‐known technique for the analysis of odour‐active compounds such as aldehydes and volatile fatty acids .…”

Section: Introductionmentioning

confidence: 99%

Direct analysis of aldehydes and carboxylic acids in the gas phase by negative ionization selected ion flow tube mass spectrometry: Quantification and modelling of ion–molecule reactions

Ghislain

Costarramone

Sotiropoulos

et al. 2019

Rapid Comm Mass Spectrometry

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Rationale The concentrations of aldehydes and volatile fatty acids have to be controlled because of their potential harmfulness in indoor air or relationship with the organoleptic properties of agri‐food products. Although several specific analytical methods are currently used, the simultaneous analysis of these compounds in a complex matrix remains a challenge. The combination of positive and negative ionization selected ion flow tube mass spectrometry (SIFT‐MS) allows the accurate, sensitive and high‐frequency analysis of complex gas mixtures of these compounds. Methods The ion–molecule reactions of negative precursor ions (OH−, O•−, O2•−, NO2− and NO3−) with five aldehydes and four carboxylic acids were investigated in order to provide product ions and rate constants for the quantification of these compounds by negative ion SIFT‐MS. The results were compared with those obtained by conventional analysis methods and/or with already implemented SIFT‐MS positive ionization methods. The modelling of hydroxide ion (OH−)/molecule reaction paths by ab‐initio calculation allowed a better understanding of these gas‐phase reactions. Results Deprotonation systematically occurs by reaction between negative ions and aldehydes or acids, leading to the formation of [M − H]− primary ions. Ab‐initio calculations demonstrated the α‐CH deprotonation of aldehydes and the acidic proton abstraction for fatty acids. For aldehydes, the presence of water in the flow tube leads to the formation of hydrated ions, [M − H]−.H2O. With the NO2− precursor ion, a second reaction channel results in ion–molecule association with the formation of M.NO2− ions. Conclusions Except for formaldehyde, all the studied compounds can be quantified by negative ion SIFT‐MS with significant rate constants. In addition to positive ion SIFT‐MS with H3O+, O2+ and NO+ precursor ions, negative ionization with O•−, O2•−, OH−, NO2− and NO3− extends the range of analysis of aldehydes and carboxylic acids in air without a preparation or separation step. This methodology was illustrated by the simultaneous quantification in single‐scan experiments of seven aldehydes and six carboxylic acids released by building materials.

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PTR-MS and GC-MS as complementary techniques for analysis of volatiles: A tutorial review

Cited by 119 publications

References 89 publications

Volatile compounds profiling by using proton transfer reaction‐time of flight‐mass spectrometry (PTR‐ToF‐MS). The case study of dark chocolates organoleptic differences

Volatile compounds profiling by using proton transfer reaction‐time of flight‐mass spectrometry (PTR‐ToF‐MS). The case study of dark chocolates organoleptic differences

Unveiling the Molecular Basis of Mascarpone Cheese Aroma: VOCs analysis by SPME-GC/MS and PTR-ToF-MS

Direct analysis of aldehydes and carboxylic acids in the gas phase by negative ionization selected ion flow tube mass spectrometry: Quantification and modelling of ion–molecule reactions

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