Mobility Spectrometry Research Articles

Detection of huanglongbing infection in citrus using compositional analysis of volatile organic compounds

AbstractHuanglongbing (HLB) is caused by “Candidatus Liberibacter asiaticus” and is spread by citrus psyllids. It is a highly damaging and infectious disease of citrus for which there is no reliable treatment. Timely detection and removal of diseased trees is an effective strategy to control HLB. Various citrus cultivars infected with HLB exhibit distinct symptoms, posing a challenge to generalize HLB detection methods across multiple cultivars. Volatile organic compounds (VOCs) in HLB‐infected leaves from cultivars grown in different regions were comprehensively analysed by gas chromatography–mass spectrometry (GC‐MS) and gas chromatography‐ion mobility spectrometry (GC‐IMS), aiming to establish a new generalized HLB detection method applicable to a range of citrus cultivars. The changes in VOCs were analysed in leaves of four citrus cultivars after infection with HLB. The results showed that there was a similar response to HLB infection in different citrus cultivars, and this response was reflected in both the concentration and type of VOCs. By combining GC‐MS and GC‐IMS with orthogonal partial least squares discriminant analysis (OPLS‐DA) model, the accurate identification of the HLB infection status of different citrus cultivars was achieved, with the prediction indices reaching 0.994 for GC‐MS and 0.972 for GC‐IMS. In addition, 27 compounds were identified that were significantly different between citrus cultivars affected by HLB and healthy plants. This study provides valuable insights into the changes in VOCs in citrus cultivars after HLB infection and lays the theoretical foundation for VOC‐based HLB detection strategies.

Effects of different fermenters on the quality and flavour of fermented mandarin fish (Siniperca chuatsi)

SummaryIn this study, the effect of different fermenters on the quality and flavour of fermented mandarin fish was investigated via pH, salt content, moisture content, thiobarbituric acid, microbial community, free amino acids and volatile compounds. The results demonstrated that the inoculated fermentation effectively suppressed fish fat oxidation, resulting in significantly higher levels of umami amino acids in mandarin fish compared to the natural fermentation group (P < 0.05). Additionally, certain bitter amino acids were also inhibited. Moreover, the total amino acid content of the mixed inoculated fermentation group was significantly elevated compared to other groups, reaching 300.21 ± 5.37 mg/100 g. The synergistic effect of free amino acids and flavour‐enhancing nucleotides significantly influenced the taste of the fermented fish, with the mixed inoculation fermentation group exhibiting a significantly higher Equivalent umami concentration (EUC) value compared to other groups, reaching 216.06 ± 20.13 mgMSG/100 g on the sixth day of fermentation. A total of 47 volatile compounds were detected by using headspace gas chromatography‐ion mobility spectrometry (HS‐GC‐IMS), and the results demonstrated that inoculated fermentation positively influenced the development of fish flavour, and mixed inoculated fermentation proved to be more effective. This study provides a theoretical foundation for the industrial production of fermented fish products and offers potential avenues for technical enhancement.

Effect of Lactobacillus rhamnosus and Saccharomyces cerevisiae on the flavour profile of sweet fermented glutinous rice (Jiu Niang)

SummaryRecently, there has been growing interest in intentionally incorporating fermentation starters into the traditional brewing process. Our study examined the impact of Saccharomyces cerevisiae and Lactobacillus rhamnosus on the flavour profiles of sweet fermented glutinous rice (SFGR). Saccharomyces cerevisiae obviously increased the ethanol content, whereas Lactobacillus rhamnosus notably raised the total acidity. Lactic acid became the dominant organic acid after the addition of Lactobacillus rhamnosus. The volatiles were analysed using electronic nose (E‐nose) and gas chromatography‐ion mobility spectrometry (GC‐IMS). S4 sensor of E‐nose exhibited the most extensive response to all samples. Saccharomyces cerevisiae increased ethanol and 3‐methylbutan‐1‐ol levels, while Lactobacillus rhamnosus led to a significant increase in acetone. Principal component analysis effectively discriminated the aroma of SFGR with different starters. Additionally, a strong correlation was observed between the E‐nose and GC‐IMS results. Our study shows that Saccharomyces cerevisiae and Lactobacillus rhamnosus can enhance the flavour of fermented rice products.

Screening tools combined with multivariate data analysis to predict or confirm virgin olive oil classification by the Panel test

AbstractA particular aspect of quality control of virgin olive oil (VOO) is the mandatory application, together with chemical and instrumental determinations, of a standardized and official method for sensory assessment. The latter, known as Panel test, is carried out by trained assessors and contributes to the classification of VOOs into three commercial categories (extra virgin, virgin, and lampante). One drawback of this method is related to the large number of samples to be analyzed, compared to the work capacity of a sensory panel, especially during the selection for purchase by companies that blend and market virgin oils and the quality control conducted by the authorities to verify the declared commercial category. For this reason, it is helpful to develop and validate robust and rapid screening methods, based on volatile fingerprints, to preclassify each sample into one of the three commercial categories. Considering the strict relation between volatile compounds and the main sensory attributes (fruity and defects), a gas‐chromatographic volatile fingerprint can be the right choice. In this paper, the comparison of two emerging techniques, namely, headspace‐gas chromatography‐ion mobility spectrometry (HS‐GC‐IMS) and flash‐gas chromatography (FGC), applied on a sample set of 49 VOOs, using calibrations previously built with a larger number of samples, is presented. The number of correctly classified samples, with respect to the commercial category determined by the Panel test, was satisfactory and comparable (92% for HS‐GC‐IMS, and 94% for FGC), confirming the effectiveness of both methods and the robustness of the predictive models.Practical Applications: The demand for rapid screening tools to reduce the number of samples to be assessed by the Panel test has increased in recent years. The validation of robust models and their joint adoption by companies that market VOOs as well as official control bodies could reduce nonconformities and increase the batches of VOO being controlled, thus better protecting the consumer. Therefore, it is desirable to have different tools available to analyze volatile compounds, together with the associated calibration models, along with detailed instructions for their application, to have different alternatives that suit the equipment of individual laboratories.

Determining the clinical utility of a breath test for screening an asbestos-exposed population for pleural mesothelioma: baseline results

Pleural mesothelioma (PM) is an aggressive cancer of the serosal lining of the thoracic cavity, predominantly caused by asbestos exposure. Due to nonspecific symptoms, PM is characterized by an advanced-stage diagnosis, resulting in a dismal prognosis. However, early diagnosis improves patient outcome. Currently, no diagnostic biomarkers or screening tools are available. Therefore, exhaled breath was explored as this can easily be obtained and contains volatile organic compounds, which are considered biomarkers for multiple (patho)physiological processes. A breath test, which differentiates asbestos-exposed (AEx) individuals from PM patients with 87% accuracy, was developed. However, before being implemented as a screening tool, the clinical utility of the test must be determined. Occupational AEx individuals underwent annual breath tests using multicapillary column/ion mobility spectrometry. A baseline breath test was taken and their individual risk of PM was estimated. PM patients were included as controls. In total, 112 AEx individuals and six PM patients were included in the first of four screening rounds. All six PM patients were correctly classified as having mesothelioma (100% sensitivity) and out of 112 AEx individuals 78 were classified by the breath-based model as PM patients (30% specificity). Given the large false positive outcome, the breath test will be repeated annually for three more consecutive years to adhere to the ‘test, re-test’ principle and improve the false positivity rate. A low-dose computed tomography scan in those with two consecutive positive tests will correlate test positives with radiological findings and the possible growth of a pleural tumor. Finally, the evaluation of the clinical value of a breath-based prediction model may lead to the initiation of a screening program for early detection of PM in Aex individuals, which is currently lacking. This clinical study received approval from the Antwerp University Hospital Ethics Committee (B300201837007).

Comprehensive characterisation of taste and aroma profiles of Daokou red‐cooked chicken by GC‐IMS and GC–MS combined with chemometrics

SummaryTaste and aroma profiles of Daokou red‐cooked chickens (DRCs) were analysed using different techniques and methods. Multivariate data analysis revealed that e‐nose and e‐tongue could successfully discriminate DRCs of various sources based on their taste and aroma profiles. Flavour nucleotide content and umami concentration of breasts were higher than those of thighs. Additionally, a fingerprint was established to analyse the distribution of different volatile compounds using gas chromatography‐ion mobility spectrometry. A total number of 54 volatile components was identified in the DRCs, mostly aldehydes, esters, ketones, terpenes and alcohols. Odour activity value demonstrated that nine volatile components, including 1‐octen‐3‐ol, 2‐pentylfuran, eucalyptol, nonanal, estragole, anisaldehyde, anethole, eugenol and hexanal, could be considered as the characteristic flavour compounds of DRCs. Furthermore, partial least squares‐discriminant analysis (PLS‐DA) analysis showed that sweet tastes, anethole, 5′‐inosine monophosphate, eugenol, eucalyptol, umami tastes, sour tastes, bitter tastes, 2,3‐butanedione, hexanal, hypoxanthine, inosine and d‐limonene were significant factors that caused the differences among DRCs of different sources. Sensory analysis revealed variations in consumer preferences of DRCs from different suppliers. Obtained results will help in understanding of how taste and flavour compounds affect quality and preferences of DRCs, which will help manufacturers improve processing methods and promote consumption of DRCs.

Characterizing the Volatile Profile and Flavor of Four Kinds of Hotpot Seasonings in China Using HS‐GC‐MS, HS‐GC‐IMS, and Sensory Evaluation

AbstractHotpot is a distinctive dish of East Asian cuisine, especially in China. Herein, headspace‐gas chromatography‐mass spectrometry, headspace‐gas chromatography‐ion mobility spectrometry, and sensory evaluation are applied to compare the volatile organic compounds (VOCs) of four types of hotpot seasoning oils (HSOs) and establish their characteristic fingerprints. A total of 203 VOCs are detected by gas chromatography‐mass spectrometry (GC‐MS). Among them, linalool, anethole, and estragole contribute to the overall aroma of all four HSOs (relative odor activity value ≥ 0.1). Gas chromatography‐ion mobility spectrometry (GC‐IMS) results reveal that 77 VOCs are identified, comprising 19 terpenoids, 18 aldehydes, 14 alcohols, 13 esters, 6 ketones, 3 acids, 2 furans, 1 pyrazine, and 1 sulfide. Meanwhile, principal component analysis demonstrates that GC‐IMS is an important tool for the rapid classification of hotpot seasonings. Finally, the sensory evaluation team concludes that the horse fat hotpot seasoning has promising development prospects. This study validates the applicability of GC‐IMS and GC‐MS for distinguishing VOCs in hotpots, and the findings provide a theoretical basis for flavor differentiation in HSOs.Practical Applications: Horse oil is significantly lower in cholesterol than butter, and thus possesses potential benefits for human health. This study provides a basis to produce horse oil hotpots and a reference for identifying the VOCs in HSOs.

Flavor changes in Lentinus Edodes enzymatic hydrolysate maillard reaction products with different sugars by gas chromatography‐ion mobility spectrometry

Flavor changes in Lentinus Edodes enzymatic hydrolysate maillard reaction products with different sugars by gas chromatography‐ion mobility spectrometry

Effect of heating temperature and time on the formation of volatile organic compounds during reactions between linoleic acid and free amino acids or myofibrillar proteins

SummaryLinoleic acid has been shown as a very important precursor for meat flavour and heating parameters may affect the reaction of linoleic acid with free amino acids (FAAs) or myofibrillar proteins (MPs) and the production of volatile organic compounds (VOCs). This study was aimed to identify the VOCs during heating of linoleic acid only or with FAAs and MPs for different times by gas chromatography‐ion mobility spectrometry (GC‐IMS). Reaction systems were set up to simulate meat, and the transformation pathway of VOCs was tracked by GC‐IMS. Finally, sixty‐two VOCs were identified, of which the content of aldehydes, which had the greatest impact on the aroma of meat, reached the peak (15.94%) when heated to 60 min and then decreased. Principal component analysis (PCA) showed that the effect of heating temperature on the flavour of the system was much greater than that of heating time, and heating at 90 °C for 60 min might be considered to obtain the best flavour. The results showed that FAAs played a critical role in the formation of VOCs that were derived from the oxidation and thermal degradation of linoleic acid, controlling the composition of FAAs may further optimise the flavour of processed meat products.

Volatile organic compound profiling as a potential biomarker in irritable bowel syndrome: A feasibility study.

BackgroundIrritable bowel syndrome (IBS) is a chronic gastrointestinal disorder for which no diagnostic tools are currently available. Patients are diagnosed using the Rome IV criteria and subtyped into a diarrhea, constipation, or mixed phenotype based on their dominant stool pattern. A recent development in the biomarker area is the analysis of volatile organic compounds (VOCs). The aim of this study was to evaluate the potential of VOCs as diagnostic and phenotypic biomarkers for IBS in breath and fecal samples.Materials and methodsBreath and fecal samples from IBS patients and healthy asymptomatic controls (HC) were analyzed with multicapillary column/ion mobility spectrometry (MCC/IMS) and classification models were created based upon VOCs and clinical characteristics.DiscussionIrritable bowel syndrome patients were differentiated from HC by means of volatile profiling in both breath and fecal samples with area under the curve (AUCs) of respectively 0.62 and 0.80. Patient subtypes could also be differentiated from each other with AUCs ranging between 0.65 and 0.78. Furthermore, VOC models could differentiate IBS patients based on clinical characteristics like psychological comorbidities and microbiota-influencing therapies.ConclusionThis study is the first to demonstrate the use of VOC profiling with the help of MCC/IMS to differentiate IBS patients. Furthermore, the importance of clinical characteristics beside the dominant stool pattern in the differentiation of IBS patients was emphasized.

Strategy for the multi‐component characterization and quality evaluation of volatile organic components in Kaixin San by correlating the analysis by headspace gas chromatography/ion mobility spectrometry and headspace gas chromatography/mass spectrometry

RationaleKaixin San (KXS) is a prescription traditional Chinese medicine (TCM) with the effects of “tonifying the kidney and brain” and “improving memory”. The volatile organic compounds (VOCs) in KXS could effectively improve senile dementia and depression, but only few studies have focused on the overall characterization of VOCs in KXS and the quantitative study of the main active components.MethodsWe have developed a strategy to correlate the results from headspace gas chromatography/ion mobility spectrometry (HS‐GC/IMS) and headspace gas chromatography/mass spectrometry (HS‐GC/MS) for the comprehensive characterization of VOCs in KXS and the quantitative analysis of the main pharmacodynamic substances.ResultsA totsal of 68 low molecular weight VOCs were identified in KXS by HS‐GC/IMS at room temperature and atmospheric pressure; 117 VOCs were identified and 10 components (isocalamenediol,α‐asarone,β‐asarone, methyl eugenol, isoeugenol methyl ether, camphor, anethol, 2,4‐di‐tert‐butylphol, linalool, asarylaldehyde) as the quality markers of KXS based on HS‐GC/MS.ConclusionsThis results from this study provide a foundation for quality control, pharmacodynamic mechanism research and further development of KXS, and provides more convincing data supporting the VOCs of other natural products.

Influence of temperature on storage characteristics of different rice varieties

AbstractBackground and objectivesIn order to study the influence of temperature on storage characteristics of different rice varieties, the physicochemical properties, microstructure morphology, and aroma were investigated at 300d of storage at 15℃, room temperature (20–25 ℃), and 37℃.FindingsHigh temperature can promote the hydrolysis of fat, inhibit the catalase activity, and cause rough surface of rice endosperm during storage, resulting in increased fatty acids and lipid oxidation. The safe storage days of rice may be 300d, 180d, and 120d at 15℃, room temperature (20–25℃), and 37℃, respectively. It was found that the content of lipid oxidation products, especially octanal, 1‐octanol, cyclohexanone monomer, and cyclohexanone dimer, increased using headspace‐gas chromatography‐ion mobility spectrometry (HS‐GC‐IMS). In addition, the increase of sulfide, and the decrease of ethyl acetate and 1‐hexanol also promoted the deterioration of rice quality.ConclusionsDifferent storage conditions, especially under high‐temperature storage, can accelerate the deterioration of rice quality.Significance and noveltyHigh temperature can accelerate the rancidity of lipids of stored rice, and HS‐GC‐IMS is a useful tool to identify flavor changes in rice samples under different storage conditions.

Development of volatile compounds fingerprints by headspace‐gas chromatography‐ion mobility spectrometry in concentrated tomato paste and distillate during evaporation processing

SummaryVolatile profiles of fresh tomato pulp, concentrated pastes and distillates during evaporation were analysed by headspace‐gas chromatography‐ion mobility spectrometry (HS‐GC‐IMS), and volatile fingerprints were established. Topographic plots showed ninety signal peaks, forty‐two peaks (monomers and dimers) for twenty‐five compounds were identified, including four alcohols, ten aldehydes, eight ketones, two esters and a furan. The fingerprints showed clear differences. After evaporation, phenylacetaldehyde, pentanal, 2‐pentanone, 3‐methylbutanal and benzaldehyde were newly detected in the concentrated pastes and distillates, while 2‐heptanol, octanal, isopropyl acetate and 2‐pentylfuran were no longer detectable. Prolonged evaporation caused volatile components in both pastes and distillates to decrease; most were evaporated into distillates, including all alcohols and esters, most aldehydes and some ketones. The fresh pulp, concentrated pastes and distillates were clearly distinguished by principal component analysis and hierarchical clustering analysis. This work provides a theoretical reference for tomato paste processing and the utilisation of distillate discarded.

Collaborative analysis combining headspace‐gas chromatography‐ion mobility spectrometry (HS‐GC‐IMS) and intelligent (electronic) sensory systems to evaluate differences in the flavour of cultured pufferfish

AbstractPufferfish (Takifugu spp.) are rapidly becoming a valuable food commodity across Asia, making the flavour characterization of the different species economically significant. In this study, the flavour characteristics of four cultured pufferfish varieties (T obscurus, T flavidus, T bimaculatus and T rubripes) were evaluated using headspace‐gas chromatography‐ion mobility spectrometry (HS‐GC‐IMS) coupled with an electronic nose and electronic tongue. A total of 37 volatile compounds, primarily aldehydes and alcohols, were identified by HS‐GC‐IMS and used to distinguish the four pufferfish species. Principal component analysis (PCA) of the volatile compound profiles indicated that the four cultivated varieties had unique chemical compositions. PCA of the electronic nose and tongue response data was consistent with HS‐GC‐IMS evaluation and revealed that the aroma and taste of T rubripes were distinct from the other varieties. The collaborative analysis method combining HS‐GC‐IMS and intelligent sensory systems could significantly advance the evaluation of flavour differences.

Peak detection and random forests classification software for gas chromatography/differential mobility spectrometry (GC/DMS) data

Gas Chromatography/Differential Mobility Spectrometry (GC/DMS) is an effective tool to discern volatile chemicals. The process of correlating GC/DMS data outputs to chemical identities requires time and effort from trained chemists due to lack of commercially available software and the lack of appropriate libraries. This paper describes the coupling of computer vision techniques to develop models for peak detection and can align chemical signatures across datasets. The result is an automatically generated peak table that provides integrated peak areas for the inputted samples. The software was tested against a simulated dataset, whereby the number of detected features highly correlated to the number of actual features (r2 ​= ​0.95). This software has also been developed to include random forests, a discriminant analysis technique that generates prediction models for application to unknown samples with different chemical signatures. In an example dataset described herein, the model achieves 3% classification error with 12 trees and 0% classification error with 48 trees. The number of trees can be optimized based on the computational resources available. We expect the public release of this software can provide other GC/DMS researchers with a tool for automated featured extraction and discriminant analysis capabilities.

Metabolic Phenotyping Using UPLC\u2013MS and Rapid Microbore UPLC\u2013IM\u2013MS: Determination of the Effect of Different Dietary Regimes on the Urinary Metabolome of the Rat

A rapid reversed-phase gradient method employing a 50 mm × 1 mm i.d., C18 microbore column, combined with ion mobility and high-resolution mass spectrometry, was applied to the metabolic phenotyping of urine samples obtained from rats receiving different diets. This method was directly compared to a “conventional” method employing a 150 × 2.1 mm i.d. column packed with the same C18 bonded phase using the same samples. Multivariate statistical analysis of the resulting data showed similar class discrimination for both microbore and conventional methods, despite the detection of fewer mass/retention time features by the former. Multivariate statistical analysis highlighted a number of ions that represented diet-specific markers in the samples. Several of these were then identified using the combination of mass, ion-mobility-derived collision cross section and retention time including N-acetylglutamate, urocanic acid, and xanthurenic acid. Kynurenic acid was tentatively identified based on mass and ion mobility data.

Characterization of aroma profile and characteristic aromas during lychee wine fermentation

Characteristic aroma substances of cis‐rose oxide imparts the odorant of “lychee‐like,” while of citronellol is the precursor of it in lychee. The characterization of volatiles of lychee wine fermentation using headspace solid‐phase microextraction gas chromatography‐mass spectrometry combined with headspace gas chromatography‐ion mobility spectrometry were done to regulate processing. Results indicated that the total of 97 volatiles (38 in common) were observed during fermentation, including 39 terpenoids, 5 alcohols, 22 esters, 4 acids, 7 alkenes, 4 ketones and ethers, 3 sulfur compounds and others. Losses of characteristic aromas mainly occurred during primary fermentation more than threefold decrease. The volatility of cis‐rose oxide was stronger than citronellol, which implied that more gentle processing should be performed to protect lychee flavor. Cis‐rose oxide was a mixture of monomer and dimer with unequal proportion, while citronellol was a monomer in lychee. The work provides important new information on aroma development during fermentation. PRACTICAL APPLICATIONS: Fruit consumption, among which tropical fruit‐based products have gained huge popularity in the recent years. The main high value‐added processed products of lychee pulp are lychee wine and vinegar; however, the typical aroma always decreased or disappeared during fermentation. Therefore, this study aims at providing more information for product improvement and process development.

Unveiling metabolic remodeling in mucopolysaccharidosis type III through integrative metabolomics and pathway analysis

BackgroundMetabolomics represent a valuable tool to recover biological information using body fluids and may help to characterize pathophysiological mechanisms of the studied disease. This approach has not been widely used to explore inherited metabolic diseases. This study investigates mucopolysaccharidosis type III (MPS III). A thorough and holistic understanding of metabolic remodeling in MPS III may allow the development, improvement and personalization of patient care.MethodsWe applied both targeted and untargeted metabolomics to urine samples obtained from a French cohort of 49 patients, consisting of 13 MPS IIIA, 16 MPS IIIB, 13 MPS IIIC, and 7 MPS IIID, along with 66 controls. The analytical strategy is based on ultra-high-performance liquid chromatography combined with ion mobility and high-resolution mass spectrometry. Twenty-four amino acids have been assessed using tandem mass spectrometry combined with liquid chromatography. Multivariate data modeling has been used for discriminant metabolite selection. Pathway analysis has been performed to retrieve metabolic pathways impairments.ResultsData analysis revealed distinct biochemical profiles. These metabolic patterns, particularly those related to the amino acid metabolisms, allowed the different studied groups to be distinguished. Pathway analysis unveiled major amino acid pathways impairments in MPS III mainly arginine–proline metabolism and urea cycle metabolism.ConclusionThis represents one of the first metabolomics-based investigations of MPS III. These results may shed light on MPS III pathophysiology and could help to set more targeted studies to infer the biomarkers of the affected pathways, which is crucial for rare conditions such as MPS III.

Exhaled breath to screen for malignant pleural mesothelioma: a validation study.

Malignant pleural mesothelioma (MPM) is predominantly caused by asbestos exposure and has a poor prognosis. Breath contains volatile organic compounds (VOCs) and can be explored as an early detection tool. Previously, we used multicapillary column/ion mobility spectrometry (MCC/IMS) to discriminate between patients with MPM and asymptomatic high-risk persons with a high rate of accuracy. Here, we aim to validate these findings in different control groups.Breath and background samples were obtained from 52 patients with MPM, 52 healthy controls without asbestos exposure (HC), 59 asymptomatic former asbestos workers (AEx), 41 patients with benign asbestos-related diseases (ARD), 70 patients with benign non-asbestos-related lung diseases (BLD) and 56 patients with lung cancer (LC).After background correction, logistic lasso regression and receiver operating characteristic (ROC) analysis, the MPM group was discriminated from the HC, AEx, ARD, BLD and LC groups with 65%, 88%, 82%, 80% and 72% accuracy, respectively. Combining AEx and ARD patients resulted in 94% sensitivity and 96% negative predictive value (NPV). The most important VOCs selected were P1, P3, P7, P9, P21 and P26.We discriminated MPM patients from at-risk subjects with great accuracy. The high sensitivity and NPV allow breath analysis to be used as a screening tool for ruling out MPM.

Assessing 2D electrophoretic mobility spectroscopy (2D MOSY) for analytical applications.

Electrophoretic displacement of charged entity phase modulates the spectrum acquired in electrophoretic NMR experiments, and this modulation can be presented via 2D FT as 2D mobility spectroscopy (MOSY) spectra. We compare in various mixed solutions the chemical selectivity provided by 2D MOSY spectra with that provided by 2D diffusion‐ordered spectroscopy (DOSY) spectra and demonstrate, under the conditions explored, a superior performance of the former method. 2D MOSY compares also favourably with closely related LC‐NMR methods. The shape of 2D MOSY spectra in complex mixtures is strongly modulated by the pH of the sample, a feature that has potential for areas such as in drug discovery and metabolomics. Copyright © 2016 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.