Rapid analysis of fragrance allergens by dielectric barrier discharge ionization mass spectrometry

High-resolution multi-reflection time-of-flight mass spectrometer with atmospheric pressure interface

RATIONALE

Atmospheric pressure interface multi-reflection time-of-flight mass spectrometry (API-MRTOF-MS) has the potential to be a rapid and high-resolution analytical tool for versatile applications in chemistry, biology, environmental science, and medicine.

METHODS

The ions were reflected in a mass analyzer via electrostatic mirrors and folded flight path. Therefore, flight distances were significantly increased. The ion flight path of the API-MRTOF-MS was extended from meters to over 1 km, and the mass resolution was increased. Furthermore, the mass analysis could be completed at around 10 ms due to the rapid response of TOF-MS.

RESULTS

A high-resolution API-MRTOF-MS approach is successfully developed in this study. The mass resolution could achieve 116 050 (full widths at half maximum [FWHM]) for Cs+ ions using an atmospheric pressure electrospray ionization within a total TOF of only 18 ms. An ion transmission efficiency of over 50% was achieved after 600 cycles.

CONCLUSIONS

The analytical performance of the newly developed API-MRTOF-MS demonstrated that it is suitable for high resolution and rapid analysis in many fields.

Exploring new dimensions: Single and multi-block analysis of essential oils using DBDI-MS and FT-IR for enhanced authenticity control

BACKGROUND

Essential oils (EOs) are complex mixtures of volatile hydrocarbons with a wide range of applications in the pharmaceutical, fragrance and food industry. The composition of EOs is highly variable and can affect their quality and pharmaceutical efficacy. Moreover, the high economic value of EOs, such as those obtained from Rosa damascena, make falsification and misclassification a lucrative business. Consequently, adulterations can lead to serious health consequences for consumers. While current quality control methods for EOs involve analysing their chromatographic profile or comparing their Fourier transform infrared (FT-IR) spectra, these methods can be time-consuming or lack sensitivity. To address these issues, we compared state-of-the-art quality control methods, including gas chromatography flame ionization detection (GC-FID) quantification and enantiomeric ratio determination, FT-IR spectrometry with dielectric barrier discharge ionization coupled to triple quadrupole mass spectrometer (DBDI-MS), in a chemometric single- and multi-block approach.

RESULTS

Our results show that the best classification accuracy of 94.7% for R. damascena samples was obtained using GC-FID combined with partial least square discriminant analysis (PLS-DA). Comparatively, the enantiomeric ratios did not improve classification accuracy. In contrast, fragmentation data from DBDI-MS (Q3), which was acquired in a fraction of the analysis time and without extensive sample preparation, achieved a classification accuracy of 84.2%. We also found that combining FT-IR with parent ion DBDI-MS (Q1) data in a multi-block sequentially orthogonalized partial least squares linear discriminant analysis (SO-PLS-LDA) model improved classification accuracy, compared to their respective single-block PLS-DA models.

SIGNIFICANCE

Overall, our study demonstrates that DBDI, as an ambient ionization method, has significant potential for high-throughput screening. When combined with MS, it can produce comparable classification accuracies to conventional methods, while offering the added benefits of speed and convenience. As such, DBDI-MS is a promising tool for EO quality control.

Plasma-based ambient mass spectrometry: Recent progress and applications

Ambient mass spectrometry (AMS) has grown as a group of advanced analytical techniques that allow for the direct sampling and ionization of the analytes in different statuses from their native environment without or with minimum sample pretreatments. As a significant category of AMS, plasma-based AMS has gained a lot of attention due to its features that allow rapid, real-time, high-throughput, in vivo, and in situ analysis in various fields, including bioanalysis, pharmaceuticals, forensics, food safety, and mass spectrometry imaging. Tens of new methods have been developed since the introduction of the first plasma-based AMS technique direct analysis in real-time. This review first provides a comprehensive overview of the established plasma-based AMS techniques from their ion source configurations, mechanisms, and developments. Then, the progress of the representative applications in various scientific fields in the past 4 years (January 2017 to January 2021) has been summarized. Finally, we discuss the current challenges and propose the future directions of plasma-based AMS from our perspective.

Hydrophobic Natural Eutectic Solvents for the Gas Chromatographic Determination of Suspected Allergens in Fragrances by Dispersive Liquid-Liquid Microextraction

The fragrance industry plays a key role in the global economy, producing a wide range of personal care and household products. However, some fragrance ingredients have been linked to allergic reactions in sensitive people, and their concentrations are regulated at the European level. For this reason, reliable, rapid, and sustainable analytical methods are needed to rapidly detect and quantify these compounds. Recently, a new class of hydrophobic eutectic solvents (HES) has been introduced; they consist of natural terpenoids or phenolic compounds that can be used as hydrogen bond donors (HBD) and acceptors (HBA), and they are more suitable for GC applications due to their higher volatility. In this study, a dispersive liquid–liquid microextraction (DLLME) approach is proposed for the analysis and quantification of a range of allergens in hydroalcoholic perfumes. The optimized method requires only 50 µL of a natural HES (thymol–eugenol), which is readily dispersed by vortexing in 2 mL of sample. After centrifugation, the HES rich phase is diluted in 400 µL EtOH and directly injected into the GC-FID system. The proposed method has been successfully applied in the analysis and quantification of commercial fragrances, demonstrating good enrichment of target allergens and suitability for aqueous matrices analysis.

Applications of ambient ionization mass spectrometry in 2021: An annual review

Ambient ionization mass spectrometry (AIMS) has revolutionized the field of analytical chemistry, enabling the rapid, direct analysis of samples in their native state. Since the inception of AIMS almost 20 years ago, the analytical community has driven the further development of this suite of techniques, motivated by the plentiful advantages offered in addition to traditional mass spectrometry. Workflows can be simplified through the elimination of sample preparation, analysis times can be significantly reduced and analysis remote from the traditional laboratory space has become a real possibility. As such, the interest in AIMS has rapidly spread through analytical communities worldwide, and AIMS techniques are increasingly being integrated with standard laboratory operations. This annual review covers applications of AIMS techniques throughout 2021, with a specific focus on AIMS applications in a number of key fields of research including disease diagnostics, forensics and security, food safety testing and environmental sciences. While some new techniques are introduced, the focus in AIMS research is increasingly shifting from the development of novel techniques toward efforts to improve existing AIMS techniques, particularly in terms of reproducibility, quantification and ease-of-use.

Hybrid Ionization Source Combining Nanoelectrospray and Dielectric Barrier Discharge Ionization for the Simultaneous Detection of Polar and Nonpolar Compounds in Single Cells

Single-cell metabolomics is expected to deliver fast and dynamic information on cell function; therefore, it requires rapid analysis of a wide variety of very small quantities of metabolites in living cells. In this work, a hybrid ionization source that combines nanoelectrospray ionization (nanoESI) and dielectric barrier discharge ionization (DBDI) is proposed for single-cell analysis. A capillary with a 1 μm i.d. tip was inserted into cells for sampling and then directly used as the nanoESI source for ionization of polar metabolites. In addition, a DBDI source was employed as a post-ionization source to improve the ionization of apolar metabolites in cells that are not easily ionized by ESI. By increasing the voltage of the DBDI source from 0 to 3.2 kV, the classes of detected metabolites can be shifted from mostly polar to both polar and apolar to mainly apolar. Plant cells (onion) and human cells (PANC-1) were investigated in this study. After optimization, 50 compounds in onion cells and 40 compounds in PANC-1 cells were observed in ESI mode (3.5 kV) and an additional 49 compounds in onion cells and 73 compounds in PANC-1 cells were detected in ESI (3.5 kV)-DBDI (2.6 kV) hybrid mode. This hybrid ionization source improves the coverage, ionization efficiency, and limit of detection of metabolites with different polarities and could potentially contribute to the fast-growing field of single-cell metabolomics.