Fatty acids (FAs) containing polymethylene-interrupted (PMI) double bonds are a component of human foods; however, they present a significant analytical challenge for de novo identification. Covalent ...adduct chemical ionization and ozone-induced dissociation mass spectrometry (MS) methods enable unambiguous assignment of PMI-FA double bond positions, however, no method has been reported with electrospray ionization (ESI) platform using off-the-shelf systems. In the current work, we studied the Paternò–Büchi (PB) fragmentation patterns of PMI-FA and triacylglycerol (TG) by analyzing several known food sources. PB-MS/MS and MS3 enabled complete double bond location assignments, including the isolated double bond in PMI-FA and triacylglycerols. Sea urchin (“uni”), oyster, pine nut, and ginkgo nut were characterized for their signature PMI-FA, 20:2(5Z,11Z), 22:2(7Z, 15Z), 18:3(5Z,9Z,12Z), and 20:3(5Z,11Z,14Z), respectively. Quantitative analyses of the relative abundance of these PMI-FA led to results similar to reference methods. 18:3(5Z,9Z,12Z) was enriched at the sn-1/sn-3 position in pine nut major TG.
Solid-state magic angle spinning 31P NMR spectroscopy is used to identify and quantify phosphorus-containing species in pet foods. The measurement is challenging due to the long spin–lattice ...relaxation times (T 1s). Data acquisition times are shortened by acquiring data with a tip angle smaller than 90° and shortening the repetition time. However, the spin–lattice relaxation times (T 1s) of the different 31P compounds are quite different, necessitating a separate measurement for each compound in the pet food. Knowledge of T 1 is used to calculate the relative amount of 31P in the samples. Samples of known concentration are also measured, enabling the quantitative measurement of total phosphorus content.
Essential oils (EOs) are valuable products commonly employed in the food industry and intensively studied as biopreservatives for the extension of food shelf-life. Unfortunately, EOs might be ...counterfeit to increase industrial profits. Among the possible adulterants, vegetable oils (VOs) must be considered for their characteristics and low costs. We aimed to apply nuclear magnetic resonance (NMR) spectroscopy for the detection and identification of VOs in mixtures with EOs. This innovative strategy is based on comparing the peak area ratio matrices of characteristic VO 13C NMR fatty acid signals with those of adulterated EOs. The identification of the VOs was achieved by calculating the matrix similarity at different confidence levels. The strategy demonstrated the capacity to efficiently recognize the presence of adulteration and the type of VO adulterant in mixtures. Thus, the method was applied to 20 commercial EOs, and VOs were detected and then identified in four samples.
An analytical method is proposed to investigate the torsional vibration of the uniform circular shaft with multiple concentrated inertias. The governing equation is established based on the ...Hamiltonian principle and verified by the dynamical method. The theoretical solutions of frequencies and mode shapes under different boundary conditions are obtained using the separation variable method and integral transformation. The effectiveness of the proposed method is verified by comparison with existing literature. Considering the change of the magnitudes/positions/number of concentrated inertias, and different boundary conditions, the natural frequencies and mode shapes are discussed. Several general rules are obtained. Moreover, some interesting phenomena have been found and explained. The analytical method has applications in the design of shafting with multiple concentrated inertias and the reliability checking of the "approximate" solutions.
Trihalomethanes (THMs) are classified as volatile organic compounds, considered to be a disinfection by-product during water disinfection process. THMs have been shown to be cytotoxic, genotoxic and ...mutagenic, with a risk of cancer when they contact with people directly. To protect public health and monitor water quality, it is important to monitor and measure THMs in drinking water. Therefore, it is crucial to develop fast, accurate, highly sensitivity and green analysis methods of THMs in various complicated matrices. Here, this review presents an overall summary of the current state of the pretreatment and detection methods for THMs in various sample matrices since 2005. In addition to the traditionally used pretreatment methods for THMs (such as headspace extraction, microwave-assisted extraction, liquid-liquid extraction), the new-developed methods, including solid-phase extraction, QuEChERS and different microextraction methods, have been summarized. The detection methods include gas chromatography-based methods, sensors and several other approaches. Additionally, benefits and limitations of different techniques were also discussed and compared. This study is anticipated to offer fruitful insights into the further advancement and widespread applications of pretreatment and detection technologies for THMs as well as for related substances.
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•Advances in pretreatment and detection methods of THMs in water samples are reviewed.•The future trends of state-of-the-art techniques are thoroughly discussed.•Simple, fast, green microextraction techniques are raising substantial interest.•A comparison of various GC-based detection methods is presented.
Proanthocyanidins (condensed tannins) are important in food chemistry, agriculture, and health, driving demand for improvements in structure determination. We used ultrahigh resolution Fourier ...transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) methods to determine the exact composition of individual species in heterogeneous mixtures of proanthocyanidin polymers from Sorghum bicolor grain and Neptunia lutea leaves. Fragmentation patterns obtained with FT-ICR ESI MS-MS (electrospray ionization) confirmed structural details from thiolysis-high-performance liquid chromatography (HPLC)–diode array detection (DAD) and 1H–13C heteronuclear single quantum coherence (HSQC) NMR. We found that A-type linkages were characteristic of shorter polymers in predominantly B-linked proanthocyanidin. We suggest that supramolecular complex formation between proanthocyanidins and matrix components such as 2,5-dihydroxybenzoic acid was responsible for anomalous 152 dalton peaks, incorrectly assigned as 3-O-galloylation, when using FT-ICR matrix-assisted laser desorption ionization (MALDI-MS). Our data illustrate the power of the ultrahigh resolution FT-ICR methods but include the caveat that MALDI-MS must be paired with complementary analytical tools to avoid artifacts.
Nitrophenols, a versatile intermediate, have been widely used in leather, medicine, chemical synthesis, and other fields. Because these components are widely applied, they can enter the environment ...through various routes, leading to many hazards and toxicities. There has been a recent surge in the development of simple, rapid, environmentally friendly, and effective techniques for determining these environmental pollutants. This review provides a comprehensive overview of the latest research progress on the pretreatment and analysis methods of nitrophenols since 2017, with a focus on environmental samples. Pretreatment methods include liquid-liquid extraction, solid-phase extraction, dispersive extraction, and microextraction methods. Analysis methods mainly include liquid chromatography-based methods, gas chromatography-based methods, supercritical fluid chromatography. In addition, this review also discusses and compares the advantages/disadvantages and development prospects of different pretreatment and analysis methods to provide a reference for further research.
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•Recent pretreatment and analysis techniques for NPs in environment samples are reviewed.•Advantages/disadvantages of different microextraction methods, as well as their development prospects, are discussed.•HRMS analyzers and their prospects are introduced.•Future prospects for emerging green and online approaches are discussed.
The physical, chemical and organoleptic characteristics of olive oil (OO) are regulated by the European Union (EU) by Reg. (EEC) 2568/91 as amended, which also establishes methods for their analysis.
...Despite the fact that the OO sector is highly regulated, it is acknowledged that there are still problems; fats and oils, including OOs, are ranked third, after meat and meat products and fish and fish products, in the 2016 EU Food Fraud report on non-compliances per product category.
For this reason, EU legislation, among the most advanced in the field, continuously chases after the emerging frauds. The process of proposing new methods or reviewing those current is constantly in progress, to ensure the robustness and the clarity required by official standardised procedures.
This review will identify current gaps in EU legislation and discuss drawbacks of existing analytical methods with respect to OO. Suggestions for replacement of specific steps within the present EU methods with more efficient analytical solutions to reduce time and/or solvent consumption will be proposed.
This review critiques existing regulatory methods and standards, highlights weaknesses and proposes possible solutions to safeguard the consumer and protect the OO market.
•Normative and standard sources for olive oil quality and purity.•Analytical methods for olive oil: drawbacks and limitations.•Normative failures and suggestions for improvements.
Abstract
We have developed a new analytical peak separation analysis for superposed
$$\gamma$$
γ
-ray peaks on
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67
Cu and
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67
Ga to measure the
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68
Zn(
p
,2
p
)
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...67
Cu and
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68
Zn(
p
,2
n
)
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67
Ga reactions, unlike in most previous works that were employing a radiochemical separation to measure them. Based on the nuclear data such as the
$$\gamma$$
γ
-ray intensity and the half-life for each nuclide, we may develop a new analytical method that enables us to estimate the respective counts arising from each nuclide, thereby obtaining the nuclear reactions. The newly developed analytical method can universally be applied to separate the superposed
$$\gamma$$
γ
-ray spectra of any two nuclides, especially superior in separating the nuclides with different half-lives. In comparison with the data in the literature, the two reactions in the present work are in good agreement with those of some previous works. In addition, we compared the present
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68
Zn(
p
,2
n
)
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Ga reaction without the peak separation to the data in the literature without the chemical separation, and find that a good agreement is evident, enhancing the reliability of the
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Zn(
p
,
x
)
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65
Zn and
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Zn(
p
,3
n
)
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66
Ga reactions, which are further measured in the present work
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