Paper spray mass spectrometry (PS-MS) combined with partial least squares discriminant analysis (PLS-DA) was applied for the first time in a forensic context to a fast and effective differentiation ...of beers. Eight different brands of American standard lager beers produced by four different breweries (141 samples from 55 batches) were studied with the aim at performing a differentiation according to their market prices. The three leader brands in the Brazilian beer market, which have been subject to fraud, were modeled as the higher-price class, while the five brands most used for counterfeiting were modeled as the lower-price class. Parameters affecting the paper spray ionization were examined and optimized. The best MS signal stability and intensity was obtained while using the positive ion mode, with PS(+) mass spectra characterized by intense pairs of signals corresponding to sodium and potassium adducts of malto-oligosaccharides. Discrimination was not apparent neither by using visual inspection nor principal component analysis (PCA). However, supervised classification models provided high rates of sensitivity and specificity. A PLS-DA model using full scan mass spectra were improved by variable selection with ordered predictors selection (OPS), providing 100% of reliability rate and reducing the number of variables from 1701 to 60. This model was interpreted by detecting fifteen variables as the most significant VIP (variable importance in projection) scores, which were therefore considered diagnostic ions for this type of beer counterfeit.
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•For the first time a supervised classification multivariate method was used for PS-MS.•Direct analysis by PS-MS combined with PLS-DA was used for fast beer differentiation.•Differentiation was studied in a forensic context for beers of a single type (lagers).•Variable selection was utilised for improving the PLS-DA model.•OPS (ordered predictors selection) provided a method with 100% of reliability rate.
Avocado (Persea americana) is a widely consumed fruit and a rich source of nutrients and phytochemicals. Its industrial processing generates peels and seeds which represent 30% of the fruit. ...Environmental issues related to these wastes are rapidly increasing and likely to double, according to expected avocado production. Therefore, this work aimed to evaluate the potential of hexane and ethanolic peel (PEL-H, PEL-ET) and seed (SED-H, SED-ET) extracts from avocado as sources of neuroprotective compounds. Minerals, total phenol (TPC), total flavonoid (TF), and lipid contents were determined by absorption spectroscopy and gas chromatography. In addition, phytochemicals were putatively identified by paper spray mass spectrometry (PSMS). The extracts were good sources of Ca, Mg, Fe, Zn, ω-6 linoleic acid, and flavonoids. Moreover, fifty-five metabolites were detected in the extracts, consisting mainly of phenolic acids, flavonoids, and alkaloids. The in vitro antioxidant capacity (FRAP and DPPH), acetylcholinesterase inhibition, and in vivo neuroprotective capacity were evaluated. PEL-ET was the best acetylcholinesterase inhibitor, with no significant difference (p > 0.05) compared to the control eserine, and it showed neither preventive nor regenerative effect in the neuroprotection assay. SED-ET demonstrated a significant protective effect compared to the control, suggesting neuroprotection against rotenone-induced neurological damage.
Mass spectrometry imaging (MSI) of neurotransmitters has so far been mainly performed by matrix-assisted laser desorption/ionization (MALDI) where derivatization reagents, deuterated matrix and/or ...high resolution, or tandem MS have been applied to circumvent problems with interfering ion peaks from matrix and from isobaric species. We herein describe the application of desorption electrospray ionization mass spectrometry imaging (DESI)-MSI in rat brain coronal and sagittal slices for direct spatial monitoring of neurotransmitters and choline with no need of derivatization reagents and/or deuterated materials. The amino acids γ-aminobutyric (GABA), glutamate, aspartate, serine, as well as acetylcholine, dopamine, and choline were successfully imaged using a commercial DESI source coupled to a hybrid quadrupole-Orbitrap mass spectrometer. The spatial distribution of the analyzed compounds in different brain regions was determined. We conclude that the ambient matrix-free DESI-MSI is suitable for neurotransmitter imaging and could be applied in studies that involve evaluation of imbalances in neurotransmitters levels.
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, also known as rumberry, is a tree native to the Brazilian Atlantic Forest, where its fruits have the potential for commercial use. This study evaluates the antioxidant potential, determines the ...phytochemical profile, and chemically characterizes the rumberry fruit. Accessions were sampled from the Rumberry Active Germplasm Bank of the Federal University of Alagoas, Brazil. Physical characteristics, chemical characteristics, and phenolic compound content were analyzed. Chemical profile characterization was carried out using PSMS. Accessions had an average weight of 0.86 g. Accession AC137 presented a higher pulp yield (1.12 g). AC132 and AC156 had larger fruits, AC137 showed greater firmness (5.93 N), and AC160 had a higher and total phenolic content ratio (279.01 ± 11.11). Orange-colored accessions scored higher in evaluated parameters, except for AC160 for phenolic content. Thirty-two compounds were identified on positive ionization mode and 42 compounds on negative ionization mode using PSMS. Flavonoids, followed by the derivatives of benzoic acid, sugars, and phenylpropanoids, were the most prominent. Myricitrin, quercitrin, and catechin stand out as flavonoids that have been reported in previous studies with antioxidant and antimicrobial properties, in addition to health and therapeutical benefits, demonstrating the potential of the rumberry fruit.
In this work, the peels of ripe banana (Musa sp.), variety “Prata”, were used to prepare a flour, which was evaluated for its physicochemical characteristics and antioxidant activity. The ...characterization of its chemical profile was performed by a fast and simple method: paper spray-mass spectrometry. This flour had high carbohydrate content and total dietary fiber, and significant amount of total phenolic compounds with antioxidant activity. In addition, this flour exhibited higher water-holding, oil-holding and swelling capacities than those of fruit by-products reported in the literature. Fourier-transform infrared spectroscopy confirmed the presence of functional groups of cellulose, hemicellulose, and lignin, constituents of insoluble dietary fiber. By the paper spray-mass spectrometry technique, it was possible to suggest the presence of 26 substances such as organic acids, phenolic acids, flavonoids, sugars, quinones, and terpenoids. Thus, this study demonstrated that the ripe banana peel flour has potential application as an ingredient for functional foods.
Jabuticaba (
) and jambolan (
) fruits are rich in phenolic compounds with antioxidant properties, mostly concentrated in the peel, pulp, and seeds. Among the techniques for identifying these ...constituents, paper spray mass spectrometry (PS-MS) stands out as a method of ambient ionization of samples for the direct analysis of raw materials. This study aimed to determine the chemical profiles of the peel, pulp, and seeds of jabuticaba and jambolan fruits, as well as to assess the efficiency of using different solvents (water and methanol) in obtaining metabolite fingerprints of different parts of the fruits. Overall, 63 compounds were tentatively identified in the aqueous and methanolic extracts of jabuticaba and jambolan, 28 being in the positive ionization mode and 35 in the negative ionization mode. Flavonoids (40%), followed by benzoic acid derivatives (13%), fatty acids (13%), carotenoids (6%), phenylpropanoids (6%), and tannins (5%) were the groups of substances found in greater numbers, producing different fingerprints according to the parts of the fruit and the different extracting solvents used. Therefore, compounds present in jabuticaba and jambolan reinforce the nutritional and bioactive potential attributed to these fruits, due to the potentially positive effects performed by these metabolites in human health and nutrition.
This study evaluated the physicochemical characteristics and the production of bioactive compounds of Pereskia aculeata Mill. at different harvest times. Here, we performed a qualitative evaluation ...of the chemical profile by paper spray mass spectrometry (PSMS), the phenolic acid and flavonoid profile by high-performance liquid chromatography (HPLC), antioxidant activity, total carotenoids, total phenolic compounds, total flavonoids, total anthocyanins, color characteristics, total soluble solids (TSS), total solids (TS), pH, and total titratable acidity (TTA). The chemical profile was not affected, with the exception of 4,5-dimethyl-2,6-octadiene and azelaic acid, which was only identified in the leaves harvested during the winter. The content of four phenolic acids and three flavonoids were analyzed; out of these, no significant amounts of ellagic acid and quercetin were detected. There was no difference in production of bioactive compounds between seasons, reflecting the antioxidant activity, which also did not differ. Brightness, chroma, and leaf pH were the only physicochemical characteristics that did not vary between seasons.
Among the many species of native fruit of Brazil that have been little explored, there is
(also known as rumberry, cambuizeiro, or guavaberry), a species with significant variability, which has ...fruits of different colors (orange, red, and purple) when ripe. The physical-chemical characteristics evaluated were fruit weight (FW), seed weight (SW), pulp weight (PW), number of seeds (NS), longitudinal diameter (LD), transverse diameter (TD), format (LD/TD), hydrogen potential (pH), soluble solids (SS), titratable acidity (TA), and ratio (SS/TA); further, the volatile organic compounds (VOCs) of nine accesses of rumberry orchards were identified. The averages of the variables FW, SW, PW, NS, LD, TD, shape, and firmness were 0.76 g, 0.22 g, 0.54 g, 1.45, 10.06 mm, 9.90 mm, 1.02, 2.96 N, respectively. LD/TD data showed that the fruits have a slightly rounded shape (LD/TD = 1). The averages for pH, SS, TA, and SS/TA were 3.74, 17.58 Brix, 4.31% citric acid, and 4.31, respectively. The evaluated parameters indicated that the fruits can be consumed both in natura and industrialized, with the red-colored fruits presenting a good balance of SS/TA, standards demanded by the processing industries. Thirty-six VOCs were identified, with emphasis on the sesquiterpenes. Caryophyllene (21.6% to 49.3%) and γ-selinene (11.3% to 16.3%) were the most predominant compounds in rumberry fruits.
A new method for the quantification of four aflatoxins (AFB1, AFB2, AFG1, and AFG2) in baby food samples is described herein. In this method, the extraction/cleanup step was performed by using ...multi-walled carbon nanotubes as a sorbent material in a dispersive solid phase procedure. In sequence, these mycotoxins were quantified via liquid chromatographic coupled with tandem mass spectrometry. The method was fully validated according to the EC/657/2002 and SANCO/12571/2013 directives. Adequate values were obtained for all figures of merit, mainly veracity (recoveries: 75.8 to 120.6%) and quantification limits (LOQs: 60.0 to 560.0 ng kg
-1
), with no noticeable matrix effects. The method was tested in real samples (
n
= 4) and aflatoxin B1 (AFB1) was detected in just one of them. Finally, this analytical procedure has an evident potential to be applied to analyze aflatoxins (and other mycotoxins) in distinct types of complex samples.
Electrospray ionization mass spectrometry (ESI‐MS) is found to gently and efficiently transfer small to large as well as singly to multiply charged X+nA−m supramolecules of imidazolium ion (X+) ionic ...liquids to the gas phase, and to reveal “magic numbers” for their most favored assemblies. Tandem mass spectrometric experiments (ESI‐MS/MS) were then used to dissociate, via low‐energy collision activation, mixed and loosely bonded A‐ ‐ ‐ ‐X‐ ‐ ‐ ‐A′− and X‐ ‐ ‐ ‐A‐ ‐ ‐ ‐X′+ gaseous supramolecules, as well as their higher homologues, and to estimate and order via Cooks' kinetic method (CKM) and B3LYP/6‐311G(d,p) calculations the intrinsic solvent‐free magnitude of hydrogen bonds. For the five anions studied, the relative order of intrinsic hydrogen‐bond strengths to the 1‐n‐butyl‐3‐methylimidazolium ion X1+ is: CF3CO2− (zero) > BF4− (−3.1) > PF6− (−10.0) > InCl4− (−16.4) and BPh4− (−17.6 kcal mol−1). The relative hydrogen‐bond strength for InCl4− was measured via CKM whereas those for the other anions were calculated and used as CKM references. A good correlation coefficient (R=0.998) between fragment ion ratios and calculated hydrogen‐bond strengths and an effective temperature (Teff) of 430 K demonstrate the CKM reliability for measuring hydrogen‐bond strengths in gaseous ionic liquid supramolecules. Using CKM and Teff of 430 K, the intrinsic hydrogen‐bond strengths of BF4− for the three cations investigated is: 1‐n‐butyl‐3‐methyl‐imidazolium ion (0) > 1,3‐di‐(R)‐3‐methyl‐2‐butyl‐imidazolium ion (−2.4) > 1,3‐di‐(R)‐α‐methylbenzyl‐imidazolium ion (−3.0 kcal mol−1). As evidenced by “magic” numbers, greater stabilities are found for the (X1)2(BF4)3− and (X1)5A4+ supramolecules (A≠InCl4−).
Gentle and efficient transfer from small to large as well as singly to multiply charged X+nA−m supramolecules of imidazolium ion (X+) ionic liquids to the gas phase was achieved by electrospray ionization mass spectrometry (see figure for example). Tandem mass spectrometry, Cooks' kinetic method as well as B3LYP/6‐311G(d,p) calculations were then used to estimate the intrinsic solvent‐free magnitude of their hydrogen bonds. As evidenced by “magic” numbers, greater stability is found particularly for (X1)5A4+ supramolecules.
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