The pollution caused by the abuse of antibiotics has posed a serious threat to the ecological environment and human health, so development of effective strategies for degradation and disposal of ...antibiotic residues is urgently needed. In this work, penicillinase, a kind of β-lactamase, was immobilized into zeolitic imidazolate framework-8 (ZIF-8) by self-assembly method and the catalytic performance of the β-lactamase@ZIF-8 porous materials for degradation of penicillins has been investigated by high performance liquid chromatography coupled with mass spectrometry. The results illustrated that the catalytic activity of the encapsulated enzyme was significantly enhanced comparing with that of free enzyme. Meanwhile, the β-lactamase@ZIF-8 exhibited excellent stability under denaturing conditions including high temperature, organic solvent and the enzyme inhibitor. The catalytic degradation mechanism of the β-lactamase@ZIF-8 for penicillins has been probed and verified, and it has been found that the Zn (II) ion on ZIF-8 frameworks could form the complex with the target molecule, which weakened the bond of the four-membered β-lactam ring in the penicillin molecule, and thus enhanced the degradation efficiency of the enzyme. This work provided a promising strategy for eliminating the penicillin residues in water environment.
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•The β-lactamase has been encapsulated into ZIF-8 MOFs by a self-assembly method.•The β-lactamase@ZIF-8 MOFs possessed excellent stability under denaturing conditions.•Catalytic activity of enzyme encapsulated into ZIF-8 MOFs was significantly enhanced.•The catalytic degradation pathway of penicillins was proposed and verified.
The review discusses the pitfalls of the matrix effect in mass spectrometry detection hyphenated to liquid chromatography separation. Matrix effect heavily influences both qualitative and ...quantitative analyses, giving rise to suppression or enhancement of the signal. As generally recognised, the predominant cause is the presence of undesired components that co-elute in the chromatographic separation and alter the ionisation process. The interfering species can be components of the sample, compounds released during the pre-treatment/extraction process or reagents added to the mobile phase to improve chromatographic resolution. The different mechanisms proposed in literature to explain the suppression or the enhancement of the signal both in electrospray and atmospheric pressure chemical ionisations are presented and the results observed in the different experimental conditions are compared and discussed. All data together lead to conclude that the chemical properties of the target analyte, the kind of matrix, the matrix to analyte concentration ratio, the extraction process, the chromatographic conditions as well as the kind of the mass spectrometry instrumentation and the ionisation conditions can play a role. Likely all these potential causes act in a synergic way and the final effect observed is hardly due to only one of them. Depending on an unpredictable combination of conditions, signal suppression or enhancement can be observed. The review discusses the matrix effects observed in HPLC–MS and HPLC–MS/MS analysis proposes hypotheses to explain the observed behaviours and proposes methods and strategies to overcome the matrix effects.
The occurrence of 13 veterinary drugs were studied in soil fertilized with animal manures in Eastern China. The 69 soil samples were obtained from twenty-three vegetable fields in 2009 and analysed ...for selected veterinary drugs by HPLC–MS/MS at soil depths of 0–20, 20–40 and 40–60 cm, and two additional samples were re-analysed from an earlier study from November 2011. Results showed that animal wastes, especially those from poultry farms, were one of pollution sources of veterinary drugs in soil. The detection frequency of veterinary drugs in soil was 83%, 91% and 87% in the three soil depths, respectively. The detection rates for the five classes of drugs in soils followed the rank order cyromazine > tetracyclines > sulfonamides > fluoroquinolones > florfenicol. Veterinary drugs were detected in soil layers at 20–40 and 40–60 cm depth to a greater extent than at 0–20 cm depth. The results of the same point in years 2009 and 2011 indicated that veterinary drugs accumulate easily and persist in the deeper soil. In addition, residue levels of veterinary drugs in soil were related to the animal species the manure was derived from. Overall, the predominance of tetracyclines in sampled soils underscored the need to regulate their veterinary use in order to improve the management and treatment of associated releases.
•Occurrence of veterinary compound residues were investigated in the study area.•More than 80% of the sampled soils were contaminated by the selected compounds.•The animal wastes were one of pollution sources of veterinary drugs in soil.•The occurrence of selected veterinary drugs in soils was related to animal species.
•Human exposure to BPS and BPF is expected to increase due to regulations on BPA.•We developed a highly sensitive and selective method to measure BPA, BPS, and BPF.•The same method could be used for ...the quantification of 11 other phenols in urine.•The method is high-throughput and can be used for epidemiological studies.
Human exposure to bisphenol A (BPA) is widespread. However, in recent years, bisphenol analogs such as bisphenol S (BPS) and bisphenol F (BPF) are replacing BPA in the production of some consumer products. Because human exposure to these alternative bisphenols may occur, biomonitoring of these bisphenol analogs is warranted. In the present study, we developed and validated a sensitive and selective method that uses on-line solid phase extraction coupled to high performance liquid chromatography-isotope dilution tandem mass spectrometry with peak focusing to measure BPA, BPF, BPS, and 11 other environmental phenols in urine. The method required a small amount of sample (100μL) and minimal sample pretreatment. The limits of detection were 0.03ng/mL (BPS), 0.06ng/mL (BPF), 0.10ng/mL (BPA), and ranged from 0.1ng/mL to 1.0ng/mL for the other 11 phenols. In 100 urine samples collected in 2009–2012 from a convenience group of anonymous adults in the United States, of the three bisphenols, we detected BPA at the highest frequency and median concentrations (95%, 0.72ng/mL), followed by BPS (78%, 0.13ng/mL) and BPF (55%, 0.08ng/mL). This sensitive, rugged, and labor and cost-effective method could be used for the analysis of large number of samples for epidemiologic studies.
•Rapid and simultaneous determination of 6 volatile fatty acids (VFAs) via HPLC-MS/MS.•The derivatisation method solves the problems of fatty acids in the detection process.•High throughput analysis ...of samples can be determined high sensitivity and accuracy.•VFAs can be accurately quantified using only microsamples (faeces, serum and urine).
A stable isotope dilution-liquid chromatography tandem mass spectrometry method based on a low-temperature derivatization strategy with 3-nitrophenylhydrazine (3-NPH) was developed for the determination of six volatile fatty acids (VFAs) in serum, urine, and feces. Ice acetonitrile was used to precipitate proteins and extract the target analytes. The extract was derivatized with 3-NPH methanol solution at 4 °C. BEH C8 (1.7 μm, 2.1 × 100 mm) column was used for chromatographic separation, and acetonitrile–water (both containing 0.01 % formic acid) were used as the mobile phase with a gradient elution of 10 min. Electrospray ionization source (ESI) in negative ion multiple reaction monitoring (MRM) mode were used for analyte detection. The regression coefficients R2 of the calibration curves for the six VFAs were in the range of 0.9963–0.9994, and the LOQs were in the range of 0.02–0.5 μg mL−1, with the recoveries in the range of 85.3–104.3 %, and the intra- and inter-day precision in the range of 1.8–9.1 %. The method is simple, accurate and reliable, and has been applied in the sensitive determination of VFAs in complex biological samples.
In this study, the chemical composition, total phenolic content and antioxidant activity (DPPH, ORAC and FRAP assays) of A. subrufescens and P. ostreatus, cultivated with handmade and commercials ...supplements, were compared. Additionally, the compounds ergosterol, saccharopine, and hexitol were identified in A. subrufescens by HPLC‐MS/MS. The antioxidant compound p‐coumaric acid and dihexoses was found in both mushroom species. A. subrufescens presented higher total phenolic content (73.8 ± 0.6 mg GAE 100 g−1) and antioxidant activity than P. ostreatus (16.6 ± 0.5 mg GAE 100 g−1). The handmade supplement based on the waste of noble grains presented statistically similar phenolic content to the mushrooms cultivated with commercial ones Spawn Mate II SE (86.1 ± 1.4 and 92.9 ± 0.3 mg GAE 100 g−1, respectively). Therefore, the results support the use of handmade supplements based on agro‐wastes as a viable alternative to the use of high‐cost commercial ones.
Pleurotus ostreatus and Agaricus subrufescens supplementation (both with commercial and handmade ones) was evaluated by the antioxidant activities and chemical composition.
•The antioxidant activity of XHP was evaluated.•XHP were separated based on molecular weight and polarity differences.•Peptide with the strongest activity had 74.45% scavenging effect on DPPH.•The ...sequence of main antioxidative peptide was identified as Asp-Leu-Glu-Glu.
This study mainly focused on the purification and identification of antioxidative peptides generated in dry-cured Xuanwei ham. Based on scavenging effect on free radicals and ferrous ion, the antioxidant activity of crude peptides from Xuanwei ham was assessed. From the scavenging effects on 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl (OH) radicals and superoxide anion (O2−), it was suggested that XHP generated during the ripening period had a strong antioxidant activity. By using size exclusion chromatography, anion exchange column and reversed-phase HPLC, fractions with a strong antioxidative activity were separated based on their molecular weight and polarity differences. The fraction with strong antioxidant effect was further characterized by LC–MS/MS. The results suggest that antioxidative peptides are produced during the long processing of Xuanwei ham among which the tetrapeptide Asp-Leu-Glu-Glu could be one of the main peptides that play key role in the antioxidant activity.
•A modified QuEChERS method was used for green tea sample preparation in pesticide residue analysis.•102 pesticides were determined simultaneously by HPLC-MS/MS.•The validated method satisfied ...linearity, sensitivity and recovery, as specified in SANCO No. 12571/2013.•The validated method was applied successfully to green tea samples from Jiangxi Province, China.•67% of green tea samples contained some pesticides.
A modified QuEChERS protocol, coupled to HPLC-MS/MS, was used for the analysis of 102 pesticides in green teas produced in Jiangxi province, China. For accurate quantification, matrix-matched calibration curves were applied to compensate for matrix effects. Recoveries for these pesticides ranged from 62% to 125% with relative standard deviations (RSDs) lower than 18%. The limits of detection and quantification ranged from 0.03 to 15 µg/kg and 0.1 to 50 µg/kg, respectively. We determined that 67% of green tea samples contained some pesticide residues and most contained more than five pesticides. Moreover, the levels of 11 pesticide residues in 18 samples were found to be greater than the values permitted in EC Regulation No. 396/2005.
The distribution of betalains in peel, flesh, and petioles of yellow and red beetroot cultivars has been investigated using an High‐performance liquid chromatography (HPLC) system with electrospray ...mass spectrometry. Differences in the levels of betacyanins and betaxanthins between different colored cultivars were individually determined for 3 plant parts. The content of almost all analyzed compounds decreased in the following order: peel > flesh > petiole. Betanin/isobetanin pigments comprised a major portion of the relative peak area measured in red beetroot peel. Isobetanin relative peak areas were also high in leaf petioles (68.94% to 74.16%) of red colored cultivars. However, betacyanins were completely absent from the extracts of all analyzed parts of yellow beet. Glutamine‐bx represented a very high relative peak area (59.54% to 64.18%) in flesh of red‐colored cultivars analyzed in the study. Our results indicate that red beet cultivars can be utilized as a potential source of red and yellow natural colorants. However, differences in pigment composition among different beetroot parts must be considered and in order to maximize the pigment yields petioles can also be used as a source rich in specific betalain compounds.
Practical Application
The studies on plant material with high betalain levels can provide new opportunities for the use of these healthy pigments in the food and pharmaceutical industries. Further investigations on highly concentrated betalains in various cultivars/plants parts can help elucidate their biological activity.
