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1.
J Pharm Biomed Anal ; 243: 116085, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38471254

RESUMO

Eltrombopag is an oral non-peptide thrombopoietin receptor (TPO-R) agonist indicated for the treatment of thrombocytopenia in patients with persistent or chronic immune thrombocytopenia (idiopathic thrombocytopenic purpura, ITP) or chronic hepatitis C infection and the treatment of severe aplastic anemia. The purpose of this research was to assess the possible impurities that may carry over to eltrombopag from its precursor Eltro-1 (3'-amino-2'-hydroxy-[1,1'-biphenyl]-3-carboxylic acid) and to develop a specific analytical method for the determination of these impurities. Eltro-1 samples synthesized by two different synthesis routes were investigated during the evaluation and method development studies. Besides the expected process-related impurities (Eltro-1A - Eltro-1J), e.g., starting materials, intermediates, and/or compounds formed from their further reactions, an unknown impurity detected above 0.10% was identified by LC-MS, synthesized and fully characterized by NMR, MS and FTIR (Eltro-1K). Accordingly, an HPLC-RP method for the determination of eleven impurities (Eltro-1A - Eltro-1K) in Eltro-1 was developed and validated according to ICH Q2. The control limits for impurities in Eltro-1 were set at ≤ 0.15% for Eltro-1A - Eltro-1J and ≤ 1.0% for Eltro-1K based on fate, spike-purge and carryover studies and in accordance with the ICH M7 classification for impurities in drug substance. Eltro-1 and eleven impurities at the specification limit were separated from each other and the diluent peaks with sufficient resolution without interference. Separation was performed on a Waters XBridge C18 column (150 × 4.6 mm, 3.5 µm) at 40 °C with a 10 µL injection volume at a detection wavelength of 220 nm and 15 °C sample temperature. The gradient elution is performed at a flow rate of 1.0 mL/min for 40 min with mobile phase A (0.1% orthophosphoric acid in water) and B (acetonitrile) according to the following program: Time (min) / Acetonitrile (%): 0/0, 35/70, 36/0, 40/0. Test and standard solutions were prepared at a concentration of 1.0 mg/mL and 1.0 µg/mL, respectively, using a mixture of mobile phase A and acetonitrile (75/25) as diluent. This is the first specific, selective, sensitive, linear, precise, accurate, and robust HPLC method for the determination of Eltro-1A - Eltro-1K in Eltro-1, which showed no significant degradation under thermal stress, photostability (UV and VIS), and standard accelerated and long-term stability conditions.


Assuntos
Benzoatos , Contaminação de Medicamentos , Hidrazinas , Espectrometria de Massa com Cromatografia Líquida , Pirazóis , Humanos , Cromatografia Líquida de Alta Pressão/métodos , Estabilidade de Medicamentos , Acetonitrilas , Reprodutibilidade dos Testes
2.
Environ Res ; 234: 116539, 2023 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-37414390

RESUMO

The characteristics of canvas fabric-derived adsorbents and their removal efficiency on five haloacetronitriles (HANs) were investigated. In addition, the effect of chemical activation with ferric chloride (FeCl3) and ferric nitrate (Fe(NO3)3) solutions on HANs removal efficiency was determined. The results indicated that the surface area increased from 262.51 m2/g to 577.25 and 370.83 m2/g, respectively, after being activated with FeCl3 and Fe(NO3)3 solutions. Increases in surface area and pore volume had a direct impact on the effectiveness of HANs removal. As compared to the non-activated adsorbent, the activated adsorbent effectively removed five species of HANs. TCAN was highly removed by the Fe(NO3)3-activated adsorbent (94%) due to the presence of mesoporous pore volume after activation with Fe(NO3)3. On the other hand, MBAN had the lowest removal efficiency of all adsorbents in this study. The activation with FeCl3 and Fe(NO3)3 showed equal removal efficiency for DCAN, BCAN, and DBAN, with percent removal higher than 50%. The hydrophilicity of HANs species affected the removal efficiency. The hydrophilicity order of five HANs species was MBAN, DCAN, BCAN, DBAN, and TCAN, respectively, which well corresponded to the obtained removal efficiency. The canvas fabric-derived adsorbents synthesized in this study were proven to be utilized as low-cost adsorbents to efficiently remove HANs from the environment. Future research will focus on the adsorption mechanism and recycling method to realize the potential for large-scale utilization.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Purificação da Água/métodos , Adsorção , Acetonitrilas , Cinética
3.
Ann Clin Biochem ; 60(5): 339-348, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37158306

RESUMO

BACKGROUND: Several studies have demonstrated the analytical sensitivity of MALDI-TOF mass spectrometry (MALDI-TOF MS) by immunoenrichment for M-protein analysis. We report the results of a novel, low-cost, reagent-based extraction process using acetonitrile (ACN) precipitation to enrich for κ and λ light chains which can be analysed by MALDI-TOF MS. METHODS: Institutional Ethics committee approval was obtained. Serum samples from patients with monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma (MM), plasmacytoma, AL amyloidosis and Waldenström macroglobulinemia (WM) underwent ACN precipitation. The images obtained were overlaid on apparently healthy donor serum samples to confirm the presence of M-protein. A sample was considered positive for M-protein if there was a sharp or broad peak within the κ or λ mass/charge (m/z) range: m/z- [M + 2H]2+: 11,550-12,300 Da and λ m/z- [M + 2H]2+: 11,100-11,500 Da. Images were acquired at a m/z range of 10,000-29,000 Da. Corresponding serum protein electrophoresis (SPEP), serum immunofixation electrophoresis (IFE) and serum free light chain (sFLC) assay by nephelometry were performed for all the samples. RESULTS: Two-hundred-and-two serum samples were included in the study: MM- 184 (91%); AL amyloidosis- 2 (1%); plasmacytoma- 8 (4%); MGUS- 6 (3%) and WM- 2 (1%). All the SPEP positive samples were identified by MALDI-TOF MS. Out of 179 samples positive for M-protein by IFE, MALDI-TOF MS was positive in 176 samples (98%). Compared to IFE, the sensitivity and specificity of M-protein identification by MALDI-TOF MS were 98.3% and 52.2%, respectively. CONCLUSIONS: This study demonstrates the feasibility of qualitatively identifying M-protein without the need for antibody-based immunoenrichment, making the technique cost-effective.


Assuntos
Amiloidose de Cadeia Leve de Imunoglobulina , Mieloma Múltiplo , Paraproteinemias , Plasmocitoma , Humanos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Cadeias Leves de Imunoglobulina , Acetonitrilas , Paraproteinemias/diagnóstico
4.
Int J Mol Sci ; 23(22)2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-36430323

RESUMO

Kirsten rat sarcoma viral oncogene homolog (KRAS) is a small GTPase protein which plays an important role in the treatment of KRAS mutant cancers. The FDA-approved AMG510 and MRTX849 (phase III clinical trials) are two potent KRASG12C-selective inhibitors that target KRAS G12C. However, the drug resistance caused by the second-site mutation in KRAS has emerged, and the mechanisms of drug resistance at atom level are still unclear. To clarify the mechanisms of drug resistance, we conducted long time molecular dynamics simulations (75 µs in total) to study the structural and energetic features of KRAS G12C and its four drug resistant variants to inhibitors. The combined binding free energy calculation and protein-ligand interaction fingerprint revealed that these second-site mutations indeed caused KRAS to produce different degrees of resistance to AMG510 and MRTX849. Furthermore, Markov State Models and 2D-free energy landscapes analysis revealed the difference in conformational changes of mutated KRAS bound with and without inhibitors. Furthermore, the comparative analysis of these systems showed that there were differences in their allosteric signal pathways. These findings provide the molecular mechanism of drug resistance, which helps to guide novel KRAS G12C inhibitor design to overcome drug resistance.


Assuntos
Simulação de Dinâmica Molecular , Neoplasias , Humanos , Proteínas Proto-Oncogênicas p21(ras)/genética , Mutação , Acetonitrilas , Neoplasias/genética
7.
J Chromatogr Sci ; 60(8): 786-799, 2022 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-34619761

RESUMO

According to the literature review, numerous chromatographic methods have been published for estimation of fixed-dose combination products of telmisartan but no reverse-phase high-pressure liquid chromatographic (RP-HPLC) method has been published yet for synchronous estimation of fixed-dose combination (FDC) products of telmisartan to save time, cost and solvent for analysis. Hence, an economical and eco-friendly RP-HPLC method has been developed for synchronous estimation of multiple FDC products of antihypertensive drugs using the quality risk management (QRM) and DoE-based enhanced analytical quality by design approach. The analytical-QRM was started with the identification of potential method risk parameters followed by their risk assessment by risk priority number ranking and filtering. The identified critical method parameters were optimized using the DoE-based central composite design. The method operable design range was navigated and the control strategy was framed for control and mitigation of risk throughout the life-cycle of the developed method. The method was developed using Shimpack Octadecyl silane (ODS) C18 column and acetonitrile-1.0%v/v triethylamine in water (pH 6.0; 45 + 55, %v/v). The developed method was validated as per the International Council for Harmonization Q2 (R1) guideline. The developed method was applied for the analysis of seven different antihypertensive dosage forms. The developed RP-HPLC method can be used as an eco-friendly, robust and economical alternative analytical tool to several published methods for estimation of FDC products of antihypertensive drugs in the pharmaceutical industry.


Assuntos
Anti-Hipertensivos , Silanos , Acetonitrilas , Cromatografia Líquida de Alta Pressão/métodos , Gestão de Riscos , Solventes , Telmisartan , Água
8.
Food Chem ; 328: 127134, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32473493

RESUMO

An efficient single quadrupole gas chromatography with mass spectrometry method was developed and validated for the determination of indoxacarb residues in tomato and soil. Residues were extracted from the samples using acetonitrile as extracting solvent and the extracts were purified through primary secondary amine and graphitized carbon black. Recoveries were obtained in the range of 92.12-110.51% with the relative standard deviation of 1.32-4.32%. Indoxacarb dissipated with half-life of 3.12-3.21 and 1.24-1.35d for tomato and soil, respectively following doses of indoxacarb 14.5% SC at 60, 90 and 120 g.a.i./ha. Safe waiting periods were found to be 1-3d. The residues were removed from tomato fruit was in the range of 16.73 to 54.32% using simple decontamination approaches. The present study suggest that the use of indoxacarb in tomato at recommended dose, does not seem to pose any dietary risk to the consumers. The soil RQ values indicated low level of risk to earthworms and arthropods.


Assuntos
Contaminação de Alimentos/análise , Oxazinas/análise , Resíduos de Praguicidas/análise , Poluentes do Solo/análise , Solanum lycopersicum/química , Acetonitrilas/química , Exposição Dietética , Análise de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas , Meia-Vida , Humanos , Índia , Oxazinas/metabolismo , Medição de Risco , Poluentes do Solo/metabolismo , Solventes/química , Fatores de Tempo
10.
Artigo em Inglês | MEDLINE | ID: mdl-31108982

RESUMO

Chlorfluazuron is used as a highly effective insect growth regulator to control a variety of crop pests. However, residues of this pesticide have been shown to be harmful to human health. To evaluate the residual dissipation pattern and risk for dietary intake of chlorfluazuron in various vegetables, a solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry method was established to analyze chlorfluazuron residues in Chinese cabbage, Chinese kale, Chinese lettuce, and cauliflower. The sample was extracted with acetonitrile and purified using an SPE amino column. The average recovery of the target sample in the analyzed four vegetables was between 75.0% and 104.1%, and the relative standard deviation was between 2.5% and 9.6%. The precision and accuracy of the analysis met the requirements of residue analysis standards. Dissipation kinetic testing of chlorfluazuron in different vegetables showed a half-life of 2.4-12.6 days, with a rapid dissipation rate. The estimated daily intake of the chlorfluazuron was 0.753-1.661 µg/(kg bw·d), and the risk quotient was 0.15-0.35. It showed that chlorfluazuron had a low risk of chronic dietary intake from vegetables in different populations in China. The results of this study has described the degradation rate of chlorfluazuron in four vegetables, evaluated the risk of dietary exposure to Chinese residents. Therefore, it provides supporting data and empirical basis for guiding the reasonable use of chlorfluazuron in vegetable production and in evaluating its dietary intake risk in vegetables.


Assuntos
Brassica/química , Lactuca/química , Resíduos de Praguicidas/química , Praguicidas/química , Compostos de Fenilureia/química , Piridinas/química , Acetonitrilas , China , Cromatografia Líquida , Contaminação de Alimentos/análise , Humanos , Medição de Risco , Extração em Fase Sólida , Espectrometria de Massas em Tandem
11.
J Pharm Biomed Anal ; 173: 86-95, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31125948

RESUMO

This paper presents integration of Quality by Design concept in the development of hydrophilic interactions liquid chromatographic methods for analysis of amitriptyline and its impurities (A, B, C, and F). This is the first time that HILIC method for amitriptyline and its impurities is developed. Using QbD concept, it is possible to design a robust method and incorporate quality directly into its development. QbD concept in combination of Design of Experiments methodology (DoE) enables creation of well-defined design space. In this study, for method optimization a Box-Behnken design was used to test the effect of acetonitrile content, buffer concentration and pH of water phase on critical system responses such as retention factor of impurity A, resolution between impurity B and impurity C, amitriptyline peak asymmetry factor and retention time of last eluted impurity F. The defined mathematical models and Monte Carlo simulations were used to identify the design space. For robustness testing, fractional factorial design was applied. Optimal chromatographic conditions were the analytical column ZORBAX NH2 (250 mm x 4.6 mm, 5 µm particle size); mobile phase consisted of acetonitrile-water phase (60 mM ammonium acetate, pH adjusted to 4.5 with glacial acetic acid) (92.5:7.5 v/v); column temperature 30 °C, mobile phase flow rate 1 mL min-1, wavelength of detection 254 nm. Finally, method was fully validated and applicability of the method in tablet analysis was confirmed.


Assuntos
Amitriptilina/análise , Contaminação de Medicamentos/prevenção & controle , Acetonitrilas/química , Amitriptilina/química , Cromatografia Líquida/métodos , Interações Hidrofóbicas e Hidrofílicas , Método de Monte Carlo , Projetos de Pesquisa , Comprimidos
12.
J Chromatogr A ; 1588: 25-32, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30598292

RESUMO

4(5)-Methylimidazole (4(5)-MI) is a potential carcinogen with low molecule weight, highly polarity, and weak basicity. The traditional way to extract and clean-up 4(5)-MI in soy sauce using solid phase extraction is tedious and time consuming. Here we proposed a method for the determination of 4(5)-MI in soy sauce by combining a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction with liquid chromatography-mass spectrometry analysis. The impacts of solution pH, water addition, and cleanup procedure on 4(5)-MI extraction efficiency were studied. An optimized sample preparation approach involved a single step liquid-liquid extraction between acetonitrile and soy sauce under alkaline conditions, followed by primary and secondary amine clean-up. The analytical method was validated with soy sauce at three spiking levels (10, 50, 500 ng/g). The method recovery (96.2-107%) and intra-day/inter-day precision (4.1-8.4%/6.9-11.7%) were satisfactory. The method quantification limit was 10 ng/g. The developed method was successfully applied for the determination of 4(5)-MI in fourteen commercial soy sauces from local markets. The results obtained in this work suggests that the method is suitable for the analysis of 4(5)-MI at low concentrations in high-salting and protein-containing soy sauce matrix.


Assuntos
Cromatografia Líquida , Análise de Alimentos/métodos , Imidazóis/análise , Alimentos de Soja/análise , Espectrometria de Massas em Tandem , Acetonitrilas/química , Aminas/análise , Análise de Alimentos/economia , Extração Líquido-Líquido , Água/química
13.
J Chromatogr A ; 1567: 47-54, 2018 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-29960737

RESUMO

A method based on matrix solid-phase dispersion (MSPD) associated to gas chromatography-flame photometric detection (GC-FPD), GC-electron capture detection (GC-ECD) and GC-mass spectrometry (GC-MS) for confirmation purposes, was developed for the determination of a representative group of twelve pesticides in honeybee with particular concern in the apicultural field (fipronil, thiamethoxam, acetamiprid, acrinathrin, metamidophos, dimetoathe, diazinon, chlorpyrifos, methidathion, profenophos, azinphos methyl and coumaphos). Factors influencing the extraction efficiency of MSPD were investigated and optimized through response surface method. The use of octadecylsilyl (C18) sorbent combined with a florisil clean-up and acetonitrile-methanol (99:1) elution was the optimal condition for the extraction of the selected pesticides. Under this condition the recovery of pesticides at the limit of quantification of the method (0.007 to 0.050 µg g-1) ranged from 68 to 102% with RSDs for within-laboratory reproducibility ≤20%. The proposed method was applied to the analysis of honeybees collected in 68 field hives from areas of great apicultural and agricultural development in central Chile. In 65% of these samples eight different pesticides were detected. Pesticides most frequently found were chlorpyrifos (34% of the samples, <0.017-0.067 µg g-1), acrinathrin (32% of the samples, <0.020-0.026 µg g-1) and diazinon (10% of the samples at values <0.015 µg g-1). The incidence of these pesticides in bees can be related to their high employ in central Chile, use to combat the varroosis in hives and hydrophobicity.


Assuntos
Abelhas/química , Cromatografia Gasosa , Cromatografia Gasosa-Espectrometria de Massas , Praguicidas/análise , Acetonitrilas/química , Animais , Chile , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/toxicidade , Reprodutibilidade dos Testes
14.
Environ Monit Assess ; 190(6): 335, 2018 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-29744742

RESUMO

A liquid chromatography with tandem mass spectrometry method was developed and validated to simultaneously determine metalaxyl and azoxystrobin in soil, potato, and potato foliage samples. The samples were extracted by 20 mL of acetonitrile and purified with dispersive solid-phase extraction using octadecyl silane as sorbent. The method showed good linearity (determination coefficients ≥ 0.9926) for metalaxyl (2.5-500 ng/mL) and azoxystrobin (5-1000 ng/mL). The limits of detection and quantification for both fungicides were 1.5-20 µg/kg. The average recoveries in soil, potato, and potato foliage were 83.07-92.87% for metalaxyl and 82.71-98.53% for azoxystrobin. The intra- and inter-day relative standard deviations were all less than 9%. The method was successfully applied on the residual analysis of metalaxyl and azoxystrobin in field trial samples. The results showed that the concentrations of metalaxyl and azoxystrobin in potato samples collected from Guizhou and Hunan were below 50 and 100 µg/kg (maximum residue limit set by China), respectively, at 5 days after the last application. When following the recommended application manual, metalaxyl and azoxystrobin do not present health concerns to the population because the risk quotients are far below 100%. All the above data could help and promote the safe and proper use of metalaxyl and azoxystrobin in potato.


Assuntos
Alanina/análogos & derivados , Monitoramento Ambiental/métodos , Fungicidas Industriais/análise , Pirimidinas/análise , Solo/química , Solanum tuberosum/química , Estrobilurinas/análise , Acetonitrilas/análise , Alanina/análise , Alanina/toxicidade , China , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida/métodos , Fungicidas Industriais/toxicidade , Limite de Detecção , Pirimidinas/toxicidade , Medição de Risco , Extração em Fase Sólida/métodos , Estrobilurinas/toxicidade , Espectrometria de Massas em Tandem/métodos
15.
Forensic Sci Int ; 282: 137-143, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29197244

RESUMO

Hair analysis has been established as a prevalent tool for retrospective drug monitoring. In this study, different extraction solvents for the determination of drugs of abuse and pharmaceuticals in hair were evaluated for their efficiency. A pool of authentic hair from drug users was used for extraction experiments. Hair was pulverized and extracted in triplicate with seven different solvents in a one- or two-step extraction. Three one- (methanol, acetonitrile, and acetonitrile/water) and four two-step extractions (methanol two-fold, methanol and methanol/acetonitrile/formate buffer, methanol and methanol/formate buffer, and methanol and methanol/hydrochloric acid) were tested under accurately equal experimental conditions. The extracts were directly analyzed by liquid chromatography-tandem mass spectrometry for opiates/opioids, stimulants, ketamine, selected benzodiazepines, antidepressants, antipsychotics, and antihistamines using deuterated internal standards. For most analytes, a two-step extraction with methanol did not significantly improve the yield compared to a one-step extraction with methanol. Extraction with acetonitrile alone was least efficient for most analytes. Extraction yields of acetonitrile/water, methanol and methanol/acetonitrile/formate buffer, and methanol and methanol/formate buffer were significantly higher compared to methanol. Highest efficiencies were obtained by a two-step extraction with methanol and methanol/hydrochloric acid, particularly for morphine, 6-monoacetylmorphine, codeine, 6-acetylcodeine, MDMA, zopiclone, zolpidem, amitriptyline, nortriptyline, citalopram, and doxylamine. For some analytes (e.g., tramadol, fluoxetine, sertraline), all extraction solvents, except for acetonitrile, were comparably efficient. There was no significant correlation between extraction efficiency with an acidic solvent and the pka or log P of the analyte. However, there was a significant trend for the extraction efficiency with acetonitrile to the log P of the analyte. The study demonstrates that the choice of extraction solvent has a strong impact on hair analysis outcomes. Therefore, validation protocols should include the evaluation of extraction efficiency of drugs by using authentic rather than spiked hair. Different extraction procedures may contribute to the scatter of quantitative results in inter-laboratory comparisons. Harmonization of extraction protocols is recommended, when interpretation is based on same cut-off levels.


Assuntos
Cabelo/química , Entorpecentes/análise , Preparações Farmacêuticas/análise , Solventes , Detecção do Abuso de Substâncias , Acetonitrilas , Cromatografia Líquida , Formiatos , Humanos , Metanol , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Espectrometria de Massas em Tandem
16.
Environ Pollut ; 236: 899-906, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29157971

RESUMO

To estimate the health risk of haloacetonitriles in different kinds of drinking water, the concentrations of haloacetonitriles in tap water, boiled water and direct drinking water were detected. The physiologically based pharmacokinetic (PBPK) model was used to calculate internal dose in the human body for haloacetonitriles through ingestion, and the probability distributions of the non-carcinogenic risk of haloacetonitriles for human via drinking water were assessed. This study found that the mean concentrations of dichloroacetonitrile (DCAN) in tap water, boiled water and direct drinking water were 0.955 µg/L, 0.207 µg/L and 0.127 µg/L, and those of dibromoacetonitrile (DBAN) were 0.221 µg/L, 0.104 µg/L, 0.089 µg/L, respectively. In China, direct drinking water is used most frequently, so the concentrations of haloacetonitriles in direct drinking water were used to obtain data on the internal dose of haloacetonitriles. In addition, the simulation results for the PBPK model showed that the highest and lowest concentrations of DCAN occurred in the liver and venous blood, respectively. The peak concentrations of DBAN in each tissue were in the decreasing order liver > rapidly perfused tissue > kidney > slowly perfused tissues > fat > arterial blood (venous blood). In addition, the highest 95th percentile hazard quotients (HQ) value of haloacetonitriles via drinking water for humans was 8.89 × 10-3, much lower than 1. The 95th percentile hazard index (HI) was 0.046, which was also lower than 1, suggesting that there was no obvious non-carcinogenic risk.


Assuntos
Acetonitrilas/análise , Água Potável/química , Poluentes Químicos da Água/análise , China , Humanos , Medição de Risco , Abastecimento de Água
17.
J Chromatogr A ; 1526: 31-38, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29106962

RESUMO

A selective, sensitive and useful method, based on modified QuEChERS cleanup combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the negative-ion electrospray ionization (ESI-) mode, was developed and validated for the simultaneous determination of three inorganic anions including perchlorate (ClO4-), bromate (BrO3-) and hypophosphite (H2PO2-) in flour. The extraction parameters and LC-MS/MS conditions were optimized by single-factor experiment and sorbent combination in modified QuEChERS clean-up was optimized through response surface analysis. Three target analytes were separated on a normal-phase Phenomenex Luna Silica (2) column (150mm×2.0mm, 5µm, 100Å) with the mobile phase of a mixture of 5mmol/L ammonium acetate water solution and acetonitrile, detected by MS/MS under multiple reaction monitoring and quantified by external standard method. The developed method was validated in terms of the sensitivity, linearity, accuracy and precision, and matrix effect. The method showed a good linearity (R2>0.999) for all analytes in their respective concentration ranges. The ILOQs and MLOQs for perchlorate, bromate and hypophosphite were 0.1, 0.5, 5.0µg/L and 2.0, 6.0, 60.0µg/L, respectively. The average recoveries of three target analytes from the negative samples spiked at three different concentrations were in a range from 84.6% to 104.9%. The intra-day precision (n=6) and inter-day precision (n=5) of the target analytes were in the ranges of 2.9%-6.9% and 6.4%-8.2%. The matrix effect of this method was observed between 0.83 and 1.17 and was acceptable. The validated method was successfully applied to determine the concentrations of these inorganic anions in flour. Results found that perchlorate and hypophosphite were detected in 33 out of 50 and 7 out of 50 flour samples.


Assuntos
Bromatos/análise , Técnicas de Química Analítica/métodos , Cromatografia Líquida , Farinha/análise , Percloratos/análise , Ácidos Fosfínicos/análise , Espectrometria de Massas em Tandem , Acetonitrilas/química , Técnicas de Química Analítica/economia , Técnicas de Química Analítica/normas , Limite de Detecção , Reprodutibilidade dos Testes , Extração em Fase Sólida
18.
Methods Cell Biol ; 142: 111-118, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28964330

RESUMO

Peptide purification from natural sources and chemical synthesis is cumbersome with various shortcomings such as low yield, high cost of production, error prone, and restricted by nature of amino acids. Though recombinant DNA technology had overcome all these setbacks for larger proteins, it is still a challenge to produce peptides that are salt free and without impurities. Our approach discussed in this chapter deals with easy and effective purification of peptides of varying sizes (up to 10kDa), expressed as fusion proteins in bacterial system. This includes cleavage of fusion affinity tag by "PreScission protease" in volatile buffer followed by selective acetonitrile precipitation of high-molecular-weight tag in order to purify peptides in solution. This method can be used to purify peptides in large scale for various biochemical and physiological studies.


Assuntos
Acetonitrilas/química , Cromatografia de Afinidade/métodos , Peptídeos/isolamento & purificação , Proteínas Recombinantes de Fusão/isolamento & purificação , Acetonitrilas/isolamento & purificação , Precipitação Química , Cromatografia de Afinidade/economia , Escherichia coli/metabolismo , Ligantes , Peptídeos/química , Proteínas Recombinantes de Fusão/química
19.
ChemSusChem ; 10(9): 2080-2088, 2017 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-28177578

RESUMO

Nonaqueous redox flow batteries (NAqRFBs) are promising devices for grid-scale energy storage, but high projected prices could limit commercial prospects. One route to reduced prices is to minimize or eliminate the expensive supporting salts typically employed in NAqRFBs. Herein, the feasibility of a flow cell operating in the absence of supporting salt by utilizing ionic active species is demonstrated. These ionic species have high conductivities in acetonitrile (12-19 mS cm-1 ) and cycle at 20 mA cm-2 with energy efficiencies (>75 %) comparable to those of state-of-the-art NAqRFBs employing high concentrations of supporting salt. A chemistry-agnostic techno-economic analysis highlights the possible cost savings of minimizing salt content in a NAqRFB. This work offers the first demonstration of a NAqRFB operating without supporting salt. The associated design principles can guide the development of future active species and could make NAqRFBs competitive with their aqueous counterparts.


Assuntos
Fontes de Energia Elétrica , Íons , Acetonitrilas , Boratos , Ácidos Bóricos/química , Economia , Fontes de Energia Elétrica/economia , Eletrólitos , Desenho de Equipamento , Estudos de Viabilidade , Oxirredução
20.
Food Chem ; 218: 192-198, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-27719897

RESUMO

A LC-MS/MS method for determination of eight pesticides (triadimefon, sulfoxaflor, flusilazole, tebuconazole, difenoconazole, amitraz, azoxystrobin, and thiophanate-methyl) in Lycium barbarum was established. The samples were extracted with acetonitrile, and then cleaned up by primary secondary amine. The extracts were diluted with 0.1% formic acid in water. The results showed that at the fortified levels of 0.01-10mg/kg, the average recoveries of these pesticides ranged from 82.1% to 96.2% with the relative standard deviations lower than 7%. The half-lives of eight pesticides were 1.3-5.0days in Lycium barbarum fruits. The pre-harvest interval of all pesticides mentioned above were investigated. Tebuconazole (14days), sulfoxaflor (14days) and flusilazole (28days) have longer pre-harvest interval than the others which have 7days. The dietary risks, assessed as hazard quotients, were far below 100%. The results showed that the eight pesticides applied to Lycium barbarum were comparably safe for the consumer.


Assuntos
Cromatografia Líquida/métodos , Lycium/química , Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Acetonitrilas/química , Medição de Risco
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