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121.
A method for the quantitative determination of non-steroidal anti-inflammatory drugs (NSAIDs) in sewage sludge was developed and validated. The target compounds were extracted using pressurized hot water extraction (PHWE) and then purified and preconcentrated by three-phase hollow fiber liquid phase microextraction (HF-LPME) followed by LC–ESI-MS analysis. The PHWE was optimized with regard to the pH of solvent as well as other operational parameters. The optimum conditions were 0.01 M NaOH as the extraction solvent, temperature of 120 °C, pressure of 100 bar, static time 5 min, 5 cycles, flush volume 90% and purge time 60 s. Spike recoveries for sludge samples spiked at 200 ng g−1 were in the range of 101–109% but for the native drugs in non-spiked sludge samples, recoveries were 38.9%, 59.8%, 90.3% and 47.8% for ketoprofen, naproxen, diclofenac and ibuprofen, respectively. Donor phase pH, ionic strength and extraction time were optimized for HF-LPME after PHWE. The optimum conditions were 2 h extraction at pH 1.5 without salt addition. Enrichment factors in the range of 947–1213 times were achieved (extraction recoveries were 23.6–30.3%) for HF-LPME after PHWE. The matrix effect on the ionization of drugs in LC–ESI-MS was also investigated. The results show that there is a smaller matrix effect (−8.9% to +14.6%) in comparison with other published values obtained using solid phase extraction (SPE) for clean-up after pressurized liquid extraction (PLE). Method detection limits (MDLs) and method quantification limits (MQLs) for different drugs were in the range of 0.4–3.7 ng g−1 and 1.5–12.2 ng g−1 in dried sludge samples, respectively. The characteristics of the proposed method were compared with those of other published works. The considerably lower ion suppression/enhancement and minimum use of organic solvents (a few microliters of di-n-hexyl ether) in the sample preparation step are two highlighted advantages of the proposed method in comparison with previously published works. The method was applied to determine NSAIDs in sewage sludge from Källby wastewater treatment plant (Lund, Sweden) in April, June, August and October 2010. The highest concentration level was recorded for ibuprofen in the April sewage sludge sample (588 ng g−1) and all of the selected NSAIDs were detected in all the samples analyzed. 相似文献
122.
123.
ABSTRACT Rhizoma cyperi (tuberal part of Cyperus rotundus Linn) obtained from 15 different zones of China was studied to determine the contents of 16 trace elements such as 4 minor (Ca, K, Mg, and Na), 9 trace (Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn), and 3 toxic (Ag, Cd, and Pb) elements. The concentration determination of 16 elements was performed by atomic absorption spectrophotometry (AAS) after microwave-assisted digestion. A microwave-assisted digestion procedure based on the mixture nitric acid–hydrogen peroxide was evaluated. The method was successfully validated with the good recoveries (97–105%) against CRM GBW07603 (bush twigs and leaves). The calibration curve furnished good linear correlation coefficients (r = 0.9956–0.9999), excellent recoveries (99.35–103.7%), and limits of detection (LOD = 1–50 ng·mL?1) suitable to determine in Rhizoma cyperi. The results showed that K, Ca, Mg, and Na were the most abundant of the major elements in Rhizoma cyperi with average concentrations of K, 26,221 µg·g?1; Ca, 1097 µg·g?1; Mg, 714 µg·g?1, and Na, 293 µg·g?1, respectively. K element was determined for the first time in this plant. 相似文献
124.
125.
The nonkeratinous proteins of wool can be partly or completely dissolved by controlled enzymatic digestion. A comparison between the keratose content of intact wool and that of wool which has been hydrolysed for 96 h with pronase confirms that specifically all the nonkeratinous components are dissolved out of the wool composite by pronase. The influence of microbial infection can be excluded.The residue of wool after the hydrolysis, i. e., a wool low in nonkeratinous proteins, has a higher internal volume, as measured by mercury porosimetry. The centrifugal swelling test shows that these wool samples also have increased hygroscopy. 相似文献
126.
A problem which has been constantly emphasized is the creation of criteria adequate to characterize the complexity of ecological analysis. The objective of the present paper is to demonstrate the capabilities of multiattribute utility theory in difficult-to-formalize problems. The multiattribute utility and the proposed algorithms provide a logically and operationally tested method which includes value in complex ecological problems. The results obtained and the constructed utility functions should be accepted as an iterative stage in real investigations, rather than as complete research that offer a final decision. The value estimations of the decision maker are the basis for interest in a given ecological problem. But they are often not explicitly or consistently addressed in the real investigations. The proposed methods account for otherwise uninterpretable information. The constructed value function can be used for automatic computer control and monitoring of anaerobic waste water digestion, which could reveal a new potential from the practical point of view. 相似文献
127.
This paper describes use of a novel glass bead-based immobilized-enzyme micro column for simple and swift on-line protein
digestion then peptide separation by reversed-phase HPLC. The inexpensive and easily made immobilized-enzyme micro column
was prepared from aminopropyl controlled-pore glass that was reacted first with glutaraldehyde then with trypsin in the presence
of phosphate buffer. Tryptic digestion of bovine serum albumin (BSA) was achieved simply by passing pretreated protein solution
through the laboratory made immobilized-trypsin column; the tryptic fragments were then separated by reversed-phase HPLC.
The peptide separation was found to be identical to separation of a sample which had undergone conventional enzymatic protein
digestion in solution. Digestion of BSA by the immobilized-trypsin column decreased with increasing flow rate of the solution
through the column, and 1.0 μL min−1 was found to be the optimum flow rate for on-line protein digestion with our system. It was also found that the sample required
pretreatment with urea before injection, because of a change in the properties of the protein in the presence of urea, and
the immobilized-trypsin column lost its function in the presence of acetonitrile. This on-line proteomics system enables simple
and rapid protein digestion and was successfully applied to partially micro two-dimensional (2D) chromatographic separation
of proteins. 相似文献
128.
Abdulaziz K. Alsharidi Ashfaq A. Khan John J. Shepherd Andrew J. Stacey 《Mathematical Methods in the Applied Sciences》2020,43(9):5729-5743
We construct the slowly varying limiting state solutions to a nonlinear dynamical system for anaerobic digestion with Monod-based kinetics involving slowly varying model parameters arising from slow environmental variation. The advantage of these approximate solutions over numerical solutions is their applicability to a wide range of parameter values. We use these limiting state solutions to develop analytic approximations to the full nonlinear system by applying a multiscaling technique. The approximate solutions are shown to compare favorably with numerical solutions. 相似文献
129.
Audra M. Judd Danielle B. Gutierrez Jessica L. Moore Nathan Heath Patterson Junhai Yang Carrie E. Romer Jeremy L. Norris Richard M. Caprioli 《Journal of mass spectrometry : JMS》2019,54(8):ii-ii
Matrix‐assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) is a molecular imaging technology uniquely capable of untargeted measurement of proteins, lipids, and metabolites while retaining spatial information about their location in situ. This powerful combination of capabilities has the potential to bring a wealth of knowledge to the field of molecular histology. Translation of this innovative research tool into clinical laboratories requires the development of reliable sample preparation protocols for the analysis of proteins from formalin‐fixed paraffin‐embedded (FFPE) tissues, the standard preservation process in clinical pathology. Although ideal for stained tissue analysis by microscopy, the FFPE process cross‐links, disrupts, or can remove proteins from the tissue, making analysis of the protein content challenging. To date, reported approaches differ widely in process and efficacy. This tutorial presents a strategy derived from systematic testing and optimization of key parameters, for reproducible in situ tryptic digestion of proteins in FFPE tissue and subsequent MALDI IMS analysis. The approach describes a generalized method for FFPE tissues originating from virtually any source. 相似文献
130.
高分辨电感耦合等离子体质谱可以区分干扰元素和目标元素微弱的质量数差别,能解决大多数多原子、氧化物干扰问题,在煤炭痕量元素分析领域受到关注,但煤炭样品中痕量金属元素尤其是稀土元素受到的质谱干扰挑战未被系统地报道.采用HNO3-HF混酸微波消解煤炭样品,优化了消解时间、赶酸、复溶等前处理条件,研究了煤炭中V、Cr、Mn、C... 相似文献