查看更多>>摘要：? 2022Purification of biopharmaceuticals has shifted toward continuous and integrated processes, in turn bringing along a need for monitoring and control to maintain a desired separation between the target pharmaceutical and any impurities it may carry. In this study, a cycle-to-cycle control of the retention volumes of two compounds in a chromatographic, ion exchange purification step was developed, allowing the process to maintain the desired retention volumes in the separation. The controller made use of a model-based, multivariate iterative learning control (ILC) algorithm that used a quadratic-criterion objective function for optimal set point control, along with feed-forward control based on direct model inversion for preemptive control of set point changes. The model was calibrated using 3 experiments, allowing for fast setup. The controller was tested by introducing three different disturbances to a sequence of otherwise identical ion exchange separation processes: a change in the salt concentration of the elution buffer, a change in set point, and a change in the pH of the elution buffer. It was capable of correcting for all disturbances within at most 3 cycles, proving its efficacy. The successful application of ILC for separation control in biopharmaceutical purification paves the way for the development of further ILC-based control strategies within the field, as well as combination with other control strategies.
查看更多>>摘要：? 2022In this work, headspace single-drop microextraction (HS-SDME) method and headspace (HS) method were developed and compared to determine methanol by gas chromatography with flame ionization detector (GC-FID). Several factors influencing extraction efficiency, such as extraction time, temperature, sample volume, stirring rate and extraction solvent were investigated and the optimal conditions could be obtained using 2.0 μL DMF as extractant, 45 °C as heating temperature, 5 min as extraction time, 6 mL sample volume and 1.5 g KCl as addition of salt. The obtained dynamic range of HS-SDME-GC-FID was from 0.05 to 2 mg·L?1 with the limit of detection (LOD) of 0.001 mg·L?1 and that of HS-GC-FID was from 10.0 to 400.0 mg L?1 with LOD of 0.5 mg·L?1. The relative standard deviations (RSD) of HS-SDME-GC-FID was 1.9% (n = 5, C = 0.005 mg·L?1), 4.8%(n = 5, C = 0.02 mg·L?1) and 3.3%(n = 5, C = 0.1 mg·L?1), then the RSD of HS-GC-FID was 4.4%(n = 5, C = 5 mg·L?1), 5.8%(n = 5, C = 20 mg·L?1) and 4.0%(n = 5, C = 40 mg·L?1). Clearly, compared with HS-GC-FID, HS-SDME-GC-FID possessed lower LOD and better reproducibility and both of them were applied to determine methanol in imported wine and the recoveries for the spiked samples were between 83.99 and 117.24%. Overall, HS-SDME approach was confirmed to be a more sensitive and efficient sample pretreatment method and could separate matrix effectively.
查看更多>>摘要：? 2022Disinfection by-products (DBPs) are detrimental to public health owing to their carcinogenicity and mutagenesis. Fast and reliable determination of DBPs is essential for ascertaining their formation, characteristics, and occurrence. This study reported an automated headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for quantifying typical nitrogenous-DBPs, including haloacetonitriles (HANs), trichloronitromethane, and trihalomethanes (THMs). The analysis was further optimized by selecting SPME fiber coatings, extraction/desorption time and temperature, and salt addition. The optimized method examined the occurrence and stability of the selected DBPs in aqueous samples under different preservation conditions and showed good sensitivity (limit of detection: 0.010–0.320 μg/L) and precision. Most THMs and HANs with high recovery were preserved in ultrapure water under dark and low-temperature conditions. However, real samples exhibited greater analytical biases due to comprehensive effects of photochemistry, biochemistry, and physiochemistry. Based on the findings of this study, we recommend that tested samples should be preserved in a frozen state and analyzed within three days.
查看更多>>摘要：? 2022For a further improvement of ion exchange chromatography for protein purification, the optimization of mobile phase composition is an important factor. The effects of salt type selection on cation exchange chromatography (CEC) have been investigated in this work. Hereby, the significance of co-ion and displacing ion selection were compared. Therefore, the suitability of a constant cationic or anionic strength for multivalent salts for the determination of salt impact were evaluated. The retention and separation behavior of the three model proteins bovine serum albumin, lysozyme and α-chymotrypsin were investigated with varying salts in the elution buffer. For this, five different cations and five different anions were used. Hereby, the effects of anion and cation selection were analyzed independently. It was shown that a constant cationic strength is a suitable setup for the determination of salt effects on protein retention in CEC, as the resulting retention factors did not show a clear trend regarding ion valence. It was observed that for the used process conditions the anion selection could change the separation factor by up to 30% and the cation selection by up to 16%. These changes were attributed to protein specific salt effects of citrate on bovine serum albumin and magnesium on α-chymotrypsin. It was demonstrated that at constant cationic strength the co-ion selection can be of the same or even of higher importance for protein separation as the selection of the displacing ion in CEC.
查看更多>>摘要：? 2022In recent years, important efforts have been put into miniaturization, coming on the scene formats such as chips, 3D-printed objects and paper-based devices. These systems have been applied to biological and chemical processes taking profit of their advantages such as waste reduction, low cost, portability, etc. Despite their benefits, there is a need to continue developing easier-to-use devices with enhanced performance addressed to face the current analytical challenges. In this sense, reticular porous materials such as metal- (MOFs) and covalent- (COFs) organic frameworks with unique features including tailorable porous architectures and tunable chemistry have attracted a lot of attention in various fields. Nevertheless, the combination of these materials with miniaturized and emerging formats has been scarcely investigated. This review is intended to bridge this gap and highlight the recent contributions of these materials in these analytical formats. Thus, this work aims to provide a comprehensive review of the field, highlighting incorporation strategies into the functional supports available to date, and the applications of the resulting systems in both off-site laboratory studies (mostly dedicated to (micro)extraction purposes) and on-site analysis. Finally, a discussion of challenges and future directions in this field is also given.
查看更多>>摘要：? 2022Cycle stability is important for preparative chromatography resins. Up to 200 cycles have been reported for Protein A affinity resins when used under optimized operating conditions. Through engineered ligands, alkaline resistant Protein A resins are available that can withstand repeated cleaning-in-place cycles with even 1 M NaOH. This enables an increase of purification cycles through the reduction of fouling while maintaining high binding capacities. Previously, non-intuitive changes in dynamic binding capacity after alkaline treatment have been observed for these novel Protein A resins, where sharper breakthrough curves and increased capacities were reported. In this work, we have systematically investigated resins with both low and high alkaline stability and studied the changes in static and dynamic binding capacities and elution behavior. We propose that the observed mass transfer increases of up to 40% are due to a switch in diffusion mechanism, as shown by confocal laser scanning microscopy. Based on our results, only a small window of alkaline treatment conditions exists, where dynamic binding capacity can be increased. Our findings may help to explain previous findings and observations of others.
查看更多>>摘要：? 2022 Elsevier B.V.Aerial parts of the rare species Salvia aegyptiaca L. and S. verbenaca L. were collected from arid habitats in southern Tunisia. Their polar (ethanol?water) and mid-polar (ethyl acetate) extracts were analyzed non-targeted via a developed high-performance thin-layer chromatography profiling hyphenated with 12 effect-directed assays and 8 different physico-chemical detections. Bioactive compound zones were observed with inhibiting activities on α-glucosidase, ?-glucosidase, ?-glucuronidase, acetylcholinesterase, butyrylcholinesterase and tyrosinase, with radical scavenging (antioxidative) effects, and with activities against Gram-negative and Gram-positive bacteria. The effect-directed profile patterns showed common bioactive zones for different collection sites of the same species and distinct differences between species. Such characteristic profiles can be used to prove authenticity. Genotoxic, estrogen-like and androgen-like compounds were not detected even at higher amounts applied (for extracts from 1.6 mg sample). In the physico-chemical profiling, further organic substances were selectively detected, which highlighted the complexity of the multi-component mixture. The Tunisian sage profiles were further compared to the frequently used S. folium L. and S. officinalis L. leaves, and to reference mixtures containing phenolic acids and tanshinones. Selected bioactive zones in the S. verbenaca extracts were characterized by high-resolution mass spectrometry, and some mass signals were attributed to a caffeic acid derivative and to oleanolic and ursolic acids. Such effect-directed non-target profiling allows straightforward comparison not only of sage but of plant extracts in general.
查看更多>>摘要：? 2022A new analytical method was developed for the separation and determination of basic orange II, acid orange II and auramine O in soybean products. The technique was focused on ionic liquid reverse micelle microextraction (IL-RMME) followed by analysis and determination by ultra-high performance liquid chromatography (UHPLC) with photodiode array detector of three chemical dyes. In this method, IL-RMME solution consisting of ionic liquid [Omim]BF6 and surfactant GenapolX-080 was used as extractant. Important parameters affecting IL-RMME efficiency, such as extraction solvent type and volume, sample solution pH, salt effect, centrifugation speed and time were investigated. Under the optimal condition, the linearity of the method was in the range of 0.1–10 ng mL?1with correlation coefficient above 0.9994 and the limits of detection below 0.03 ng mL?1. At the same time, relative standard deviations of the developed procedure for intra- (n = 5) and inter-day (n = 5) precision were in the range of 5.04–8.50%. The results demonstrated that a simple fast environmentally friendly efficient method was successfully applied in the separation and determination of three chemical dyes in soybean products.
查看更多>>摘要：? 2022 Elsevier B.V.The study presents the development and validation of a method for the determination of seven priority polycyclic aromatic hydrocarbons (PAHs, including fluoranthene and benzo[a]pyrene, for which the EU has set environmental quality standards, EQS, for biota) in gammarid samples combining focused ultrasound solid–liquid extraction and dispersive solid-phase extraction clean-up in one step followed by gas chromatography–triple quadrupole tandem mass spectrometry (GC–QqQ-MS/MS). The method is designed to analyse small about 100 mg dry weight (dw) samples obtained after lyophilisation of 500 mg wet weight (ww) samples. The sample preparation procedure is simple, environment friendly (method was classified as “an excellent green analysis” according to the analytical Eco-Scale assessment), non-laborious and low-cost and, apart from the sample extract concentration step, is quick. Thorough disintegration of the gammarids is achieved by a combination of sonication and the addition of granular anhydrous Na2SO4 to the gammarid suspension, thus avoiding the need to grind the sample prior to analysis. The QqQ-MS/MS detector, thanks to its excellent selectivity and sensitivity, allows to meet the EQS requirements for PAHs in biota with a good margin (limits of quantification in the range of 0.12 and 0.56 ng g?1 ww). The method has been successfully validated (in terms of linearity, method limits, precision, trueness, robustness, measurement uncertainty and comparative analysis of real samples), and has been shown to be suitable for monitoring and evaluating the PAHs contamination in surface water biota.
查看更多>>摘要：? 2022Incorporation of highly selective and stable adsorbent with facile extraction technology is desired in practical analysis. Here we show the rational preparation of a urea-linked covalent organic framework functionalized polytetrafluoroethylene film (COF-117-PTFE) with ordered porous structure, rich functional groups, and large surface area-to-volume ratio as the effective adsorbent for convenient, selective and rapid thin film microextraction (TFME) of rhodamine B (RB). The COF-117-PTFE based TFME coupled with high performance liquid chromatography-fluorescence detector (HPLC-FLD) successfully realized the determination of RB with the limit of detection of 0.007 μg L?1, the linear range of 0.1 - 100 μg L?1. The relative standard deviation (RSD) of intraday (n = 5) and interday (n = 5) for the determination of 10 μg L?1 RB were 2.3% and 6.8%, respectively. The absolute recoveries were 80.3%, 71.2% and 67.9% in river water, chili powder and Sichuan pepper powder, respectively. The recoveries for RB spiking in complicated real samples (dry chili, chili powder, dry Sichuan pepper, Sichuan pepper powder and river water) ranged from 90.4% to 107.5%. The developed COF-117-PTFE based TFME-HPLC-FLD method is promising in practical application. This work reveals the high potential of functionalized COF film as the adsorbent for effective extraction of trace contaminants in complicated samples.
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