This paper shows the in situ synthesis of an hexyl acrylate monolith in PDMS microfluidic devices and its subsequent use as stationary phase for electrochromatography on chip. To overcome the ability ...of PDMS material to absorb organic monomers, surface modification of the enclosed channels was realized by UV‐mediated graft polymerization. This grafting procedure is based on the preliminary adsorption of a photoinitiator onto the PDMS surface and polymerization of charged monomers. Next, hexyl acrylate monoliths were cast in situ using photopolymerization process. The chromatographic behavior of the monolithic column was confirmed by the successful separation of derivatized catecholamines in the PDMS device using a 30 mm effective separation length (100 μm×100 μm section). Efficiencies reached up to 200 000 plates per meter.
•An experimental method for scaling-up in countercurrent chromatography.•Three experiments on small CPC column and a single experiment on the large CPC column.•Method adaptable to different column ...types.•Method adaptable for maximum load per run or for maximum productivity (load per time).
Centrifugal Partition Chromatography (CPC) is a purification technique using a biphasic liquid system. As a preparative separation technique, scale-up is of primary concern. Once the separation is optimized on a lab-scale instrument, the scale-up transfer is quite straightforward simply using the instrument volume ratio as the linear transfer factor, thanks to the absence of solid support. Such linear transfer underestimates the performances of large-scale CPC rotors that are usually better than that of small rotors. It means that more material than predicted by the linear estimation could be purified. A fully practical method based on experimental observations is proposed. The first step is to determine experimentally the free space volume available between the two peaks of interest doing two analytical separations, one with the small analytical CPC instrument, giving ΔV1, and the second with the large preparative one, giving ΔV2. The second step is to determine on the small CPC instrument how much material can be loaded to reach the maximum mass load still giving the required purity and recovery ratio of the desired compound. Then, an accurate prediction of the maximal quantity of sample that the large-scale rotor can purify is simply obtained by multiplying the maximum mass load on the analytical CPC instrument by the free-space between peaks ΔV2/ΔV1 ratio. For demonstration purposes, the method is applied to the transfer of the CPC separation of a synthetic three-GUESS-compound mixture from a 35mL-rotor to a semi-prep 239-mL rotor. The paper addresses also the operating condition optimization depending on industrial production strategy (maximal load per run or maximal productivity).
Le dispositif « devoirs faits » a été mis en place dans les collèges depuis l’année 2017. Dans le cadre d’un projet de recherche sur le suivi et l’accompagnement de cette mise en place dans un ...collège REP + à Marseille, nous nous intéressons à ce que les acteurs (élèves et intervenants) déclarent des effets perçus de ce type de dispositif, des difficultés et obstacles rencontrés.
The « homework done » (« devoirs faits ») devise has been in place in french « collèges » since 2017. As a part of a research project on monitoring and accompanying this implementation in a « REP + Collège ») in Marseille, we are interested in what actors (students, teachers and education assistants) report on the perceived effects of this type of devise, difficulties and obstacles encountered.
Background We observed an increased rate of Pseudomonas aeruginosa bacteremia in our hematology unit in 2004-2007 without an identified environmental source. Methods We conducted a matched ...case-control study to investigate factors associated with P aeruginosa bacteremia in patients with hematologic malignancies. Results Forty-two episodes of P aeruginosa bacteremia were identified. At presentation, 26 patients (62%) had pneumonia and 9 patients (21%) were in shock. Twenty-five patients (60%) were aplastic. The clinical cure rate was 40%. Comparing the 42 cases with 84 matched controls identified the following independent risk factors for P aeruginosa bacteremia: hospitalization in the previous 3 months (odds ratio OR, 12.84; 95% confidence interval CI, 2.98-55.18), antibiotic therapy in the previous 3 months (OR, 5.34; 95% CI, 2.14-13.30), receipt of ceftriaxone in the previous 3 months (OR, 2.38; 95% CI, 1.08-5.27), receipt of aminoglycosides in the previous 3 months (OR, 6.65; 95% CI, 1.15-38.25) and receipt of fluoroquinolones in the previous 3 months (OR, 3.22; 95% CI, 1.48-7.00). Conclusions Local antibiotic therapy algorithms were modified to decrease prescriptions of ceftriaxone and combination therapy with aminoglycosides and fluoroquinolones in an effort to decrease the risk of P aeruginosa bacteremia.
•Practical study of stationary phase retention versus mobile phase flow rate.•Effect of the centrifugal field strength (rotor rotation).•Effect of flow rate and field strength on peak ...efficiencies.•Optimization of preparative productivity.
Centrifugal partition chromatography (CPC) is the branch of countercurrent chromatography (CCC) that works with single axis hydrostatic columns with rotary seals. The hydrodynamic of the liquid stationary phase-liquid mobile phase equilibrium in the CPC chambers has been studied theoretically and with specially designed CPC columns. In this work, we selected a simple analytical separation (no loading study) of three test solutes, coccine red, coumarin and carvone, with a commonly used heptane/ethyl acetate/methanol/water 1:1:1:1v/v biphasic liquid system and two different rotors: a commercially available 30-mL CPC instrument and a 80-mL prototype rotor designed for productivity. We fully studied this separation in many possible practical operating conditions of the two rotors, aiming at a generic column characterization. The rotor rotation was varied between 1000 and 2800rpm, the aqueous mobile phase flow rate was varied between 1 and 22mL/min with the 30-mL rotor and 10 and 55mL/min with the 80-mL rotor, the upper limits being mechanical constraints and some liquid stationary phase remaining in the rotor. The variations of Sf, the volume ratio of stationary phase in the rotor, were studied versus mobile phase flow rate and rotor rotation speed. A maximum mobile phase linear velocity was found to depend on the centrifugal field for the 30-mL rotor. This maximum velocity was not observed with the 80-mL rotor. Studying the changes in coumarin and carvone peak efficiencies, it is established that the number of cells required to make one theoretical plate, i.e. one chromatographic exchange, is minimized at maximal rotation speed and, to a lesser extent, at high mobile phase flow rate (or linear velocity). Considering the throughput, there is evidence of an optimal flow rate depending on the rotor rotation that is not necessarily the highest possible.
•Determination of Abraham parameters for 21 biphasic solvent systems.•Use of a spider diagram for the classification of countercurrent/centrifugal partition chromatography columns.•Selection of ...orthogonal columns is facilitated.
The method development of liquid-liquid chromatography, either countercurrent chromatography or centrifugal partition chromatography, is slowed down by the selection of the biphasic solvent system that constitutes its column. This paper introduces a classification of 19 solvent systems, including the most popular systems based on heptane/ethyl acetate/methanol/water, some non-aqueous systems and some greener systems. This classification is based on Abraham descriptors determined through the partition coefficients of 43 probes. Among 21 determined models, nine of them allow an accurate prediction of partition coefficients from solute descriptors and another ten provide a description of the chromatographic interactions at the 5% significance level. A graphical tool (spider diagram) is built for the comparison of the chromatographic columns previously characterized with the solvation parameter model. The position of a solvent system in this spider diagram relates to the interactions at stake, thus the selection of columns offering similar or orthogonal interactions is facilitated, with no previous knowledge of the solute required. This semi-empirical strategy cannot fully predict the retention behavior but can judiciously orientate the user towards a limited number of solvent systems to be experimentally tested.
•Carnosol is an active pharmaceutical principle found in rosemary.•The purification method is optimized on a small centrifugal partition chromatography column (CPC).•To be quickly transferred on ...larger CPC instruments using the recently proposed “free space between peaks” method.
This paper illustrates the application of a recently proposed protocol allowing the scale-up prediction on hydrostatic countercurrent chromatography columns (centrifugal partition chromatographs or CPC). A commercial extract of rosemary (Rosmarinus officinalis L.) was used as the starting material containing 0.48% of carnosol, an active pharmaceutical ingredient with great potential. After a rapid method development on a small-scale 35-mL CPC instrument that allowed for the determination of the solvent system and maximum sample concentration and volume, the purification was transferred on two larger instruments using the “free space between peaks” method. The method takes into account the technical limitations of the larger instruments, such as pressure and/or maximum centrifugal field, and allows, by simply running an analytical-sized injection on the large scale rotor, to give an accurate prediction of the maximum sample load and best throughput. The 0.27g of rosemary extract maximum load on a 35-mL CPC was transferred as a 1.9g load on a 254-mL medium size CPC and 9g load on a 812-mL CPC. The maximum process efficiency of 3.1mg of carnosol per hour obtained on the small 35-mL column was transferred on the 254-mL CPC giving 8.3mg/h and, on the larger 812-mL column 49.4mg of carnosol could be obtained per hour. If the scaling-up in CPC instruments is not directly homothetic, it can be highly predictable through a few simple experiments.
•Optimisation of an off-line LC x SFC-HRMS method was carried out for the analysis of HTL wastewater•In-depth investigations into 1D flow rate, number of fractions, composition of the injection ...solvent and injection volume in SFC have been performed.•Water-rich LC fractions were injected into the SFC column•The combination of LC and SFC was highly orthogonal for the compounds from algae HTL wastewater.
An off-line multidimensional method involving liquid chromatography combined with supercritical fluid chromatography was developed for the characterization of the wastewater of hydrothermal liquefaction of microalgae Chlorella sorokiniana. The first dimension consisted of a phenyl hexyl column operated in reversed-phase mode, whereas the second dimension was performed on a diol stationary phase. Optimization of the kinetic parameters of the first and second dimensions were performed, taking into account the fraction collection system. The beneficial effect of working at high flow rate in both dimensions, as well as the need to work with short columns (50 mm) in the second dimension was evidenced. Injection volume was also optimized in both dimensions. The first dimension benefited from on-column focusing, while in the second dimension, untreated water-rich fractions could be injected without peak deformation. The performances of offline LCxSFC were compared to LC-HRMS, SFC-HRMS and LCxLC-HRMS for the analysis of the wastewater. Despite a long analysis time of 3.3h, the off-line separation coupled to high-resolution mass spectrometry exhibited a very large orthogonality with 75 % occupation rate of the separation space, reaching an effective peak capacity of 1050. While other evaluated techniques were faster, one-dimensional techniques failed to separate the numerous isomers while LCxLC exhibited lower orthogonality (45% occupation rate).
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Background: Despite largely diffused guidelines, Pneumococcal and Influenza vaccination coverage (VC) remains insufficient in cancer patients receiving chemotherapy. We evaluated ...VC and carried out an interventional study to improve VC in cancer patients treated in 3 medical oncology departments in 3 hospitals of North-of-France. Methods: Using a standardized questionnaire, we assessed the VC in adult cancer patients receiving anticancer treatment in day hospital between 02 and 07 Dec. 2019. Then, in each hospital, we organized trainings with physicians to discuss the current vaccination guidelines (January 2020). Finally, to assess the impact of this intervention on Pneumococcal and Influenza VC, we have conducted a similar survey using the same questionnaire in March 2020. Since there were no specific guidelines on Diphtheria-Tetanus-Pertussis (DTP) VC and we did not expect an improvement, we have monitored DTP VC as internal control. Results: 272 patients have been enrolled in the “before study” in the 3 hospitals, whereas 156 patients have been enrolled in the “after study” in only 2 hospitals (the after-study was not feasible in 3
rd
hospital because of COVID-19 pandemic national containment). Predictors associated with DTP VC was age, with Pneumococcal VC was center and with Influenza VC were age, gender and tumor histology (adenocarcinoma vs others). Influenza VC was significantly improved after intervention (42.6 vs 55.1% with p = 0.016) especially in fragile patients, but Pneumococcal VC was not (11.8 vs 15.4% with p = 0.357). Conclusions: As expected, VC was very low in cancer patients, our figures are consistent with literature data. The impact of intervention (training of physicians) is limited without improvement of Pneumococcal VC. We presume that this increase in Influenza VC mainly reflects the overall result of national Influenza vaccination campaign.
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