In Silico Screening of Comprehensive Two-Dimensional Centrifugal Partition Chromatography × Liquid Chromatography for Multiple Compound Isolation.

Isolation of unknown compounds for structural identification and the collection of target molecules to generate unavailable standards remain a challenge when dealing with complex samples. While tedious multistep purification is commonly used, it is not appropriate for a limited amount of sample or when a full recovery of expensive molecules is required. Two-dimensional preparative chromatography in a comprehensive mode provides an effective means to collect a large number of molecules in such a case. However, there is currently a lack of metrics to estimate preparative performances with a minimal number of experiments. An in silico comparative study of various pairs of chromatographic systems is proposed, focusing on the occupation rate and the homogeneity of peak spreading in the 2D separation space. Off-line combination of centrifugal partition chromatography (CPC) with liquid chromatography (LC) exhibits numerous advantages for 2D preparative separation. Our in silico approach was illustrated through the isolation of eight bioactive compounds with very similar structures from Cyclopia genistoides plant by CPC×LC. The column screening was performed considering predictive 2D plots in light of the preparative performance descriptors and compared to real 2D preparative separations.

Comparison between centrifugal partition chromatography and preparative liquid chromatography as first dimensions in off-line two-dimensional separation: Application to the isolation of multi-targeted compounds from Edelweiss plant.

Preparative two-dimensional chromatography is gaining interest in the elucidation of complex samples as it allows the recovery of a large number of molecules without the risks inherent to tedious multi-step sample preparation. While the second dimension is often selected to be liquid chromatography, it may be of interest to compare the specificities of two different techniques, namely liquid chromatography and centrifugal partition chromatography, to be used as first dimension. A fair comparison between off-line CPCxLC and prepLCxLC in selective comprehensive mode for preparative purposes is carried out in this study, illustrated by the isolation of five compounds from high-value Edelweiss plant. The method development of each configuration is achieved on laboratory scale instruments. The quality of separation is compared using 2D-contour plots. The prepLCxLC exhibits a large separation space that leads to an overall large peak capacity, which is of great interest for complex samples. But its limited loading capacity involves a large number of 2 D runs increasing the running costs for preparative purposes. On the other hand, CPCxLC provides a low peak capacity due to the poor efficiency provided by CPC. However, this liquid-liquid technique can be finely tuned to generate a high selectivity, decreasing the number of runs necessary to produce a limited number of target solutes.

The Impact of Clinical Pilates Exercises on Tension-Type Headaches: A Case Series.

Tension-type-headaches appear as the third most common disease in the general population and have a big impact on quality of life. The aim is to verify the impact of clinical Pilates exercises on pain intensity, impact headaches, neck disability, state of anxiety, depression, stress and quality of sleep in higher-education students. After a sample selection questionnaire was completed, a series of cases was carried out with 9 undergraduate students with tension-type headaches. Five instruments were applied before and after an intervention program: (i) Numerical Rating Scale-NRS, (ii) Headache Impact Test-HIT-6™, (iii) Neck Disability Index, (iv) Depression, Anxiety, Stress Scales and (v) Pittsburgh Sleep Quality Index. Four sessions of 30 min classes of Pilates exercises were held for 2 weeks. The pain intensity decreased in only 2 participants. The impact of tension-type headaches on normal daily life and ability to function was improved in all patients, and only one patient's functional disability caused by pain in the cervical region did not improve. In regard to negative emotional states, 6 individuals reported improvements, and only one individual reported a lower quality of sleep after the program. The exercise program can induce positive effects on disorders associated with tension-type-headaches.

Classification of biphasic solvent systems according to Abraham descriptors for countercurrent chromatography.

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.

Centrifugal partition chromatography a first dimension for biomass fast pyrolysis oil analysis.

Biomass fast pyrolysis oils contain molecules having a large variety of chemical functions and a wide range of molecular weights (from several tens to several thousand grams per mole). The good knowledge of their complex composition is essential for optimizing the conversion of bio-oils to biofuels, thereby requiring powerful separation techniques. In this work, we investigate the interest of centrifugal partition chromatography (CPC) as a first dimension for the analysis of a bio-oil. A CPC method is proposed to separate oxygen containing compounds according to their partition coefficients in the solvent system. This approach is a powerful and easy-to-use technique that enables fractionation of a bio-oil at a semi-preparative scale, without any sample loss related to adsorption on the stationary phase. Collected fractions are then injected in liquid chromatography as a second dimension of separation. Contour plot representations of the CPC × LC separation are established to discuss the potential of this approach. These representations can be used as a veritable fingerprint in the comparison of different samples or samples at different steps of a conversion process but also as a powerful tool to identify new compounds and describe the entire composition of the bio-oil.

Preparative two dimensional separations involving liquid-liquid chromatography.

The increasing performances of analytical techniques, especially two-dimensional liquid chromatography hyphenated with highly sensitive detectors, allow discovery of new targeted compounds in highly complex samples, whether biomarkers in environmental effluents, natural metabolomes in natural products or unknown impurities in synthetic chemical process. While structural identification can usually be achieved through mass spectrometry and databases, it can be useful to confirm the potential structure via NMR analysis and/or to obtain standard reference material for quantitative purposes, incentive for the production of µg to mg of new target compounds. Hence, preparative chromatography, which was initially run for large-scale production, is now facing new challenges, with small volumes of highly complex samples to deal with. Unfortunately, one dimensional chromatographic methods exhibit limited performances when targets are minor compounds in a complex matrix. Moreover, for process intensification or limited amount of sample, it is now a priority to be able to isolate multiple components with the largest yield possible using as few purification steps as possible. With these specifications in mind, a comprehensive multidimensional chromatographic method for preparative purposes is becoming appealing.

Two-dimensional multi-heart cutting centrifugal partition chromatography-liquid chromatography for the preparative isolation of antioxidants from Edelweiss plant.

The Edelweiss plant has been recognized as a very valuable source of anti-aging principles due to its composition of antioxidants compounds: leontopodic acid A and 3,5-dicaffeoylquinic acid. In this work, off-line multi-heart cutting CPC-LC separation was set up at industrial scale in order to isolate and produce new high quality reference material of these two antioxidants from Edelweiss. For this purpose, CPC and HPLC methods were developed and optimized at laboratory scale and a comprehensive CPCxHPLC analysis of the crude extract was established. Thereby, the CPC method led to a first separation of the target compounds according to their partition coefficient in the solvent system and the HPLC method was performed on the recovered fractions to lead to a second separation. A 2D CPCxHPLC plot was established in order to know the fractions to select at the industrial scale. Then, the CPC and HPLC methods were transferred at industrial scale and the multi-heart cutting CPC-LC was performed in off-line mode. Using CPC with methyl ter-butyl ether-water 1:1 (v/v) solvent system and LC with Denali C18 column, 2g of crude extract sample were injected and leontopodic acid A and 3,5-dicaffeoylquinic acid were recovered with purity over 97%. The compounds were identified by MS and NMR.