Preparation of polymer based sorbents for solid phase extraction of polyphenolic compounds

Oligonucleotides Isolation and Separation—A Review on Adsorbent Selection

Oligonucleotides have many important applications, including as primers in polymerase chain reactions and probes for DNA sequencing. They are proposed as a diagnostic and prognostic tool for various diseases and therapeutics in antisense therapy. Accordingly, it is necessary to develop liquid chromatography and solid phase extraction methods to separate oligonucleotides and isolate them from biological samples. Many reviews have been written about the determination of these compounds using the separation technique or sample preparation for their isolation. However, presumably, there are no articles that critically review the adsorbents used in liquid chromatography or solid phase extraction. The present publication reviews the literature from the last twenty years related to supports (silica, polymers, magnetic nanoparticles) and their modifications. The discussed issues concern reversed phase (alkyl, aromatic, cholesterol, mixed ligands), ion-exchange (strong and weak ones), polar (silica, polyhydroxy, amide, zwitterionic), and oligonucleotide-based adsorbents.

Conductive Polymer-Based Nanocomposites as Powerful Sorbents: Design, Preparation and Extraction Applications

Conductive polymers as composite materials have been attracted tremendous attention due to their versatile and excellent features such as tunable conductivity, facile synthesis and fabrication, high chemical and thermal stability etc. These characteristics make them versatile and let them being used in numerous fields including microelectronics, optics and biosensors. Throughout the mentioned fields, conductive polymers particularly perform as effective sorbents. Although tremendous efforts have been put into this topic, to the best of our knowledge, a comprehensive up-to-date review on the applications of conductive polymers as efficient sorbents has not been reported. The main objective of this paper is to make a significant contribution to the recent literature toward the synthesis and extraction applications of conductive polymers as efficient sorbents.

Synthesis of Oxidant Functionalised Cationic Polymer Hydrogel for Enhanced Removal of Arsenic (III)

A cationic polymer gel (N-[3-(dimethylamino)propyl]acrylamide, methyl chloride quaternary)(DMAPAA-Q gel)-supported oxidising agent (KMnO₄ or K₂Cr₂O₇) was proposed to remove As from water. The gel could adsorb arsenite, As(III), and arsenate, As(V), through the ion exchange method, where the oxidising agent oxidised As(III) to As(V). theoretically speaking, the amount of oxidant in the gels can reach 73.7 Mol%. The maximal adsorption capacity of the D-Mn gel (DMAPAA-Q gel carrying MnO₄⁻) and D-Cr gel (DMAPAA-Q gel carrying Cr₂O₇²⁻) for As(III) could reach 200 mg g⁻¹ and 263 mg g⁻¹, respectively; moreover, the As(III) removal rate of the gels could still be maintained above 85% in a neutral or weak acid aquatic solution. Studies on the kinetic and adsorption isotherms indicated that the As adsorption by the D-Mn and D-Cr gels was dominated by chemisorption. The thermodynamic parameters of adsorption confirmed that the adsorption was an endothermic process. The removal of As is influenced by the co-existing high-valence anions. Based on these results, the gels were found to be efficient for the As(III) adsorption and could be employed for the As(III) removal from the industrial wastewater.

Review on sample preparation methods for oligonucleotides analysis by liquid chromatography

Antisense oligonucleotides have been successfully investigated for the treatment of different types of diseases. Detection and determination of antisense oligonucleotides and their metabolites are necessary for drug development and evaluation. This review focuses mainly on the first step of the analysis of oligonucleotides i.e. the sample preparation stage, and in particular on the techniques used for liquid chromatography and liquid chromatography coupled with mass spectrometry. Exceptional sample preparation techniques are required as antisense oligonucleotides need to be determined in complex biological matrices. The text discusses general issues in oligonucleotide sample preparation and approaches to their solution. The most popular techniques i.e. protein precipitation, protein enzyme digestion and liquid-liquid extraction are reviewed. Solid phase extraction methods are discussed and the issues connected with the application of each method are highlighted. Other newly reported promising techniques are also described. Finally, there is a summary of actually used techniques and the indication of the direction of future research.

Comparison of Three Solid Phase Materials for the Extraction of Carboxylic Acids from River Water Followed by 2D GC × GC-TOFMS Determination

The extraction and determination of aliphatic and aromatic carboxylic acids as well as their influence on the aromaticity and molecularity relationship of natural organic matter (NOM) in water are reported in this study. Three solid phase extraction (SPE) sorbents were used and their extraction efficiencies evaluated after chromatographic determinations (using gas chromatography with a time of flight mass spectrometer (GC × GC-TOFMS) and liquid chromatography with organic carbon detector (LC-OCD)). More than 42 carboxylic acids were identified in raw water from the Vaal River, which feeds the Lethabo Power Generation Station, South Africa, with cooling water. The aromatic carboxylic acid efficiency (28%) was achieved by using Strata™ X SPE while the highest aliphatic carboxylic acid efficiency (92.08%) was achieved by silica SPE. The hydrophobic nature of NOM in water depends on the nature of organic compounds in water, whether aromatic or aliphatic. The LC-OCD was used to assess the hydrophobicity levels of NOM as a function of these carboxylic acids in cooling water. The LC-OCD results showed that the aromatic nature of NOM in SPE filtered water followed the order Silica>Strata X>C-18. From the results, the hydrophobicity degree of the samples depended on the type and number of carboxylic acids that were removed by the SPE cartridges.

A new approach for cytokinin isolation from Arabidopsis tissues using miniaturized purification: pipette tip solid-phase extraction

BACKGROUND

We have developed a new analytical approach for isolation and quantification of cytokinins (CK) in minute amounts of fresh plant material, which combines a simple one-step purification with ultra-high performance liquid chromatography-fast scanning tandem mass spectrometry.

RESULTS

Plant tissue samples (1-5 mg FW) were purified by stop-and-go-microextraction (StageTip purification), which previously has only been applied for clean-up and pre-concentration of peptides. We found that a combination of two reverse phases and one cation-exchange phase, was the best tool, giving a total extraction recovery higher than 80%. The process was completed by a single chromatographic analysis of a wide range of naturally occurring cytokinins (bases, ribosides, O- and N-glucosides, and nucleotides) in 24.5 minutes using an analytical column packed with sub-2-microne particles. In multiple reaction monitoring mode, the detection limits ranged from 0.05 to 5 fmol and the linear ranges for most cytokinins were at least five orders of magnitude. The StageTip purification was validated and optimized using samples of Arabidopsis thaliana seedlings, roots and shoots where eighteen cytokinins were successfully determined.

CONCLUSIONS

The combination of microextraction with one-step high-throughput purification provides fast, effective and cheap sample preparation prior to qualitative and quantitative measurements. Our procedure can be used after modification also for other phytohormones, depending on selectivity, affinity and capacity of the selected sorbents.