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Chemical Reviews Oct 2021Separation and characterization of complex mixtures are of crucial importance in many fields, where extremely high separation power is required. Three-dimensional... (Review)
Review
Separation and characterization of complex mixtures are of crucial importance in many fields, where extremely high separation power is required. Three-dimensional separation techniques can offer a path toward achieving high peak capacities. In this Review, online three-dimensional separation systems are discussed, including three-dimensional gas chromatography, and hyphenated combinations of two-dimensional gas chromatography with liquid chromatography or supercritical-fluid chromatography. Online comprehensive two-dimensional liquid chromatography provides detailed information on complex samples and the need for higher peak capacities is pushing researchers toward online three-dimensional liquid chromatography. In this review, an overview of the various combinations are provided and we discuss and compare their potential performance, advantages, perspectives, and results obtained during the most recent 10-15 years. Finally, the Review will discuss a novel approach of spatial three-dimensional liquid separation to increase peak capacity.
Topics: Chromatography, Liquid
PubMed: 33878259
DOI: 10.1021/acs.chemrev.0c01244 -
Journal of Chromatography. A Mar 2022Structural elucidation of compounds detected with liquid chromatography coupled to high resolution mass spectrometry is a challenging and time-consuming step in the...
Structural elucidation of compounds detected with liquid chromatography coupled to high resolution mass spectrometry is a challenging and time-consuming step in the workflow of non-targeted analysis and often requires manual validation of the results. Retention time, alongside exact mass, isotope pattern, fragmentation spectra, and collision cross-section, is valuable information for ruling out unlikely structures and increasing the confidence in others. Different approaches to predict retention times have been used previously for reversed phase chromatography and hydrophilic interaction liquid chromatography (HILIC), but application is limited to a small set of mobile phases and gradient profiles. Here, we expand the toolbox available for retention time predictions by developing a random forest regression model for predicting retention times for four column types and twenty mobile phase systems. MultiConditionRT was built using a dataset containing 78 compounds analyzed with C18 reversed phase, mixed mode, HILIC, and biphenyl columns. In addition, different eluent compositions were used: both methanol and acetonitrile were combined with different aqueous phases with pH from 2.1 to 10.0 (formic acid, acetic acid, trifluoroacetic acid, formate, acetate, bicarbonate, and ammonia). The root mean square error (RMSE) of the test set predictions was 1.55 min for C18 reversed phase, 1.79 min for mixed-mode, 1.93 min for HILIC, and 1.56 min for biphenyl column. Additionally, MultiConditionRT can be applied to different gradient profiles with a general additive model-based calibration approach. The approach of MultiConditionRT was validated externally and internally with 356 and 151 compounds respectively, yielding an RMSE of 2.68 and 2.32 min. 324 and 84 of these compounds were not in the dataset used in the model development.
Topics: Chromatography, Liquid; Chromatography, Reverse-Phase; Hydrophobic and Hydrophilic Interactions; Indicators and Reagents; Methanol
PubMed: 35139450
DOI: 10.1016/j.chroma.2022.462867 -
International Journal of Molecular... Nov 2022The aim of this research was to develop a simple and efficient ion-pair reagent-free chromatographic method for the separation and qualitative determination of...
The aim of this research was to develop a simple and efficient ion-pair reagent-free chromatographic method for the separation and qualitative determination of oligonucleotide impurities, exemplified by synthesis of raw products of the two single strands of patisiran siRNA. The stationary phases with mixed hydrophobic/hydrophilic properties (cholesterol and alkylamide) were firstly used for this purpose with reversed-phased high-performance liquid chromatography. Several different chromatographic parameters were tested for their impact on impurities separation: type, concentration, pH of salt, as well as organic solvent type in the mobile phase. The pH was the most influential factor on the separation and signal intensities in mass spectrometry detection. Finally, the optimized method included the application of cholesterol stationary phase, with mobile phase containing 20 mM ammonium formate (pH 6.5) and methanol. It allowed good separation and the identification of most impurities within 25 min. Since not all closely related impurities could be fully resolved from the main peak in this oligonucleotide impurity profiling, two-dimensional liquid chromatography was used for peak purity determination of the target oligonucleotides. The Ethylene Bridged Hybrid (BEH) Amide column in hydrophilic interaction liquid chromatography was applied in the second dimension, allowing additional separation of three closely related impurities.
Topics: Chromatography, Liquid; Mass Spectrometry; Chromatography, Reverse-Phase; Hydrophobic and Hydrophilic Interactions; Oligonucleotides; Indicators and Reagents; Cholesterol; Chromatography, High Pressure Liquid
PubMed: 36499291
DOI: 10.3390/ijms232314960 -
Analytical and Bioanalytical Chemistry Jan 2012Hydrophilic interaction liquid chromatography (HILIC) provides an alternative approach to effectively separate small polar compounds on polar stationary phases. The... (Review)
Review
Hydrophilic interaction liquid chromatography (HILIC) provides an alternative approach to effectively separate small polar compounds on polar stationary phases. The purpose of this work was to review the options for the characterization of HILIC stationary phases and their applications for separations of polar compounds in complex matrices. The characteristics of the hydrophilic stationary phase may affect and in some cases limit the choices of mobile phase composition, ion strength or buffer pH value available, since mechanisms other than hydrophilic partitioning could potentially occur. Enhancing our understanding of retention behavior in HILIC increases the scope of possible applications of liquid chromatography. One interesting option may also be to use HILIC in orthogonal and/or two-dimensional separations. Bioapplications of HILIC systems are also presented.
Topics: Amino Acids; Chromatography, Liquid; Hydrophobic and Hydrophilic Interactions; Peptides; Proteins
PubMed: 21879300
DOI: 10.1007/s00216-011-5308-5 -
Journal of Chromatography. A Oct 2007The absolute need to improve the separating power of liquid chromatography, especially for multi-constituent biological samples, is becoming increasingly evident. In... (Review)
Review
The absolute need to improve the separating power of liquid chromatography, especially for multi-constituent biological samples, is becoming increasingly evident. In response, over the past few years, there has been a great deal of interest in the development of two-dimensional liquid chromatography (2DLC). Just as 1DLC is preferred to 1DGC based on its compatibility with biological materials we believe that ultimately 2DLC will be preferred to the much more highly developed 2DGC for such samples. The huge advantage of 2D chromatographic techniques over 1D methods is inherent in the tremendous potential increase in peak capacity (resolving power). This is especially true of comprehensive 2D chromatography wherein it is possible, under ideal conditions, to obtain a total peak capacity equal to the product of the peak capacities of the first and second dimension separations. However, the very long timescale (typically several hours to tens of hours) of comprehensive 2DLC is clearly its chief drawback. Recent advances in the use of higher temperatures to speed up isocratic and gradient elution liquid chromatography have been used to decrease the time needed to do the second dimension LC separation of 2DLC to about 20s for a full gradient elution run. Thus, fast, high temperature LC is becoming a very promising technique. Peak capacities of over 2000 and rates of peak capacity production of nearly 1 peak/s have been achieved. In consequence, many real samples showing more than 200 peaks with signal to noise ratios of better than 10:1 have been run in total times of under 30 min. This report is not intended to be a comprehensive review of 2DLC, but is deliberately focused on the issues involved in doing fast 2DLC by means of elevating the column temperature; however, many issues of broader applicability will be discussed.
Topics: Algorithms; Chromatography, Gas; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Chromatography, Liquid; Image Processing, Computer-Assisted
PubMed: 17888443
DOI: 10.1016/j.chroma.2007.08.054 -
Journal of Food and Drug Analysis Mar 2022Perfluoroalkyl substances (PFASs), as coating materials, possess oil-resistant and waterproof properties. However, their persistency and toxicity have caused concerns.... (Review)
Review
Perfluoroalkyl substances (PFASs), as coating materials, possess oil-resistant and waterproof properties. However, their persistency and toxicity have caused concerns. This study developed a method for determining five types of 20 PFASs with ultra-performance liquid chromatography/tandem mass spectrometry, and measured seven categories of 32 commercial samples of oil-resistant food packaging in Taiwan. The assay was validated according to the specification of Taiwan Food and Drug Administration (TFDA). Samples of 100 cm were cut into pieces and were ultra-sonicated in 20-mL methanol at 50 °C for 45 minutes. The extracts were concentrated to 1 mL for instrumental analysis. Most matrix effect factors and extraction efficiencies of the analytes were 50%-80% and 52%-99%, respectively. Most limits of detection and limits of quantification were between 0.07-11.3 ng/dm and 0.17-18.3 ng/dm, respectively. Most recoveries ranged from 70% to 117% at three tested levels, and the precisions (%RSD) were lower than 19%. Microwave popcorn paper contained more types and higher levels of PFASs than other packaging, with perfluoroalkyl acids at 8.3-1960 ng/dm and fluorotelomer alcohols (FTOHs) at 9.7-7188 ng/dm. High concentrations of FTOHs were also observed in one oil-proof paper bag at 454-2595 ng/dm and in one French fries paper bag at 22.4-167 ng/dm.
Topics: Chromatography, High Pressure Liquid; Chromatography, Liquid; Fluorocarbons; Food Packaging; Taiwan; Tandem Mass Spectrometry; Ultrasonics; United States
PubMed: 35647722
DOI: 10.38212/2224-6614.3397 -
Analytical and Bioanalytical Chemistry Mar 2022This work presents a comparative study for the analysis of carbohydrates for four common chromatographic methods, each coupled to mass spectrometry. Supercritical fluid...
This work presents a comparative study for the analysis of carbohydrates for four common chromatographic methods, each coupled to mass spectrometry. Supercritical fluid chromatography (SFC), hydrophilic interaction liquid chromatography (HILIC), reversed-phase liquid chromatography (RP-LC) and gas chromatography (GC) with detection by triple quadrupole mass spectrometer (QqQ-MS) are compared. It is shown that gas chromatography and reversed-phase liquid chromatography, each after derivatisation, are superior to the other two methods in terms of separation performance. Furthermore, comparing the different working modes of the mass spectrometer, it can be determined that a targeted analysis, i.e. moving from full scan to single ion monitoring (SIM) and multiple reaction monitoring (MRM), results in an improvement in the sensitivity as well as the repeatability of the method, which has deficiencies especially in the analysis using HILIC. Overall, RP-LC-MS in MRM after derivatisation with 1-phenyl-3-methyl-5-pyrazolone (PMP) proved to be the most suitable method in terms of separation performance, sensitivity and repeatability for the analysis of monosaccharides. Detection limits in the nanomolar range were achieved, which corresponds to a mass concentration in the low µg/L range. The applicability of this method to different biological samples was investigated with various herbal liquors, pectins and a human glycoprotein.
Topics: Carbohydrates; Chromatography, Liquid; Chromatography, Reverse-Phase; Gas Chromatography-Mass Spectrometry; Humans; Mass Spectrometry
PubMed: 34928405
DOI: 10.1007/s00216-021-03845-z -
Analytical and Bioanalytical Chemistry May 2008In proteomics, nanoflow multidimensional chromatography is now the gold standard for the separation of complex mixtures of peptides as generated by in-solution digestion... (Review)
Review
In proteomics, nanoflow multidimensional chromatography is now the gold standard for the separation of complex mixtures of peptides as generated by in-solution digestion of whole-cell lysates. Ideally, the different stationary phases used in multidimensional chromatography should provide orthogonal separation characteristics. For this reason, the combination of strong cation exchange chromatography (SCX) and reversed-phase (RP) chromatography is the most widely used combination for the separation of peptides. Here, we review the potential of hydrophilic interaction liquid chromatography (HILIC) as a separation tool in the multidimensional separation of peptides in proteomics applications. Recent work has revealed that HILIC may provide an excellent alternative to SCX, possessing several advantages in the area of separation power and targeted analysis of protein post-translational modifications. [figure: see text]
Topics: Chromatography, Liquid; Proteomics; Water; Wettability
PubMed: 18264818
DOI: 10.1007/s00216-008-1865-7 -
Journal of Pharmaceutical and... May 2022Tetracaine hydrochloride (TCH) is a nasal anesthetic and oxymetazoline hydrochloride (OZH) is a nasal decongestant. A moderate to acute overdosage of OZH and TCH can...
Rapid and sensitive simultaneous separation and electrochemical detection of tetracaine hydrochloride and oxymetazoline hydrochloride in pharmaceutical formulations via core-shell reversed-phase liquid chromatography.
Tetracaine hydrochloride (TCH) is a nasal anesthetic and oxymetazoline hydrochloride (OZH) is a nasal decongestant. A moderate to acute overdosage of OZH and TCH can lead to mydriasis, nausea, cyanosis, tachycardia, dyspnoea, cardiovascular failure, disorientation, seizures, and even death. Liquid chromatography (LC) has been mainly utilized for the individual determination of either TCH or OZH; however, there is a need for rapid and efficient methods for simultaneous analysis in pharmaceutical formulations and aqueous samples. This study highlights the use of the fast and efficient separation capabilities of core-shell silica particles in liquid chromatography (LC) for the simultaneous determination of TCH and OZH using UV detection and the enhanced selectivity afforded by electrochemical detection at a boron-doped diamond (BDD) electrode. Rapid reversed-phase (RP) separation and detection of OZH and TCH in nasal spray and eye drops was achieved within 45 s using a poroshell 120 EC-C column, by adjusting the ratio of organic solvent, mobile phase pH, detection potential and mobile phase flow rate. Sensitivity was compared using ultraviolet (UV) detection at 280 nm, and ECD at + 1.3 V with detection limits of 40 and 70 nM for TCH and OZH, respectively. The developed rapid method was utilized successfully in the analysis of pharmaceutical formulations, where the estimated levels of TCH and OZH in these formulations are in agreement with the specified values outlined by the manufacturers.
Topics: Chromatography, High Pressure Liquid; Chromatography, Reverse-Phase; Drug Compounding; Oxymetazoline; Pharmaceutical Preparations; Tetracaine
PubMed: 35358771
DOI: 10.1016/j.jpba.2022.114717 -
Journal of Chromatography. A Feb 2022Over 170 post-transcriptional RNA modifications have been described and are common in all kingdoms of life. These modifications range from methylation to complex...
High-performance nano-flow liquid chromatography column combined with high- and low-collision energy data-independent acquisition enables targeted and discovery identification of modified ribonucleotides by mass spectrometry.
Over 170 post-transcriptional RNA modifications have been described and are common in all kingdoms of life. These modifications range from methylation to complex chemical structures, with methylation being the most abundant. RNA modifications play a key role in RNA folding and function and their dysregulation in humans has been linked to several diseases such as cancer, metabolic diseases or neurological disorder. Nowadays, liquid chromatography-tandem mass spectrometry is considered the gold standard method for the identification and quantification of these modifications due to its sensitivity and accuracy. However, the analysis of modified ribonucleosides by mass spectrometry is complex due to the presence of positional isomers. In this scenario, optimal separation of these compounds by highly sensitive liquid chromatography combined with the generation of high-information spectra is critical to unequivocally identify them, especially in high-complex mixtures. Here we present an analytical method that comprises a new type of mixed-mode nano-flow liquid chromatography column combined with high- and low-collision energy data-independent mass spectrometric acquisition for the identification and quantitation of modified ribonucleosides. The method produces content-rich spectra and combines targeted and screening capabilities thus enabling the identification of a variety of modified nucleosides in biological matrices by single-shot liquid chromatographic analysis coupled to mass spectrometry.
Topics: Chromatography, High Pressure Liquid; Chromatography, Liquid; Humans; Mass Spectrometry; Ribonucleosides; Ribonucleotides
PubMed: 35042139
DOI: 10.1016/j.chroma.2022.462803