Gormsenstougaard4824

A pentafluorobenzoylation (PFBz)-liquid chromatography-tandem mass spectrometry method was developed for qualitative and quantitative analysis of ethanolamines (EAs, nitrogen mustard degradation products). With this method, highly hydrophilic EAs can be sufficiently analyzed with a commonly used reversed phase column (retention times (PFBz)2-methyl diethanolamine, 9.1 min; (PFBz)2-ethyl diethanolamine, 9.8 min; and (PFBz)3-triethanolamine, 17.6 min). The applicability of the method for real samples was investigated via recovery tests. Methyl diethanolamine and ethyl diethanolamine were detected at concentrations as low as 1 ng/mL in serum and 10 ng/mL in urine, and quantified within the range of 1-1000 ng/mL and 10-1000 ng/mL, respectively.A novel kind of magnetic porous carbon nano-fibers (Fe3O4@P-CNFs) materials was successfully prepared and used as an adsorbent. Based on the above-mentioned adsorbent, a simple and effective magnetic disperse solid-phase extraction (MSPE) method was developed and first utilized to the enrichment and purification of five Sudan dyes (including Sudan I, Sudan II, Sudan III, Sudan IV, and Sudan Red 7B) in foodstuffs for the first time. High-performance liquid chromatography was used to determine the content of the Sudan dyes. The parameters affecting the extraction performance were studied and optimized, including the amount of the adsorbent and inorganic salt, type and the volume of the eluent, pH of the sample solution and extraction time. Under the optimized experimental conditions, the results show that the proposed method has a good linear relationship (r≥ 0.9993). The limits of detection range from 0.88 μg L-1 to 1.27 μg L-1. The recoveries range from 86.6% to 99.7% with the relative standard deviations ranging from 0.6% to 7.9% in the methodology validation. The above-mentioned results indicate that the proposed method is a sensitive and reliable procedure with good reproducibility for the detection of Sudan dyes residues in foodstuffs.A twin-column Multicolumn Countercurrent Solvent Gradient Purification (MCSGP) process has been developed for the purification of a therapeutic peptide, glucagon, from a crude synthetic mixture. This semi-continuous process uses two identical columns operating either in interconnected or in batch mode, thus enabling the internal recycle of the portions of the eluting stream which do not comply with purity specifications. Because of this feature, which actually results in the simulated countercurrent movement of the stationary phase with respect to the mobile one, the yield-purity trade-off typical of traditional batch preparative chromatography can be alleviated. Moreover, the purification process can be completely automatized. Aim of this work is to present a simple procedure for the development of the MCSGP process based on a single batch experiment, in the case of a therapeutic peptide of industrial relevance. AZD1208 This allowed to recover roughly 90% of the injected glucagon in a purified pool with a purity of about 90%. A comparison between the performance of the MCSGP process and the classical single column batch process indicates that percentage increase in the recovery of target product is +23% when transferring the method from batch conditions to MCSGP, with an unchanged purity of around 89%. This improvement comes at the expenses of a reduction of about 38% in productivity.The chromatographic performances of four coated and immobilized amylose phenylcarbamate-based chiral columns were evaluated and compared under normal phase (NP) elution conditions by using chiral 4,4'-bipyridine derivatives as analytes. n-Hexane/2-propanol 9010 and n-hexane/2-propanol/methanol 9055 mixtures were employed as mobile phases (MPs), and the effect of adding methanol in the MP on retention and selectivity was considered. The effect of temperature on retention and selectivity was also evaluated, and overall thermodynamic parameters associated with the analyte adsorption onto the CSP surface were derived from van't Hoff plots. Interesting cases of enantiomer elution order (EEO) reversal, which are dependent on the nature of polar modifier, analyte structure, column-type, and temperature, were observed. The impact of substitution pattern and electronic properties of analytes and selectors on the separation behaviour was investigated by correlating chromatographic parameters and molecular properties determined by using density functional theory (DFT) calculations. Both coated and immobilized amylose tris(3,5-dimethylphenylcarbamate) columns allowed for the baseline enantioseparation (2.0 ≤ RS ≤ 4.9) of all 4,4'-bipyridines considered in this study. These results appear particularly useful because both enantiomers of these 4,4'-bipyridine derivatives are currently under investigation as new inhibitors of transthyretin fibrillogenesis, a biochemical phenomenon which is implicated to cause amyloid diseases.Additives are added to polymers in small concentration to achieve desired application properties widely used to tailor the properties. The rapid diversification of their molecular structures, with often only minute differences, necessitates the development of adequate chromatographic techniques. While modified silica so far is the workhorse as stationary phase we have probed the potential of porous graphitic carbon (HypercarbTM) for this purpose. The results show that the multitude of physicochemical interactions between analyte molecules and the graphitic surface enables separations of polyolefin stabilizers with unprecedented selectivity. To support the chromatographic results the adsorption capability of HypercarbTM for selected antioxidants and UV absorbers has been determined by Raman spectroscopy and argon physisorption measurements. The shift of the Graphite-band in the Raman spectra of HypercarbTM upon infusion with additives correlates with the changes in the Adsorption Potential Distributions. The results of argon physisorption measurements go hand in hand with the chronology of desorption of the additives in liquid chromatography experiments. The elution sequence can be explained by van der Waals or London forces, π-π-interactions and electron lone pair donor-acceptor interactions between the graphite surface and analyte functional groups.