Journal of Chromatography A最新文献

The unique properties of pillar[5]arene, including hydrophobic cavities, π-π conjugated and easy modification, make it a promising candidate as stationary phase for HPLC. Herein, we fabricated a novel propanediamine modified pillar[5]arene bonded silica as the stationary phase (PDA-BP5S) for reversed-phase liquid chromatography (RPLC). Benefiting from the significant hydrophobicity, π-π conjugative, p-π effect, and hydrogen bonding, the PDA-BP5S packed column showed high separation performance of versatile analytes involving polycyclic aromatic hydrocarbons, alkyl benzenes, phenols, arylamine, phenylethane/styrene/ phenylacetylene, toluene/m-xylene/mesitylene, halobenzenes, benzenediol and nitrophenol isomers. Especially, the separation of halobenzenes appeared to be controlled by both the size of the halogen substituents and the strength of the noncovalent bonding interactions, which was further confirmed by molecular dynamics simulation. The satisfactory separation and repeatability revealed the promising prospects of amine-pillar[5]arene-based stationary phase for RPLC.

In recent years, scientists have started evaluating the portion of PM-bound pollutants that may be liberated (bioaccessible fraction) in human fluids and spread through the digestive system ultimately entering systemic circulation (known as the bioavailable fraction). In the current research, an analytical procedure was validated and applied to characterize the oral bioavailable fraction of PM₁₀ samples. The approach encompassed the determination of 49 organic contaminants. The proposed method aims to biomimetic complete mouth-gastric-intestinal system basing on an adaptation of the unified bioaccessibility method (UBM) modified by the inclusion of a dialysis membrane to mimic intestinal absorption and obtain the orally bioavailable fractions. It was followed by a vortex-assisted liquid-liquid extraction (VALLE) step, using gas chromatography-tandem mass spectrometry (GC-MS/MS). Analytical procedure was effectively validated by employing selected reaction monitoring (SRM) mode in MS/MS, matrix-matched calibration, and deuterium-labelled surrogate standards. This approach ensured heightened sensitivity, minimized matrix effects, and compensated for any losses during the process. The validation process covered various aspects, including studying linearity, determining detection and quantification limits, assessing analytical recoveries at three concentration levels, and evaluating precision both within a single day and across multiple days. The validated method was applied to PM₁₀ samples, revealing that polycyclic aromatic hydrocarbons (PAHs) were the most frequently detected, with significant seasonal variations in their concentrations. Organophosphorus flame retardants (OPFRs) like TCPP were also detected in bioavailable fractions, highlighting their potential health impact. Bisphenols, SMCs, and PAEs were not detected, suggesting low levels in the studied urban area. Further research is needed to understand the bioavailability of PM-bound pollutants in different environments.

Mechanistic models are powerful tools for chromatographic process development and optimization. However, hydrophobic interaction chromatography (HIC) mechanistic models lack an effective and logical parameter estimation method, especially for multi-component system. In this study, a parameter-by-parameter method for multi-component system (called as mPbP-HIC) was derived based on the retention mechanism to estimate the six parameters of the Mollerup isotherm for HIC. The linear parameters (k_s,i and k_eq,i) and nonlinear parameters (n_i and q_max,i) of the isotherm can be estimated by the linear regression (LR) and the linear approximation (LA) steps, respectively. The remaining two parameters (k_p,i and k_kin,i) are obtained by the inverse method (IM). The proposed method was verified with a two-component model system. The results showed that the model could accurately predict the protein elution at a loading of 10 g/L. However, the elution curve fitting was unsatisfactory for high loadings (12 g/L and 14 g/L), which is mainly attributed to the demanding experimental conditions of the LA step and the potential large estimation error of the parameter q_max. Therefore, the inverse method was introduced to further calibrate the parameter q_max, thereby reducing the estimation error and improving the curve fitting. Moreover, the simplified linear approximation (SLA) was proposed by reasonable assumption, which provides the initial guess of q_max without solving any complex matrix and avoids the problem of matrix unsolvable. In the improved mPbP-HIC method, q_max would be initialized by the SLA and finally determined by the inverse method, and this strategy was named as SLA+IM. The experimental validation showed that the improved mPbP-HIC method has a better curve fitting, and the use of SLA+IM reduces the error accumulation effect. In process optimization, the parameters estimated by the improved mPbP-HIC method provided the model with excellent predictive ability and reasonable extrapolation. In conclusion, the SLA+IM strategy makes the improved mPbP-HIC method more rational and can be easily applied to the practical separation of protein mixture, which would accelerate the process development for HIC in downstream of biopharmaceuticals.

As a result of their metabolic processes, medicinal plants produce bioactive molecules with significant implications for human health, used directly for treatment or for pharmaceutical development. Chromatographic fingerprints with solvent gradients authenticate and categorise medicinal plants by capturing chemical diversity. This work focuses on optimising tea sample analysis in HPLC, using a model-based approach without requiring standards. Predicting the gradient profile effects on full signals was the basis to identify optimal separation conditions. Global models characterised retention and bandwidth for 14 peaks in the chromatograms across varied elution conditions, facilitating resolution optimisation of 63 peaks, covering 99.95 % of total peak area. The identified optimal gradient was applied to classify 40 samples representing six tea varieties. Matrices of baseline-corrected signals, elution bands, and band ratios, were evaluated to select the best dataset. Principal Component Analysis (PCA), k-means clustering, and Partial Least Squares-Discriminant Analysis (PLS-DA) assessed classification feasibility. Classification limitations were found reasonable due to tea processing complexities, involving drying and fermentation influenced by environmental conditions.

Polymer monoliths can be polymerised within different molds, but limited options are available for the preparation of free-standing polymer monoliths for analytical sample preparation, and in particular, solid-phase extraction (SPE). Commercial melamine-formaldehyde sponges can be used as supports for the preparation of polymer monoliths, due its flexibility, giving various shapes to monoliths. Herein, the crosslinker/porogen ratio of highly porous sponge-nested divinylbenzene (DVB) polymer monoliths has been evaluated. Monoliths prepared using different crosslinker/porogen ratios were applied to the extraction of bisphenol F, bisphenol A, bisphenol AF, and bisphenol B. Monoliths containing 50 wt % DVB and 50 wt % porogens presented the highest recovery of bisphenols. Under the optimised conditions, the developed method showed a linear range between 2.5 µg L^-1 and 150 µg L^-1 for BPA and BPAF, and between 5 µg L^-1 and 150 µg L^-1 for BPB and BPF. The limits of detection (LOD, S/N = 3) and limits of quantification (LOQ, S/N = 10) ranged from 0.36 µg L^-1 to 1.09 µg L^-1, and from 1.20 µg L^-1 to 3.65 µg L^-1, respectively. The recoveries for spiked bisphenols (10 µg L^-1) in tap water and water contained in a polycarbonate containers were between 82 % and 114 %.

An extraction chromatography resin, prepared by the impregnation of bis-octyloxy-calix[4]arene-mono-crown-6 (BOCMC)onto an acrylic ester based polymeric support material, gave excellent uptake data for the removal of radio-cesium (Cs-137) from nitric acid feed solutions. The weight distribution coefficient (K_d) value of >300 obtained during the present study at 3 M HNO₃ was the highest reported so far while using a calix-crown-6 based extraction chromatographic resin material. Analogous resin reported previously has yielded a K_d value <100 at comparable feed conditions. The sorbed metal ions could be efficiently desorbed with de-ionized water. Kinetic modeling of the uptake data indicated that both the film and the intra-particle diffusion mechanism are simultaneously operating in the sorption of Cs⁺ion onto the BOCMC resin. The metal ion sorption data were fitted to the sorption isotherm models and did not conform to the chemisorptions of physisorption models and indicated a pi-pi interaction between the benzene rings of the calix-crown-6 ligand and the Cs⁺ ion. The reusability of the resins was quite satisfactory after 5 cycles and the radiation stability of the resin material was very good upto an absorbed dose of 500 kGy. The results of column studies were quite encouraging with 15 mL (9 bed volumes) as the breakthrough volume while the elution was complete in about 12 bed volumes of de-ionized water.