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Diffusion coefficients derived from the equation were in a range of 10-13 to 10-10 cm2/s and were dependent on the type of additive and solution.The description of the profiles of chromatographic peaks has been studied extensively, with a large number of proposed mathematical functions. Among them, the accuracy achieved with modified Gaussian models that describe the deviation of an ideal Gaussian peak as a change in the peak variance or standard deviation over time, has been highlighted. These models are, in fact, a family of functions of different complexity with great flexibility to adjust chromatographic peaks over a wide range of asymmetries and shapes. However, an uncontrolled behaviour of the signal may occur outside the region being fitted, forcing the use of different strategies to overcome this problem. In this work, the performance of the LMG (Linear Modified Gaussian), PVMG (Parabolic Variance Modified Gaussian), and PLMG (Parabolic-Lorentzian Modified Gaussian) models is compared with variants obtained by combination of the modified Gaussian models with an equation that adds an exponential tail and with other functions that limit the growth of the independent variable. The behaviour of the approaches is checked through the simultaneous fitting of enantiomeric peaks showing a wide range of characteristics, obtained in the separation of drugs with chiral activity by liquid chromatography using enantioselective columns. The study is also carried out with the purpose of performing the deconvolution of the peaks of the enantiomers, when these are not completely resolved, in order to evaluate the enantiomeric fraction.Trapping multiple dual mode (trapping MDM) is a preparative liquid-liquid chromatography (LLC) technique well-suited to difficult separations of intermediately-eluting components from similarly structured impurities. In this demonstrative study, a design approach for high process throughput is applied for the trapping MDM separation of a target component, nootkatone (NK), initially comprising 16.7% of an industrial side stream mixture with over 90 impurities. This design approach, previously developed and validated using ternary mixtures of model solutes, is applied to a complex real mixture for the first time. The approach consists of five steps (1) determination of the maximum starting mixture concentration for feed preparation; (2) determination of the maximum flow rate for maintenance of the pre-set stationary phase fraction; (3) determination of the partition coefficients of the target and main impurities; (4) selection of step durations and number of cycles using an established short-cut method; (5) execution of the trapping MDM separation. The target, NK, was obtained along with a co-eluting component at 78.7% purity and 84.6% yield, demonstrating the effectiveness of trapping MDM for the separation of intermediately-eluting natural product target components from complex starting mixtures.Per- and polyfluoroalkyl substances (PFASs) are ubiquitous in the environment. However, only a limited number of predominantly persistent perfluoroalkyl acids (PFAAs) have been analyzed in edible plants so far. We present a generic trace analytical method that allows for quantification of 16 intermediate fluorotelomer alcohol (FTOH)- or perfluoroalkane sulfonamidoethanol (FASE)-based transformation products as well as 18 PFAAs in plants. Additionally, 36 suspected intermediate PFAS transformation products were qualitatively analyzed. The ultrasound-assisted solid-liquid extraction of wheat and maize grain, maize leaves, Jerusalem artichoke and ryegrass (1-5 g plant sample intake) was followed by a clean-up with dispersive solid-phase extraction using graphitized carbon adsorbent (5-10 mg per sample) and chemical analysis by reversed phase liquid chromatography-tandem mass spectrometry. The method was based on matrix matched and extracted calibration and displayed good precision with relative standard deviatio(PFOS) and perfluorodecanoic acid (PFDA) were frequently detected. For perfluoroalkyl carboxylic acids (PFCAs), according to earlier findings, short chain homologues generally displayed the highest levels (up to 98 µg/kg for perfluorobutanoic acid (PFBA) in maize leaves). However, maize grain was an exception showing the highest concentrations for long chain PFCAs, whereas PFBA was not detected. The uptake of high levels of PFASs into plants is of concern since these may be used as animal feed or represent a direct exposure medium for humans.In sample pre-treatment, millifluidic electromembrane platforms have been developed to extract and pre-concentrate target molecules with good clean-up that minimize matrix effects. Optimal operation conditions are normally determined experimentally, repeating the extractions at different conditions and determining the efficiencies by an analytical technique. JTZ-951 research buy To shorten and simplify the optimization protocol, millifluidic platforms have been electrically characterized by impedance spectroscopy. The magnitude of the resistance of the electromembrane has been found very predictive of the migration capacity and extraction efficiency of three different parabens on real time. The optimal conditions (4 V of applied potential) (Electromembrane extraction low voltage) have been successfully applied in the extraction of parabens from urine samples, that not only improves the extraction efficiency (100% for all compounds) but also provides a very low current intensity (7 µA), which is very important in electromembrane to minimize electrolysis phenomena. The possibility to optimize one of the most critical and important parameters such as the voltage with a simple electrical model may accelerate the production of application-specific millifluidic electromembrane platforms in a short development time. The results showed that millifluidic electromembrane extraction based low voltage has a future potential as a simple, selective, and time-efficient sample preparation technique allowing a simple battery as power supply.Fluorous affinity means remarkably specific interaction between highly organic fluorides. This work aims to explore the potential of fluoro-functionalized stationary phase for the separation of organic fluorides by means of fluorous-fluorous interaction. Here, by using the Michael addition strategy between 1H,1H,2H,2H-perfluorodecanethiol (PFDT) and polydopamine (PD), a novel fluoro-functionalized stationary phase was synthesized for open-tubular capillary electrochromatography (OT-CEC). The PFDT@PD was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray Photoelectron Spectrometer (XPS). The PFDT@PD@capillary exhibited outstanding separation performance towards neutral compounds (such as alkylbenzenes and chlorobenzenes) and organic fluorides (such as fluorobenzenes and perfluoroalkyl methacrylates etc.) with high resolution and high separation efficiency by hydrophobic interaction and fluorous-fluorous interaction. In addition, the column shows good stability and reproducibility.