Xueqiao Xie

Extraction mechanism of sulfamethoxazole in water samples using aqueous two-phase systems of poly(propylene glycol) and salt.

Based on the poly(propylene glycol)(400) (PPG(400))-salt aqueous two-phase system (ATPS), a green, economical and effective sample pretreatment technique coupled with high performance liquid chromatography was proposed for the separation and determination of sulfamethoxazole (SMX). The extraction yield of SMX in PPG(400)-salt ATPS is influenced by various factors, including the salt species, the amount of salt, pH, and the temperature. Under the optimum conditions, most of SMX was partitioning into the polymer-rich phase with the average extraction efficiency of 99.2%, which may be attributed to the hydrophobic interaction and salting-out effect. This extraction technique has been successfully applied to the analysis of SMX in real water samples with the recoveries of 96.0-100.6%, the detection limits of 0.1 μg L(-1), and the linear ranges of 2.5-250.0 μg L(-1).

Extraction of trace acetylspiramycin in real aqueous environments using aqueous two-phase system of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate and phosphate

The partitioning of acetylspiramycin was carried out in an aqueous two-phase system (ATPS) formed by a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoraborate, [Bmim]BF4) and NaH2PO4. This ATPS is a simple, non-toxic and effective sample pretreatment technique, which was developed for the simultaneous separation, enrichment and rapid analysis of acetylspiramycin coupled with molecular fluorescence spectrophotometry. Analysis of the liquid-liquid equilibrium of [Bmim]BF4-salt ATPS demonstrated that the salting-out ability of different salts may be related to the Gibbs energy of hydration of the ions. The effects of types of salts, concentration of NaH2PO4, and temperature were analysed. Under optimum conditions, the average extraction efficiency and partition coefficient were 90.14% and 91.1, respectively. Thermodynamic functions provide some information about the molecular mechanism involved in acetylspiramycin transfer to the top phase, suggesting an important acetylspiramycin-[Bmim]BF4 interaction. The method yielded a linear range in the concentration from 1.0 to 10.0 µg mL−1 of acetylspiramycin, and the limit of detection was 0.02 µg mL−1. This method could be successfully applied for the analysis of acetylspiramycin in lake water, river water and groundwater. The proposed extraction technique appears to be suitable as a first step for the separation of macrolide antibiotics from real aqueous environments.

Cloud point behavior of thermosensitive triblock copolymer L61 in the presence of electrolytes

ABSTRACT Herein the effect of additives on the cloud point of thermosensitive copolymer Poly (ethylene oxide)–Poly (propylene oxide)–Poly (ethylene oxide) (PEO–PPO–PEO, L61) was investigated, including NaCl, NaOH, NaBr, Na2CO3, Na3PO4, Na2SO4, Na2HPO4, ZnSO4, FeSO4 and MnSO4 at different concentrations. It was found that the cloud point of L61 was lowered by adding the electrolytes and decreased linearly with increasing electrolytes concentration. In these systems, the addition of polyvalent anions resulted in a more pronounced salting-out effect than monovalent anions. A depression in the cloud point of L61 in the presence of multivalent electrolytes was observed in a trend of > >Cl−. Meanwhile, the ability of divalent anion lower cloud point evaluated by Gibbs free energy was appropriated, and the order as follows: > > . The capacity of divalent cation to reduce the cloud point followed the order Zn2+>Fe2+>Mn2+. GRAPHICAL ABSTRACT

A simple method for purification of bromelain in a thermosensitive triblock copolymer-based protection system and recycling of phase components

ABSTRACT In the work, we chose stem bromelain as a model to investigate the storage and purification of bromelain from pineapple peel. Extraction of bromelain from pineapple peel using a two-stage aqueous two-phase extraction system composed of a thermoseparating copolymer EOPOEO and K2HPO4. Bromelain predominantly partitioned to the EOPOEO-rich phase and then re-extract to the top dilute phase. The recovery of enzyme activity (68.6%) and purification factor (6.53) were determined under optimum conditions. The EOPOEO-rich phase and salt were recycled, and the recovery of enzyme activity could reach up to 60%. This method has been proved to obtain highly purified and stable bromelain.