Combination of atom transfer radical polymerization and alkyne-azide click-chemistry for the synthesis of phosphonic acid cation exchange materials

Phosphonic acid cation exchange materials (PCX) are synthesized by atom transfer radical polymerization (ATRP) followed by alkyne-azide click-chemistry. ATRP is used to synthesize polymeric chains of diethyl 4-vinylbenzylphosphonate with different chain lengths, which are covalently bonded to the surface of monodisperse polystyrene-divinylbenzene (PS/DVB) particles by click-chemistry. The functionalized particles are characterized by FIB-SEM, IR and Schoeniger combustion followed by chromatographic experiments. The effect of chain length on chromatographic behavior is investigated by comparing four PCX columns with different chain lengths. Polar ionic pesticides and non-polar triazines are used as model analytes for chromatographic characterization. The chain length showed an influence on the retention of doubly charged analytes, which can be explained by the increased local charge density with longer chains. The resolution of the constitutional isomers prometryn and terbutryn increased with the chain length, leading to an isocratic separation of seven triazines in 35 min. They also showed secondary interactions with the polymeric support material that are not influenced by capacity or chain length.

Magnetic graphene oxide carbon dot nanocomposites as an efficient quantification tool against parabens in water and cosmetic samples

A new method is developed for the simultaneous detection and extraction of parabens, including methyl paraben (MP), ethyl paraben (EP), propyl paraben (PP), and butyl paraben (BP), based on magnetic graphene oxide carbon dot nanocomposites (Fe3O4@GO@CD). Fe3O4@GO@CD has been synthesized using one pot hydrothermal method by intercalating iron oxide and carbon dots between the layers of graphene oxide. Fe3O4@GO@CD was applied as the magnetic solid phase sorbent for the simultaneous extraction and detection of parabens from water (tap and river water) and cosmetic samples (hair serum and sunscreen cream). MP was measured at concentration of 0.25-0.26 ng/mL in hair serum, while PP at 0.32-0.33 ng/mL in sunscreen cream. Notably, good recoveries (88.74-98.03%; RSD = 2.31-6.88%) for river and tap water with detection limit of 0.039-0.046 ng/mL were attained. The method has good cyclability up to 16 cycles and was highly repeatable. All these findings suggest that the Fe3O4@GO@CD would be potential sorbent for the analysis of parabens.

Determination of Budesonide and Sulfasalazine in Water and Wastewater Samples Using DLLME-SFO-HPLC-UV Method

Dispersive liquid–liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) was applied to isolate budesonide (BUD) and sulfasalazine (SULF) from aqueous samples. The effects of different parameters on the efficiency on the extraction such as type of extrahent and dispersive solvent, ionic strength, pH of sample, and centrifugation time were investigated. Moreover, the influence of foreign substances on a studied process was tested. The calibration curves were recorded. The linearity ranges for BUD and SULF were 0.022–8.611 µg mL−1 and 0.020–7.968 µg mL−1 with the limit of detection (LOD) 0.011 µg mL−1 and 0.012 µg mL−1, respectively. The enrichment factors (EF) for two analytes were high: for BUD it was 145.7 and for SULF, 119.5. The elaborated procedure was applied for HPLC-UV determination of these analytes in water and wastewater samples.

Automated dispersive liquid-liquid microextraction based on the solidification of the organic phase

In this work, the dispersive liquid-liquid microextraction technique based on the solidification of the organic phase (DLLME-SFO) has been automated for the first time. DLLME-SFO is automated by hyphenating a sequential injection analysis (SIA) system with a custom-made robotic phase separator. Automated in-syringe DLLME is followed by phase separation in a 3D printed device integrating a Peltier cell set, mounted on a multi-axis robotic arm. The combined action of the flow system and the robotic arm is controlled by a single software package, enabling the solidification/melting and collection of the organic phase for further analyte quantification. As proof-of-concept, automated DLLME-SFO was applied to the extraction of parabens followed by separation using liquid chromatography, obtaining LODs between 0.3 and 1.3 µg L^-1 (4 mL of sample extracted in 1 mL of 1-dodecanol: MeOH, 15:85, v-v). The method showed a high reproducibility, obtaining intraday RSDs between 4.6% and 5.8% (n = 6), and interday RSDs between 5.6% and 8.6% (n = 6). The developed method was evaluated for the determination of parabens in water, urine, saliva, and personal care products.

Development of an eco-friendly approach based on dispersive liquid–liquid microextraction for the quantitative determination of quercetin inNasturtium officinale,Apium graveolens,Spinacia oleracea,Brassica oleracea var. sabellica, and food samples

A fast, sensitive, inexpensive and environment-friendly dispersive liquid–liquid microextraction technique was developed based on solidification of floating organic drops.