Automated and semi-automated packed sorbent solid phase (micro) extraction methods for extraction of organic and inorganic pollutants

Advancements in effervescent-assisted dispersive micro-solid phase extraction for the analysis of emerging pollutants

Emerging pollutants pose an increasing threat to the environment and human well-being, requiring substantial progress in analytical methodologies. Dispersive micro-solid phase extraction (μ-dSPE) has proven successful in detecting and measuring these contaminants, particularly in trace quantities. However, challenges persist in achieving a uniform sorbent distribution and efficient separation from the sample matrix. To address these issues, effervescent-assisted dispersive micro-solid phase extraction (EA-μ-dSPE) was developed. This method uses on-site produced carbon dioxide as a dispersing agent, eliminating the need for vortexing or ultrasonication. Due to the sorbent dispersion in the sample solution, the contact surface between the analyte and the sorbent increases, resulting in increased extraction efficiency, reduced extraction time, and promotes of sustainability. Several parameters are critical to the successful execution of this procedure to extract the analytes, including the type and structure of sorbent, composition of dispersing agents, sorbent separation procedure, and type and properties of desorption solvents. The sorbent plays a critical role in successful extraction of emerging pollutants. It is clear that for the extraction of the analyte on the sorbent, proper interaction must be established between the analyte and the sorbent via physical and chemical interactions. This review thoroughly evaluates the underlying principles of the approach, its potential, and the significant advancements that have been documented. It explores the method's capacity to analyse and identify emerging pollutants, emphasising its potential across various sample matrices for enhanced pollutant identification and quantification.

Lab-made automated parallel-dispersive pipette extraction device for the determination of polycyclic aromatic hydrocarbons in distilled beverages (sugarcane spirits) using HPLC-DAD

This work describes the development of a new automated parallel dispersive tip microextraction method (Au-Pa-DPX) for the determination of eleven polycyclic aromatic hydrocarbons (PAHs) in four samples of Brazilian sugarcane spirit beverages, with separation and detection done by the HPLC-DAD. The results obtained with the Au-Pa-DPX approach were also compared with those obtained via the conventional parallel manual DPX method with the same samples and optimized extraction process. Desorption solvent and cycles of desorption, cleaning and extraction were optimized using response surface methodology and univariate approaches. For the Au-Pa-DPX method, the coefficient of determination (R2) ranged from 0.9948 to 0.9997. The limits of detection and quantification were all 0.303 μg l-1 and 1.00 μg l-1, respectively. Interday and intraday precision ranged from 7.6 % to 31.7 % and 0.40 % to 15.8 %, respectively. For the manual parallel DPX method, the interday and intraday precision ranged from 8.2 % to 38.1 % and 5.40 % to 18.7 %, respectively. The relative recovery values obtained with the proposed method ranged from 53.29 to 124.94 %. The enrichment factors ranged from 15.13 to 22.35. The sum of PAH concentrations in the four samples ranged from undetected to 25.58 μg l-1. These results, when correlated to other methods, highlight the gains in regards to precision obtained with the automated apparatus. Furthermore, when compared to other methods from the literature, it is an interesting green alternative for the determination of these analytes and this sample, with high throughput (4.67 min per sample), low consumption of solvents and samples, generating less waste and reducing health risks to the analyst.

A novel block copolymer containing gadolinium oxide nanoparticles in ultrasound assisted-dispersive solid phase microextraction of total arsenic in human foodstuffs: A multivariate optimization methodology

A new poly(3-hydroxy butyrate)-b-poly(dimethyl amino ethyl methacrylate) amphiphilic block copolymer containing gadolinium oxide nanoparticles (PHB-PDMAEMA-Gd2O3-NPs) were synthesized and used as composite adsorbent for extraction of total arsenic. Characterization of the composite adsorbent material PHB-PDMAEMA-Gd2O3-NP was studied using spectroscopic techniques. Plackett-Burman design and central composite design were employed to screening and optimization of the experimental parameters. This composite adsorbent was utilized in ultrasound assisted-dispersive solid phase microextraction (UA-dSPµE) for the determination of total inorganic arsenic in foodstuffs through hydride generation atomic absorption spectrometry (HG-AAS). It demonstrates a linear relationship across arsenic concentration range of 0.07-1.12 µg/L with a correlation coefficient (0.996). It's showed an enrichment factor of 128 and a limit of detection 0.02 µg/L for total inorganic arsenic determination. Accuracy of the developed method was confirmed through the analysis of certified reference materials with 96.0-98.5% recovery. It proved to be significantly useful UA-dSPµE method for determining total inorganic arsenic in different foodstuffs.

High-Throughput Capillary Liquid Chromatography Using a Droplet Injection and Application to Reaction Screening

The cycle time of a standard liquid chromatography (LC) system is the sum of the time for the chromatographic run and the autosampler injection sequence. Although LC separation times in the 1-10 s range have been demonstrated, injection sequences are commonly >15 s, limiting throughput possible with LC separations. Further, such separations are performed on relatively large bore columns requiring flow rates of ≥5 mL/min, thus generating large volumes of mobile phase waste when used for large scale screening and increasing the difficulty in interfacing to mass spectrometry. Here, a droplet injector system was established that replaces the autosampler with a four-port, two-position valve equipped with a 20 nL internal loop interfaced to a syringe pump and a three-axis positioner to withdraw sample droplets from a well plate. In the system, sample and immiscible fluid are pulled alternately from a well plate into a capillary and then through the injection valve. The valve is actuated when sample fills the loop to allow sequential injection of samples at high throughput. Capillary LC columns with 300 μm inner diameter were used to reduce the consumption of mobile phase and sample. The system achieved 96 separations of 20 nL droplet samples containing 3 components in as little as 8.1 min with 5-s cycle time. This system was coupled to a mass spectrometer through an electrospray ionization source for high-throughput chemical reaction screening.

Designing of a cellulose-based ion-imprinted biosorbent for selective removal of lead (II) from aqueous solutions

Developing an effective adsorbent for Pb2+ removal from wastewater has huge economic and environmental implications. Adsorbents made from cellulosic materials that have been modified with certain chelators could be used to get rid of metal cations from aqueous solutions. However, their selectivity for specific metals remains very low. Here, we describe the synthesis of 4-(2-pyridyl)thiosemicarbazide (PTC) hydrazidine-functionalized cellulose (Pb-PTC-CE), a polymer imprinted with Pb2+ ions that may be used to remove Pb2+ ions from wastewater. Owing to its potent -NH2 functionalization, PTC hydrazidine not only served as an efficient chelator to effectively supply coordinating sites and construct hierarchical porous structures on Pb-PTC-CE, but it also made it possible for cross-linking to occur through the glyoxal cross-linker. The abundant chelators, along with the hierarchical porous construction of the developed Pb-PTC-CE with PTC functionality, result in a greater sorption capacity of 336 mg/g and a short sorption period of 40 min for Pb2+. Additionally, Pb-PTC-CE exhibits highly selective Pb2+ uptake compared to competing ions. This study proposes a feasible methodology for the development of high-quality materials for Pb2+ remediation by combining the advantages of active ligand functionality with ion-imprinting techniques in a straightforward way.