Layered double hydroxides: Emerging sorbent materials for analytical extractions

Dedicated to Professor Frantisek Svec on the occasion of his 75th BirthdayThis review summarizes recent developments made in the incorporation of functional materials into organic polymer monoliths, together with new monolithic forms and formats, which enhance their application as supports and stationary phase materials for sample preparation and chromatographic separations. While polymer monoliths are well-known supports for the separation of large molecules, recent developments have been made to improve their features for the separation of small molecules. The selectivity and performance of organic polymer monoliths has been improved by the incorporation of different materials, such as metal-organic frameworks, covalent organic frameworks, or other types of nanostructured materials (carbon nanohorns, nanodiamonds, polyoxometalates, layered double hydroxides, or attapulgite). The surface area of polymer monoliths has been significantly increased by polymer hypercrosslinking, resulting in increased efficiency when applied to the separation of small molecules. In addition, recent exploration of less conventional supports for casting polymer monoliths, including photonic fibres and 3D printed materials, has opened new avenues for the applications of polymer monoliths in the field of separation science. Recent developments made in these topics are covered, focusing on the strategies followed by the authors to prepare the polymer monoliths and the effect of these modifications on the developed analytical applications. K E Y W O R D S3D printing, covalent organic frameworks, hypercrosslinking, metal-organic frameworks, polymer monoliths 1564

Section: Incorporation Of Other Nanostructured Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recent strategies to enhance the performance of polymer monoliths for analytical separations

Maya

Paull

2019

“…The pH influence on extraction recovery was studied in the range between 4 and 12. HNO 3 solution (0.1 M) was used to adjust the pH values in the acidic range (4-6), and the NaOH solution (0.1 M) was used to adjust it in the basic range (8)(9)(10)(11)(12). Figure 3 shows that in acidic medium, the EFs increased when the pH was reduced.…”

Section: Effect Of Phmentioning

confidence: 99%

Determination of haloacetic acids in water using layered double hydroxides as a sorbent in dispersive solid‐phase extraction followed by liquid chromatography with tandem mass spectrometry

Alsharaa

Sajid

Basheer

et al. 2016

Self Cite

In the present study, highly efficient and simple dispersive solid-phase extraction procedure for the determination of haloacetic acids in water samples has been established. Three different types of layered double hydroxides were synthesized and used as a sorbent in dispersive solid-phase extraction. Due to the interesting behavior of layered double hydroxides in an acidic medium (pH˂4), the analyte elution step was not needed; the layered double hydroxides are simply dissolved in acid immediately after extraction to release the analytes which are then directly introduced into a liquid chromatography with tandem mass spectrometry system for analysis. Several dispersive solid-phase extraction parameters were optimized to increase the extraction efficiency of haloacetic acids such as temperature, extraction time and pH. Under optimum conditions, good linearity was achieved over the concentration range of 0.05-100 μg/L with detection limits in the range of 0.006-0.05 μg/L. The relative standard deviations were 0.33-3.64% (n = 6). The proposed method was applied to different water samples collected from a drinking water plant to determine the concentrations of haloacetic acids.

“…Low cost, 2D structure, high surface area, positive charge on the surface, high anion‐exchange capacities, tunable interior architecture, and resistant to changes upon heating are some characteristics that have been reported for layered double hydroxides . Furthermore, due to excellent adsorbing properties of layered double hydroxides such as the large interlayer spaces (which leads to high porosity), huge number of exchangeable anions between the positively charged layers, and water‐resistant structure, layered double hydroxides have been introduced as ideal sorbents for the sorption‐based extraction methodologies .…”

Section: Introductionmentioning

confidence: 99%

“…K E Y W O R D S caffeine, fiber-in-tube, layered double hydroxides, molecular tracers, polyaniline solid-phase microextraction Article Related Abbreviation: SCE, saturated calomel electrode Conflict of interest: The authors have declared no conflict of interest.In recent years, layered double hydroxides with variable chemical composition and structures have been represented as a fascinating group of materials [9]. Layered double hydroxides are 2D nanostructured materials that consist of positively charged layers of metal hydroxides with chargebalancing anions and some water molecules located between the layers [10]. They are denoted by the general formula of [M 2+ 1−x M 3+ x (OH) 2 ] x+ (A n− ) x/n .mH 2 O, where M 2+ and M 3+ are di-and trivalent metal cations and A n− is the interlayer guest ion with n − valence electrons [11].…”

mentioning

confidence: 99%

Fiber‐in‐tube solid‐phase microextraction of caffeine as a molecular tracer in wastewater by electrochemically deposited layered double hydroxide

Lashgari

Yamini

2018

Modified stainless-steel wires with a layer of polyaniline conductive polymer were coated by electrochemical deposition with Zn/Al layered double hydroxide to make solid-phase microextraction fibers. The coating layer was also electrochemically deposited on the inner surface of a stainless-steel tube. Then, ten prepared fibers were put inside the inner coated tube to make a fiber-in-tube solid phase microextraction device. The device was applied for the extraction of caffeine (1,3,7-trimethylxanthine) from domestic wastewater samples. Extraction conditions including extraction and desorption times, pH and ionic strength of the sample solution, and content of the organic desorption solvent were investigated and optimized. Under the optimized conditions, the fiber-in-tube solid phase microextraction exhibited excellent extraction efficiency toward caffeine. The precision of the method was evaluated. Average relative standard deviation of 5.7% (n = 6) for intraday analysis and 8.3% (n = 5) for interday analysis was obtained. The limits of detection and limits of quantification of the method (at signal to noise ratio of 3 and 10) were obtained as 0.14 and 0.37 ng/mL, respectively. The current study can provide new prospective applications of layered double hydroxide conductive polymer fiber coatings.