Ion-pair Extraction Research Articles

Electrochemical and Spectroscopic Analyses for Extracted Rh(III) Complex in Phosphonium-Based Ionic Liquids

In this study, the phosphonium-based ionic liquids (IL) have been investigated for the extraction of Rh(III). The ion-pair extraction of Rh(III) was confirmed by slope analysis with the concentration dependence of the phosphonium cation. On the other hand, the IL-Rh(III) complex was identified by means of UV-Vis-NIR and Raman spectroscopic analyses. According to the spectroscopic analysis, the extracted IL-Rh(III) complex found to be present in IL medium and the [NTf2]- anion is not coordinated at the first coordination sphere. In addition, the electrochemical analysis revealed that the extracted Rh(III) can be reduced to Rh(0) by a single step. The diffusion coefficient of the extracted Rh(III) was also evaluated from the semi-differential analysis. Furthermore, the electrodeposits can be recovered from continuous solvent extraction and electrodeposition process. Consequently, SEM/EDX, XPS and XRD identified the electrodeposits as predominantly Rh metal.

Recovery of Rhodium by Solvent Extraction using N, N, N′, N′, N″, N″-Hexahexyl-nitrilotriacetamide and Electrodeposition

The development of solvent extraction and direct electrodeposition processes is crucial for reducing the volume of secondary waste. In this study, the extraction behavior of Rh(III) using N, N, N, N′, N′, N′-hexahexyl nitrilotriacetamide (NTAamide(C6)) was investigated with three different diluents that have relatively high dielectric constants. Slope analysis revealed that the extraction mechanism of Rh(III) is based on ion-pair extraction. The electrochemical behavior of the extracted Rh(III) complexes in each diluent was investigated using cyclic voltammetry. Rh(III) was reduced to Rh(0) through a three-electron transfer in the NTAamide(C6)/acetophenone, 1,2-dichloroethane, and 1-octanol systems. Moreover, the diffusion coefficient of the extracted Rh(III) complex was evaluated using semi-differential analysis. The electrodeposits were recovered through continuous solvent extraction and direct electrodeposition. The electrodeposits were identified as Rh metals by X-ray photoelectron spectroscopy and X-ray diffraction analyses.

Diphosphonic ionic liquids as anion-exchangers for palladium(II) and platinum(IV): Synthesis, complexation and selective extraction from hydrochloric solutions

The demand for platinum group metals (PGMs) continues to grow. To reduce the negative environmental impact, it is necessary to switch to secondary sources of PGMs and to improve the separation and purification processes of these metals. In this work, new phosphonium-based ionic liquids (diphosphonium salts) were synthesized as extractants for the selective recovery of palladium(II) and platinum(IV) from hydrochloric acid solutions. Substances synthesized contain a doubly-charged cation, which significantly affects the selectivity of extraction compared to singly charged phosphonium extractants. It was found that diphosphonium salts have a high extraction efficiency of metallic ions that form stable doubly-charged chloride anionic complexes. Thus, solutions of synthesized ionic liquids in 3-nitrobenzotrifluoride can selectively extract palladium(II) and platinum(IV) in the presence of all d‐metal ions studied, which are contained in PGMs secondary sources. The extraction efficiency under optimal conditions is 99.6 % and 98.5 % for palladium(II) and platinum(IV), respectively. The extraction mechanism has been investigated by X-ray diffraction, DFT calculations and 31P, 111Cd NMR spectroscopy. Extraction proceeds through the anion-exchange mechanism, however, in the case of the studied compounds, the significant role of bromide as a counterion of ligands was shown. It was found that bromide is likely included in the extracted ion pair, displacing chloride ions from anionic metal complexes during extraction.

Preliminary studies on ion-pair extractions of Zr, Hf, Nb, and Ta using extractants having tertiary N atom from H2SO4 and HF

Abstract Ion-pair extraction enables the recovery of anionic metal ions, such as pertechnetate and chlorinated rhodium ions, by protonated extractants with tertiary amino N atom in their structures. We expand this technique for other anionic species dissolved in different mineral acids. Extractions of Zr, Hf, Nb, and Ta, metal anions present in sulfuric and hydrofluoric acids (H2SO4 and HF), are examined. Zr and Hf in H2SO4, and Zr, Hf, Nb, and Ta in HF can be extracted by ion-pair extraction using NTAamide (nitrilotriacetamide), methylimino-N, N’-dioctylacetamide (MIDOA), and trioctylamine (TOA). Basic information about their extraction behavior was obtained through this study.

Liquid-liquid extraction equilibrium study of vanadium(V) from nitrate medium by technical grade D2EHPA dissolved in kerosene

The extraction behaviour of vanadium (V) from nitric acid solutions was studied using technical grade D2EHPA in kerosene as an extractant. The effects of aqueous pH, the concentration of vanadium (V) and nitrate ion in the aqueous phase, and the concentration of D2EHPA in the organic phase were investigated. The extraction equilibration time was 30 min. Metal ion dependencies appeared non-ideal due to the non-constancy of the aqueous phase acidity and the equilibrium extractant concentration. Two types of extraction mechanisms originated from the study of pH dependency. The study conceded that the extraction of vanadium (V) occurred via ion exchange or chelation type of extraction when the pH(eq) <2.50. On the other hand, the solvated ion-pair extraction mechanism occurs when the pH(eq) was above 2.50. The extractant dependencies showed that vanadium (V) species were extracted by one molecule of D2EHPA. The salting-out effect was observed from the effect of nitrate ion concentration. The effect of various types of diluents on vanadium (V) extraction with technical grade D2EHPA was studied; kerosene appeared to be a suitable diluent. The temperature dependence data revealed that the system was exothermic with the ΔH value of -12.34 kJ/mol. The loading capacity was 6.11 g vanadium (V) per 100 g extractant. The H2SO4 (0.5 mol/L) was the right stripping agent for the extracted species.

Ion pair sites for efficient electrochemical extraction of uranium in real nuclear wastewater

Electrochemical uranium extraction from nuclear wastewater represents an emerging strategy for recycling uranium resources. However, in nuclear fuel production which generates the majority of uranium-containing nuclear wastewater, fluoride ion (F−) co-exists with uranyl (UO22+), resulting in the complex species of UO2Fx and thus decreasing extraction efficiency. Herein, we construct Tiδ+-PO43− ion pair extraction sites in Ti(OH)PO4 for efficient electrochemical uranium extraction in wastewater from nuclear fuel production. These sites selectively bind with UO2Fx through the combined Ti-F and multiple O-U-O bonds. In the uranium extraction, the uranium species undergo a crystalline transition from U3O7 to K3UO2F5. In real nuclear wastewater, the uranium is electrochemically extracted with a high efficiency of 99.6% and finally purified as uranium oxide powder, corresponding to an extraction capacity of 6829 mg g−1 without saturation. This work paves an efficient way for electrochemical uranium recycling in real wastewater of nuclear production.

A simple and green ion-pairing extraction colorimetric determination of chlorhexidine employing coconut oil as a natural solvent with image processing

A cost-effective, simple, and green determination of chlorhexidine is proposed. A commonly available bromothymol blue serves as a reagent. The ion-pairing of chlorhexidine and bromothymol blue in an aqueous solution can be extracted into an organic phase of coconut oil, which is proposed as an alternative natural green solvent, replacing the conventional toxic organic solvents. An investigation of the chlorhexidine-bromothymol blue ion pair was made spectrophotometrically and via image processing using a smartphone camera. Downscaling is operated for the extraction of 500 μL of an aqueous mixture containing chlorhexidine and bromothymol blue in phosphate buffer (pH 7.5, 5 mmol/L) with 500 μL of coconut oil for 3 min by hand-shaking. A set of 12 extraction tubes can be operated in one run. After phase separation by centrifuging (3000 rpm, 3 min), the 12 tubes are photographed in one shot using a smartphone. Images of both aqueous and organic phases are evaluated for red-green-blue (RGB) color intensity system. Linearity equations: R intensity = 1.205 [Chlorhexidine] – 23.6 (r2: 0.9795), and ΔB intensity = 1.525 [Chlorhexidine] – 36.75 (r2: 0.9907), are obtained for aqueous and organic phases, respectively. The limits of detection (LOD) and quantitation (LOQ) were 12 and 40 mg/L for aqueous, while 11 and 34 mg/L for organic phases, respectively. The proposed procedure was applied to real samples of active pharmaceutical ingredients (API), disinfectant cleaner, and mouthwash. The results obtained by the proposed procedure agree with the high-performance liquid chromatography (HPLC) reference method that utilizes a UV detector. In evaluations using the green analytical procedure index (GAPI) and analytical greenness (AGREE), the proposed procedure was found to be the greenest compared to the conventional spectrophotometric method and HPLC. The proposed procedure involved the UN-SDGs #3, #4, and #12 and scored the highest value of the need, quality, and sustainability (NQS) index. The proposed procedure encourages sustainable chemistry and pharmacy.

Ammonium halide selective ion pair recognition and extraction with a chalcogen bonding heteroditopic receptor.

The first example of a heteroditopic receptor capable of cooperative recognition and extraction of ammonium salt (NH4X) ion-pairs is described. Consisting of a bidentate 3,5-bis-tellurotriazole chalcogen bond donor binding cleft, the appendage of benzo-15-crown-5 (B15C5) substituents to the tellurium centres facilitates binding of the ammonium cation via a co-facial bis-B15C5 sandwich complex, which serves to switch on chalcogen bonding-mediated anion binding potency. Extensive quantitative ion-pair recognition 1H NMR titration studies in CD3CN/CDCl3 (1 : 1, v/v) solvent media reveal impressive ion-pair binding affinities towards a variety of ammonium halide, nitrate and thiocyanate salts, with the heteroditopic receptor displaying notable ammonium halide salt selectivity. The prodigious solution phase NH4X recognition also translates to efficient solid-liquid and liquid-liquid extraction capabilities.

Ion-pairing extraction and their reaction modeling of anionic M-Cl species with cationic NTAamide(C6) extractant and comparison with density functional theory calculations

Solvent extraction is conducted using a total of 20 di-, tri-, and tetravalent metals, revealing high stability constants with Cl− and the N,N,N′,N′,N″,N″-hexahexyl-nitrilotriacetamide (NTAamide(C6)) extractant. The metals used here may behave as anions at high Cl− concentrations, and NTAamide(C6), which contains a tertiary N atom, is protonated under acidic conditions. Most of the metal ions in this study display higher distribution ratios (D(M)) from HCl than those from HNO3, although NO3− hardly forms metal-complexes, and exhibit 1:1 stoichiometries with NTAamide, based on the slopes of acid and metal extraction. The high D(M) may be due to ion-pair extraction based on the combination of cationic extractants and anionic metal-chloride ions. Following the experimental results, the association constants and distribution coefficients of the group 12 elements are calculated via ion-pair extraction modeling using density functional theory calculations, and the simulations of D yield calculated values with the same trend as that of the measured values. In the future, it will be possible to calculate the distribution ratio precisely by considering the size effect in the exosphere of metal and chloride ions and the HSAB rule.

Extraction of Rh(III) from hydrochloric acid by protonated NTAamide(C6) and analogous compounds and understanding of extraction equilibria by using UV spectroscopy and DFT calculations.

Extraction of Rh from hydrochloric acid is conducted using NTAamide(C6) (N,N,N´,N´,N´´,N´´-hexahexyl-nitrilotriacetamide) and other related compounds. We use the ion-pair extraction of anionic species of Rh-chloride and protonated extractant. Rh ions exist as Rh(Cl)n(H2O)6-n (n ≤ 5) and the tertiary nitrogen atom in an extractant are protonated to produce a quaternary amine in acidic condition. The D(Rh) values are changeable because the Rh-Cl-H2O complex forms from + 3 to - 2 valency. Rh-chloride ion with a peak of spectrum at 504nm can be extracted effectively, where RhCl4(H2O)- and RhCl5(H2O)2- exist from Density functional theory calculation and UV spectrum. The maximum distribution ratio (D) of Rh(III) is 16, and 85mM Rh can be extracted from 1M HCl dissolving 96mM, due to less third phase formation. Approximate 80% of Rh can be stripped by the water-soluble reagents having the activities of neutralization and solvation. The figure for the Graphical Index saved in the JPEG, PNG or TIFF format at 300 dpi should be pasted with the size adjusted to the frame below (5 cm long and 8 cm wide).

Characterization of the natural peptidome of four leeches by integrated proteogenomics and pseudotargeted peptidomics

Animal-derived drugs are an indispensable part of folk medicine worldwide. However, their chemical constituents are poorly approached, which leads to the low level of the quality standard system of animal-derived drugs and further causes a chaotic market. Natural peptides are ubiquitous throughout the organism, especially in animal-derived drugs. Thus, in this study, we used multi-source leeches, including Hirudo nipponica (HN), Whitmania pigra (WP), Whitmania acranulata (WA), and Poecilobdella manillensis (PM), as a model. A strategy integrating proteogenomics and novel pseudotargeted peptidomics was developed to characterize the natural peptide phenotype and screen for signature peptides of four leech species. First, natural peptides were sequenced against an in-house annotated protein database of closely related species constructed from RNA-seq data from the Sequence Read Archive (SRA) website, which is an open-sourced public archive resource. Second, a novel pseudotargeted peptidomics integrating peptide ion pair extraction and retention time transfer was established to achieve high coverage and quantitative accuracy of the natural peptides and to screen for signature peptides for species authentication. In all, 2323 natural peptides were identified from four leech species whose databases were poorly annotated. The strategy was shown to significantly improve peptide identification. In addition, 36 of 167 differential peptides screened by pseudotargeted proteomics were identified, and about one-third of them came from the leucine-rich repeat domain (LRR) proteins, which are widely distributed in organisms. Furthermore, six signature peptides were screened with good specificity and stability, and four of them were validated by synthetic standards. Finally, a dynamic multiple reaction monitoring (dMRM) method based on these signature peptides was established and revealed that one-half of the commercial samples and all of the Tongxinluo capsules were derived from WP. All in all, the strategy developed in this study was effective for natural peptide characterization and signature peptide screening, which could also be applied to other animal-derived drugs, especially for modelless species that are less studied in protein database annotation.

An Indirect Colorimetric Method for Potassium Determination in Soil Using a Paper Device and Smartphone

This study presents a simple method for determination of potassium in microliter scale using a paper device together with a smartphone. The method begins with the ion-pair extraction of dibenzo-18-crown-6-K+ complex into dichloromethane with an excess amount of calmagite. The aqueous phase containing the remaining calmagite is transferred to the paper device, where a smartphone is used to capture the color and convert to RGB value. The linear detection range was found to cover potassium concentrations from 20 mg L-1 to 120 mg L-1. The detection and quantification are 5.41 mg L-1 and 18.03 mg L-1, respectively. Potassium detection was carried out in a variety of actual soil samples, and the results were validated against spectrophotometric results using a paired t-test, which indicated high accuracy. The proposed method is simple, fast, and inexpensive, and it requires no complicated equipment, making it ideally suited for detection of potassium in soil.

Extraction and Complexation Investigation of Palladium(II) by a Nitrilotriacetate-Derived Triamide Ligand.

Effective and selective separation and recovery of the fission product palladium from high-level liquid waste are conducive not only to reducing its hazards to the public health and environment but also to alleviate the pressure on the increasing demand for natural palladium. Herein, the Pd2+ extraction in an HNO3 solution with a nitrilotriacetate-derived triamide ligand NTAamide(n-Oct) and the complexation between them were investigated. Using n-octanol as a diluent, NTAamide(n-Oct) demonstrated an excellent selectivity, strong extractability, and high loading capacity for Pd2+ extraction. Combined with the results of single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, electrospray ionization-mass spectroscopy, microcalorimetric titration, and slope analysis, the extracted complexes were determined as [PdL2](NO3)2 and [PdL2][Pd(NO3)4] (where L denotes the NTAamide ligand) in 0.10 and 3.0 mol/L HNO3 solutions, respectively. The extraction model closely depended on the solvation state of Pd2+ in the HNO3 solution. An ion-pair extraction model was proposed and discussed.

Spectrophotometric Determination of Alprazolam in Pure and Pharmaceutical Forms using Triphenyl Methane Dyes

Three simple and sensitive extractive spectrophotometric methods have been described for the assay of Alprazolam either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with bromothymol blue (BTB), bromophenol blue (BPB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbance maxima at 410, 408 and 405nm with use of the cited reagents, respectively. The stoichiometry of the complex is found to be 1:1 in each case. Beer’s law is obeyed in the concentration ranges 3.0-25, 4.0-30, and 4.5-40μg/ml with BTB, BPB and BCG respectively. The effect of concentration of dye, pH, and interference of excipients have been studied and optimized. The limits of detection and quantification have been determined for three methods. All the three methods have been validated as per the guidelines of ICH. The methods have been applied to the determination of drug in commercial tablets and results of analysis were validated statistically through recovery studies.

Extraction and Preconcentration of Cd (II) by using Crown Ether DB18C6

Extracted Cd(II) as (CdCl3-) and (CdCl42-) from HCl media after preparing ion pair complexes according to liquid ion exchange method by using DB18C6 after changing to liquid ion exchanger K-Crown+; Cl-, spectrophotometric studies showed that the extracted ion pair complex had a wave length for maximum absorbance of λmax=277nm. Limitations to the study include optimum conditions for extraction in this study show a need for 0.3M HCl, to be present 50µg for Cd(II), in addition to study extracted complex structure by Slope ratio method, the result appear more probable structure of extracted complex [K DB18C6]+;HCdCl4- and [K-DB18C6]+; CdCl3-. This method applied to spectrophotometric determination of Cd(II) in different sample and compare the results with atomic absorption spectroscopy.

Simple spectrophotometric method for the determination of haloperidol from pharmaceutical formulations

A simple, sensitive, rapid, accurate and cost effective spectrophotometric method has been developed and validated for the estimation of haloperidol in bulk drug and for its pharmaceutical formulations. The proposed method is based on the formation of chloroform extractable ion pair complex of haloperidol with bromothymol blue. The absorbance of the coloured extractable ion pair complex is measured at the wavelength of maximum absorbance 420 nm against the reagent blank. Beer’s law is obeyed over a concentration range of 20 to 100 µg/ml of haloperidol, for a linear calibration curve. Results are statistically validated and found to be reproducible.

Fluorometric quantification of alkaloids in the homeopathic mother tinctures of Vinca minor L. and Fumaria officinalis L.

To assess the toxic potential of the alkaloids, a quantification method is necessary. An ion pair extraction method was used for quantitative fluorometric determination of vincamine, protopine and all contained alkaloids in the mother tinctures of Vinca minor and Fumaria officinalis. The non-fluorescent alkaloids were transformed into an ion pair with sodium-9,10-dimethoxy-anthracene-sulfonate and then fluorometrically determined and quantified in this study. The applicable ion pair was extracted in a suitable organic solvent, where dichloromethane has proven to be beneficial. Conditions for the ion pairing and fluorometric quantification are given. The recovery rate was used to investigate the quality of determinability and the influence of the mother tincture matrix. The method was applied to determine the concentration of protopine in the range 0.1 - 15 μg/ml and of vincamine in the range of 0.5 - 20 μg/ml. The limit of detection was < 0.3 μg/ml, and the limit of quantification < 0.9 μg/ml for both alkaloids.

Design and application of online derivatization device for polar organics on atmospheric particulate filter

设计制作了一套用于气相色谱-质谱(GC-MS)分析极性有机物的在线衍生装置,并将其应用于大气颗粒物样品中极性有机物的检测。将大气颗粒物滤膜样品置于GC-MS进样口,通过使用套针组件,匀速引入气态衍生试剂N-甲基-N-(三甲基硅烷)三氟乙酰胺(MSTFA),使其在衬管内于310 ℃下与待测物接触,10 min即可完成硅烷化在线反应。反应过程中,色谱柱箱保持低温,衍生产物得以在柱头保留,反应完成后色谱柱箱程序升温,使衍生产物直接进行后续分离检测。应用在线衍生装置建立有机酸分析方法,获得了一元酸、二元酸、芳香酸、醇等极性有机物的检测信息,涵盖了大气化学分析常见的大部分目标化合物。该方法检出限为0.02~0.53 mg/L,线性相关系数为0.976~0.996,日内、日间RSD为0.27%~7.28%,适用于批量大气环境样品检测。与传统离线衍生技术相比,本装置使衍生反应处于高温惰性气体氛围,排除空气中水分对衍生试剂的损耗和衍生产物降解风险,反应稳定、效率高;固体滤膜上有机物进行热解吸的同时完成在线衍生,样品需求量小,操作简单,零有机试剂污染,并有望应用于醇类、酚类等多种极性有机化合物的分析。此外, 该装置搭建简单,可模块化设计,适用于不同品牌气相色谱仪,具有商业化推广前景。

Utilizing an Amino Acid Scaffold to Construct Heteroditopic Receptors Capable of Interacting with Salts under Interfacial Conditions.

A 4-nitro-L-phenylalanine scaffold was used to construct effective ion pair receptors capable of binding anions in an enhanced manner with the assistance of alkali metal cations. A benzocrown ether was linked to a receptor platform via the amide function so as to support the squaramide function in anion binding and to allow all three NHs to act simultaneously. The binding properties of the receptors were determined using UV-vis, 1H NMR, 2D NMR, and DOSY spectroscopy in MeCN and in the solid state by X-ray measurements. Ion pair receptor 2 was found to interact with the most strongly with salts, and the removal of its key structural elements was shown to hinder the receptor action. The amide proton was recognized to switch from having involvement in an intramolecular hydrogen bond to interacting with anions upon complexation. Apart from carboxylates, which promote deprotonation, and other monovalent salts creating 1:1 complexes with the receptor, more complex equilibria were established upon the complexation of 2 with sulfates. Receptor 2 was shown to be capable of the extraction of ion pairs from the aqueous to organic phase and of the cation-enhanced transport chloride and sulfate anions across a bulk chloroform membrane. These features may open the door for its use in regulating ion concertation under interfacial conditions and acting as a potential drug to treat channelopathies.

A Review on Cetylpyridinium Chloride

Cetylpyridinium chloride (CPC) is a quaternary ammonium surfactant having broad spectrum antimicrobial activity. The hexadecane chain of the CPC disorganizes lipid membrane and produces a complete rupture of the bacterial cell membrane. At low concentration of CPC, it leads to activation of intracellular latent ribonucleases of microbes to promote cell autolysis. At high concentration, CPC forms a vesicle-like structure in the bacterial cell surface and leads to leakage of cytoplasmic content. CPC can be estimated using several methods like HPLC, ion-pair extraction TLC, spectrophotometry, chemiluminescence, and spectrometry. It is a strong antimicrobial, anti plaque, deodorizer and bleeding control agent and is widely used in mouthwashes, tooth paste, sanitizers and disinfecting liquids. Keywords: Cetylpyridinium chloride, antimicrobial agent, deodorizer, anti plaque agent.