An Erratum to this paper has been published: https://doi.org/10.1134/S106193482237002X

Review of authors' works in the field of the use of new ionic liquids (IL), salts of quaternary ammonium cations with carbonic or sulfonic acid anions, in extraction is presented. Properties of IL important for solvent extraction are discussed, and a comparison with the classical IL, including substituted imidazolium cations and fluorine-containing anions, is made. The most important applications of IL for the extraction of organic compounds of various classes, including analytical reagents, from aqueous solutions are presented. Data on the extraction of metal ions are presented; various approaches to the use of IL: as inert diluents of complexing agents and extraction solvents/extractants active with respect to the extracted substance are discussed. The features and advantages of microextraction with the dispersion of the solvent in IL formed in situ are discussed.

The second, final part of the review. The use of ionic liquids in voltammetry and amperometry as organic electrolytes for carrying out electrochemical processes, extraction, and voltammetric analysis and for the development of composite materials and the creation of electrochemical sensors is discussed. The most important use of ionic liquids for modifying electrode membranes is considered: as an inert matrices allowing the immobilization of ionophore components and also as ionophore components of membranes of liquid-based and solid-state ion-selective electrodes.

The first part of the review presents general information and brief historical notes about ionic liquids (ILs) along with various versions of microextraction preconcentration using ILs: single-drop extraction, membrane extraction, dispersive liquid–liquid microextraction, in situ ionic liquid-based dispersive microextraction, etc. A review of papers on the extraction of metal ions and organic compounds in ILs for chemical analysis is presented. Aqueous biphasic systems based on ILs immiscible with water and salting-out agents are described; examples of such systems, their advantages, and factors affecting phase separation are considered.

Phenoxy-substituted boron subphthalocyanine was synthesized and studied as an ionophore of plasticized polyvinyl chloride membranes of ion-selective electrodes. The electrodes exhibit reversible response to dobutamine, demonstrating the cation function, as well as reversible response to the salicylate anion. The effects of concentration of the ionophore (0.2–5 wt %) and ionic components (sodium tetraphenylborate, TPhBNa, and tributylhexadecylphosphonium bromide, TBGDPBr), including ionic liquids (ILs), such as diphenylbutylethylphosphonium bis(triflyl)imide, diphenylbutylethylphosphonium hexafluorophosphate, and 1,3-dihexadecylimidazolium chloride, as well as plasticizers, such as ortho-nitrophenyloctyl ether and diethyl sebacate, on the electrochemical characteristics of membranes were studied. For the electrode containing 2% of the phenoxy-substituted boron subphthalocyanine in dobutamine and salicylate solutions, the slopes of the electrode function were 36 ± 1 mV/dec and–46 ± 3 mV/dec and the limits of detection (LODs) were 4 × 10–5 M and 3 × 10–4 M, respectively. The addition of an ionic liquid containing the diphenylbutylethylphosphonium cation and the bis(triflyl)imide and hexaflurophosphate anions to the membrane composition had no effect on the response of membrane electrodes to both dobutamine and salicylate. The use of phenoxy-substituted boron subphthalocyanine in an amount of 2% and the TPhBNa additive significantly improved sensor characteristics: the slope of the electrode function (S) for the dobutamine-selective electrode was (54 ± 1) mV/dec and LOD was 1 × 10–5 M. Dobutamine can be determined in the presence of dopamine, adrenalin, and glucose. Electrodes based on 2% phenoxy-substituted boron subphthalocyanine and 0.5% (C16H33)2ImCl, or TBGDPBr in salicylate solutions demonstrate the slope of the electrode function close to the theoretical one and a low limit of detection: S = (–59 ± 1) mV/dec, LOD = 2 × 10–5 M and S = (–57 ± 1) mV/dec, LOD = 4 × 10–5 M, respectively. The anti-Hofmeister selectivity of sensors was observed. The electrode based on phenoxy-substituted boron subphthalocyanine and (C16H33)2ImCl was used for the assay of acetylsalicylic acid in the drug Cardiomagnyl.

The possibility of using solid-state and liquid PVC-membrane electrodes based on ionic liquids to design a potentiometric multisensor system is assessed. Ionic liquids with 1,3-dihexadecylimidazolium cation and chloride, bromide, iodide, and nitrate anions are used. The sensitivity parameters of the sensors are determined. A multisensor array is applied to detect chloride and iodide anions in the multicomponent mixture. The designed system is used to discriminate between mineral waters of different compositions by applying the method of principal component analysis (PCA).

Extraction of cadmium(II), lead(II), cobalt(II), copper(II), and zinc(II) into ionic liquids tetraoctylammonium N-lauroyl sarcosinate and trioctylmethylammonium salicylate is studied. Cadmium(II), lead(II), copper(II) in tetraoctylammonium N-lauroyl sarcosinate and copper(II) in trioctylmethylammonium salicylate are quantitatively extracted from neutral and weakly alkaline solutions in the absence of additional reagents. The effect of the composition of aqueous and organic phases, as well as the contact time, on metal extraction is investigated.

Cobalt(II) porphyrazine is synthesized and studied as an active component of a polyvinyl chloride plasticized membrane ion-selective electrodes (ISEs). It is established that regardless of their structure, ISEs are sensitive to iodide. The introduction to the ISE of an ionic additive, ionic liquid 1,3-dihexadecylimidazolium chloride, significantly improves the electrochemical characteristics: the slope of the electrode function reaches −(57 ± 1) mV/dec, c min = 8.3 × 10–6 M. Solid-state screen-printed electrodes the surfaces of which are modified by a 1: 4 mixture of cobalt(II) porphyrazine and ionic liquid 1,3-dihexadecylimidazolium chloride demonstrate satisfactory electrochemical characteristics: the slope of the electrode function is −(56 ± 4) mV/dec and c min = 2.5 × 10–5 M. The potentiometric selectivity of the ISEs for iodide is studied. It is found that the effect of lipophilic interfering ions is significantly lower for solid state ISEs than for plasticized membrane electrodes.

An ion-selective electrode based on tetraoctylammonium N-lauroyl sarcosinate ionic liquid, which is solid at room temperature, is responsive to anionic forms of amino acids. Preconditioning in copper sulfate solution and the introduction of more high-melting and hydrophobic ionic liquid (1,3-dihexade-cylimidasolium bromide) allowed the limit of detecting phenylalanine to be lowered by several times (c min = 2.7 × 10–5 M) and significantly improves the service life of the ion-selective electrode. The possibility was shown for using two ionic liquids for designing ISE with one of them that serves as an inert solid matrix for immobilizing the second one, which in turn ensured the analyte binding and the generation of a potentiometric signal.

The simultaneous dissolution of tetraoctylammonium bromide and sodium N-lauroyl sarcosinate in water leads to the in situ formation of a water-immiscible ionic liquid, tetraoctylammonium N-lauroyl sarcosinate. The new phase formed can extract cadmium, cobalt, copper, nickel, lead, and zinc ions from aqueous solution in the presence of 4-(2-pyridylazo)resorcinol (PAR), while it can extract cadmium ions in the absence of PAR.

In this study screen-printed solid-state electrodes using low-melting ionic liquids with cation of 1,3-dihexadecylimidazolium and such anions as chloride, iodide, and thiocyanate were developed. Potentiometric response and electrochemical characteristics of ion-selective electrodes in KCl, KI, and KSCN solutions were studied. All sensors exhibited sensitivity toward the corresponding anions, the slopes close to Nernstian ones, low detection limits (3.0∙10−6M for SCN−), and high selectivity in the presence of the extraneous anions. Operation time of the sensors was not less than one year. The applicability of the developed electrodes for the potentiometric determination of iodide in pharmaceuticals and thiocyanate in human saliva was demonstrated.

Water-immiscible water-rich ionic liquids + water-soluble analytical reagents = a novel extraction-based platform for the determination of metal ions.