Paweł Dżygiel

Combination of supported liquid membrane and solid-phase extraction for sample pretreatment of triazine herbicides in juice prior to capillary electrophoresis determination

A possibility of a combination of supported liquid membrane (SLM) and solid-phase extraction (SPE) for the determination of atrazine at microgram level in different type of fruit juices is presented. In comparison to SPE extraction from juice samples, the application of SLM-SPE enrichment provides much cleaner extracts and the possibility of lowering the limit of detection as low as 30 microg/l. However, it was also shown that by appropriate manipulation of SLM extraction conditions mainly flow-rate of donor phase and volume ratio between donor and acceptor phase, the level of detection can be further decreased to 10 microg/l. The results suggest that the application of SLM extraction prior to SPE is an alternative method for atrazine enrichment from complicated liquid matrices and could be used as routine method for the clean-up of such samples.

Extraction of glyphosate by a supported liquid membrane technique.

The possible application of the supported liquid membrane (SLM) technique for the extraction of glyphosate is presented. For the extraction of this compound the SLM system has been applied with utilisation of Aliquat 336 as a cationic carrier incorporated into the membrane phase. The extraction efficiency of glyphosate [N-(phosphonomethyl)glycine] is dependent on the donor phase pH, carrier concentration in the organic phase and NaCl concentration in the acceptor phase. The optimal extraction conditions are: donor phase pH>11, acceptor phase of 2 M NaCl solution and the organic phase composed of 20% (w/w) Aliquot 336 solution in di-hexyl ether. Counter-coupled transport of chloride anions from the acceptor phase to the donor phase is a driving force of the mass transfer in this system.

Extraction of amino acids with emulsion liquid membranes using industrial surfactants and lecithin as stabilisers

Abstract Industrial surfactants (being the mixtures of several individual compounds) were used as stabilisers of emulsion liquid membranes (ELMs). Although, some impurities present in technical formulations of these compounds were extracted to aqueous solutions of amino acids, most of the used surfactants well served to this purpose. In the case of amino acid transport, they do not act as carriers and application of additional carrier (such as D2EHP) was required in order to facilitate the transport. Interestingly, the same properties were found for lecithin, industrially important natural surfactant. Lecithin applied as a chiral discriminator, used either as an emulsion stabiliser or carrier, shows that this compound possesses insignificant enantioselective properties.

Determination of optical purity of phosphonic acid analogues of aromatic amino acids by capillary electrophoresis with α-cyclodextrin

A simple and efficient method for the determination of enantiomeric purity of structurally diverse phosphonic and phosphinic acid analogues of phenylalanine and phenylglycine using capillary electrophoresis is presented. These preliminary studies indicated that the enantiomer separation is strongly dependent on the structure of the aminophosphonic acid.

Supported Liquid Membranes and Their Modifications: Definition, Classification, Theory, Stability, Application and Perspectives

Publisher Summary This chapter discusses the principle, kinetic and transport mechanisms, stability of supported liquid membrane (SLM) design followed by thier configuration. In the examples of SLM applications presented in this chapter, the possibility to separate high quantities of compounds using small volumes of organic phases shows that this method is still a very attractive choice when an efficient and selective method is necessary. Also, as a result of the development and commercialization of hydrophobic hollow-fiber membrane contactors, SLM might be applied successfully for industrial purposes. This is due to the high-membrane surface per unit of volume with satisfactory liquid membrane stability and that HF-SLM technology is easily scalable. Therefore, there is much research to increase the applicability of SLM in the pharmaceutical and chemical industry, metal separation and recovery, wastewater treatment, gas separation, biotechnology, and analytical chemistry. Many of the new, interesting applications of SLM describe the use of the SLM concept. Thus, in the pharmaceutical industry, SLMs can be utilized in the production processes of fine chemicals and even drugs. One such possibility is described in this chapter, the resolution of drug enantiomers, the production of which is a very challenging task. The other, also involving the new advance of SLM separation in biotechnology, is to use this technique for recovery of various pharmaceutically important compounds from fermentation broths. SLMs were used to separate and recover such compounds as amino acids, for example, L-valine and antibiotics, including β-lactam or cephalosporin antibiotics. Also, other important substances were separated using an SLM system with the aim of using supported liquid membranes in bioindustrial processes.

Separation of aromatic aminophosphonic acid enantiomers by capillary electrophoresis with the application of cyclodextrins

The detailed studies concerning capillary electrophoresis separation of aminophosphonic acid enantiomers with various commercially available cyclodextrins are presented. The obtained results show that the separation of these stereoisomers is dependent on pH of background electrolyte, concentration of cyclodextrin as well as on the type of applied chiral selector. The separation mechanism is based on the co-operative effect of hydrogen bond type interactions enhanced by hydrophobic forces and sterical constrains between aminophosphonate and cyclodextrin. With application of elaborated method, enantiomeric baseline or partial separation of 18 alpha-aminophosphonic acids was achieved. This separation can be successfully used for routine aminophosphonic acids enantiopurity determination.

Supported liquid membrane extraction of glyphosate metabolites

Use of the supported liquid membrane (SLM) technique for (aminomethyl)phosphonic acid (AMPA) extraction is presented. For the extraction of this analyte a suitable SLM system involves a liquid membrane containing Aliquat 336 – a cationic carrier that facilitates AMPA transport. The extraction of this compound, as in the case of glyphosate, is dependent on the donor phase pH and the concentration and type of counter-ion in the acceptor phase, although some differences are also observed. In both cases the transport mechanism is counter-coupled transport in which the driving force of mass transport over the membrane is created by the gradient of chloride anions from the acceptor to donor phase.