Membrane pertraction of Lu(III) with di(2-ethylhexyl) phosphoric acid as a carrier

Introduction: In a supported liquid membrane (SLM) extraction, also named pertraction, target analytes are extracted from an aqueous feed sample, the ‘donor phase’, into an organic phase entrapped in micropores of a hydrophobic support membrane, and further transferred into an acceptor phase. Different approaches and applications of SLM extraction are described in scientific literature such as analysis of drugs, pesticides, metal ions, organic pollutants1 etc. Though a number of SLM extraction investigations on metal ion separation have been reported in literature2, very little work has been doneon the application of membrane extraction for radionuclide separation3,4. Radiopharmaceuticals are drugs labeled with radionuclide which are used in various diagnostic and therapeutic applications in nuclear medicine. The interest for the usage of radiolabeled peptides and monoclonal antibodies for therapy is growing in the last decade. Also, radioactive isotope 177Lu and labeled radiopharmaceuticals are being increasingly used as therapeutic agents in nuclear medicine5. Although the percentage of binding the radionuclide to a target molecule is usually very high (~ 98%), there is always a fraction of the free radionuclide. This is very important in the case of radiopharmaceutical for radiotherapy. The single dose for radiotherapy can be very high (up to 30 GBq), thus the absolute amount of free radionuclide can be significant. The free 177Lu(III) accumulates in bones, thus is very important to separate free 177Lu(III) from the labeled compound. The most commonly applied technique for this purification is chromatography. Except that, the application of SLM extraction with flat membrane for separation labeled compound and free 177Lu(III) was proposed and studied in our previous paper4. Recently, SLM extraction has been simplified by introduction of a SLM extraction in a single hollow fiber without any special device6. The SLM extraction in a single hollow fibre can be operated only in a batch mode without any phase flow rate. Apart from common characteristics of membrane extraction such as large interfacial areas, low consumption of organic solution, good opportunity for process automation etc, SLM in a single hollow fibre has additional advantages such as easy to handle equipment, no special device to avoid accidental release of radioactive material and a sample volume as low as 1 cm3. The aim of the present study was to investigate the pertraction of Lu(III) from an aqueous phase by applying miniaturized SLM extraction in a single hollow fibre. The influence of the donor pH, content of the carrier in the organic phase and the time of extraction on lutetium extraction and stripping were investigated

Comparison of static and continuous hollow fibre liquid-phase extraction of lutetium

This work is a comparative study of the efficiency of the lutetium (III) extraction in membrane-assisted liquid-phase extraction (LPE) carried out under static and continuous operation mode using di(2-ethylhexyl)phosphoric acid (DEHPA) as a carrier. The removal of Lu(III) from the donor solution and its recovery into the acceptor phase were compared for the two operation modes investigated. Additionally, the applicability of both systems for purification of 177Lu-radiopharmaceutical was discussed

Pertraction of Lu(III) in a hollow fibre contactor

Pertraction of Lu(III) in a hollow fibre contacto

Liquid-phase microextraction in a single hollow fibre: determination of mass transfer coefficient

In this study, the mass transfer coefficient of two local anesthetics in liquidphase microextraction (LPME), which is performed in a single hollow fibre, was investigated. Previously developed mathematical model has been applied for the determination of the overall mass transfer coefficient based on the acceptor phase, KA, in an unsteady-state LPME

Novel 90Sr-90Y generator system based on a cross-flow hollow fiber supported liquid membrane contactor

Separation of yttrium(III) from strontium(II) with 15% (v/v) di(2-ethylhexyl)phosphoric acid (DEHPA) in dodecane was carried out in a hollow fiber supported liquid membrane (SLM) extraction system operated under closed-loop recirculation of the donor and acceptor phase. The donor phase was a mixture of 5.7 mmol dm-3 of Sr(II) and 0.23 mmol dm-3 of Y(III) in 0.1 mol dm-3 HCl, the acceptor solution was 3 mol dm-3 HCl, and the donor to acceptor phase volume ratio was 6.2. At the donor flow rate of 4.7 cm3 min-1 and the acceptor flow rate of 0.8 cm3 min-1, the yield of Y(III) in the acceptor phase reached 60% after 360 min with a molar ratio of Y(III) to Sr(II) in the acceptor of 250:1, as compared to 1:25 in the donor phase. The yield of Y(III) was 72% at the acceptor flow rate to 1.9 cm3 min-1, but a breakthrough of Sr(II) through liquid membrane increased from 0.02 to 0.2%

Separation of yttrium from strontium by hollow fibre supported liquid membrane containing di(2-ethylhexyl)phosphoric acid

Separation of Y(III) from Sr(II) was performed using the hollow fibre membrane contactor operated in a recirculation mode. The steady-state was established after ~5 h of operation and the maximum removal of Y(III) from the donor to the acceptor was achieved at the donor flow rate of 4.7 cm3 min-1 . The investigated system showed promising results as a method which could be potentially applied for the preparation of 90Sr/ 90Y generator system

Separation of yttrium from strontium by hollow fibre supported liquid membrane containing di(2-ethylhexyl)phosphoric acid

Separation of Y(III) from Sr(II) was performed using the hollow fibre membrane contactor operated in a recirculation mode. The steady-state was established after ~5 h of operation and the maximum removal of Y(III) from the donor to the acceptor was achieved at the donor flow rate of 4.7 cm3 min-1. The investigated system showed promising results as a method which could be potentially applied for the preparation of 90Sr/90Y generator system

Membrane-assisted liquid phase extraction of Lu(III) in U-shaped contactor with a single hollow fibre membrane under recirculation mode of operation

Extraction of Lu(III) from an aqueous LuCl3 solution at pH 3.5 into an organic phase containing 5% (v/v) di(2-ethylhexyl)phosphoric acid (DEHPA) in di-n-hexyl ether (DHE) immobilized within a polypropylene hollow fibre membrane and a simultaneous back-extraction of Lu(III) into 2 mol dm-3 HCl solution has been investigated using two miniaturized supported liquid membrane (SLM) systems: (i) a single hollow fibre membrane, with stagnant acceptor phase in the lumen, immersed into a donor phase reservoir; (ii) U-shaped module containing a single hollow fibre membrane with a closed-loop recirculation of aqueous phases through the module. In the stagnant SLM system, the maximum extraction efficiency was 8.8% due to limited acceptor volume and absence of flow within the lumen. In recirculating SLM system, after 80 min of operation at the donor phase flow rate of 5.3 cm3 min-1, the acceptor phase flow rate of 0.4 cm3 min-1 and the donor-to-acceptor phase volume ratio of 6.7, the equilibrium removal efficiency of Lu(III) reached 88% and less than 5% of Lu(III) extracted from the feed solution was kept in the organic phase. For shell side flow of the donor phase at the Reynolds number of 3−34, the overall mass transfer coefficient was proportional to the donor flow rate raised to the power of 0.63 and increased from 2.3 to 8.8 × 10-5 m s-1. The rate-limiting step was the mass transfer of Lu(III) within the boundary layer of the donor phase adjacent to the outer wall of the hollow fibre

Determination of the overall mass transfer coefficient of Lu(III) in a single fibre pertraction

Determination of the overall mass transfer coefficient of Lu(III) in a single fibre pertractio

Mass transfer resistance in a liquid-phase microextraction employing a single hollow fiber under unsteady-state conditions

In this study, the mass transport resistance in liquid-phase microextraction (LPME) in a single hollow fiber was investigated. A mathematical model has been developed for the determination of the overall mass transfer coefficient based on the acceptor phase in an unsteady state. The overall mass transfer coefficient in LPME in a single hollow fiber has been estimated from time-dependent concentration of extracted analyte in the acceptor phase while maintaining a constant analyte concentration in the donor phase. It can be achieved either using a high volume of donor to acceptor phase ratio or tuning the extraction conditions to obtain a low-enrichment factor, so that the analyte concentration in the sample is not significantly influenced by the mass transfer. Two extraction systems have been used to test experimentally the developed model: the extraction of Lu(III) from a buffer solution and the extraction of three local anesthetics from a buffer or plasma solution. The mass transfer resistance, defined as a reciprocal values of the mass transfer coefficient, was found to be 1.2 x 103 cm-1 min for Lu(III) under optimal conditions and from 1.96 to 3.3 x 103 cm-1 min for the local anesthetics depending on the acceptor pH and the hydrophobicity of the drug