Production and Semi-Automated Processing of 89Zr Using a Commercially Available TRASIS MiniAiO Module

The increased interest in 89Zr-labelled immunoPET imaging probes for use in preclinical and clinical studies has led to a rising demand for the isotope. The highly penetrating 511 and 909 keV photons emitted by 89Zr deliver an undesirably high radiation dose, which makes it difficult to produce large amounts manually. Additionally, there is a growing demand for Good Manufacturing Practices (GMP)-grade radionuclides for clinical applications. In this study, we have adopted the commercially available TRASIS mini AllinOne (miniAiO) automated synthesis unit to achieve efficient and reproducible batches of 89Zr. This automated module is used for the target dissolution and separation of 89Zr from the yttrium target material. The 89Zr is eluted with a very small volume of oxalic acid (1.5 mL) directly over the sterile filter into the final vial. Using this sophisticated automated purification method, we obtained satisfactory amount of 89Zr in high radionuclidic and radiochemical purities in excess of 99.99%. The specific activity of three production batches were calculated and was found to be in the range of 1351–2323 MBq/µmol. ICP-MS analysis of final solutions showed impurity levels always below 1 ppm.


Introduction
Zirconium-89 ( 89 Zr), a positron-emitting isotope, has emerged as an attractive radionuclide in the development of pre-clinical and clinical radiopharmaceuticals for positron-emission tomography (PET) imaging. This is due to the favourable physical characteristics of the isotope which decays via positron emission (T 1/2 : 78.4 h, β + 22.7%, E β+max = 901 keV; average E β+max = 396 keV) [1,2] and electron capture (EC 77%, Eγ = 909 keV) to the stable yttrium-89 ( 89 Y). The longer half-life matches the need for large biomolecules such as antibodies, antibody fragments and nanoparticles which require prolonged circulation time in order to reach optimal target accumulation [3,4]. Furthermore, the β + branching ratio, average β + energy and short positron range (R ave = 1.23 mm) provide high spatial resolution and image quality of the 89 Zr PET probes [5].
The combination of antibody-based targeting vectors and PET-based imaging, known as immuno-PET, is rapidly becoming a powerful tool for highly selective imaging agents [6,7]. Radiolabeling of the targeting vector requires a stable radiometal chelate that can be readily conjugated manually. So far, the processing of 89 Zr from the target has mainly been achieved manually or has been based on semi-automated systems. These have not been widely adopted because they are based on in-house developed systems instead of commercially available equipment [13][14][15]. Moreover, regulatory demands are increasing and consequently the application of 89 Zr in clinical studies is becoming challenging. To maintain the high quality of the 89 Zr, a reliable process with quality control and good manufacturing practice-compliant automated module in the production is required. Additionally, there are several advantages of using automation in radiochemistry, such as lower radiation exposure to the production personnel, high reproducibility, more precise control of the parameters and ease of handling. Mostly, automated modules are placed inside dedicated lead shielded hot cells to protect the operator and environment from radiation exposure. Commercially available automated modules can be classified into two types, namely, those that consist of fixed tubing in which fluid flows are regulated by inert gas, and those that consist of sterile disposable cassettes where fluid flow is regulated by a syringe pump. The main disadvantage of using fixed tubing is bacterial contamination in the product if a validated cleaning method is not implemented. Usually this tubing is used for multiple productions and needs to be cleaned after each synthesis. Also, a single system cannot be used for multiple radioisotopes or for the production of other radiopharmaceuticals. These issues can be solved by using sterile, single-use cassettes manufactured in current Good Manufacturing Practices (cGMP)-compliant clean rooms.
The focus of this present work is the implementation of the semi-automated purification of 89 Zr using a commercially available automated synthesis unit that could fulfil regulatory requirements.

Cyclotron Irradiation
Yttrium-89-coated niobium coins were purchased from Advanced Cyclotron Systems Inc. (ACSI, Richmond BC, Canada). The niobium target body had a diameter of 24 mm and a thickness of 1 mm. The yttrium was adhered on the frontal face of niobium target body with a diameter of 10 mm and approximately 200 µm thickness. Aluminium degrader coins (99.0% 24 mm with 0.80 mm thickness) were purchased from Goodfellow (Coraopolis, PA, USA).
The target body along with 0.80 mm-thick aluminium degrader was mounted on TR-24 cyclotron (ACSI, Richmond, BC, Canada) at the Saskatchewan Centre for Cyclotron Sciences (SCCS) and bombarded for 2 h with the initial proton energy of 17.8 MeV and 40 µA current calculated as ≈12.8 MeV degraded beam energy at the target to produce 89 Zr via the nat Y(p, n) 89 Zr reaction. During irradiation, the target was cooled on the frontal side by helium gas and on the back side by chilled water. After irradiation, the target was left on the target station for 2-3 h to allow for the decay of short-lived isotopes, in particular 88m Zr (t 1/2 = 4.16 m). The target was released into a lead pig using target release valve located outside the cyclotron vault. The lead pig containing the irradiated target was manually retrieved from the vault and transported to the hot cells on a shielded cart.

Automation Adopted for 89 Zr Separation and Purification
A mini AlliOne (miniAiO) cassette-based automatic synthesis unit (ASU) from TRASIS (Ans, Belgium), with dimensions 21.5W × 41.2H × 40.8D cm, was used for the automated separation and purification of 89 Zr ( Figure 1). The miniAiO consists of 12 rotary actuators and 2 linear actuators for operating syringes. All liquids were transferred through PEEK tubing. All tube connections were assembled using non-metallic connectors to reduce exposure to the metals which may affect radionuclidic purity and specific activity. Many of the liquid connection pieces were flangeless fittings designed for high pressure fluidic connection and ferrules are manufactured from tefzel™ (ETFE). The fluidic path was controlled using the built-in three-way valve actuators. All liquids hydroxamate resin cartridge were preloaded onto the cassette prior to starting the sequence on the miniAiO. The miniAiO ASU was located within a lead hot cell and remotely controlled through a graphical user interface (PC). A sequence was created on the TRASIS software using a graphical user interface which distributes commands and controls to the automation unit. The operator can initiate a preprogrammed 89 Zr target dissolution and purification process. Radioactive detectors are built-in at different locations within the ASU to monitor and record the location of the radioactivity. The radioactivity in the dissolution vial, hydroxamate cartridge and final vial was monitored.

TRASIS MiniAiO Preparation
Automation of the process for separation and purification of 89 Zr, based on chemistry previously reported in the literature, was performed using a miniAiO ASU in a hot cell [1,12,16]. The miniAiO is a commonly used radiochemistry module for clinical GMP-grade radiopharmaceutical production. The ASU is designed for use with disposable kits and allows processing with full audit trail functionality for GMP production runs. Liquid transport was achieved using a syringe pump and transfer of liquids was controlled by three-way stopcock valves. For each liquid transfer step, the production protocols were adequately adapted and optimized. In brief, the following general steps were implemented in the production of 89 Zr. The hydroxamate resin (100 mg) was packed into an empty reversible SPE tube (0.5 mL). The hydroxamate resin was preconditioned with acetonitrile (MeCN) (8 mL, trace metal grade), water (15 mL, trace metal grade) and 2.0 M HCl (2 mL) and installed on the cassette (valve #10) of the miniAiO ASU ( Figure 2). The following vials were installed on the cassette: 2 M HCl (20 mL) in a glass vial with septa installed at cassette valve #4, water (10 mL) in a glass vial with septa installed at cassette valve #5, 1 M oxalic acid (1.5 mL) in a glass vial with septa installed at cassette valve #6, a waste vial (40 mL) connected to cassette valve #7 and a [ 89 Zr]zirconium oxalate product vial (5 mL) connected to cassette valve #11. The miniAiO ASU was located within a lead hot cell and remotely controlled through a graphical user interface (PC). A sequence was created on the TRASIS software using a graphical user interface which distributes commands and controls to the automation unit. The operator can initiate a pre-programmed 89 Zr target dissolution and purification process. Radioactive detectors are built-in at different locations within the ASU to monitor and record the location of the radioactivity. The radioactivity in the dissolution vial, hydroxamate cartridge and final vial was monitored.

TRASIS MiniAiO Preparation
Automation of the process for separation and purification of 89 Zr, based on chemistry previously reported in the literature, was performed using a miniAiO ASU in a hot cell [1,12,16]. The miniAiO is a commonly used radiochemistry module for clinical GMP-grade radiopharmaceutical production. The ASU is designed for use with disposable kits and allows processing with full audit trail functionality for GMP production runs. Liquid transport was achieved using a syringe pump and transfer of liquids was controlled by three-way stopcock valves. For each liquid transfer step, the production protocols were adequately adapted and optimized. In brief, the following general steps were implemented in the production of 89 Zr. The hydroxamate resin (100 mg) was packed into an empty reversible SPE tube (0.5 mL). The hydroxamate resin was preconditioned with acetonitrile (MeCN) (8 mL, trace metal grade), water (15 mL, trace metal grade) and 2.0 M HCl (2 mL) and installed on the cassette (valve #10) of the miniAiO ASU ( Figure 2). The following vials were installed on the cassette: 2 M HCl (20 mL) in a glass vial with septa installed at cassette valve #4, water (10 mL) in a glass vial with septa installed at cassette valve #5, 1 M oxalic acid (1.5 mL) in a glass vial with septa installed at cassette valve #6, a waste vial (40 mL) connected to cassette valve #7 and a [ 89 Zr]zirconium oxalate product vial (5 mL) connected to cassette valve #11. The irradiated target was transferred to the custom-made dissolution vial and the vial was placed inside the aluminium block heater on a hot plate that had been pre-heated to 80 °C. After placing the vented glass cover with attached PEEK tubing on the dissolution vial, the hot cell was closed, and the purification sequence was initiated using the program interface for the miniAiO. Hydrochloric acid (2.0 M, 4 mL) was drawn into the syringe and pushed into the dissolution vial to dissolve the target. The target solution was heated at 80 °C for 20 min, and after cooling for 20 min, was passed through the hydroxamate resin using the syringe actuator at 1 mL/min flowrate to maximize trapping of 89 Zr on the resin. The dissolution vial was rinsed with 2 M HCl (2 mL) and passed through the hydroxamate resin again at 1 mL/min flowrate. The 89 Zr remained trapped on the resin as indicated by the in-process monitoring of the radiation detector at the column. The resin was washed with 2 M HCl (14 mL) at 3 mL/min flowrate followed by water (10 mL) at 3 mL/min flowrate. Finally, the 89 Zr was eluted with 1 M oxalic acid solution (1.5 mL) at 0.5 mL/min flow rate and collected in a sterile 5 mL product vial.

Determination of Radionuclidic Purity
The radionuclidic purity of 89 Zr was determined by gamma-spectroscopy using a high purity germanium (HPGe) detector (Ortec, Oak Ridge, TN, USA). A 4-h scan of a diluted aliquot (50-80 kBq) was performed at the end of purification. To determine longer-lived contaminants, scanning was repeated after three half-lives.

Determination of Effective Specific Activity
The effective specific activity (MBq/µmol) of 89 Zr was determined by labeling p-SCN-Bz-DFO with purified [ 89 Zr]zirconium oxalate. p-SCN-Bz-DFO was selected as it is a commonly used chelator for labeling antibodies with 89 Zr [17,18]. Specific activity was calculated for three consecutive batches of [ 89 Zr]zirconium oxalate. A stock solution of p-SCN-Bz-DFO in DMSO (1 mg/mL) was prepared and The irradiated target was transferred to the custom-made dissolution vial and the vial was placed inside the aluminium block heater on a hot plate that had been pre-heated to 80 • C. After placing the vented glass cover with attached PEEK tubing on the dissolution vial, the hot cell was closed, and the purification sequence was initiated using the program interface for the miniAiO. Hydrochloric acid (2.0 M, 4 mL) was drawn into the syringe and pushed into the dissolution vial to dissolve the target. The target solution was heated at 80 • C for 20 min, and after cooling for 20 min, was passed through the hydroxamate resin using the syringe actuator at 1 mL/min flowrate to maximize trapping of 89 Zr on the resin. The dissolution vial was rinsed with 2 M HCl (2 mL) and passed through the hydroxamate resin again at 1 mL/min flowrate. The 89 Zr remained trapped on the resin as indicated by the in-process monitoring of the radiation detector at the column. The resin was washed with 2 M HCl (14 mL) at 3 mL/min flowrate followed by water (10 mL) at 3 mL/min flowrate. Finally, the 89 Zr was eluted with 1 M oxalic acid solution (1.5 mL) at 0.5 mL/min flow rate and collected in a sterile 5 mL product vial.

Determination of Radionuclidic Purity
The radionuclidic purity of 89 Zr was determined by gamma-spectroscopy using a high purity germanium (HPGe) detector (Ortec, Oak Ridge, TN, USA). A 4-h scan of a diluted aliquot (50-80 kBq) was performed at the end of purification. To determine longer-lived contaminants, scanning was repeated after three half-lives.

Determination of Effective Specific Activity
The effective specific activity (MBq/µmol) of 89 Zr was determined by labeling p-SCN-Bz-DFO with purified [ 89 Zr]zirconium oxalate. p-SCN-Bz-DFO was selected as it is a commonly used chelator for labeling antibodies with 89 Zr [17,18]. Specific activity was calculated for three consecutive batches of [ 89 Zr]zirconium oxalate. A stock solution of p-SCN-Bz-DFO in DMSO (1 mg/mL) was prepared and 15 reaction tubes were prepared by 1:2 serial dilution in ultrapure water (500 µL) to give a final p-SCN-Bz-DFO concentration in the range of 2.07E-02 to 1.267E-06 µmol. A solution of [ 89 Zr]zirconium oxalate was neutralized with the 2 M NaCO 3 (pH 7 ± 0.2) and added to the p-SCN-Bz-DFO solutions. The resulting solutions were incubated at 37 • C on a shaker at 650 RPM for one hour. After incubation, 1 µL aliquots were spotted on iTLC and analysed by using citrate buffer (100 mM, pH 5.0) as a mobile phase. iTLC plates were measured using radio-TLC scanner. The results of the p-SCN-Bz-DFO titration with 89 Zr were plotted and fitted with a sigmoidal dose-response curve to generate an EC 50 value which was used to calculate specific activity in MBq/µmol.

Characterization of Radioactive Impurities Produced during Irradiation
Typical impurities in the production of 89 Zr are 88 Y, 88 Zr, 89 Y, 90 Zr and 56 Fe. Usually, impurities are derived from impure starting materials ( 89 Y), produced during proton bombardment due to inappropriate beam energy ( 88 Y and 88 Zr) or introduced via the buffers and recourses ( 90 Zr and 56 Fe). These impurities can be reduced using proper buffers and recourses and some of these impurities were removed by purifying the 89 Zr-solution using a hydroxamate column. All impurities were characterized using gamma-spectroscopy using a high purity germanium (HPGe) detector (Ortec, Oak Ridge, TN, USA).

Elemental Analysis by ICP-MS
The ICP-MS of three batches of final 89 Zr solution to determine metallic impurities were performed and validated by an ISO 9001:2015 certified Institution (Saskatchewan Research Council, Saskatoon SK, Canada). Niobium and yttrium were analyzed using an Agilent 7900 ICP-MS (Santa Clara, CA, USA) and all other elemental analysis were done using an Agilent 8800 ICP-MS (Santa Clara, CA, USA).

Preparation of p-SCN-Bz-DFO Conjugated Antibody
Conjugation of p-SCN-Bz-DFO to trastuzumab (DFO-trastuzumab) was performed following published procedures with slight modification [3,19]. Briefly, trastuzumab (5 mg/mL) in PBS was buffer exchanged in 0.1 M NaHCO 3 (pH 9) using centrifugal filters and concentrated to 10 mg/mL trastuzumab in the bicarbonate solution. A sixteen-fold mole excess of p-SCN-Bz-DFO (16 µg) in DMSO was added dropwise to the trastuzumab (2 mg) solution. The reaction mixture was incubated at 37 • C on a shaker at 650 RPM for an hour. The reaction mixture was cooled to room temperature and the unreacted DFO was removed by centrifugations using a spin-cap column (size 10-12 kDa). The buffer was exchanged with PBS using the same centrifugal filters.

Radiolabeling of DFO-Trastuzumab and Determination of Specific activity of [ 89 Zr]Zirconium Oxalate
Zirconium-89 in 1 M oxalic acid was neutralized by diluting with 1 M HEPES pH 7.4 followed by adding 2 M NaCO 3 (pH 11) dropwise until the solution was neutralized (pH 7 ± 0.2). Radiolabeling was performed using 15 different concentrations of DFO-trastuzumab and was prepared by 1:2 serial dilution in HEPES (100 µL) to give final DFO-trastuzumab masses in the range of 200 µg to 0.024 µg. Approximately 3.3 MBq of the neutralized [ 89 Zr] solution was added to each reaction tube. The reaction mixture was incubated at 37 • C in a shaker at 650 RPM for two hours. The reaction mixture was cooled to room temperature and 1 µL aliquots were analysed using iTLC with 0.15 M sodium citrate as a mobile phase. iTLC was measured using radioTLC scanner. The results of DFO-trastuzumab titration were plotted and fit with a sigmoidal dose-response curve to create an EC 50 value and used to calculate specific activity in MBq/ug.

Cyclotron Irradiation of 89 Y
Zirconium-89 was produced by proton irradiation of commercially available 89 Y sputtered on a niobium coin using the 89 Y(p, n) 89 Zr reaction on a TR-24 cyclotron. Proton irradiation on 89 Y-targets has been investigated by several research groups [1,12,15,20,21]. Damage to the yttrium coins (yttrium solid and sputtered coins) was reported by Queern et al. [20]. In their production method, cyclotron irradiations were performed using proton beam energy 17.8 MeV degraded to 12.8 MeV using a 0.75 mm aluminium degrader. Beam currents of 40-45 µA were applied. Using the same irradiation conditions, we did not observe any damage to the yttrium target when irradiated for up to 4 h. The activity of the purified 89 Zr solutions was in the range of 866-1160 MBq after 2 h of irradiation using 45 µA beam current. Contamination of 88 Zr and 88 Y was not observed, as the formation of 88 Zr and 88 Y occurs via the 89 Y(p,2n) 88 Zr reaction at higher incident proton energies >13 MeV.

Automation
With the vast development of 89 Zr radiolabeled antibodies for diagnostic application using PET imaging and increasing demand for their clinical use, there is a need for cGMP grade 89 Zr. In this study, we have adopted a commercially available cGMP-compliant TRASIS miniAiO to achieve efficient and reproducible batches of 89 Zr. This automated module was used for the target dissolution and separation of 89 Zr from the yttrium. In our method, the separation time including dissolution of the target was completed within 1 h. In addition, automated data acquisition was employed, allowing for full GMP-compliant documentation of the process. Furthermore, hydroxamate resin cartridge preconditioning and sterile-filter integrity testing were programmed in the same sequence file. The 89 Zr was eluted with a very small volume of oxalic acid (1.5 mL) directly over the sterile filter into the final vial. The automation of 89 Zr resulted in a significant reduction in the radiation dose and increased the GMP compliance.
Wooten et al. [14]. described an in-house automation system for 89 Zr processing constructed from extruded Al modular framing attached to walls made of ultra-high molecular weight polyethylene with components mounted on the plastic walls and a computer-controlled separation. This in-house automation method suffered from rather low and inconsistent recoveries (44-97%; average 74% ± 16%), while this work had a consistent recovery of 88.2-98.1% (average 93.6% ± 5%). Unlike the in-house module, the use of the GMP-certified AllinOne ASU produced under ISO 9001 offers an easier pathway to obtaining 89 Zr that meets cGMP needs for clinical studies.

Specific Activity and Radionuclidic Purity
The specific activity in the 89 Zr-immuno-PET imaging is vitally important because the amount of antibody injected in the preclinical or clinical subjects can alter the quality immuno-PET images and quantification. Particularly, tumour-specific antibodies or peptides for diagnostic and therapeutic applications where only small amounts of antibodies are injected to ensure site-specific uptake. Metallic impurities can compete with the radioisotope for binding sites or ligands during the radiolabelling process with a resulting decrease in radiolabelling efficiency. In order to achieve higher radiolabelling efficiency, radionuclides need to be free from metallic impurities and this can be achieved by selecting high purity target material, energy window for irradiation and trace metal grade solutions for processing. The conventional method to determine effective specific activity (ESA) of 89 Zr is titration with commonly used chelator deferoxamine (DFO). In this method, the known quantities of p-SCN-Bz-DFO is titrated with 89 Zr. The specific activity of three production batches was calculated and was found to be in the range of 1351-2323 MBq/µmol. Our effective specific activities by titration method were low compared to reported data by Queern et al. [20], but similar to those of Wooten et al. [14]. Our ICP-MS analysis showed significantly lower concentration of metallic impurities compared with those of Queern et al. [20]. The radionuclidic purity of 89 Zr mainly depends on the purity of the target material and irradiation conditions. The [ 89 Zr]zirconium oxalate solution was tested for radionuclidic identity and purity using a high purity germanium (HPGe) detector ( Figure 3A). The analysis showed the presence of 909 and 511 keV peaks. No additional radioactive contamination was detected. In these studies, the radionuclidic purity of the isolated 89 Zr fractions was found to be >99.99%. Similar values for radionuclidic purity have been reported by other authors [1,14,20].
Molecules 2020, 25, x 8 of 11 presence of 909 and 511 keV peaks. No additional radioactive contamination was detected. In these studies, the radionuclidic purity of the isolated 89 Zr fractions was found to be >99.99%. Similar values for radionuclidic purity have been reported by other authors [1,14,20]. Gamma spectrometry of waste was also performed to determine radioactive impurities produced during irradiation. These impurities were successfully removed using hydroxamate resin as these impurities were not adhered on hydroxamate resin cartridge. The radioactive impurities produced during production were 52 Mn, 54 Mn, 56 Co, 65 Zn, 67 Ga, 96 Tc, 48 V ( Figure 3B).

Radiolabeling and Characterization of 89 Zr-DFO-Trastuzumab
Radiolabeling experiments were performed as described in the literature [3,19]. To obtain the quantitative radiolabeling yield and to determine specific activity, several reactions with different concentrations of DFO-trastuzumab were performed and analysed on iTLC (Figure 4 A and B). Reported specific activities of 89 Zr-DFO-trastuzumab typically range from 0.067 to 0.296 MBq/µg [20,22,23].
The labeling efficiency of 89 Zr-DFO-trastuzumab was 100% ± 5% when 25 µg of DFOtrastuzumab and 3.3 MBq 89 Zr was used. The specific activity was 0.308 MBq/µg. which is comparable to Queern et al. [20] (specific activity 0.296 MBq/µg with DFO-trastuzumab). The results of radiolabelling efficiencies are summarized in Table 1.  Gamma spectrometry of waste was also performed to determine radioactive impurities produced during irradiation. These impurities were successfully removed using hydroxamate resin as these impurities were not adhered on hydroxamate resin cartridge. The radioactive impurities produced during production were 52 Mn, 54 Mn, 56 Co, 65 Zn, 67 Ga, 96 Tc, 48 V ( Figure 3B).

Radiolabeling and Characterization of 89 Zr-DFO-Trastuzumab
Radiolabeling experiments were performed as described in the literature [3,19]. To obtain the quantitative radiolabeling yield and to determine specific activity, several reactions with different concentrations of DFO-trastuzumab were performed and analysed on iTLC ( Figure 4A,B). Reported specific activities of 89 Zr-DFO-trastuzumab typically range from 0.067 to 0.296 MBq/µg [20,22,23].

Elemental Analysis
The ICP-MS analyses of three batches of the final 89 Zr solution (1.0 mL) were performed after decay of 89 Zr. The concentrations of impurities such as yttrium, zirconium, zinc, aluminium, copper, nickel, iron, chromium, niobium and magnesium were quantified by ICP-MS (Table 2). All impurity levels were significantly lower than previously reported values [15,20] and always below <1.0 ppm

Conclusions
We report a simplified and efficient automated purification method for [ 89 Zr]zirconium oxalate with high radionuclidic purity using the commercially available TRASIS miniAiO automation module. This method showed reproducible results for the production of [ 89 Zr]zirconium oxalate. Additionally, the automated process with disposable cassettes provides sterile [ 89 Zr]zirconium oxalate and documentation of the manufacturing process that can be used to fulfil cGMP requirements. This automated process can also be adopted for [ 89 Zr]Cl2 production. With adequate shielding, the module ensures safe user operation and environmental radiation protection. This study The labeling efficiency of 89 Zr-DFO-trastuzumab was 100% ± 5% when 25 µg of DFO-trastuzumab and 3.3 MBq 89 Zr was used. The specific activity was 0.308 MBq/µg. which is comparable to Queern et al. [20] (specific activity 0.296 MBq/µg with DFO-trastuzumab). The results of radiolabelling efficiencies are summarized in Table 1.

Elemental Analysis
The ICP-MS analyses of three batches of the final 89 Zr solution (1.0 mL) were performed after decay of 89 Zr. The concentrations of impurities such as yttrium, zirconium, zinc, aluminium, copper, nickel, iron, chromium, niobium and magnesium were quantified by ICP-MS ( Table 2). All impurity levels were significantly lower than previously reported values [15,20] and always below <1.0 ppm

Conclusions
We report a simplified and efficient automated purification method for [ 89 Zr]zirconium oxalate with high radionuclidic purity using the commercially available TRASIS miniAiO automation module. This method showed reproducible results for the production of [ 89 Zr]zirconium oxalate. Additionally, the automated process with disposable cassettes provides sterile [ 89 Zr]zirconium oxalate and documentation of the manufacturing process that can be used to fulfil cGMP requirements. This automated process can also be adopted for [ 89 Zr]Cl 2 production. With adequate shielding, the module ensures safe user operation and environmental radiation protection. This study strongly reinforces the utility of commercially available automated modules for the production of cGMP grade 89 Zr.