Next Article in Journal
Pharmacological Evaluation of 3-Carbomethoxy Fentanyl in Mice
Next Article in Special Issue
Radiosynthesis and Radiotracer Properties of a 7-(2-[18F]Fluoroethoxy)-6-methoxypyrrolidinylquinazoline for Imaging of Phosphodiesterase 10A with PET
Previous Article in Journal
L-Arginine Supplementation and Metabolism in Asthma
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:

Magnesium-Molybate Compounds as Matrix for 99Mo/99mTc Generators

Fabiola Monroy-Guzman
Thania Susana Jimenez Martinez
Humberto Arriola
2 and
Luis Carlos Longoria Gandara
National Institute of Nuclear Research (ININ) Carretera Mexico-Toluca, 52750, Mexico
Faculty of Chemistry, National University of Mexico, Coyoacan 04510, Mexico
Author to whom correspondence should be addressed.
Pharmaceuticals 2011, 4(2), 215-232;
Submission received: 30 November 2010 / Revised: 5 January 2011 / Accepted: 13 January 2011 / Published: 25 January 2011
(This article belongs to the Special Issue Radiochemistry)


: This work reports the preparation of a 99mTc generator based on conversion of 99Mo produced by neutron irradiation, into insoluble magnesium 99Mo-molybdates compounds as matrix. The effect of magnesium salt types and concentration, Mg:Mo molar ratios, pH of molybdate solutions, eluate volume as well as the addition order of molybdate and magnesium solutions' influences on the final 99mTc were evaluated. Polymetalates and polymolybdates salts either crystallized or amorphous were obtained depending on the magnesium salt and Mg:Mo molar ratio used in matrix preparation. 99Mo/99mTc generator production based on magnesium-99Mo molybdate compounds allow reduction of preparation time and eliminates the use of specialized installations. The best generator performances were attained using matrices prepared from 0.1 mol/L MgCl2·6H2O solutions, ammonium molybdate solutions at pH 7 and at a Mg:Mo molar ratio of 1:1.

1. Introduction

Technetium-99m (99mTc) is used for more than two thirds of nuclear imaging techniques because of its short 6.02 h half-life, simple decay scheme (a single 141 KeV photon), minimum whole-body dose, versatile chemistry, and availability from the 99Mo/99mTc generator [1-2]. This system is based on adsorption of 99Mo on an alumina column where 99mTc formed from decay of the 99Mo is periodically eluted from the column using physiological saline, as sodium pertechnetate (Na99mTcO4) while 99MoO42− remains attached to alumina. The limited loading capacity of alumina for molybdenum (2 mg Mo/g alumina) forces the use of a uranium fission product with a high specific activity, 99Mo (105 Ci/g Mo) [3], thus requiring sophisticated separation processing infrastructure and disposal of large amounts of radioactive wastes [4-5]. To avoid this, alternative methods of 99Mo/99mTc generator production have been investigated using low and medium specific activity 99Mo, produced from (n,γ) nuclear reaction with natural Mo (activation method) and directly converted into insoluble substrates that can be eluted in a column. 99Mo/99mTc generator based on heteropolyanions such as zirconium molybdate, titanium molybdate, molybdocerates, etc., [6-12] have been developed by some laboratories around the world. This is due to the molybdates' matrix capacity to incorporate up to 30% in weight of 99Mo [13] compared to 0.2% in traditional alumina based generators. Although these generators has opened a way of making column type 99mTc generator even using low and medium specific activity 99Mo, the handling problems (precipitation, filtration drying, fragmentation, etc.) still exist because these 99Mo-molybdates are mostly synthesized from 99Mo, requiring sophisticated remote handling facilities and at least 6 h processing time [12,14]. To simplify the production process of these systems, we propose preparing 99Mo/99mTc generators based on magnesium 99Mo-molybdate compounds by synthesizing magnesium molybdate compounds, followed by irradiation. This approach has three advantages: (1) it eliminates the use of specialized installations for molybdates synthesis; (2) it reduces 99Mo/99mTc generator preparation time and (3) it minimizes radiological contributions at 99mTc eluats due to the only radioisotope produced for the manganesium (24Mg) during magnesium molybdate compound irradiation which has a short half life: 9.46 min.

Systematic studies on 99Mo/99mTc generators based on magnesium 99Mo-molybdate compounds were performed. The effect of six parameters on the 99Mo/99mTc generator performance were evaluated: magnesium concentration and salt type, Mg:Mo molar ratios, molybdates solutions and precipitated pH, and addition order of molybdate and magnesium solutions. The physical-chemical properties of magnesium molybdate compounds were also determined to relate their properties with generator performance.

2. Results and Discussion

2.1. Performances of 99Mo/99mTc Generators Based on Magnesium 99Mo-Molybdate Compounds

Table 1 shows the performances of the 99Mo/99mTc generators based on magnesium 99Mo-molybdate compounds prepared in this research. Results are divided into three series, in line with the type of magnesium salts used in the generator preparation: magnesium chloride hexahydrate (series A), magnesium nitrate hexahydrate (series B) and magnesium sulfate hexahydrate (series C). The generator performances were compared with those advised by the Pharmacopoeia for the 99mTc eluates used with medical purposes: 99Mo breakthrough less than 0.015%, a minimum percentage of 95% for the radiochemical purity, a chemical purity less than 10 ppm for aluminium and pH values between 4.5 and 7.5 [15].

99Mo breakthrough percentages of less than 0.015% were only obtained in the matrices prepared from: (a) 0.5 mol/L MgCl2·6H2O (series A) and b) 1 mol/L MgNO3·6H2O solutions (series B) using ammonium molybdate solutions at pH of 7 and a Mg:Mo molar ratio of 1:2 (Figure 1). However, 99mTc elution efficiencies of theses generators were less than 48%, except for the matrix B7. On the other hand, the highest elution efficiencies (>70%) were obtained in the generators prepared from 0.1 mol/L Mg(NO3)2·6H2O solutions, at a Mg:Mo molar ratio of 0.2:1 and ammonium molybdate solutions at pH values between 4.5 and 10, however under these conditions, 99Mo breakthrough of the eluates were more than 0.7%, apart from the matrix B7. 99mTc eluates of the matrices prepared preferably with Mg:Mo molar ratio of 2:1 presented radiochemical purity of more than 95% and, in general, those made from MgCl2·6H2O solutions which satisfy the eluate pH values fixed by the Pharmacopoeia: between 4.5 and 7.5, while the eluate pH values obtained from the matrices formed with MgSO4·6H2O were the more acid, between 1 and 3. The average elution volume of all the generators studied ranged between 2 and 3.5 mL and all 99mTc eluates had an Al content of less than 10 ppm. It is important to note that a high 99Mo breakthrough percentage in the eluates entails the presence of Mg2+ in solution.

The Mo and Mg content in the generators is directly connected with: the Mg:Mo molar ratio, the type and concentration of magnesium salt used during matrix synthesis and matrix washing before irradiation. Thus the highest (75-50%) and lowest (18–7%) Mo percentages, and vice versa for Mg content, were recorded in the washed matrices and those prepared from MgSO4·6H2O solutions at Mg:Mo molar ratio of 2:1 respectively.

Matrix washing caused a decrease of the 99mTc elution efficiencies and Mg percentage in the matrix, while an increase in magnesium salt concentration (series C) induced a drop in the 99mTc elution efficiency and acidification of 99mTc eluates. The addition order of magnesium salt and ammonium molybdate solutions, and ammonium molybdate pH in the matrix process preparation (series B) did not cause meaningful changes in 99Mo/99mTc generator performance.

99mTc eluates produced by the generators prepared from MgCl2·6H2O solutions (series A) mostly attained the pH values established by the Pharmacopoeia: between 4.5 and 7.5, while higher acid eluates were obtained in the matrices synthesized from MgSO4·6H2O solutions. When the Mg proportion was higher than Mo in the Mg:Mo molar ratio, 99Mo breakthrough percentage increased in the 99mTc eluates and the Mo percentages in the matrix decreased. All 99mTc eluates of series A were colorless, those prepared from MgNO3·6H2O solutions at pH 10 or adding the ammonium molybdate solutions to magnesium salts (series B) presented a yellow coloration, while some of series C eluates showed a yellow coloring or a blue precipitate, in fact only the 99mTc eluates obtained from generator prepared with 0.1 mol/L MgSO4·6H2O solutions were colorless.

2.2. Characterization of Magnesium Molybdate Compounds

Crystalline phases identified by XRD (see Table 1 and Figure 2a) showed that the type of magnesium salt used in preparing generator matrices determines their chemical composition. In accordance with these data, Mg-Mo compounds prepared from MgCl2·6H2O, Mg(NO3)2·6H2O and MgSO4·6H2O solutions are mainly constituted of: (a) NH4MgCl3·6H2O, MoO3 and NH3(MoO3)3; (b) amorphous compounds and unidentified crystalline phases and (c) NH4MgCl3·6H2O, (NH4)2Mg(SO4)2·6H2O and amorphous compounds, respectively. These results are congruent with the thermogravimetric and infrared spectra shown in Figures 2b which present a characteristic pattern for each magnesium salt used. The thermal decomposition step multiples of different matrices prove the presence of compound mixtures. In series A, it is possible to identify five main causes for weight-loss, firstly water elimination of ammonium magnesium chloride hydrate (∼116 °C), later the transformation of NH4MgCl3 in Mg(OH)Cl and NH4Cl (160–170 °C), after NH4Cl decomposition (∼220 °C), the formation of MgO from Mg(OH)Cl (350–550 °C) and finally the decomposition of MoO3 (770–800 °C) [8,16]. Three weight-losses are evident in the series B at 214, 330 y 770 °C which could be derived from NH3Cl, Mg(OH) and MoO3 decomposition respectively considering that amorphous materials and the unidentified phases (Figure 2b) are constituted by Mo, Mg, NO3, NH3 and Cl and making an analogy with the compounds formed in series A. In the case of series C, the weight-loss is fixed by the NH4MgCl3·6H2O, (NH4)2Mg(SO4)2·6H2O and amorphous molybdenum compound decomposition (see Table 1 and Figure 2b): dehydratation (96–130 °C), elimination of [NH4+] in NH4MgCl3 (167 °C) and (NH4)2Mg(SO4)2 (451 °C), decomposition of NH4Cl (∼237 °C), formation of MgO (300–400 °C) and decomposition of MoO3 (756 °C) [16].

The effect of magnesium salt on forming different magnesium-molybdenum compounds during generator matrices preparation was also demonstrated by infrared analysis shown in Figure 2c. The matrix spectra prepared using MgCl2*6H2O, Mg(NO3)2*6H2O and MgSO4*6H2O solutions have similar troughs in the 3500-1200 cm−1 region, but with differences in band intensities.

In this region, ammonium and water displays strong broad N-H and O-H stretching bands between 3500 and 3300 cm−1 and bands at 1405 and 1640 cm−1 respectively [8,17-18]; while significant differences in intensities and wavenumber values and of each matrix were noted in fingerprint region (1200–400 cm−1). All matrices spectra exhibit characteristic absorption bands of Mo-O-Mo vibration at 960, 910 cm−1 and N-H bonds at 1075 and 1220 cm−1 as well as a band at 620 cm−1 possibly originated from Mg vibrations [8,18-19]. Only the matrix prepared from Mg(NO3)2*6H2O presented broad bands at around 470 cm−1 attributed to Mg-O bonds [19], and that from MgSO4*6H2O showed characteristic bands assigned to [SO42−] (628, 700, 1075, 1130, 1287 cm−1) and Mo-O vibrations at 792 and 880 cm−1 whereas that from MgCl2*6H2O presented peaks 760 and 545 cm−1 assigned to the Mo-O vibrations and possibly to Mg-Cl bonds respectively [8,18-19].

The X-ray diffraction patters and thermograms of a typical matrix washed and unwashed are shown in Figure 3a and 3b. The diffractograms show that the washed matrix before irradiation is constituted only by MoO3 and the unwashed one by a mixture of MoO3 and NH4MgCl3*6H2O. These data match with thermograms of the washed and unwashed matrix which have typical patterns of pure and mixed compounds respectively. Thus, washed matrices before irradiation cause soluble compounds to be removed, mainly those containing ammonium and magnesium in the matrix and conversion of the molybdenum compounds in MoO3. It is important to note that this behavior is independent of the type of magnesium salt used in preparing the matrix (Table 1).

The effect of matrix washing on morphology is shown in Figure 3c. The unwashed matrices present a crystalline phase soaked in an amorphous material, and the washed matrices only have the crystalline phase, constituted by rods of different thicknesses and length.

2.3. Discussion

The performance of the 99Mo/99mTc generators based on magnesium-molybdate compounds depends upon matrix preparation and treatment methods. The latter has to be an insoluble precipitate to avoid 99Mo leakage, whilst simultaneously allowing 99mTc release, and have a high Mo content that enables the use of low specific activities of 99Mo (2.5 Ci/g) in the generator and a good thermal and radiation stability.

Magnesium molybdate is fairly soluble in water [20-21] and literature has reported obtaining magnesium molybdate precipitates, mainly used in catalysis, applied suitable thermal treatments and magnesium and molybdate concentrations. For example, Yoon et al. have reported magnesium molybdates precipitation from Mg(NO3)2·6H2O and (NH4)3Mo7O24·4H2O solutions and calcining at different temperatures (200–650 °C) [19]. Ozeki et al. prepared magnesium molybdate solids by concentrating a mixed solution of 0.1 mol/L sodium molybdate and 4.5 mol/L magnesium chloride [20]. Amber et al. obtained MgMoO4·H2O from 0.1 mol/L Na2MoO4 and 0.5 mol/L MgCl2 solutions at pH 6 treated at 155 °C for 3 days [22].

In this work, insoluble magnesium molybdate compound precipitation was favored by adjusting pH and irradiation, and not by thermal treatment. Under these experimental conditions, magnesium molybdate compounds obtained were mainly polymetalates salts such as xNH4MgCl3·yMoO3, and polymolybdates [NH4Mo5O15(OH)] (see Figure 2 and Table 2). Assuming that compound formation is the result of three steps, firstly the formation of ammonium molybdates according to reaction (1):

Mo O 3 + 2 N H 4 OH ( N H 4 ) Mo O 4 + H 2 O

The molybdate ion generally exists as MoO42− in alkaline or neutral solutions (pH > 6) while polymolybdate ions such as [Mo7O24]6−, [Mo8O26]4−, [Mo36O112]8− are formed in acid solutions [19,23-27]:

xMo O 4 2 + y H + M o x O z ( OH ) 8 x y 2 z ( 2 x y ) + ( y 4 x z ) H 2 O

Thus the ammonium molybdate solutions prepared at pH 10 and 7 contain simply MoO42- ions and those at pH 4.5 a mixture of polymolybdate ions where the predominant species is probably the [Mo7O24]6− ion [18]. In the second step, ammonium molybdates react with magnesium solutions to form magnesium-molybdates solutions. Considering these solutions pH values can vary between 8 and 4.3, the magnesium molybdates can be constituted by MoO42− (pH > 6) or polymolybdates (pH < 6) according to:

( N H 4 ) Mo O 4 + MgX MgMo O 4 + N H 4 X
( N H 4 ) ( 2 x y ) M o x O z ( OH ) 8 x y 2 z + ( 2 x y ) MgX M g ( 2 x y ) M o x O z ( OH ) 8 x y 2 z + ( 2 x y ) N H 4 X X = C l , N O 3 or S O 4 2 ,

In the last step, the magnesium molybdates are induced to precipitate by adjusting pH values of the solutions to be between 1.9 and 0.3. At pH < 2, literature has reported the presence of very large polymolybdate species like [Mo36O112]8− [23,25] or MoO3·2H2O precipitation [19,28-29]. X-ray diffraction data (see Table 2 and Figure 2) suggests polymetalates formation such as xNH4MgCl3·yMoO3 or polymolybdates according to:

MgMo O 4 + 2 N H 4 X + 2 HCl N H 4 MgC l 3 · Mo O 3 · H 2 O + N H 4 X
uMgMo O 4 + vN H 4 X + wHCl u NH 4 MgC l 3 · ( N H 4 ) ( 2 x y ) M o x O z ( OH ) 8 x y 2 z + ( v u 2 x y ) N H 4 X
M g ( 2 x y ) Mo x O z ( OH ) 8 x y 2 z + vN H 4 X + wHCl ( 2 x y ) N H 4 MgC l 3 · ( N H 4 ) ( 2 x y ) M o x O z ( OH ) 8 x y 2 z + v ( 2 x y ) N H 4 X

The Cl ion usually displaces NO3 and SO42− ions [30] when magnesium nitrate and sulfate are employed in preparing magnesium molybdates; for that reason ammonium magnesium chlorides (NH4MgCl3) were present in all the series studied (see Table 2 and Figure 2), however mixtures of NH4MgCl3 and (NH4)2Mg(SO4)2 were also identified in matrices prepared from magnesium sulfates.

An excess of molybdenum favors polymolybdates and formation of amorphous phases whereas a surplus of magnesium the presence of ammonium magnesium salts and crystalline phases. Thus, the crystallinity degree of the compounds contained in the matrix is closely attached to 99Mo/99mTc generator performances. For example amorphous matrices presented the best 99mTc elution efficiencies (series B) while the crystalline (series A) presented lower 99Mo breakthrough (see Table 1, Figure 1). Assuming that amorphous materials also consist of molybenum oxides or polymolybdates and that the oxides and hydrous oxides of Mo(VI) exhibit cation exchange properties and show little or no anion exchange character even in acid solution [31] and ammonium magnesium salts have no adsorption properties, so the separation mechanism of the 99Mo and 99mTc in the generators can be explained by free diffusion of 99mTcO4 ion inside the matrix because the 99mTcO4 anion produced in the generator is not adsorbed in the matrix and can be removed from the chromatographic column by elution with isotonic saline solution, leaving the 99Mo inside. In accordance with this argument, a crystalline matrix acts as a molecular sieve preventing 99mTc mobility and causing generator efficiency decrease. Whereas a flexible random network (amorphous) increases generator efficiency and radiochemical purity because the matrix is more elastic but simultaneously harder and more resistant to mechanical breakdown and more difficult to dissolve. The low 99mTc eluate radiochemical purities obtained in some generators can be explained by Tc(VII) reduction caused by the presence of insoluble species of polymolybdates, which are strong oxidizing agents [18].

Inorganic materials are susceptible to irradiation-induced amorphization producing particularly volume changes in crystalline or amorphous phases. The main concern with large differential volume changes is that it may affect atomic bonding, local coordination, and the pathways for ion exchange, all of which can impact the release rates of radionuclides [32]. Thus the matrix amorphization caused by its irradiation could be linked to the high 99Mo breakthrough obtained in generators for which matrices are mainly formed by amorphous compounds such as the series B and C.

3. Experimental

3.1. Preparation of Magnesium 99Mo-Molybdate Compounds

Magnesium 99Mo-molybdate compounds were formed from magnesium and molybdate solutions. The molybdate solutions were prepared from MoO3 natural pellets, previously heated to 650 °C for 1 h and dissolved in 2 mol/L NH4OH at a MoO3:2NH4OH molar ratio [8]. The pH of the formed ammonium molybdates was adjusted by adding 4 mol/L HCl and converted into magnesium molybdate by reacting with magnesium solutions. Magnesium molybdates pH were also adjusted using 4 mol/L HCl. The resulting solids were dried for 2 days using an infrared lamp and crushed in an agate mortar. One portion of magnesium molybdate precipitate was placed on a funnel to be washed using 200 mL of distilled water and the washed and unwashed solids were dried for 1 day at 40 °C in a stove. The dried magnesium molybdate were irradiated for 2 h at a neutron fluence of about 1.61 × 1013 n cm−2s−1 in the Triga Mark III Reactor (Mexico). After irradiation, about 1 g of magnesium 99Mo-molybdate (∼4.9 MBq/g) were added into a glass column (12 mm × 70 mm) containing a bed of 1 g acid alumina. The column was finally washed with 20 mL of saline solution [8,17-18]. The magnesium molybdate compounds were synthesized in duplicate at different conditions; where parameters such as magnesium salts and concentrations (MgCl2·6H2O, Mg(NO3)2·6H2O, MgSO4·6H2O), Mo:Mg molar ratios, ammonium and magnesium molybdates pH and the addition order of magnesium and molybdenum solutions were evaluated (see Table 2).

3.2. Elution of Generators and Eluate Analysis

The generators were eluted with 6 mL of 0.9% NaCl every 24 h for 1 week and the following parameter of the 99mTc eluates were determined: 99mTc elution efficiency, 99Mo breakthrough, 99mTc elution profile, 99mTc radiochemical purity, pH eluate and aluminium concentration. The 99mTc elution efficiency and the 99Mo breakthrough were calculated from the 99mTc and 99Mo activities measured in a CRC-10R Capintec dose calibrator and a GeHp solid state detector (Canberra 7229P) coupled to a PC-multichannel analyzer (ACUSPECT-A, Canberra, Australia). The radiochemical purity of the 99mTc eluate was determined by paper chromatography using 1 CHR (Whatman®) paper as solid phase and 85% methanol as mobile phase. The 99mTcO4Rf was 0.66–0.72. Aluminium and magnesium concentrations in 99mTc eluates were determined by the aluminon and Eriochrome Black T methods [18,33]. The eluate pH values were determined by pH paper.

3.3. Gel Characterization

Magnesium-molibdate compounds were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectrometry, thermogravimetry and neutron activation analysis. The X-ray diffraction patterns were obtained on a Siemens D500 diffractometer for 1 h and scanned from 2.5° to 70° with steps of 0.02°. SEM imaging was performed by Philips SL30. Digital images were obtained at 5,000×, 3,000×, 1,000× and 500× magnifications in randomly selected fields. The infrared measurements were taken on a Nicole Mgna-IR™ spectrometer 550 with the samples pressed in KBr pellets. The thermogravimetric analyses were performed using a Phillips unit at a heating rate of 10°/min under a nitrogen atmosphere [8,18]. Molybdenum and magnesium concentrations were determined by neutron activation. The procedure described in previous works was applied for molybdenum and in the case of magnesium, 50 mg of each magnesium molybdate and MgO, used as reference material, were irradiated in the Triga Mark II reactor at a neutron fluence of about 1.65 × 1012 n cm−2s−1 for 15 s. Magnesium was determined by the 843.4 keV γ-ray of 27Mg by means of a HPGe detector at a counting time of 100 s [13].

4. Conclusions

The performances of 99mTc generators are strongly related to the chemical composition of the matrix and consequently their preparation conditions. The magnesium molybdate compounds obtained were mainly salts of polymetalates such as NH4MgCl3·MoO3, NH4MgSO4·MoO3 and polymolybdates [MoxOz(OH)8x − y − 2z(2x − y)−] crystallized or amorphous. The type of magnesium salt and the Mg:Mo ratio used in the matrix preparation inhibits or favours polymetalate salts and polymolybdates amorphization. Crystalline NH4MgCl3·MoO3 were preferably obtained from MgCl2·6H2O solutions while amorphous compounds, probably constituted by polymetalates (see reactions 6 and 7) and unidentified crystalline phases were formed from Mg(NO3)2·6H2O solutions and mixtures of cristalline NH4MgCl3·MoO3 and NH4MgSO4·MoO3 and amorphous phases, also possible formed by polymetalates, were produced from MgSO4·6H2O solutions. An excess of molybdenum or magnesium during the matrix preparation favors amorphous or crystalline phases formation respectively. The degree of ordering of Mg-Mo compounds defines the 99mTc generators performances: high 99mTc elution efficiencies were obtained from amorphous matrices while lower 99Mo breakthrough by crystalline matrices. The free 99mTcO4 diffusion is proposed as separation mechanism of the 99Mo and 99mTc in the generators considering that polymetalates act as cation exchanges and the 99mTcO4 anion produced in the generator is not adsorbed in the matrix.

99Mo/99mTc generator production based on magnesium-99Mo molybdate compounds allow reduction of preparation time and eliminates the use of specialized installations. The best generator performances were attained using matrices prepared from 0.1 mol/L MgCl2·6H2O solutions, ammonium molybdate solutions at pH 7 and at a Mg:Mo molar ratio of 1:1.

Figure 1. Distribution of magnesium 99Mo-molybdate generator performances (99mTc eluate efficiency and pH, radiochemical purity) in function of 99Mo breakthough.
Figure 1. Distribution of magnesium 99Mo-molybdate generator performances (99mTc eluate efficiency and pH, radiochemical purity) in function of 99Mo breakthough.
Pharmaceuticals 04 00215f1a 1024Pharmaceuticals 04 00215f1b 1024
Figure 2. Magnesium salt effect used in the preparation of magnesium-molybdates in (a) X-ray diffraction patters, (b) thermograms and (c) infrared spectra.
Figure 2. Magnesium salt effect used in the preparation of magnesium-molybdates in (a) X-ray diffraction patters, (b) thermograms and (c) infrared spectra.
Pharmaceuticals 04 00215f2a 1024Pharmaceuticals 04 00215f2b 1024Pharmaceuticals 04 00215f2c 1024
Figure 3. Generator matrix washing effect on (a) X-ray diffraction patters; (b) thermograms and (c) morphology.
Figure 3. Generator matrix washing effect on (a) X-ray diffraction patters; (b) thermograms and (c) morphology.
Pharmaceuticals 04 00215f3a 1024Pharmaceuticals 04 00215f3b 1024
Table 1. Performances of 99Mo/99mTc generators based on magnesium 99Mo-molybdate compounds.
Table 1. Performances of 99Mo/99mTc generators based on magnesium 99Mo-molybdate compounds.
Series[Mg2+]Mg:MopH ammonium molybdatesEluate colorEluate Volume (mL)99Mo Breakthrough (%)99mTc elution efficiency (%)99mTcO4 (%)Al3+ 10ppmMg2+10ppmpH eluatewashedMo %Mg %Crystalline phases
A10.5 M0.64:17colorless3.50.02272.368-82<<3.8–4.4no61.4411.00MoO3, NH4 MgCl3*6H2O
A20.5 M0.93:17colorless20.01417.773<<4.5–5no49.448.89MoO3, NH4 MgCl3*6H2O
A2w0.5 M0.93:17colorless2.50.07131.175<<3.3–5yes47.982.52MoO3
A30.5 M1.08:17colorless604889<<3.2no67.417.11MoO3, NH4 MgCl3*6H2O
A3w0.5 M1.08:17colorless3.50.249.850<<3.2–4.2yes55.972.51MoO3
A40.5 M1.18:17colorless20.02524.284–94<<4.4–5.7no75.8311.55MoO3, NH4 MgCl3*6H2O
A4w0.5 M1.18:17colorless2.50.002643.237–77<<4.5–5yes47.204.29MoO3
A51 M2:17colorless21.372993<>2.8–3.7no15.821.35NH4 MgCl3*6H2O, NH3(MoO3)3, NH4Cl
A5w1 M2:17colorless30.0353493<<2.2–3.1yes28.030.69MoO3
A605 M2:17colorless30.855290<<4.8–5.5no11.2822.27NH4 MgCl3*6H2O, NH3(MoO3)3
A6w05 M2:17colorless30.061698<<4.3–6.8yes58.811.62MoO3
A70.5 M1:17colorless2.54.829.398<>4–4.2no28.0520.71NH4 MgCl3*6H2O, NH3(MoO3)3, NH4Mo5O15(OH)*2H2O
A80.5 M1:27colorless2.302084<<5.2–7.2no47.518.55NH4 MgCl3*6H2O, NH3(MoO3)3, NH4Mo5O15(OH)*2H2O
A90.1 M1:27colorless3.57.071092<>6.8–7no18.1610.8NH4 MgCl3*6H2O, NH3(MoO3)3, MoO3
A100.5 M2:14.5colorless2.80.16995<<4.0–5.2no9.0819.35NH4 MgCl3*6H2O, NH4Cl, NH3(MoO3)3
A110.5 M1:24.5colorless2.51.13720<<4.3–5.5no49.719.22NH3(MoO3)3, MoO3, NH4Mo5O15(OH) 2H2O, NH4 MgCl3*6H2O
A120.5M1:14.5colorless30.9526.296<<2.4–4no68.54MoO3, MoO3*H2O
B10.1M0.2:17colorless24.2483.987<<2.7–3no27.195.03amorphous, unidentified phases
B20.1M0.2:17yellow2.51.987.891<<1.7–2.6no19.973.63amorphous, unidentified phases
B30.1M0.2:14.5colorless21.167779<<2.2–4no21.312.45amorphous, unidentified phases
B40.1M0.2:14.5yellow210.7470.185<<2–3no26.052.89amorphous, unidentified phases
B50.1M0.2:110yellow2.51.881.389<<2–3.6no26.912.93amorphous, unidentified phases
B5w0.1 M0.2:110yellow60.7476.8483<<3.8–2.6yes
B60.1 M0.2:110yellow2.51.679.390<<2.3–5.3no25.831.56amorphous, unidentified phases
B6w0.1 M0.2:110yellow2.54.1742.778<>2.9–3.7yesMoO3, NH3(MoO3)3
B71 M1:17colorless5079.752–92<>3.4–4.2no42.333.37NH4 MgCl3*6H2O, NH3(MoO3)3
B7w1 M1:17colorless30.3955.498<<4.6–5yes64.90.88MoO3
B80.1 M1:24.5colorless30.03553.596–90<<5–6.3no47.65MoO3, NH4 MgCl3*6H2O, (NH4)2Mo3O10
B90.1 M2:14.5colorless21.2357.599<<4.3–4.8yes4.12amorphous, unidentified phases, NH4 MgCl3*6H2O
C11 M2:14.5yellow2.50.822982<>1–1.6no18.1635.72NH4 MgCl3*6H2O, (NH4)2Mg(SO4)2*6H2O
C20.1 M2:14.5colorless40.195089–96<<1.9–3.6no15.719.93NH4 MgCl3*6H2O, (NH4)2Mg(SO4)2*6H2O, NH4Cl,
C2w0.1 M2:14.5colorless22.22089–93<<3.9–4.4yes74.280.57MoO3
C30.05 M2:14.5yellow-clear23.8956.590<>3.1–3.4no7.1124.2NH4MgCl3 6H2O
C3w0.05 M2:14.5Blue precipited1.53.85081–94<2.5–1.7yes34.162.84amorphous, unidentified phases
C41 M1:17clear precipited2.5.5940.678<>1.9–2no11.3410.08NH4 MgCl3*6H2O, (NH4)2Mg(SO4)2 6H2O, amorphous
C4w1 M1:17colorless30.721581–95<<3.4–4.2yes69.53MoO3
Table 2. Preparation conditions of magnesium molybdate compounds.
Table 2. Preparation conditions of magnesium molybdate compounds.
SeriespH Ammonium molybdatesMg:Mo[MgCl2*6H2O] mol/L[MgCl2*6H2O] pHpH Magnesium molybdateAddition order
A170.64:10.50.720.05Mg(NO3)2→ [MoO42−]
A270.93:10.50.720.49Mg(NO3)2→ [MoO42−]
A371.08:→ [MoO42−]
A471.18:→ [MoO42−]
A572:115.91.2Mg(NO3)2→ [MoO42−]
A672:→ [MoO42−]
A771:→ [MoO42−]
A871:→ [MoO42−]
A971:→ [MoO42−]
A104.52:→ [MoO42−]
A114.51:→ [MoO42−]
A124.51:→ [MoO42−]
SeriespH Ammonium molybdatesMg:Mo[Mg(NO3)2*6H2O] mol/LpH [Mg(NO3)2*6H2O]pH Magnesium molybdateAddition order
B170.2:→ [MoO42−]
B270.2:[MoO42−] → Mg(NO3)2
B34.50.2:→ [MoO42−]
B44.50.2:[MoO42−] → Mg(NO3)2
B5100.2:→ [MoO42−]
B6100.2:[MoO42−] → Mg(NO3)2
B771:115.50.1Mg(NO3)2→ [MoO42−]
B84.51:20.1M5.51.0Mg(NO3)2→ [MoO42−]
B94.52:10.1M5.51.9Mg(NO3)2→ [MoO42−]
SeriespH Ammonium molybdatesMg:Mo[MgSO4*6H2O] mol/LpH [MgSO4*6H2O]pH Magnesium molybdateAddition order
C14.52:115.41.0Mg(NO3)2→ [MoO42−]
C24.52:→ [MoO42−]
C34.52:→ [MoO42−]
C471:115.41.0Mg(NO3)2→ [MoO42−]


This work was supported by the CONACYT (J-33049). The authors are indebted to the technical staff of the reactor department, and to the chemical nuclear laboratory for performing the IR and TGA analyses and to Ms. Leticia Carapia.


  1. Technetium-99m Radiopharmaceuticals: Manufacture of Kits; Technical Reports Series No. 466; IAEA: Vienna, Austria, 2008; pp. 7–21.
  2. Verbruggen, A.M. Technetium-99m radiopharmaceuticals: Current situation and perspectives. In Trends in Radiopharmaceuticals (ISTR-2005); Proceedings Series, IAEA: Vienna, Austria, 2007; Volume 1, pp. 3–19. [Google Scholar]
  3. Arino, H.; Kramer, H.H. Fission product 99mTc generator. Int. J. App. Rad. Isot 1975, 26, 301–303. [Google Scholar]
  4. Vandegrift, G.F.; Snelgrove, J.L.; Aase, S.; Bretscher, M.M.; Buchholz, B.A.; Chaiko, D.J.; Chamberlain, D.B.; Chen, L.; Conner, C.; Dong, D.; et al. Converting targets and processes for fission-product molybdenum-99 from high -to low-enriched uranium. In Production technologies for molybdenum-99 and technetium-99m; IAEA-TECDOC-1065 IAEA: Vienna, Austria, 1999; pp. 25–75. [Google Scholar]
  5. Savushkin, I.A.; Gourko, O.B. Tc-99m production on the basis of Central Generator and Wasteless reactor Zr-Mo Gel-Technology. In Advances in Nuclear and Radiochemistry; Qaim, S.M., Coenen, H.H., Eds.; Forschungszentrum Julich GmbH: Aachen, Germany, 2004; pp. 336–338. [Google Scholar]
  6. Evans, J.V.; Shying, M.E. Zirconium Molybdate Gel as a Generator for Technetium-99m; Australian Atomic Energy Comission, AAEC/E59: Sutherland, Australia, 1984. [Google Scholar]
  7. Vanaja, P.; Ramamoorthy, N.; Iyer, S.P.; Mani, R.S. Development of a new 99mTc generator using neutron irradiated titanium molybdate as column matrix. Radiochim. Acta. 1987, 42, 49–52. [Google Scholar]
  8. Monroy-Guzmán, F.; Cortes Romerio, O.; Díaz Velásquez, H. Titanium molybdate gels as matrix of 99Mo/99mTc generators. J. Nucl. Radiochem. Sci. 2007, 8, 11–19. [Google Scholar]
  9. El Absy, M.A.; El Nagar, M.; Audah, A.I. Technetium-99m generators based on neutron irradiated 12-molybdocerate as column matriz. J. Radioanal. Nucl. Chem. 1994, 183, 339–350. [Google Scholar]
  10. El Absy, M.A.; El-Bayoumy, S. The use of stannic molybdate-99Mo as a 99mTc generator. Isotopenpraxis 1990, 26, 60–63. [Google Scholar]
  11. El Kolaly, M.T. A 99Mo/99mTc generator based on the use of zirconium molybdophosphate-99Mo gel. J. Radioanal. Nucl. Chem. 1993, 170, 293–298. [Google Scholar]
  12. Narasimhan, D.V.S.; Vanaja, K.P.; Mani, R.S. A new method for Tc-99m generator preparation. J. Radioanal. Nucl. Chem. 1984, 85, 345–356. [Google Scholar]
  13. Monroy-Guzman, F.; Arriola Santamaría, H.; Ortega Álvarez, I.; Cortés Romero, O.; Díaz Archundia, L.V. Determination of Mo, W and Zr in molybdates and tungstates of zirconium and titanium. J. Radioanal. Nucl. Chem. 2007, 271, 523–532. [Google Scholar]
  14. Monroy-Guzman, F.; Barron Santos, E.S.; Hernandez, S. Synthesis installation of zirconium-99Mo-molybdate gels to 99Mo/99mTc generador. In Synthesis and Applications of Isotopically Labelled Compounds; Dean, D.C., Filer, C.N., McCarthy, K.E., Eds.; Wiley: England, 2004; Volume 8, pp. 325–329. [Google Scholar]
  15. Farmacopea de los Estados Unidos Mexicanos, 9th ed.; SSA: Mexico, Mexico, 2008.
  16. Nouveau Traité de Chimie Minérale; Pascal, P., Ed.; Masson: Paris, France, 1958; Volume IV.
  17. Monroy-Guzman, F.; Diaz-Archundia, L.V.; Contreras Ramírez, A. Effect of Zr:Mo ratio on 99mTc generador performance based on zirconium molybdate gels. Appl. Rad. Isot. 2003, 59, 27–34. [Google Scholar]
  18. Monroy-Guzmán, F.; Díaz-Archundia, L.V.; Hernández-Cortés, S. 99Mo/99mTc generators performances prepared from zirconium molybate gels. J. Braz. Chem. Soc. 2008, 19, 380–388. [Google Scholar]
  19. Yoon, Y.S.; Suzuki, K.; Hayakawa, T.; Hamakawa, S.; Shishido, T.; Takehira, K. Structures and catalytic properties of magnesium molybdate in the oxidative dehydrogenation of alkanes. Catal. Lett. 1999, 59, 165–172. [Google Scholar]
  20. Ozeki, T.; Murata, K.; Kihara, H.; Hikime, S. Studies on the interaction of molybdate ion and magnesium ion observed in the Raman Spectra of the Mixture Solutions. Bull. Chem. Soc. Jpn. 1987, 60, 3585–3589. [Google Scholar]
  21. Essington, M.E. Formation of calcium and magnesium molybdate complexes in dilute aqueous solutions. Soil Sci. Soc. Am. J. 1992, 56, 1124–1127. [Google Scholar]
  22. Amberg, M.; Günter, J.R.; Schmalle, H.; Blasse, G. Preparation, crystal structure and luminiscence of magnesium molybate and tungstate monohydrates, MgMO4*H2O and MgWO4*H2O. J. Sol. Stat Chem. 1988, 77, 162–169. [Google Scholar]
  23. Tytko, H.K.; Glemser, O. Isopolymolybdates and isopolytungstates. In Advances Inorganic Chemistry and Radiochemistry; Academic Press: NY, USA, 1976; Volume 19, pp. 35–40. [Google Scholar]
  24. Honing, D.S.; Kustin, K. Relaxation spectra of molybdate polymers in aqueous solutions: Temperature-jump studies. Inorg. Chem. 1972, 11, 65–71. [Google Scholar]
  25. Pope, M.T. Heteropoly and Isopoly Oxometalates; Springer-Verlag: NY, New York, 1983; pp. 42–70. [Google Scholar]
  26. Baker, L.C.W.; Glick, D.C. Present general status of understanding of heteropoly electrolytes and a tracing of some major highlights in the history of their elucidation. Chem. Rev. 1998, 98, 3–50. [Google Scholar]
  27. Cruywagen, Y.Y. Potentiometric investigation of molybdenum (VI) equilibria at 25 °C in 1 M NaCl medium. Inorg. Chem. 1980, 19, 552–554. [Google Scholar]
  28. Sengupta, A.K. A unified approach to interpret unusual observations in heterogeneous ion exchange. J. Coll. Inter. Sci. 1988, 123, 201–215. [Google Scholar]
  29. Nekovář, P.; Schrötterová, D. Liquid-liquid exctration of Mo(VI) and V(V) by Prime JMT. J. Radioanal. Nucl. Chem. 1998, 228, 95–98. [Google Scholar]
  30. Jacobson, C.A. Encyclopedia of chemical reactions. J. Chem. Educ. 1940, 17, 406. [Google Scholar]
  31. Fuller, M.J. Inorganic ion-exchange chromatography on oxides and hydrous oxides. Chromatogr. Rev. 1971, 14, 45–76. [Google Scholar]
  32. Weber, W.J.; Ewing, R.C.; Catlow, C.R.A.; Díaz de la Rubia, T.; Hobbs, L.W.; Kinoshita, C.; Matzke, Hj.; Motta, A.T.; Nastasi, M.; Slje, E.K.H.; Vance, E.R.; Zinkle, S.J. Radiation effects in crystalline ceramics for the immobilization of high-level nuclear waste and plutonium. J. Mater. Reser. 1998, 13, 1434–1484. [Google Scholar]
  33. Sandell, E.B.; Onishi, H. Photometric Determination of Traces of Metals; Wiley: NY, USA, 1978. [Google Scholar]

Share and Cite

MDPI and ACS Style

Monroy-Guzman, F.; Jimenez Martinez, T.S.; Arriola, H.; Longoria Gandara, L.C. Magnesium-Molybate Compounds as Matrix for 99Mo/99mTc Generators. Pharmaceuticals 2011, 4, 215-232.

AMA Style

Monroy-Guzman F, Jimenez Martinez TS, Arriola H, Longoria Gandara LC. Magnesium-Molybate Compounds as Matrix for 99Mo/99mTc Generators. Pharmaceuticals. 2011; 4(2):215-232.

Chicago/Turabian Style

Monroy-Guzman, Fabiola, Thania Susana Jimenez Martinez, Humberto Arriola, and Luis Carlos Longoria Gandara. 2011. "Magnesium-Molybate Compounds as Matrix for 99Mo/99mTc Generators" Pharmaceuticals 4, no. 2: 215-232.

Article Metrics

Back to TopTop