Selective polarographic determination of stannous ion in technetium radiopharmaceutical cold kits.

UNLABELLED: The aim of this work was to develop a selective method for quantification of Sn(II) and Sn(IV) in dimercaptosuccinic acid (DMSA), ethylcysteinate dimer (ECD), methylenediphosphonic acid (MDP), and pyrophosphate radiopharmaceutical cold kits by differential pulse polarography. METHODS: A dripping mercury electrode 150 polarographic/stripping analyzer with a conventional 3-electrode configuration was used with 3 M H(2)SO(4) and 3 M HCl supporting electrolytes for Sn(II) and Sn(IV), respectively. The polarographic analysis was performed using a 1-s drop time, 50-mV·s(-1) scan rate, -50-mV pulse amplitude, 40-ms pulse time, and 10-mV step amplitude. To quantify Sn(IV), oxidation of Sn(II) by H(2)O(2) was performed. The calibration curves for Sn(II) and Sn(IV) were obtained in the range of 0-10 µg·mL(-1). RESULTS: The analytic curves for Sn(II) in 3 M H(2)SO(4) and Sn(IV) in 3 M HCl were represented by the following equations: i (µA) = 0.098 [Sn(II)] + 0.018 (r(2) = 0.998) and i (µA) = 0.092 [Sn(IV)] + 0.016 (r(2) = 0.998), respectively. The detection limits were 0.21 µg·mL(-1) for Sn(II) and 0.15 µg·mL(-1) for Sn(IV). In DMSA, ECD, MDP, and pyrophosphate, 90.0%, 64.9%, 93.2%, and 87.5%, respectively, of the tin was present as Sn(II). In this work, selective determination of Sn(II) and Sn(IV) was achieved using 2 supporting electrolytes (H(2)SO(4) and HCl). In 3 M H(2)SO(4), only Sn(II) produced a polarographic wave with the maximum current in -370 mV. Under the same conditions, no current could be determined for Sn(IV). In 3 M HCl, Sn(II) and Sn(IV) were electroactive and the maximum currents of the 2 waves appeared in -250 and -470 mV. No other components of the lyophilized reagents had any influence. CONCLUSION: The developed polarographic method was adequate to quantify Sn(II) and Sn(IV) in DMSA, ECD, MDP, and pyrophosphate cold kits.

A portable test system for determination of bacterial endotoxins in 18F-FDG, 99mTc, and lyophilized reagents for labeling with 99mTc.

UNLABELLED: A rapid quantitative kinetic chromogenic test in an automated portable test system has been developed for in-process and end-product determination of bacterial endotoxins in water using the Limulus amebocyte lysate. The aim of this work was to validate the method for (18)F-FDG, (99m)Tc, and the lyophilized reagents methylene diphosphonic acid (MDP) and pyrophosphate for labeling with (99m)Tc radiopharmaceuticals with no interfering factors. METHODS: Experiments were performed on 3 consecutive batches of (18)F-FDG, (99m)Tc, MDP, and pyrophosphate produced at the Nuclear Energy and Research Institute of São Paulo, Brazil, using a portable test system. The maximum valid dilution (=500) was calculated to establish the extent of dilution to avoid interfering test conditions. RESULTS: Better results were obtained above a 1:5 dilution factor for (18)F-FDG and (99m)Tc, 1:20 for MDP, and 1:100 for pyrophosphate. The requirements of the test were satisfied (R ≤ 0.980, recovery of product positive control between 50% and 200%, and coefficient variation of samples < 25%), and the endotoxin concentration was lower than the lowest concentration of the standard curve (0.05 endotoxin unit mL(-1)) and therefore less than the established limit in pharmacopoeias. CONCLUSION: The portable test system is a rapid, simple, and accurate technique using the quantitative kinetic chromogenic method for bacterial endotoxin determination. For this reason, the test is practical for radiopharmaceutical uses and tends to be the method of choice for the pyrogen test. For (18)F-FDG, (99m)Tc, MDP, and pyrophosphate, the validation was successfully performed.