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Background When using iTLC-SG thin layer chromatography plates to measure radiochemical impurities in 99mTc medronate, falsely high values were obtained for 99mTc pertechnetate impurity. Preliminary investigations indicated that the mass of 99mTc medronate applied to the plate influences the value. Aim The goal of this study was to determine if the concentration of medronate influences the value obtained for 99mTc pertechnetate impurity. Experimental 99mTc medronate was prepared at two concentrations: 4 mg/mL and 0.2 mg/mL. Impurity levels were measured using three stationary phases: dried and undried iTLC-SG and 54SFC paper. Two mobile phases were used: methyl ethyl ketone to detect 99mTc pertechnetate and sodium acetate 136 g/L to detect hydrolysed and colloidal 99mTc. Sample spot drying and volume were also investigated. Results With 4 mg/mL samples, the three stationary phases measured similar impurity levels (p > 0.05). With the 0.2 mg/mL samples, higher levels of 99mTc pertechnetate were measured with iTLC-SG than with paper (p

Background: The rate at which radioactive albumin particles clear from the bloodstream is used to measure reticuloendothelial capacity. Traditionally, iodine radioisotopes have been used. Non-active albumin particles mixed with the technetium-99 m labelled particles of the readily available radiopharmaceutical 99 mTc Albumin Nanocolloid (ANC) would be more convenient. Aim: To prepare human albumin nanospheres (HAN) with a diameter similar to 99 mTc-ANC and to investigate their stability. Experimental: HAN were prepared by heating 30 g/l albumin solution pH 10 at 70°C for 20 min then 75°C for 17.5 min, adjusting to pH 7.5 and sterilizing by filtration. Seven batches were prepared. The HAN diameter was measured by photon correlation spectroscopy at 0–3 months. Various measures of stability were performed. Results: The mean diameter of the HAN was 3.9 ± 1.9, 4.0 ± 1.5, 4.4 ± 1.6 and 4.2 ± 2.0 nm at 0, 1, 2 and 3 months. After mixing HAN and 99 mTc-ANC, no changes in particle size or radiolabelling of ANC were detected. Conclusions: HAN with a diameter comparable to the particles in 99 mTc-ANC were prepared successfully. The diameter of HAN does not change over 3 months or after mixing with 99 mTc-ANC. The particle size and labelling efficiency of 99 mTc-ANC are not affected by the addition of HAN. Copyright © 2011 John Wiley & Sons, Ltd.

Background: The European Pharmacopoeia and radiopharmaceutical manufacturers specify Instant Thin-Layer Chromatography Silica Gel impregnated glass fibre (ITLC-SG) as the stationary phase for measuring the radiochemical purity (RCP) of most technetium-99m (99mTc) radiopharmaceuticals. During 2008, The Pall Corporation stopped manufacturing ITLC-SG. A replacement is required. Aim: To evaluate Varian's Glass Microfibre Chromatography Paper impregnated with salicic acid (GMCP-SA) as a replacement. Experimental: Samples of six 99mTc radiopharmaceuticals (albumin nanocolloid, colloidal tin, exametazime, medronate, pentetate and succimer) were prepared containing levels of radiochemical impurities between 0 and 10%. Samples were tested using ITLC-SG and GMCP-SA with the mobile phase specified in the pharmacopoeia or by the manufacturer. Analysis was performed by thin-layer radiochromatogram scanning. Results: For measuring the RCP of albumin nanocolloid, colloidal tin, exametazime and succimer, GMCP-SA is a suitable replacement for ITLC-SG. For medronate, GMCP-SA is suitable for measuring colloidal 99mTc impurity despite producing slightly higher values than ITLC-SG, but unsuitable for measuring 99mTc pertechnetate impurity due to significant over-estimation. For pentetate, GMCP-SA is suitable for measuring colloidal 99mTc impurity but gives slightly higher values for 99mTc pertechnetate impurity than ITLC-SG. Conclusion: GMCP-SA is a suitable alternative to ITLC-SG for analysing some 99mTc radiopharmaceuticals but is not a universal replacement. Copyright © 2009 John Wiley & Sons, Ltd.

Background: The European Pharmacopoeia specifies Instant Thin-Layer Chromatography Silica Gel (ITLC-SG) as the stationary phase for measuring radiochemical impurities in 99mTc Medronate. The Pall Corporation has stopped manufacturing ITLC-SG. Aim: To investigate chromatography papers as alternatives to ITLC-SG. Experimental: The resolution of the main 99mTc Medronate and impurity peaks were compared on five Whatman papers (1CHR, 31ET, 3MM, 4CHR and 54SFC) using the pharmacopoeial mobile phases: methyl ethyl ketone for detecting 99mTc pertechnetate impurity and sodium acetate solution (136 g/l) for detecting hydrolysed reduced and colloidal 99mTc impurities. The effects of three sample spot treatments (wet, hot dried and air dried) on the distribution of the radiochemical impurities were compared. The levels of radiochemical impurities measured in samples of 99mTc Medronate were compared. Results: The highest resolutions were obtained with 1CHR, 4CHR and 54SFC. Sample spot drying resulted in the measurement of artifactually high levels of 99mTc pertechnetate impurity. When analysing 99mTc Medronate, erroneously high levels of colloidal and 99mTc pertechnetate impurities were measured with 1CHR and 4CHR. Conclusions: 54SFC paper is a suitable alternative to ITLC-SG for measuring radiochemical impurities in 99mTc Medronate. The sample spot should be wet when the paper strip is placed in the chromatography tank. Copyright © 2009 John Wiley & Sons, Ltd.