Adsorption of some technetium-99m radiopharmaceuticals onto disposable plastic syringes.

OBJECTIVE: The purpose of this study was to determine the adsorption behavior of some widely used, commercially available 99mTc radiopharmaceuticals onto different types of plastic syringes. METHODS: Kits were reconstituted with 99mTc-pertechnetate diluted with 0.9% saline to produce maximum radioactive concentrations, as stated by the manufacturers. Aliquots of the solutions were transferred to four different brands of 2-ml syringes. The activity in the syringes was measured before and after injections or simulated injections. The amount adsorbed to the plastic syringe barrel and plunger before and after washout also was measured at different time intervals. Comparisons between products from different manufacturers were made for 99mTc succimer (DMSA) and 99mTc macroaggregated albumin (MAA). RESULTS: Some 99mTC preparations undergo significant adsorption to plastic syringes. Adsorption differs considerably between products from different manufacturers. There was significantly higher residual activity in some types of syringes. In some cases the residual was as high as 40%-50% of the initial activity, and most of the adsorption occurred within 15 min of filling the syringe. CONCLUSION: The data suggest that the extent of adsorption depends on pharmaceutical excipients in the kits and/or the type of syringe used. When inappropriate syringes are used, the reduction in the administered activity may result in poor-quality images. Therefore, the compatibility between radiopharmaceutical and syringe should be investigated under normal conditions of preparation and use every time a new brand of syringe or a new radiopharmaceutical comes into use in diagnostic nuclear medicine.

Analysis of prostaglandins in aqueous solutions by supercritical fluid extraction and chromatography.

Trace amounts of prostaglandins (PGs) were selectively analysed without derivatization using supercritical fluid extraction (SFE) and open tubular column supercritical fluid chromatography (SFC). The specific compounds studied were prostaglandin F2 alpha (PGF2 alpha), esters of PGF2 alpha, prostaglandin F1 alpha) and prostaglandin E2 (PGE2). An open tubular column was used with carbon dioxide as the mobile phase and with universal flame ionization detection. Samples were introduced into the column by direct injection using a 1-microliter sample loop or by SFE with solute focusing. The 11 standard compounds were effectively separated within 35 min using a density program at constant temperature. The minimum detectable quantity (signal-to-noise ratio = 3) using the direct injection method was 9 ng for 15-propionate PGF2 alpha isopropyl ester. Using the extraction method, the sample size in the extraction cell was increased to 100 microliters, which made it possible to analyse compounds that were present in low concentrations. Aqueous PG samples were extracted from adsorbents onto which the samples had been loaded.

Evaluation of platelets prepared by apheresis and stored for 5 days. In vitro and in vivo studies.

To evaluate the effect of storage on apheresis platelets collected with a closed-system blood cell separator, an in vitro investigation was performed, with measurements of pH, lactate, ATP, the ratio of ATP to the total adenine nucleotide content, and adenylate kinase. Unmodified apheresis platelets and apheresis platelets with plasma added were compared with conventional platelets stored in PL-1240 or PL-732 plastic containers. During 6 days of storage, there were similar changes in all variables with one exception: the extracellular activity of adenylate kinase was lower in apheresis platelets with plasma than in the other three groups (p less than 0.01). In vivo studies were carried out with 111Indium-labeled autologous platelets in eight volunteers. Apheresis platelets with 100 mL of plasma added were stored in two 1000-mL containers (PL-732) at 22 degrees C during agitation. Platelets from one of the containers were labeled with 111Indium and transfused into the volunteer within 24 hours. Platelets from the other container were labeled after 5 days of storage and transfused into the same donor. There were no significant differences between apheresis platelets stored for 1 day and those stored for 5 days: the mean percentage of recovery was 58.4 and 57.6 percent, t1/2 was 69 and 67 hours, and the survival time was 5.5 and 5.6 days, respectively.