Radiochemical purity solutions

The concentration was further corrected for radiochemical purity according to the manufacturer s specifications because liquid scintillation counting measures the total sample activity and does not account for the presence of radiolabeled impurities. Stock solutions were stored at -15°C or -20° C in order to minimize sample loss due to hydrolysis. Injected sample solutions were prepared in 0.25 mL plastic vials by diluting stock solutions with buffer or deionized water and were also stored at -15° C or -20° C. 

A solution of 50-mCi portions of [3H3]-130 in 9 1 EtOH/H20 mixture have been stored at — 20 °C at a radioactive concentration of 4.5 mCi ml -1 and the radiochemical purity of the sample was 95-96% after one year. No labile tritium was found after refluxing a portion of the sample for 1 h in a methanolic solution of NaOH. The intermediate 131, 5-(4-chlorobenzoyl)-4-methyl-l//-pyrrole-2-acetic acid, has been obtained in an eight-step synthesis starting with tert-buiyX acetoacetate (equation 52). 

Liquid radioactive waste was directed from the waste storage tank to the 8 m feed reservoir. After pretreatment with PP depth filters and injection of antisealant, the wastes were directed to the first stage of RO. The retentate from this stage was concentrated in the third RO unit. The concentrated solution could be directly solidified if the concentration of the total solute was appropriate (<250 g/dm ). The salt concentration is limited by the conditions of concrete solidification. If the concentration was not sufficient, the further concentration took place in the evaporator. Permeate from the first and third stages was directed to the permeate reservoir before the second RO unit. The product from the membrane installation (permeate from the second stage) was of required radiochemical purity and after the control of specific activity and salinity was discharged to the communal sewage. 

A volume of 10 pL of the labelled peptide solution (0.8 pg/lO pL) was incubated at 37°C in 1 mL of fresh human serum. Radiochemical purity was determined by HPLC analysis using 15 pL samples taken at designated times between 30 min and 24 h post-labelling. 

The radiolabelled preparations were stored at room temperature in 0.4M sodium acetate or 0.3M ascorbic acid solution up to 72 h post-labelling for Lu-DOTATATE and up to 36 h post-labelling for " Y-DOTATATE, The influence of the radioactive concentration of the stored preparation on its stability was investigated using solutions of various radioactive concentrations 1.0, 20 and 50 mCi/mL for Y-DOTATATE. and 1.0, 15 and 35 mCi/mL for Lu-DOTATATE. The stability of the preparations (described as the radiochemical purity) was determined by HPLC and SepPak separation. 

Labelling with 1 was carried out following a procedure similar to that for 2 1. However, to evaluate the yield and radiochemical purity of the labelled peptide as a function of the reaction parameters, the amounts of DOTATATE and chloramine T were varied. Briefly, 10-15 pL of Na I in O.OIM NaOH (pH9, 3.8 GBq/mL of 1) was added to 5 pL of aqueous solution of peptide (Ipg/pL) in 10 pL of 0.5M phosphate buffer at pH7.5. To this mixture was added 10 pL of freshly prepared solution of chloramine T (0.13-60 pg/pL), followed by vortexing [16.4]. After 1 min of reaction time at room temperature, the labelled peptide was isolated from the reaction mixture by SepPak purification or by reversed phase HPLC. 

F-FMISO is synthesized in one-step reaction between the protected precursor, l-(2/-nitro-l,-imidazolyl)-2-0-tetrahydropyranyl-3-0-toluenesulfonyl-propanediol (NITTP) and 18F-containing Kryptofix 2.2.2 in acetonitrile solution (Kamarainen et al, 2004). The labeled product is hydrolyzed with acid to give 18F-FMISO, which is further purified by column chromatography using a Sep-Pak cartridge. From an automated synthesis, the radiochemical yield is 34% at EOB after a synthesis time of 50 min. HPLC shows a radiochemical purity of 97%. The molecular structure of 18F-FMISO is shown in Fig. 8.2f. 

Effect of Concentration and Formulation. Moist CHECK soil (26.4% moisture, 30 g oven-dry weight) was treated with technical grade alachlor (prepared in acetone) or an emulsifiable concentrate formulation (Lasso 4EC, 45.1% a.i., prepared in water) to yield application rates of 10, 100, and 1000 ppm soil. Stock solutions of alachlor were prepared by mixing the appropropiate amount of either the technical grade or emulsifiable alachlor with 2.6 (XCi of uniformly ring-labelled 14C alachlor (Monsanto Co., specific activity=13.74 mg/mCi, radiochemical purity=95%). 

Identity and purity, stability, and sterility and apyrogenicity. The identity and purity of radiopharmaceuticals is verified by determining the radionuclidic and radiochemical purity. Stability concerns the radioactive label, which is related to radiochemical purity at a certain time after preparation. Since Tc pharmaceuticals are formulated as sterile, pyrogen-free solutions, the safety requirements of drugs for parenteral use do apply. Safe handling of the radionuclide is equally important and must comply with Euratom Directives, regulated by national law for radiation protection, which also concerns the application of radionuclides in adults and in children for diagnostic procedures. 

Radiochemical Purity. The European Pharmacopeia requires thin-layer chromatography on silica gel fiberglass sheets and a migration distance 10-15 cm for the identification of impurities, using 0.9% sodium chloride solution (saline) as solvent. Free " Tc-sodium pertechnetate is measured at an Rf of 1.0, and " Tc-tin colloid is identified at the origin. The radiochemical purity of " Tc-tin colloid should not be less than 95% (Council of Europe 2005)... 

In order to assure high quality of the injection solution, the radiochemical purity is determined before administration of " Tc(l)-sestamibi to patients (Hung 1991). 

Radiochemical Purity. Tc-exametazime is included in the Ph. Eur. (Council of Europe 2005). Thin-layer chromatography on silica gel fiberglass plates using two solvent systems is described to determine the radiochemical purity of the injection solution. Free Tc-Na-pertechnetate (B) is determined in saline, the lipophilic Tc-HMPAO complex (D) is quantified indirectly by a subtraction method (Tab. 1). Previously, three solvent systems had been used, as recommended by the manufacturer. 

Radiochemical Purity. Tc-depreotide is not described in the European Pharmacopeia. Thin-layer chromatography (TLC) is recommended by the manufacturer, using instant (I)TLC-silica gel (SG) strips as a stationary phase and analysis in two solvent systems. Using methanol/1 M ammonium acetate 1 1 (MAM) as mobile phase, the insoluble Tc components are measured at the start (J y = 0-0.4). With saturated NaCl solution as mobile phase, free Tc-sodium pertechnetate, Tc-glucoheptonate, and 99m-pc-edetate move with the solvent front and are measured at J y = 0.75-1.0. 

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