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Monoclonal antibodies CHX-A-DTPA-HuM195 specific to CD 33 antigens on leukemia cells were labeled with carrier free 149Tb and 149Gd. Labeling yield and radiochemical purity were determined and in vitro studies concerning immunoreactivity, internalization and killing of leukemia HL-60 cells were performed.

The different parameters of 11C formaldehyde synthesis from 11CO2 have been systematically studied in order to improve yields, reproductibility and specific radioactivity. With modifications brought to gas and reagents purity, 11CO2 trapping system, target and dehydrogenation catalyst treatment, 100 to 200 mCi of 11C formaldehyde are obtained at EOB + 10 mn, with a specific activity on the order of 600 mCi/μmole (maximum 1 Ci/μmole).

Nuclear decay of C3H4 in the presence of gaseous furan represents a simple and convenient synthetic route to carrier-free multitritiated 3-methyl- and 2-methyl-furan. Their application for biological studies appears particularly promising, on account of the favourable characteristics of the followed synthetic approach.

Mercury(II) oxide oxidation of naltrexone (1a) and naloxone (1b) gave 15,16-didehydronaltrexone (4a) and 15,16 didehydronaloxone (4b). Subsequent reduction of 4a with tritium gas afforded naltrexone-15,16-3H2 having a-specific activity of 15.3 Ci/mmole. Subsequent equilibration of 4b with carrier free tritium oxide followed by sodium cyanoborohydride reduction yielded naloxone-15-3H having a specific activity of 4 Ci/mmole.

The alpha emitting radiohalogen 211At has potential use as a radiotherapeutic agent when linked to biologically active molecules. The range of compounds which may be astatinated is limited by relative lack of knowledge of organoastatine syntheses. The production of astatovinyl steroids was carried out via electrophilic substitution of tri-n-butylstannylvinyl steroids with astatide in the presence of mild oxidizing agents. The astatinated steroids are synthesized rapidly and in carrier-free fashion yielding compounds of high radiochemical purity.

Oxygen-15 labelled water has been prepared at high specific activities (> 100 mCi/ml) by nuclear recoil techniques available for use after 1 min from EOB. Radiogenic oxygen-15 atoms generated in a cyclotron by the 14N(d, n)15O reaction, are allowed to react directly with molecular hydrogen in the gas phase to produce labelled “carrier-free” H215O which can be used for biomedical purposes.

A simple new method for synthesis of a carrier free(131I)-4-iodoantipyrine has been developed. The procedure uses dry column chromatography on silica gel, where reaction between iodine-131 and antipyrine is carried out simultaneously with elution of (131I)-4-iodoantipyrine. The labelling yield is around 80 per cent; radiochemical purity of the final product exceeds 98 per cent.