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In this work,a calculation method of chemical kinetics was established for labeling reaction of 99mTc-N-ethyl-N2S2-memantine,a potential NMDA receptor imaging agent prepared in our laboratory.Four groups of vials (3 vials per group) were added with 0.02 mL (1 mg/mL) N-ethyl-N2S2Memantine,0.08 mL (40 mg/mL) GH,0.05 mL (10 mg/mL) EDTA-2Na,0.035 mL (2 mg/mL) SnF2,0.8 mL phosphate buffer(1mol/L,pH 6.5) and 37 MBq Na99mTcO4.The vials were incubated at 70℃,80℃,90℃ or 100℃.Samples were taken with capillary from the vials at 2,5,10,20,30,40 and 60min.Labeling yields were determined by TLC.Order of reaction n,rate constant k,activation energy Ea and half life t1/2 of labeling reaction were calculated with the kinetics software we compiled.Mean labeling yields of 99m Tc-N-ethyl-N2S2-memantine at 2,5,10,20,30,40 and 60min were (1) 13.5,15.7,34.0,64.8,81.9,91.4 and 95.4 at 70℃;(2) 13.2,20.5,40.1,70.0,88.2,94.5 and 95.6 at 80℃;(3) 15.6,22.9,43.7,74.3,87.2,93.4 and 96.1 at 90℃;and (4) 20.5,25.8,45.3,81.1,92.2,95.6 and 96.0 at 100℃.The other parameters were;n =1;k=0.053,0.061,0.063 and 0.076 L/min at 70℃,80℃,90℃ and 100℃,respectively;Ea=12.38 kJ/L;t1/2=13.11,11.45,11.05 and 9.07min at 70℃,80℃,90℃ and 100℃,respectively.The mean labeling yield increased with temperature and time,optimized at 100℃ and 40-60min.The concentration of 99mTc-N-ethyl-N2S2-Memantine was larger than that of Na99mTcO4,so n=1.The k increased with reaction,hence the accelerated reaction rate at higher temperatures.The labeling reaction was not so difficult because of the low Ea.The t1/2 decreased with increasing reaction temperature,hence the acceleration of labeling reaction.
In this work, a calculation method of chemical kinetics was established for labeling reaction of 99mTc-N-ethyl-N2S2-memantine, a potential NMDA receptor imaging agent prepared in our laboratory. Folk groups of vials (3 vials per group) were added with 0.02 mL (1 mg / mL) of N-ethyl-N2S2Memantine, 0.08 mL of 40 mg / mL of GH, 0.05 mL of 10 mg / mL of EDTA-2Na, 0.035 mL of 2 mg / mL SnF2 and 0.8 mL of phosphate buffer (1 mol / L, pH 6.5) and 37 MBq Na99mTcO4.The vials were incubated at 70 ° C, 80 ° C, 90 ° C or 100 ° C. Samples were taken with capillary from the vials at 2,5,10,20,30,40 and 60 min. Labeled was determined by TLC. Ofder of reaction n, rate constant k, activation energy Ea and half life t1 / 2 of labeling reaction were calculated with the kinetics software we compiled. Materiratory yields yields 99m Tc-N-ethyl (2) 13.2, 20.5, 40.1, 70.0, 88.2, 94.5 and 95.6 at 80 ° C .; (3) 15.6, 22.9, 43.7, 74.3, 87.2, 93.4 and 96.1 at 90 ° C .; and (4) 20.5, 25.8, 45.3, 81.1, 92.2, 95.6 and 96.0 at 100 ° C .; other parameters were; n = 1; k = 0.053,0.061,0.063 and 0.076 L / min at 70 ° C, 80 ° C, 90 ° C and 100 ° C , respectively; Ea = 12.38 kJ / L; t1 / 2 = 13.11, 11.45, 11.05 and 9.07 min at 70 ° C., 80 ° C., 90 ° C. and 100 ° C., respectively. The mean labeling yield increased with temperature and time, optimized at 100 ° C and 40-60 min. The concentration of 99mTc-N-ethyl-N2S2-Memantine was larger than that of Na99mTcO4, so n = 1.The k increased with reaction, hence the accelerated reaction rate at higher temperatures. The labeling reaction was not so difficult because of the low Ea. t1 / 2 decreased with increasing reaction temperature, hence the acceleration of labeling reaction.