Hello dear researchers

According to SEDEX method, prepare CDB 0.3/1 M reagent (1 M NaHCO3, 0.3 M Na3-citrate, and Na-dithionite) is required. In the first step, it needs to be dissolve 84 gram of NaHCO3 in 1 litre distilled water. But it cannot be dissolved even in 40 centigrade degree and by using mixer. Is there anybody have the same experience? I need to find where is the mistake?