2'- O- (6- Aminohexylcarbamoyl)guanosine- 3', 5'- cyclic monophosphorothioate, Sp- isomer, immobilized on agarose gel (Sp-2'-AHC-cGMPS-Agarose)[2'- O- (6- Aminohexylcarbamoyl)guanosine- 3', 5'- cyclic monophosphorothioate, Sp- isomer, immobilized on agarose gel (Sp-2'-AHC-cGMPS-Agarose)]