c detection wavelength 280 nm a 20 mm citrate buffer containing per ml 0 02 mg of benzalkonium chloride and 100 mg of d mannitol ph 6 0 a 20 mm citrate buffer containing per ml 100 mg of d mannitol ph 6 0 a 20 mm maleate buffer containing per ml 0 02 mg of benzalkonium chloride and 100 mg of d mannitol ph 6 0 a 20 mm maleate buffer containing per ml 100 mg of d mannitol ph 6 0 a 20 mm succinate buffer containing per ml 0 02 mg of benzalkonium chloride and 100 mg of d mannitol ph 6 0 a 20 mm succinate buffer containing per ml 100 mg of d mannitol ph 6 0 to each of the above six buffer solutions was added an equal volume of a 6 8 mg ml natural type hgh aqueous solution and gently mixed to give aqueous compositions 1 6 respectively final ph 6 then each of the solutions was passed through a filter with a pore size of 0 22 u03bcm and drawn into needled syringes by 1 ml each removed of air babbles and then sealed to give samples a portion of each of the above aqueous preparations was subjected to horizontal shaking amplitude 20 mm 220 cycles min at 2 8 u00b0 c for 24 hours table 1 shows the results out of the aqueous preparations.