tube bring the ph to 10 u00b1 0 1 with soda 0 1 n add 20 ml of a solution of cenu1 in acetonitrile 2 16 mm the mixture is agitated by ultrasound for 15 minutes at a temperature of 60 u00b0 c the quantitative analysis is done by high performance liquid chromatography the derivation yield is greater than 99 u00b1 6 the quantitative analysis is done again after 22 days in order to check the stability of the histamine derivative the yield after 22 days storage at ambient temperature and in light is greater than 99 u00b1 6 put a 20 ml sample of an aqueous solution of histamine 270 u03bcm in a tube bring the ph to 10 u00b1 0 1 with soda 0 1 n add 20 ml of a solution of cenu1 in acetonitrile 2 16 mm the mixture is agitated by ultrasound for 15 minutes at a temperature of 60 u00b0 c the quantitative analysis is done by high performance liquid chromatography the derivation yield is greater than 99 u00b1 6 the quantitative analysis is done again after 22 days in order to check the stability of the histamine derivative the yield after 22 days storage at ambient temperature and in light is greater than 99 u00b1 6 put a 20 ml sample of an aqueous solution of histamine 9 2 u03bcm in a tube bring the ph to 10 u00b1 0 1 with soda 0 1 n add 20 ml of a solution of cenu2 in acetonitrile 2 16 mm the mixture is agitated by ultrasound for 15 minutes at a temperature of 60 u00b0 c the quantitative analysis is done by high performance liquid chromatography the derivation yield is greater than 99 u00b1 18 the quantitative analysis.