Figure 3: HPLC chromatogram of histamine (200 ppm) and 1,1-dimethylbiguanide standard in KPi buffer (pH 7.0, 37°C); conditions: column Optimal ODS-H C18 (250 mm×4.6 mm i.d.) at +35°C, buffer solution: methanol: acetonitrile (75:10:15, v/v/v) at a flow-rate of 1.0 mL min-1, injection loop 30 μL and monitored at 214 nm.