Table 2.

The optimisation of the pH of phosphate buffer (buffer:methanol is 85:15)

Mobile phase	Theoretical plates (N)	Symmetry	Retention time (tR) (min)	Peak shape
pH 2.5	9485	0.85	5.020	+
pH 2.8	8119	0.90	4.273	+++
pH 3.0	8218	0.93	4.270	+++
pH 3.5	8360	0.95	4.276	+++
pH 4.0	8076	0.90	4.262	+++
pH 5.0	7774	0.90	4.242	+++
pH 6.0	7551	0.90	4.241	+++
pH 7.0	7338	0.91	4.268	+++
pH 8.0	7178	0.88	7.861	+

+, good peak shape