Table 1 Preliminary trial runs

1

BDS C18

(250 mm × 4.6 mm, 5 μm)

Methanol:

0.1 % OPA

(40:60)

Only MET was eluted with less theoretical plates

2

BDS C18

(250 mm × 4.6 mm, 5 μm)

ACN: KH₂PO₄

(40:60)

Only MET was eluted

3

Agilent C18

(250 mm × 4.6 mm, 5 μm)

ACN: 0.1 % OPA

(60:40)

Peak symmetry of both the peaks was good but with increased retention time

4

Kromasil C18

(150 mm × 4.6 mm, 5 μm)

ACN: 0.1 % OPA

(50:50)

Peak symmetry was good but MET eluted at 1.6 min

5

Kromasil C18

(150 mm × 4.6 mm, 5 μm)

ACN: 0.1 % OPA

(65:35)

Peak symmetry was good with system suitability parameters in limits