Table 1
Stepwise eluent gradient during PSPE of urine sample containing metabolites of tolfenamic acid
Fraction
Eluent Volume (l)
Eluent Composition Methanol/1% Acetic acid (v/v)
1
4
50 /50
2
4.5
50 /50
3
1.5
80 /20
4
4.5
80 /20
5
1
100 /0