A good result was obtaioned using RSpak CARB-413 column. The time required for one anaylsis is almost same for both two cases. But, additional time is necessary required for reconditioning the system in the case of gradient elution though such additinal time is unnecessary in the case of isocratic elution. As the serult, total average time required for one analysis with isocratic elution is about half of that with gradient elution.
Column : RSpak CARB-413 (4.6mmID*150mm)
Other conditions : Refer to Analysis Method of N-methyl Carbamates