Molecularly imprinted solid phase microextraction fiber for trace analysis of catecholamines in urine and serum samples by capillary electrophoresis

► A new selective and flexible monolithic molecularly imprinted polymer (MIP) fiber. ► Developed a simple synthetic method by using a flexible capillary as a mold. ► Highly selective extraction of trace catecholamines in urine and serum samples. ► Very lower detection limits were achieved in range of 0.8-1.2 ng mL−1.