Figure 5: (I) SWVs of the a buffer, b extracted blank plasma c extracted plasma spiked sample (2000ng/mL). (II) SWVs in a buffer b urine blank previous extraction, c urine blank after extraction and d extracted urine spiked sample (2000 ng/mL). Frequency = 50 Hz, pulse amplitude = 30 mV and step potential = 5 mV.