MRCP2-0589

A 49-year-old farmer is discovered unconscious in his barn with a suicide note and evidence of ingesting various pesticides and herbicides from his inventory. Upon arrival at the Emergency department, his Glasgow coma scale is 10, his pupils are pinpoint and unresponsive. His blood pressure is 100/70 mmHg, his pulse is regular at 88 beats per minute. He groans incoherently when you press on his stomach. You suspect a potential paraquat overdose. What screening methods can be used to confirm this suspicion?