Determination of paraquat in biologic materials by a simplified solid phase extraction and spectrophotometry

A rapid measurement of low paraquat levels in body fluids is important for diagnosis and prognosis of paraquat intoxication. A simple and sensitive method for the determination of submicrogram levels of paraquat by solid phase extraction in conjunction with spectrophotometry has been developed. Serum, urine and formalin from fixed tissue were passed through this column and paraquat was eluted with 2 mL 2N NaOH. The eluent was reduced with dithionite and spectrophotometrically quantified with the zero- or second-order derivative. The detection limits of paraquat by this method are 0.05 mg/L and 0.01 mg/L with the zero-order and 0.005 mg/L and 0.001 mg/L with the second-order derivative, using 2 mL of serum and 10 mL of urine or formalin. The proposed method prevents the interference of biologic specimens as well as providing high extraction efficiency and good precision. The entire procedure can be completed within 30 minutes without special skills, reagents or equipment. These results show that this method is suitable for clinical and forensic toxicologic purposes.