Solid Phase Microextraction Procedure for the Determination of Furoic Acid and Creatinine in Urine by Gas Chromatography/Mass Spectrometry

The solid-phase microextraction (SPME) technique was evaluated for the determination of furoic acid and creatinine in urine. For furoic acid, the alkaline hydrolysis step was first performed to hydrolyze the furoic acid-glycine conjugate to free furoic acid. Afterwards, the poly(dimethylsiloxane)/ divinylbenzene (PDMS/DVB) fiber was used with direct urine sample immersed for 60 sec under 1200 rpm magnetic stirring. Analysis with gas chromatography/mass spectrometry (GC/MS) was followed. For the determination of creatinine, the PDMS/DVB fiber was aslo directly immersed into urine sample for 60 sec under 1200 rpm magnetic stirring. Then the fiber was transferred to a 4 mL vial which was filled with 100 μL of trifluoroacetic anhydride (TFAA) and stood 30 sec for headspace extraction. Afterward the fiber was transferred again to another blank 4 mL vial and stood 10 min for on-fiber derivatization before the analysis with GC/MS. The absorption-time profiles for both furoic acid and creatinine were examined. The precision, accuracy and method detection limits (MDLs) were evaluated. The relative standard deviations were less than 10% and the accuracy were 100±10% for both furoic acid and creatinine. With 2 mL of urine sample, MDLs were 0.0077 and 0.13 g L for furoic acid and creatinine, respectively. Compared with other techniques, the study shown here provided a simple, fast and reliable method for the analysis of furoic acid and creatinine in urine.