Title: Novel method for simultaneous aqueous in situ derivatization of THC and THC-COOH in human urine samples: validation and application to real samples.
Journal: Journal of analytical toxicology 20110501
Title: Determination of organic acids in urine by solid-phase microextraction and gas chromatography-ion trap tandem mass spectrometry previous 'in sample' derivatization with trimethyloxonium tetrafluoroborate.
Journal: Biomedical chromatography : BMC 20081001