Hexyl chloroformate has been used as derivatization reagent in: determination of sarcosine and N-ethylglycine in urine and urinary sediments by solid-phase micro extraction and fast GC-MS analysis determination of benzoylecgonine in urine by GC-quadrupole ion trap mass spectrometry Hexyl chloroformate has been used as derivatization reagent in: determination of sarcosine and N-ethylglycine in urine and urinary sediments by solid-phase micro extraction and fast GC-MS analysis determination of benzoylecgonine in urine by GC-quadrupole ion trap mass spectrometry