Sample preparation with an automated robotic workstation for organic acid analysis by gas chromatography-mass...

We attempted to automate sample preparation for analysis of organic acids by gas chromatography-mass spectrometry using a computer-controlled, automated robotic workstation that is integrated and connected to the gas chromatography-mass spectrometry (HP-5890/5971) system. Of the two methods developed, one employed solvent extraction, while the other utilized a silica, solid-phase extraction cartridge. Both automated methods were compared to a manual, solvent extraction procedure used routinely in our laboratory. Normal, spiked urine, and urine from patients with a variety of metabolic abnormalities were analyzed. The robotic workstation did not meet all our requirements for a rapid, reliable, laboratory device. Recoveries with the automated procedures were less than with the manual method, and some organic acids important in the diagnosis of inborn errors of metabolism were not detected. Additionally, the robotic device had mechanical and design problems that made it slower and less reliable than the manual procedure.