Abstract
During analyses of prostaglandin (PG) methoxime methyl trimethylsilyl (MO‐ME‐TMS) ether derivatives by gas chromatography, we consistently observed a contaminant peak which we identified as di‐2‐ethylhexyl phthalate (DEHP). The diazomethane prepared from N‐methyl‐N‐nitroso‐p‐toluenesulfonamide (MNTSA) using the Diazald kit was the major source of DEHP. Several other materials also were significant sources. The concentrations of DEHP in these materials were quantified by gas chromatography‐mass spectrometry.