Solid-phase extraction and liquid chromatographic determination of monophthalates and phthalide extracted from solution administration sets.

A liquid chromatographic procedure is described for the determination of phthalide, monobutyl phthalate, and mono-2-ethylhexyl phthalate leached by water from solution administration sets. Recoveries varied from 88.8% for phthalide at 1 micrograms/50 mL to 113% for monobutyl phthalate at 6 micrograms/50 mL. Relative standard deviations at 1 micrograms/50 mL were 2.59% for phthalide, 3.54% for monobutyl phthalate, and 11.6% for mono-2-ethylhexyl phthalate. At 6 micrograms/50 mL, the relative standard deviation for mono-2-ethylhexyl phthalate decreased to 3.88%. Reproducibilities for 5 standard injections were 1.40% for phthalide, 1.84% for monobutyl phthalate, and 1.95% for mono-2-ethylhexyl phthalate. Correlation coefficients were 1.00 for the 3 compounds. Five sets from 2 manufacturers were examined. No phthalide or monobutyl phthalate was found. One manufacturer's sets contained 37.6-44.4 micrograms/L mono-2-ethylhexyl phthalate. The sample matrix had some interference if phthalide or monobutyl phthalate was present.