HPLC determination of rubber septum contaminants in the iodinated intravenous contrast agent (sodium iothalamate).
A simple and rapid method is described for the determination of 2-mercaptobenzothiazole and mercaptobenzothiazole disulfide leached from rubber closures into the iodinated contrast medium (sodium iothalamate). The contaminants were extracted with methylene chloride and analyzed by high-performance liquid chromatography using ultraviolet detection at wavelengths of 272 and 328 nm. The structures of the impurities were confirmed unequivocally by mass spectrometry. The minimum detectable level was 1 microgram/100 mL (0.01 ppm). The quantitation of contaminants leached from rubber stoppers provides a means for evaluating possible health risks of the extractables.
Capillary GC analysis of compounds leached into parenteral solutions packaged in plastic bags.
A number of investigators have reported finding the plasticizer di(2-ethylhexyl)phthalate in plasma, urine, and parenteral solutions. These findings have been associated with the use of polyvinyl chloride packaging materials. Capillary gas chromatography--mass spectrometry, packed column gas chromatography, and high-performance liquid chromatography were used for the analyses. The screening procedure described herein accurately and quantitatively analyzes the plasticizers di(2-ethylhexyl)phthalate and dibutylphthalate and some of the degradation products plus 2,6-di-tert-butyl-p-cresol and cyclohexanone. Liquid--liquid extraction followed by capillary gas chromatography is used. Linear regression analysis of standard solutions gives correlation coefficients from 0.99963 to 0.99989 for six compounds. Recoveries for these compounds vary from 84.9% to 114% with relative standard deviations ranging from 2.51% to 6.33%.
Gas-chromatographic micro-scale procedure for theophylline, with use of a nitrogen-sensitive detector.
We report a micro-scale procedure for determination of theophylline by use of gas chromatography with nitrogen-sensitive detection. The procedure requires only 10 mul of serum, plasma, or saliva. This sample size makes the determination especially appropriate for monitoring in a pediatric population. With the sample volume used, background interference is equivalent to about 0.1 mg/liter and 0.5 mg of theophylline per liter can easily be measured. The new method correlates well with our earlier flame ionization gas-chromatographic procedure that required 1 ml of sample [Clin. Chem. 21, 1038 (1975)]. The selectiviey of the nitrogen detector allows a simplified extraction procedure. Between-run precision (CV) is 2.8% at a theophylline concentration of 14.8 mg/liter.