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.
The determination of commonly used iodinated contrast media in postmortem samples using HPLC and TLC.
A rapid micro method is described for the determination of diatrizoic, iothalamic, ioxaglic, and iopanoic acids in postmortem liver and blood. The compounds were extracted with methanol and analyzed by high performance liquid chromatography using a C18 column. The mobile phase consisted of methanol:PIC A with ultraviolet detection at 232 and 242 nm. Recoveries of about 85% were obtained. A thin layer chromatographic system is described which separates the four compounds. The spots were hydrolyzed and sprayed with a diazonium coupling reagent to produce colored spots with sensitivities of 0.02 to 0.1 micrograms. Postmortem levels are given for two deaths involving diatrizoic acid.
High resolution mass spectrometry.—II Some substituted benzothiazoles
The mass spectra of nineteen substituted benzothiazoles have been recorded and the identity of the various ions in the mass spectra has been established by high resulution (accurate) mass measurement. Deuterium labelling has been used to elucidate the fragmentation processes of these compounds. The parent compound of the series, benzothiazole, exhibits the loss of hydrogen cyanide and carbon monosulphide from the parent ion as the most important decomposition pathways. The hydrogen atom concerned in the loss of hydrogen cyanide is shown to originate from the 2-position of benzothiazole, while in 2-substituted benzothiazoles, different mechanisms are apparent for the loss of hydrogen cyanide, and these are clarified by deuterium labelling. Some substituted benzothiazoles can lose sulphur from their molecular ions, a process which does not occur in benzothiazole itself. The substituted benzothiazoles undergo many other types of fragmentations, in some cases retaining the substituent, and in other cases losing it prior to collapse of the thiazole ring.