Determination of bis(tributyltin) oxide by GC--MS with on-line hydride derivatization: application to drug substance analysis.

We report the determination of residual bis(tributyltin) oxide in a drug substance by GC-MS after extraction and on-line conversion to tributyltin hydride. Gas chromatography was performed using a 15 m x 0.25 mm i.d. DB-5 HT column with a temperature program from 100 to 160 degrees C at 15 degrees C min(-1). A mass range of 165-185 amu was monitored with the MS detector. Hydride generation is performed by placing a small amount of solid sodium borohydride in the injection port of a gas chromatograph and injecting samples and standards through this material. Conversion to tributyltin hydride is shown to be quantitative and linear for levels of bis(tributyltin) oxide between 1 and 100 ppm in the drug substance. The use of GC-MS provides sensitive and selective detection of tin containing species and the tin isotope pattern allows for confirmation of the presence of tin in chromatographic peaks. Recovery at 6 ppm was 89% with an injection precision of 6%. The limit of detection for bis(tributyltin) oxide in drug substance is 1 ppm.

Micellar enhanced cyanide ion determination in samples from synthetic organic processes.

A method was developed for the recovery and determination of cyanide ion in organic sample matrices. To facilitate the solubilization of cyanide ions, cetyltrimethylammonium bromide (CTAB) was added at concentrations above the critical micelle concentration. Sample cyanation reaction products consisted of solvent mixtures of a hydroxynitrile in DMF-toluene or DMF-isopropylacetate (IPAC). Spectrophotometric determination of cyanide ion at 578 nm by the pyridine-barbituric acid method was automated by flow injection analysis. Recovery of cyanide ion from spiked samples was 93.2% in DMF-IPAC solvent matrix and 93.9% in DMF-toluene. Low alkali concentration was observed to favor solubilization of cyanide ion in the micellar solution.

A quantitative rotational test of vestibular function.

This paper describes a quantitative vestibular test in which the stimulus is a constant angular acceleration of 3 degrees/sec2 for 80 sec. The nystagmus output is plotted as cumulative slow phase eye displacement against time and is displayed on an oscilloscope screen along with the output from a mathematical model describing vestibulo-oculomotor function. External dials allow one to change the equation constants thereby altering the shape of the model output. Values for equation constants which match the model output to the patient can be read directly from the dials, thus providing a description of the vestibular system under test. Results indicate that vestibular asymmetry (manifest by spontaneous nystagmus is not uncommon in normals, and only when spontaneous nystagmus is coupled with vestibular gain does one get a measure of abnormality. The significance of altered vestibular parameters in certain pathological states is discussed.