M.G. Horning

Liquid chromatograph—mass spectrometer—computer analytical systems: A continuous-flow system based on atmospheric pressure ionization mass spectrometry

Abstract Atmospheric pressure ionization (API) mass spectrometry is a novel form of mass spectrometry in which ions are generated in a reaction chamber external to the low-pressure region of a quadrupole mass spectrometer. Using this ionization technique a liquid chromatograph—mass spectrometer analytical system was constructed. The entire effluent stream from the chromatograph is vaporized throught the API source. The primary ionization source for this work was a corona discharge The very high ion densities generated by the corona discharge extend the linear range of the API source into the microgram region.

Fatty Acid Esterification with N,N-Dimethylformamide Dialkyl Acetals for GC Analysis

Abstract The methyl, ethyl, n-propyl, n-butyl or t-butyl esters of long chain fatty acids can be prepared quantitatively by reaction with dimethylforma-mide dialkylacetals (alkyl group = methyl, ethyl, n-propyl, n-butyl or t-butyl, respectively). A gas chromatographic separation can be carried out as soon as solution is achieved.

Gas chromatographic determination of polyols and aldoses in human urine as polyacetates and aldononitrile polyacetates

Thirty urinary collections from female and male neonates, juveniles, and adults have been analyzed by a new gas chromatographic (GC) method. Sixty meter high resolution open tubular glass capillary columns with a coating containing a dispersion of small particles of silanized silicic acid (Silanox) in SE-30 liquid phase were employed. Seventeen urinary polyols and aldoses were quantified through use of an internal reference compound and detector response factors. The components were analyzed as polyacetyl esters (from the polyols) and poly-O-acetylaldonic nitriles (from the aldoses).

Nicotine in smokers, non-smokers and room air

Abstract Nicotine is commonly observed in smokers urine, and this circumstance was used as a means of developing atmospheric pressure ionization (API) mass spectrometric techniques for the detection of volatile components of urine which behave as bases in the gas phase. When these methods where applied in an examination of urinary bases of non-smokers who shared the laboratory areas with smokers, nicotine was found to be present to the extent of about 5% of that observed for smokers. Two routes of nicotine transfer seemed possible: water and air. The water supply was found to be nicotine-free. An air analysis method was devised; this showed that nicotine was present in the laboratory air, so that the probable route of transfer for non-smokers is through room air.

Profiles of volatile metabolites in body fluids

Abstract A method for the analysis of volatile metabolites present in plasma, urine, breast milk and amniotic fluid collected from mother-infant pairs has been developed which requires only 100 μl of plasma, 3 ml of urine, 20 μl of breast milk and 500 μl of amniotic fluid. After extraction with diethyl ether, the volatile compounds were adsorbed on glass wool in a special concentration tube and subsequently desorbed and transferred to a 100-m nickel capillary column for analysis by gas chromatography and gas chromatography-mass spectrometry. The separations, carried out by temperature programming, were complete in 90 min.

Gas phase analytical methods for the study of human metabolites : Metabolic profiles obtained by open tubular capillary chromatography

Abstract A method has been developed for the preparation of high-resolution (100,000 or more theoretical plates), thermostable glass open tubular capillary columns. The key to column preparation lies in the inclusion of silanized silica particles (Silanox, 6–10 μ diameter) in the film. A special coating process is used for SE-30 columns. These columns have been used in metabolic profile separations of human urinary steroids, urinary sugars and polyols, and drugs and drug metabolites.

Benzyloxime Derivatives of Steroids. A New Metabolic Profile Procedure for Human Urinary Steroids Human Urinary Steroids

Abstract Benzyloxime (BO) and benzyloxime-trimethylsilyl (BO-TMSi) derivatives of steroids may be prepared in the same way as methoxime (MO) and MO-TMSi derivatives. They are eluted much later than the corresponding MO derivatives. This effect makes it easy to distinguish steroids with a reactive ketone group from closely related steroids containing hydroxyl groups alone, or with an unreactive ketone (11-one) group. The mass spectra (electron impact) have characteristic peaks which are readily recognized. These derivatives may be employed in metabolic profile separations of adult and newborn human urinary steroids. A Dexsil 300 column was employed in adult studies; an SE-30 column was used in infant studies.

Characterization and estimation of urinary steroids of the newborn human by gas-phase analytical methods

Abstract Procedures have been developed for obtaining urinary steroid profiles for newborn human infants. The GLC profiles contain five steroids which have been identified previously, and numerous steroids which are not yet identified. The method chosen for general use was the separation of the TMSi ethers of steroids obtained by enzymic hydrolysis, or by the Fotherby-Roy method, using a 12 ft 1% SE-30 or OV-1 column. Qualitative and quantitative comparisons can be made for normal infants, for the same infant with increasing age, and for infants with profiles altered by placental transfer of drugs.

Detection of 5-(3, 4-Dihydroxy-1, 5-Cyclohexadien-1-Yl) -5-Phenylsydantoin as a Major Metabolite of 5, 5-Diphenylhydantoin (Dilantin) in the Newborn Human

Abstract The metabolism of 5, 5-diphenylhydantoin was studied in the newborn human in two instances; one involved direct administration of the drug, and the other was by placental transfer of the drug from the mother. 5-(3,4-Dihydroxy-1, 5-cyclohexadien-1-yl)-5-phenylhydantoin was found to be a major metabolite. The GC and GC-MS methods employed here are well suited to the problem of studying drug metabolism in the newborn.

Metabolism of biphenyl in the rat.

The metabolism of biphenyl in the rat has been studied by using gas chromatographic and mass spectrometric methods. The free and conjugated urinary metabolites were characterized. Eight new metabolites were isolated: a dihydrodiol and two hydroxydihydrodiols were characteristic for the epoxide--diol pathway. There were two dihydroxybiphenyls, a trihydroxybiphenyl, a trihydroxymethoxybiphenyl and 4,4-dihydroxy-3-methylthiobiphenyl. The mass spectra of the trimethylsilyl derivatives of the metabolites exhibited characteristic doubly charged and metastable ions.