A novel mass spectrometer with an external ionization source can be used to detect picogram quantities of compounds of biologic interest. The source contains a 63Ni foil, and is at atmospheric pressure. Samples are introduced in a flowing gas stream in selected common solvents. Positive ions are formed by a complex series of ion molecule reactions. The ionization reaction for the sample may involve either proton transfer or charge transfer. Negative ions are formed by either resonance or dissociative capture of thermal electrons, or by ion-molecule interactions. In a favorable case (very little adsorption on the reaction chamber walls), 5-10 picograms could be detected by single ion monitoring, and a scanned mass spectrum could be obtained with as little as 25 picograms. The potential uses include incorporation into LC-MS-COM and GC-MS-COM analytical systems.

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Finally, the validity of employing "half-intensity" integrations is tested. When full resolution of a profile is lacking but the central portion of the profile is not affected by interferences which occur on only one side of the profile, then the profile is scanned from its free side and the intensity integration is performed only for the free half of the profile, that is, up to the peak-height channel. A user option programs profiles for half-intensity integration at the time of acquisition. The results in Table V indicate excellent precision for 9Be, an isotope for which all lines were computed by half-intensity integration. Also, the effect of mixing half-intensity and full-intensity calculations has not harmed the precision for integrated intensity vs. peak-height intensity for those isotopes so indicated in Table V.

1. A gas-liquid-chromatographic procedure is described which permits separation and identification on the same chromatogram of a wide range of substances occurring in urine or tissue extracts. The method uses hydrogen flame ionization, which detects organic compounds whether free or conjugated with no requirement for specific reactive groups. 2. For chromatography, carboxyl groups are quantitatively converted into methyl esters or trimethylsilyl esters. Phenolic, alcoholic and potential enolic groups are converted into trimethylsilyl ethers. Separations are carried out on a 6ft. column of either 10% F-60 (a polysiloxane) or 1% F-60, temperature programming at 2 degrees /min. being used over such part of the temperature range 30 degrees -260 degrees as is required. Propionyl derivatives of hydroxy compounds can also be used, but only on a non-quantitative basis. Derivatives and columns have been selected for optimum range of usefulness when large numbers of samples are examined by using automated gas chromatography. 3. The method is applicable to: fatty acids above butyric acid; di- and tri-carboxylic acids; hydroxy acids and keto acids; polyhydroxy and alicyclic compounds such as glycerol, inositol, quinic acid, shikimic acid, ascorbic acid and sugar alcohols; aromatic hydroxy and acidic compounds, both benzenoid and indolic; sesquiterpenes; steroids; glycine conjugates; mercapturic acids; glucuronides. It is not satisfactory for sulphate conjugates, iminazoles or polypeptides. 4. Methylene units provide an accurate and reproducible parameter for characterizing peak position. Methylene unit values are reported for a large variety of substances occurring in, or related to those occurring in, urine and tissue extracts. 5. The nature of derivatives was confirmed by combining gas chromatography with mass spectrometry. Combined gas chromatography-mass spectrometry gives a diagnostic tool of great power in the evaluation of metabolic patterns, and various uses are discussed.

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Multicomponent analyses were carried out for three types of urinary constituents: steroids, acids, and drugs and drug metabolites. The methods were based on gas-phase analytical techniques, which include the use of instruments and instrumental systems for gas chromatography, gas chromatography—mass spectrometry, and mass spectrometry—computerization. After isolating an analytical sample, we prepared derivatives in each instance. Gas chromatography was used for separations, mass spectrometry for identification. These procedures for obtaining metabolic profiles may be used in various ways, including studies of abnormal conditions, drug metabolism, and the effects of drugs on metabolic pathways, as well as for human developmental studies.

The use of methone (5,5-dimethyldihydroresorcinol) as a reagent for the identification and characterization of aldehydes is well known (1, 2, 3, 4, 5). A disadvantage attending the use of methone has been the lack of agreement on conditions recommended for the preparation of derivatives and a lack of data obtained by proposed general methods. A method for the characterization of aldehydes with methone, applicable to aliphatic and aromatic aldehydes, is described in the experimental section. The aldehyde is treated with methone

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