Deconvolution gas chromatography/mass spectrometry of urinary organic acids--potential for pattern recognition and automated identification of metabolic disorders

The National Institute of Standards and Technology (NIST) Automated Mass Spectral Deconvolution and Identification System (AMDIS) is applied to a selection of data files obtained from the gas chromatography/mass spectrometry (GC/MS) analysis of urinary organic acids. Mass spectra obtained after deconvolution are compared with a special user library containing both the mass spectra and retention indices of ethoxime-trimethylsilyl (EO-TMS) derivatives of a set of organic acids. Efficient identification of components is achieved and the potential of the procedure for automated diagnosis of inborn errors of metabolism and for related research is demonstrated.     

How Fast can a Subharmonic Function Decay Along a Ray?

Much is known about the connection between the growth and decayof subharmonic functions. The results indicate that there isa general principle: asubharmonic function cannot decay ‘toofast’ relative to its growth.Three theorems are provedwhich, together with work previously published elsewhere, givea fairly complete account of how this principle works out fora subharmonic function having extremal decay along a ray. 1991Mathematics Subject Classification: 30D20, 31A05.     

Isatin (indole-2,3-dione) in urine and tissues. Detection and determination by gas chromatography-mass spectrometry

A simple procedure based upon capillary column gas chromatography-mass spectrometry (GC-MS) is described for the detection and determination of isatin (indole-2,3-dione) in body fluids and tissues. After addition of 5-methylisatin as internal standard to urine or tissue homogenates, organic extracts are dried and derivatized successively with hydroxylamine hydrochloride and the reagent N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA). The tert.-butyldimethylsilyl derivatives obtained show good GC-MS properties and allow quantification by selected-ion monitoring of m/z 333 (isatin) and m/z 347 (internal standard). Adult and newborn human urine output values lie in the ranges 0.4-3.2 mg/mmol of creatinine (5-30 mg per 24 h) and 0.002-0.518 mg/mmol of creatinine, respectively. There is a discontinuous regional distribution in rat tissues. The GC-MS properties of a number of derivatives formed by successive reaction of isatin with hydroxylamine hydrochloride (or methoxyaminehydrochloride or ethoxyamine hydrochloride) and MTBSTFA, bis(trimethylsiyl)trifluoroacetamide, pentafluoropropionic anhydride or pentafluorobenzyl bromide are also described.     

Search for isovector giant monopole resonances via the Pb(3He,tp) reaction

The (nat)Pb(3He,tp) reaction at E(3He) = 177 MeV was studied to identify 2Planck's over 2piomega isovector monopole strength in Bi isotopes. Monopole strength was found in the region -45相似文献   

Analogy between unconventional superconductivity and unconventional states of liquid crystals

An analogy is stressed between the order-parameter symmetries of the two-dimensional d-pairing wave superconductors and of liquid-crystal mesophases formed from achiral bent-shaped molecules. It leads to a definition of a class of liquid-crystal states which are the analogs of the unconventional superconducting states, and are characterized by a loss of discrete symmetry operations of the parent state.