Some industrial developments and applications of multidimensional techniques.

Industrial analytical chemistry includes the measurement of the elemental composition and structure of molecules; the measurement of the concentration of specific molecules, atoms, and ions in contact with other molecules, atoms, and ions, the measurement of the energy and speed with which these reactions occur; and the separation of molecules, atoms, and ions specifically from other molecules, atoms and ions. It is also the measurement of the physical (interaction) and chemical (reaction) behavior of collections of molecules and how this behavior is controlled by the presence of other molecules and ions. Many excellent devices for separation and measurement have been developed to accomplish these tasks. Each of these attains a level of sensitivity and selectivity beyond which further improvement would be difficult. However, by coupling these techniques in various configurations, improved data can be generated in a short time span. Such techniques are often referred to as hyphenated, tandem, combined, or coupled. A more inclusive term is multidimensional techniques. In this paper, we briefly describe some of the most significant developments our laboratory has made in these and related techniques.

Thermospray liquid chromatography-mass spectrometry with a quadrupole ion trap mass spectrometer.

A theromospray ion source using corona discharge ionization was interfaced to a quadrupole ion trap mass spectrometer via a multi-element lens system. Ions were injected into the trap periodically where they were stabilized by collisions with helium bath gas. Mass spectra were recorded on the trapped ions using the mass-selective instability scan mode. Data are shown for a peptide and a nucleoside and the effects of some experimental variables on the spectra are explored.

Metabolism and disposition of dipropylene glycol monomethyl ether (DPGME) in male rats.

Male Fischer 344 rats were given a single oral dose of approximately 1289 mg/kg (8.7 mmol/kg) of [14C]DPGME. After dosing, expired air, excreta, and tissues were analyzed for 14C activity, and metabolites in urine were isolated and identified. Approximately 60% of the administered 14C activity was excreted in urine, while 27% was eliminated as 14CO2 within 48 hr after dosing. DPGME, PGME, dipropylene glycol, propylene glycol, as well as sulfate and glucuronide conjugates of DPGME were identified in urine of animals given [14C]DPGME. Results of the study indicate that DPGME is metabolized via the same routes to the same general types of metabolites as previously identified for propylene glycol monomethyl ether (PGME).

N-Acetyl decarboxylated S-adenosylmethionine, a new metabolite of decarboxylated S-adenosylmethionine: isolation and characterization.

Treatment with ornithine decarboxylase inhibitors leads to a marked increase of decarboxylated S-adenosylmethionine (dc-SAM) in various tissues, accompanied by the concomitant formation of a metabolite of dc-SAM. This metabolite has been isolated from rat prostate samples by a combination of chromatographic procedures. The use of IH-NMR and of fast atom bombardment mass spectometry and the synthesis of an authentic sample allowed the unambiguous characterization of this unknown compound as the N-acetyl derivative of dc-SAM. A reverse-phase high performance liquid chromatography procedure was developed for the separation of dc-SAM and its N-acetyl derivative into their diastereomers resulting from the chiral sulfonium group.