Abstract: An ultra-low flow rate electrospray ionization (ESI) source provides flow rates in the range of 1.0 nL/min or less. The source is comprised of a needle which is fabricated by laser-heated pulling of fused-silica tubing, followed by chemical etching and surface metallization. The pulling results in formation of a slowly tapering capillary within the needle which tapers to a tip having a very small inner diameter. The etching process sharpens the outer wall of the needle to a very sharp tip, and the combination of these parameters results in the ultra-low flow rate capability. After a metal electrical contact is formed on the exterior wall of the needle, an electrically insulating overcoating is preferably deposited thereon which locks the contact in place, thereby greatly increasing needle life, and also restricting the electrical contact point to the very tip of the needle.

Abstract: The simultaneous collection of multiple spectra using tandem and multidimensional mass spectrometry from multiple precursors yields correspondingly enhanced sensitivity through Hadamard transform deconvolution. For MS.sup.n spectra, the product relationships are coded by a Hadamard differences method wherein the combined daughter spectrum of a selected half of the precursors is subtracted from the combined daughter spectrum of the remaining precursors, so that no ions are lost.

Abstract: A method for increasing the signal to noise and/or the speed of data collection for obtaining a collective secondary ion spectrum from selected combinations of primary ions is disclosed. The multiplicative capability of dissociating any combination of parent ions to form the collective secondary ion spectrum different combinations, each incorporating approximately 1/2 of the parent ions in a sample are measured in each cycle of measurement, and n collective spectra are obtained for n parent ions. The individual contributions at each specific mass in each secondary ion spectrum are calculated from the n simultaneous equations representing the summed intensity values at each mass.

Abstract: An automated mass spectrometric system which is capable of analyzing and identifying a wide variety of chemical compounds. A sample of an unknown compound, in liquid, solid or gaseous state, is introduced into the invented system. It may be a pure sample or a mixture of compounds. In either case, its mass spectrum is searched for selected peaks and an attempt is made to match such peaks to previously stored, characteristic spectra of one or more compounds in a predetermined family of compounds. Matching is on a probabilistic basis, reflecting the occurrence probabilities or uniqueness of the mass peaks found, and the accuracy with which the relative peak intensity pattern matches that of any of the compounds in the family of compounds sought. If one or more of the compounds in the family of compounds is identified as being present in the sample, its quantity is also determined automatically by the invention.

Abstract: Liquid chromatography-mass spectrometer apparatus and method are disclosed for analyzing the components of a complex mixture, characterized in that at least a portion of the eluted effluent from the liquid column is continuously introduced directly into the ionization chamber of a chemical ionization mass spectrometer for detection of the eluted sample components. Use is made of restricted capillary tube means for introducing the complex mixture directly into the chemical ionization ion source chamber, and diffusion pump and cryogenic pump means for obtaining the desired vacuum in the ion source chamber. The solvent is used as the agent necessary for chemical ionization, thereby making it unnecessary to remove all of the solvent before introducing the sample into the analyzer. Mass spectra is taken either on a repetitive basis, or the instrument is operable to monitor the total abundance of peaks other than those resulting from the solvent.