简介:Introduction
Mass Spectrometry (MS) is one of the
fastest-growing areas in analytical instrumentation.
The use of mass spectrometry in support
of synthetic, organic, and pharmaceutical
chemistry is well established.简介:Introduction
Mass Spectrometry (MS) is one of the
fastest-growing areas in analytical instrumentation.
The use of mass spectrometry in support
of synthetic, organic, and pharmaceutical
chemistry is well established. Mass spectrometry
is also used in materials science, environmental
research, and forensic chemistry. It has
also evolved into one of the core methods used
in biotechnology. However, currently available
ion sources place extreme restrictions on
the speed and convenience of sample analysis
by mass spectrometry. Here we report a
method for using mass spectrometry to instantaneously
analyze gases, liquids, and solids in
open air at ground potential under ambient
conditions.
Traditional ion sources used in mass spectrometry
require the introduction of samples
into a high vacuum system. Traditional ion
sources operated in vacuum include electron
ionization (EI)[1], chemical ionization (CI)[2],
fast atom bombardment (FAB)[3], and field
desorption/field ionization (FD/FI)[4]. These
techniques have been used successfully for
decades. However, the requirement that samples
be introduced into a high vacuum for
analysis is a severe limitation. Gas or liquid
samples must be introduced through a gas
chromatograph or a specially designed inlet
system. Solid samples must be introduced by
using a direct insertion probe and a vacuum
lock system. Direct insertion probes can result
in vacuum failure and/or contamination of the
ion source if too much sample is introduced.
Atmospheric pressure ion sources such as
atmospheric pressure chemical ionization
(APCI)[5], electrospray ionization (ESI)[6-8],
matrix-assisted laser desorption ionization
(MALDI)[9-10] and atmospheric pressure
photoionization (APPI)[11] have broadened
the range of compounds that can be analyzed
by mass spectrometry. However, these ion
sources require that samples be exposed to elevated
temperatures and electrical potentials,
ultraviolet irradiation, laser radiation, or a
high-velocity gas stream. Safety considerations
require that the ion source be fully
enclosed to protect the operator from harm.
The new ion source reported herein overcomes
these limitations. The new technique,
referred to as Direct Analysis in Real Time
(DARTtm), has been coupled to the AccuTOFLCtm
atmospheric pressure ionization mass
spectrometer to permit high-resolution, exact
mass measurements of gases, liquids, and
solids[12,13]. DART successfully sampled
hundreds of chemicals, including chemical
agents and their signatures, pharmaceutics,
metabolites, pesticides and environmentally
significant compounds, peptides and oligosaccharides,
synthetic organics, organometallics,
drugs of abuse, explosives, and toxic industrial
chemicals. These chemicals were detected on a
variety of surfaces such as concrete, human
skin, currency, airline boarding passes, fruits
and vegetables, body fluids, cocktail glasses,
and clothing. The composition of drug capsules
and tablets was directly analyzed.详细>