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Modern analytical instrumentation must be able to perform rapid, reliable, and sensitive analysis. The on-line combination of analytical techniques such as capillary electrophoresis (CE), electrospray ionization (ESI) and mass spectrometry (MS) can provide solutions to numerous problems related to complex mixtures of organic/inorganic, or biological materials. Optimum performance of complex instrumentation such as this can be achieved only if each individual component operates with maximum proficiency, and is in full harmony/compatibility with the other components. The present paper reports on the evaluation and optimization of a CE-ESI time-of-flight mass spectrometry (TOF-MS) system. The main features of the instrument are speed and sensitivity. Low amol (3–11) detection limits have been achieved with continuous infusion experiments, and the acquisition rate can be as high as 10 000 spectra s −1 . For CE–TOF-MS, minimum detection was in the very-low fmol (1–10) range. The major contributing factors to high quality analysis characteristic to each separate technique are considered, relevant examples are discussed, and fast, and sensitive analysis is demonstrated.

The electrospray technique has developed into a widely used ionization source for interfacing capillary electrophoresis (CE) to mass spectrometry (MS). However, its implementation is not always straightforward. A large number of factors have been found to be important contributors to the production of a high quality spray, and the efficient transfer of analytes from the CE column into the mass spectrometer can become, in certain cases, troublesome. An electrospray device which can accommodate operation with a liquid sheath, nebulizing gas and make-up gas, as well as operation without a liquid sheath in the microelectrospray mode, was constructed. The electrospray source was evaluated for efficient CE separations, which require the best performance.

High-efficiency separation methods such as capillary electrophoresis (CE) interfaced with structural information-producing detection systems such as mass spectrometry (MS) represent invaluable tools in analytical chemistry. Most CE applications to date have been reported using UV absorption detection. To extend the analytical power of CE, new detectors which demonstrate increased speed, sensitivity, and specificity must be developed. In this paper, we describe the design of an electrospray ionization time-of-flight mass spectrometer and its performance as a detector for CE. Emphasis is placed on fulfillment of the speed and sensitivity requirements. Low attomole and low femtomole detection limits are demonstrated for continuous infusion and CE−MS operation, respectively.

A new, high-speed data acquisition system was tested for high storage rate time-of-flight mass spectrometry (TOFMS) detection in capillary electrophoresis (CE). For high spectral acquisition rates of 4 kHz, a spectral storage rate of 80 spectra s(-)(1) was achieved. The resulting detection limit was in the low amol range (10-25 amol) for continuous infusion investigations.

An improved capillary zone electrophoresis (CZE)/ mass spectrometer interface comprises a liquid junction adapted to makeup the volume/flow rate of the CZE column eluent stream to be more compatible with the ion spray LC/MS interface flow rates required by mass spectrometer detectors in on-line separation/detection systems for variouscompositions and mixtures including biological fluids and environmental samples. Analytes eluting from the CZE capillary column are diluted with a suitable buffer thereby adjusting the volume and flow rates to prevent flow and pressure discrepanies which would otherwise result in peak broadening. The new liquid junction system for CZE/MS and CZE/MS/MS is useful in separating, detecting and analyzing compositions and mixtures such as amino acids, pesticides, peptides, mucleotides, sulfonated azo dyes and enzymatic digests such as tryptic digest of recombinant bovine somatotropan. Detection can be carried out in both positive and negative ion modes. High separation efficiencies ranging from 50,000 to 1,000,000 theoretical plates and peak asymmetries of 1.2 to 1.8 for tryptic digest are achieved.

Full-scan capillary zone electrophoresis/mass spectrometry and capillary zone electrophoresis/tandem mass spectrometry (CZE/MS/MS) are demonstrated for the determination of monosulfonated and polysulfonated azo dyes at the low picomole levels. Under selected ion monitoring conditions femtomole levels of the dyes are detectable. Ion evaporation via the ion spray liquid chromatography/mass spectrometry interface is a mild form of ionization exhibiting only deprotonated singly charged or poly-deprotonated multiply charged negative molecular ions for sulfonated azo dyes. CZE/MS/MS daughter ion scanning after collision-induced dissociation of the molecular species for all sulfonated azo dyes contained the sulfonate ion (m/z 80). The presence of three sulfonated azo dyes in a wastewater extract was confirmed by parent ion scanning for the sulfonate daughter ion (m/z 80).