Although liquid chromatography and gas chromatography are the main workhorses in the analytical laboratory, samples can only be analyzed consecutively in an instrument. In this study, capillary zone electrophoresis and micellar electrokinetic chromatography separations are performed in a 96-capillary array system with laser-induced fluorescence detection. Migration times of four kinds of fluoresceins and six polyaromatic hydrocarbons (PAHs) are normalized to one of the capillaries using two internal standards. The relative standard deviations after normalization are 0.6-1.4% for the fluoresceins and 0.1-1.5% for the PAHs. Quantitative calibration of the separations based on peak areas is also performed, again with substantial improvement over the raw data. This opens up the possibility of performing massively parallel separations for high-throughput chemical analysis for process monitoring, combinatorial synthesis, and clinical diagnosis.
Aerosol droplet sizes and velocities from a direct injection nebulizer (DIN) are measured with radial and axial spatial resolution by phase Doppler particle analysis (PDPA). The droplets on the central axis of the spray become finer and their size becomes more uniform when ≍ 20% methanol is added to the usual aqueous solvent. This could explain why the analyte signal is a maximum at this solvent composition when the DIN is used for inductively coupled plasma-mass spectrometry (ICP-MS). Mean droplet velocities are 12 to 22 ms−1 with standard deviations of ±4 to ±7 ms−1. The outer fringes of the aerosol plume tend to be enriched in large droplets. The Sauter mean diameter ( D3,2) and velocity of the droplets also vary substantially with axial position in the aerosol plume.
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