Continuous full filling capillary electrochromatography-electrospraying chromatographic nanoparticles.

The influence of instrumental parameters affecting the ionization in continuous full filling capillary electrochromatography/electrospray ionization mass spectrometry (CFF-CEC/ESI-MS) was investigated. The investigated parameters were the BGE and sheath liquid ion strength and organic modifier content, the nebulizer gas pressure, and the concentration of nanoparticles in the BGE. It was found that the nebulizer pressure had the largest influence on the separation efficiency and apparent retention.

Continuous full filling capillary electrochromatography: nanoparticle synthesis and evaluation.

Reversed phase continuous full filling capillary electrochromatography with electrospray ionisation mass spectrometric detection was performed with highly sulphated poly[styrene-co-(lauryl methacrylate)-co-(divinylbenzene)] nanoparticles. The nanoparticles that contained a hydrophobic core and a hydrophilic surface were prepared in a one step synthesis using soap free emulsion polymerisation. By changing the concentration of monomers, the polymerisation temperature, and the polarity of the dispersive phase, the size of the nanoparticles could be controlled.

Continuous full filling capillary electrochromatography: chromatographic performance and reproducibility.

Continuous full filling capillary electrochromatography with nanoparticles as pseudostationary phase interfaced with electrospray ionisation mass spectrometric detection was used for reversed phase separations with very high separation efficiency. Several batches of nanoparticles were synthesised and their electrochromatographic performance were evaluated. Different parameters, such as repeatability, reproducibility, limit of detection, and peak asymmetry, were investigated yielding excellent results.

On-line capillary based quantitative analysis of a heterocyclic amine in human urine.

A high through-put miniaturised separation-quantification method for the heterocyclic aromatic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in urine was developed. The limit of detection was of 0.65 fmol (0.

Nanoparticle-based continuous full filling capillary electrochromatography/electrospray ionization-mass spectrometry for separation of neutral compounds.

Highly efficient reversed-phase capillary electrochromatography (CEC) separations (plate numbers up to 700 000/m), with electrospray ionization mass spectrometry detection were achieved utilizing novel dextran-coated polymer nanoparticles as a pseudostationary phase. A continuous full filling (CFF) technique in which nanoparticles are continuously introduced into the capillary was employed for separation of neutral analytes (dialkyl phthalates), utilizing an orthogonal electrospray interface to prevent nanoparticles from entering the mass spectrometer. CFF-CEC benefits from that an entirely fresh column is employed for every analysis, avoiding carryover effects associated with stationary-phase contamination.

Nanospray mass spectrometry with indirect conductive graphite coating.

An easy and cost-effective method to manufacture a robust conductive graphite coating for nanospray mass spectrometry (nESI-MS) and capillary electrophoresis (CE)-nESI-MS is described. The method involves graphite coating of a tube sleeve, into which the nESI emitter is inserted and connected to a transfer capillary, instead of coating the actual emitter. The coating, made of graphite from a pencil and epoxy glue, was stable over long periods of use (>80 h) and showed excellent resistance toward various solvents.

In-capillary micro solid-phase extraction and capillary electrophoresis separation of heterocyclic aromatic amines with nanospray mass spectrometric detection.

A miniaturised technique to analyse and detect heterocyclic aromatic amines (HAs) using micro solid-phase extraction ( microSPE) coupled on-line (in-capillary) to capillary electrophoresis (CE) separation with nanospray (nESI) mass spectrometry (MS) detection has been developed. HAs are mutagenic and carcinogenic compounds formed at low levels in protein-rich food during cooking. Due to the low concentrations of HAs and the high complexity of the matrix in which they exist, sensitive and selective analytical methods are required for quantification.

Affinity two-phase partitioning in acoustically levitated drops.

Miniaturized (<1 microL) biospecific affinity two-phase partitioning in an acoustically levitated drop is described. Miniaturization commonly gives unfavorable surface/volume ratios, but in the levitation approach adsorption problems are minimized since the only surrounding wall is the liquid/air interface of the drop. Biotinylated liposomes were partitioned in aqueous poly(ethylene glycol)/dextran two-phase drops with NeutrAvidin-dextran as the affinity ligand.

Nanoparticles as pseudostationary phase in capillary electrochromatography/ESI-MS.

A novel technique that uses polymer nanoparticles as pseudostationary phase in capillary electrochromatography with electrospray ionization mass spectrometry detection is described. A continuous full filling technique in which the nanoparticles were suspended in the entire electrolyte volume as well as a conventional partial filling technique is presented. No nanoparticles entered the mass spectrometer, which was fitted with an orthogonal electrospray interface, despite the continuous flow of nanoparticles into the interface.