Determination of fluoroquinolones in bovine milk samples using a pipette-tip SPE step based on multiwalled carbon nanotubes prior to CE separation.

A simple CE-UV method was developed for the simultaneous determination of ciprofloxacin, norfloxacin, and ofloxacin in milk samples. The optimum separation was obtained using a 20 mM ammonium dihydrogenphosphate solution with 2 mM cetyltrimethylammonium bromide at pH 3.0 as the BGE.

New method for fabrication of fused silica emitters with submicrometer orifices for nanoelectrospray mass spectrometry.

In this paper, we describe a new method for fabrication of nanoelectrospray emitters. The needles were pulled from fused silica capillary tubing, which was melted by means of a plasma, formed by electrical discharges between two pointed platinum electrodes. A key feature of the pulling device is a rotating configuration of the electrodes, which results in an even radial heating of the capillary.

Electrospray ionization mass spectrometry from discrete nanoliter-sized sample volumes.

We describe a method for nanoelectrospray ionization mass spectrometry (nESI-MS) of very small sample volumes. Nanoliter-sized sample droplets were taken up by suction into a nanoelectrospray needle from a silicon microchip prior to ESI. To avoid a rapid evaporation of the small sample volumes, all manipulation steps were performed under a cover of fluorocarbon liquid.

Separation and characterization of aggregated species of amyloid-beta peptides.

We have investigated the use of isoelectric focusing and immunodetection for the separation of low molecular weight species of amyloid-beta (Abeta) peptides from their aggregates. From solutions of Abeta(1-40) or Abeta(1-42) monomeric peptides, low molecular weight material appeared at a pI value of ca. 5, while the presence of aggregates was detected as bands, observed at a pI of 6-6.

Electrospray ionization from an adjustable gap between two silicon chips.

In this paper, a silicon chip-based electrospray emitter with a variable orifice size is presented. The device consists of two chips, with a thin beam elevating from the center of each of the chips. The chips are individually mounted to form an open gap of a narrow, uniform width between the top areas of the beams.

Electrospray ionization from a gap with adjustable width.

In this paper, we present a new concept for electrospray ionization mass spectrometry, where the sample is applied in a gap which is formed between the edges of two triangular-shaped tips. The size of the spray orifice can be changed by varying the gap width. The tips were fabricated from polyethylene terephthalate film with a thickness of 36 microm.