Enhanced sensitivity and metabolite coverage with remote laser ablation electrospray ionization-mass spectrometry aided by coaxial plume and gas dynamics.

Laser ablation electrospray ionization-mass spectrometry (LAESI-MS) allows for direct analysis of biological tissues at atmospheric pressure with minimal to no sample preparation. In LAESI, a mid-IR laser beam (λ = 2.94 μm) is focused onto the sample to produce an ablation plume that is intercepted and ionized by an electrospray at the inlet of the mass spectrometer.

Subcellular metabolite and lipid analysis of Xenopus laevis eggs by LAESI mass spectrometry.

Xenopus laevis eggs are used as a biological model system for studying fertilization and early embryonic development in vertebrates. Most methods used for their molecular analysis require elaborate sample preparation including separate protocols for the water soluble and lipid components. In this study, laser ablation electrospray ionization (LAESI), an ambient ionization technique, was used for direct mass spectrometric analysis of X.

Remote laser ablation electrospray ionization mass spectrometry for non-proximate analysis of biological tissues.

Rationale: We introduce remote laser ablation electrospray ionization (LAESI), a novel, non-proximate ambient sampling technique. Remote LAESI allows additional analytical instrumentation to be incorporated during sample analysis. This work demonstrates the utility of remote LAESI and, when combined with optical microscopy, allows for the microscopy-guided sampling of biological tissues.

Top-down mass spectrometry imaging of intact proteins by laser ablation ESI FT-ICR MS.

Laser ablation ESI (LAESI) is a recent development in MS imaging. It has been shown that lipids and small metabolites can be imaged in various samples such as plant material, tissue sections or bacterial colonies without any sample pretreatment. Further, LAESI has been shown to produce multiply charged protein ions from liquids or solid surfaces.

A study of electrospray ionization emitters with differing geometries with respect to flow rate and electrospray voltage.

The performance of several electrospray ionization emitters with different orifice inside diameters (i.d.s), geometries, and materials are compared.

Analyte transport past a nanofluidic intermediate electrode junction in a microfluidic device.

A glass microfluidic device is presented in which a microchannel is split into two regions with different electric fields by a nanochannel intermediate electrode junction formed by dielectric breakdown. The objective is to sink current through the nanochannel junction without sample loss or broadening of the band as it passes the junction. This type of performance is desired in many microfluidic applications, including the coupling of microchannel/CE with ESI-MS, electrochemical detection, and electric field gradient focusing.

Simultaneous separation and detection of cations and anions on a microfluidic device with suppressed electroosmotic flow and a single injection point.

A rapid and simultaneous separation of cationic and anionic peptides and proteins in a glass microfluidic device that has been covalently modified with a neutral poly(ethylene glycol) (PEG) coating to minimize protein adsorption is presented. The features of the device allow samples that contain both anions and cations to be introduced from a central flow stream and separated in different channels with different outlets-all in the presence of low electroosmotic flow (EOF) imparted by the PEG coating. The analytes are electrophoretically extracted from a central hydrodynamic stream and electrophoretically separated in two different channels, in which pressure driven flow has been suppressed through the use of hydrodynamic restrictors.

A theoretical and experimental study of the electrophoretic extraction of ions from a pressure driven flow in a microfluidic device.

The electrophoretic extraction of ions from a hydrodynamic flow stream is investigated at an intersection between two microfluidic channels. A pressure gradient is used to drive samples through the main channel, while ions are electrophoretically extracted into the side channels. Hydrodynamic restrictors and a neutral coating are used to suppress bulk flow through the side channels.