Search results for "laser"
showing 10 items of 3161 documents
A new interface to couple thin-layer chromatography with laser desorption/atmospheric pressure chemical ionization mass spectrometry for plate scanni…
2005
An interface to allow on-line qualitative and quantitative full-plate detection and analysis of compounds separated by thin-layer chromatography (TLC) is presented. A continuous wave diode laser is employed as a desorption source. Atmospheric pressure chemical ionization mass spectrometry ionizes and subsequently identifies the desorbed sample molecules. Besides direct laser desorption on untreated TLC plates, graphite particles were used as a matrix to couple in the laser power and improve the efficiency of desorption.
Measurement of nanoparticle mass distributions by laser desorption/ionization time-of-flight mass spectrometry.
2011
In this paper, access to the mass distribution analysis of nanoparticles is described based on laser desorption/ionization and time of flight mass spectrometry. Two examples are given, demonstrating the accurate mass distribution analysis of nanoparticles fabricated both ex situ and in situ during the laser-assisted desorption process. The potentials and the limitations of the method are discussed, with special emphasis on carbonaceous clusters and molecules.
Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry Analysis of Carbosulfan, Carbofuran, 3-Hydroxycarbofuran, and Other Metabolites in …
2007
The potential of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QqTOF-MS) to identify and confirm carbosulfan and seven of its main metabolites (carbofuran, 3-hydroxycarbofuran, 3-ketocarbofuran, 3-hydroxy-7-phenol carbofuran, 3-keto-7-phenolcarbofuran, 7-phenolcarbofuran, dibutylamine) at trace levels from food is explored for the first time. The analytical method developed consists of pressurized liquid extraction (PLE) and LC-QqTOF-MS in positive ion mode, which attains unequivocal identification and quantification of the studied compounds in food, at levels well below of those of concern (0.05 mg/kg for the sum of carbosulfan, carbofuran, and 3-hydroxycarbofuran).…
A cost-effective method for estimating di(2-ethylhexyl)phthalate in coastal sediments.
2013
This study describes the development of a new method for the analysis of di(2-ethylhexyl)phthalate (DEHP) using 0.1-0.3 g of sediment sample, based on matrix solid phase dispersion (MSPD) using C18 as dispersant phase (0.4 g) and acetonitrile-water as eluting solvent (3.4 mL 1:3.25, v/v). No evaporation step is required. 3 mL of extracts were processed on-line by in-tube solid phase microextraction (IT-SPME) coupled to capillary liquid chromatography (CapLC) and diode array detector (DAD). A short analytical column Zorbax SB C18 (35×0.5 mm, 5 μm) provided suitable results. FTIR-ATR was employed for characterizing sediment samples and MSPD procedure. The total analysis time was less than 20 …
Resonance ionization mass spectrometry for ultratrace analysis of plutonium with a new solid state laser system
2004
Abstract Resonance ionization mass spectrometry (RIMS) is well-suited for isotope selective ultratrace analysis of long-lived radioactive isotopes due to its high element and isotope selectivity and good sensitivity. For the analysis of plutonium with a pulsed RIMS apparatus, a powerful, reliable and easy to handle Nd:YAG pumped titanium–sapphire laser system has been developed and combined with a time-of-flight mass spectrometer. Spectroscopic measurements led to an efficient three step excitation and ionization scheme for plutonium with λ1 = 420.76 nm, λ2 = 847.28 nm, and λ3 = 767.53 nm. The isotope shifts in this scheme for the plutonium isotopes 238 Pu through 244 Pu have been determine…
Multi-element trace determinations in pure alkaline earth fluoride powders by high-resolution ICP-MS using wet-chemical sample preparation and laser …
2003
Four alternative analytical procedures for the determination of ten important trace impurities (Mg, Cr, Fe, Cu, Zn, Sr, Zr, Cd, Ba, and Pb) in pure alkaline earth fluoride powders were applied using high-resolution inductively coupled plasma mass spectrometry (ICP-MS). Two procedures are based on a wet-chemical microwave digestion with boric acid and quantification by the standard addition technique and isotope dilution mass spectrometry (IDMS), respectively. In addition, analyses are also performed by laser ablation as a direct solid sampling technique applying matrix-matched external calibration as well as isotope dilution of the powdered sample. For most elements good agreement between t…
Development of an isotope dilution laser ablation ICP-MS method for multi-element determination in crude and fuel oil samples
2009
An inductively coupled plasma isotope dilution mass spectrometric (ICP-IDMS) method with direct introduction of the isotope-diluted sample into the plasma by laser ablation was developed for accurate, sensitive, fast, and simultaneous determination of trace metals in different oil samples. Metallo-organic solutions of isotope spikes (50V, 53Cr, 65Cu, 57Fe, 62Ni, 68Zn, 113Cd, 117Sn, and 206Pb) were prepared from corresponding aqueous stock solutions by using liquid–liquid extraction of complexed metal ions in isobutyl methyl ketone. The isotope-diluted sample was absorbed by a cellulose material, which was fixed in a special PTFE holder for ablation, using a laser system with high ablation r…
Effect of particle size distribution in laser-induced breakdown spectroscopy analysis of mesoporous V–SiO2 catalysts
2011
In this paper, the effect of particle size on Laser-Induced Breakdown Spectroscopy (LIBS) analysis of mesoporous V–SiO2 catalyst samples was investigated. The measurements were realized on three LIBS devices with different parameters. Concentrations of V in samples used for LIBS experiments previously determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) varied from 1.2 to 4.7 w/w%. Granulometry of silica samples was modified by two grinding methods (conventional vibration mill and cryogenic mill) and three sets of samples with different particle size distributions were obtained. Ground samples were then deposited in the form of a thin layer on the adhesive tape a…
Cavity ring down spectrometry for disease diagnostics using exhaled air
2017
In this paper we report the current stage of the development of a cavity ring-down spectrometer (CRDS) system using exhaled human breath analysis for the diagnostics of different diseases like diabetes and later lung cancer. The portable CRDS system is made in ultraviolet spectral region using Nd:Yag laser 266 nm pulsed light. Calibration of the CRDS system was performed using generated samples by KinTek automated permeation tube system and self-prepared mixtures with known concentration of benzene and acetone in air. First experiments showed that the limits of detection for benzene and acetone are several tens of ppb.
Calibration of LA-ICP-MS via standard addition using dried picoliter droplets
2020
A novel microanalytical calibration approach for quantitative spatially resolved analysis of thin layered materials with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is presented. This method relies on standard addition via the generation of dried pL-droplet residues. Therefore, a drop on demand dosing device based on a modified commercial ink cartridge and a dosing interface, both accessible via a self-constructed microcontroller, were developed. This dosing device enables the precise deposition of pL-droplets onto solid samples for the generation of residues with dimensions in the low μm-range. The LA-ICP-MS analysis of such residues allows calibration over at l…