Filters/filtering mass spectrometry

There are otlier teclmiques for mass separation such as tire quadmpole mass filter and Wien filter. Anotlier mass spectrometry teclmique is based on ion chromatography, which is also capable of measuring tire shapes of clusters [30, 31]. In tills metliod, cluster ions of a given mass are injected into a drift tube witli well-defined entrance and exit slits and filled witli an inert gas. The clusters drift tlirough tills tube under a weak electric potential. Since the... 

BS ISO 12884 Polycyclic aromatic hydrocarbons Collection of filters with gas chromatography/mass spectrometry... 

Field desorption mass spectrometry radiopharmacological agents, 6,976 Filter dyes photography, 6, 104 Fissile material criticality... 

METEOR Rule-based Metabolite prediction software Predicts the metabolic fate of chemicals Displays results as a metabolic tree. User can filter results for likely metabolites. Links directly to MetaboLynx for analysis of mass spectrometry data www.lhasalimited.org... 

When the aim is isolation for identification by direct probe insertion mass spectrometry (MS), plastic materials, filter papers, and blenders should be avoided to prevent contamination during extraction and chromatography. It is also very important to avoid the cis-trans isomerization of carotenoids in solution, which is accelerated by heat, light, acids, and active surfaces. Therefore, a pure carotenoid or even a crude extract should never be stored in solution it should be kept completely dry in an inert atmosphere at low temperature. 

Separation and detection methods The common methods used to separate the Cr(III)/(VI) species are solvent extraction, chromatography and coprecipitation. In case of Cr(VI) from welding fumes trapped on a filter, a suitable leaching of the Cr(VI) from the sample matrix is needed, without reducing the Cr(VI) species. The most used detection methods for chromium are graphite furnace AAS, chemiluminescence, electrochemical methods, ICP-MS, thermal ionization isotope dilution mass spectrometry and spectrophotometry (Vercoutere and Cornelis 1995)- The separation of the two species is the most delicate part of the procedure. 

McCann MT, Thompson MM, Gueron IC et al. (1996) Methyl malonic acid quantification by stable isotope dilution gas chromatography-mass spectrometry from filter paper urine samples. Clin Chem 42 9io-9i4. 

A. Fox and R. M. T. Rosario, Quantification of muramic acid, a marker for bacterial peptidoglycan in dust collected from hospital and home air-conditioning filters using gas-chromatography mass spectrometry. Indoor Air-Intemat. J. Air Quality Cl. 4 239 (1994). 

Air is sampled through a glass-fiber filter disk for 6 h at a rate of 2 L min. The filter is placed in a vial containing acetonitrile and the vial is heated at 70 °C for 40 min. After cooling, the vial is ultrasonicated for 15 min. An aliquot of the acetonitrile is filtered and analysed by gas chromatography/mass spectrometry (GC/MS). 

Luo X, Rehkamper M, Lee D-C, Halliday AN (1997) High precision °Th/ Th and " U/ U measurements using energy-filtered ICP magnetic sector mrrltiple collector mass spectrometry. Inti J Mass Spectrom Ion Processes 171 105-117... 

To assure consistency and speed in multidisciplinary structure analysis of low-MW compounds involving various techniques (IR, NMR, MS, etc.) most industrial laboratories use a Standard Operating Procedure (SOP). In such schemes IR analysis is frequently used as a cheap filter for a quick starting control and as a means for verification. As IR detects only structural units identification of an unknown compound on the basis of IR is difficult. Mass spectrometry is used as the prime identification tool and is especially important in the determination of the exact mass and gross formulae. While structural prognostication on the basis of MS is difficult for the non-expert, a posteriori interpretation is quite feasible. H NMR is both easy and cheap, however requires greater sample quantities than either... 

In mass spectrometers, ions are analysed according to the ml7. (mass-to-charge) value and not to the mass. While there are many possible combinations of technologies associated with a mass-spectrometry experiment, relatively few forms of mass analysis predominate. They include linear multipoles, such as the quadrupole mass filter, time-of-flight mass spectrometry, ion trapping forms of mass spectrometry, including the quadrupole ion trap and Fourier-transform ion-cyclotron resonance, and sector mass spectrometry. Hybrid instruments intend to combine the strengths of the component analysers. 

Accelerator mass spectrometry Acousto-optical tuneable filter Acousto-optical tuneable spectrometer/scanning Atom probe... 

Different mass analysers can be combined with the electrospray ionization source to effect analysis. These include magnetic sector analysers, quadrupole filter (Q), quadrupole ion trap (QIT), time of flight (TOF), and more recently the Fourrier transform ion cyclotron resonance (FTICR) mass analysers. Tandem mass spectrometry can also be effected by combining one or more mass analysers in tandem, as in a triple quadrupole or a QTOF. The first analyzer is usually used as a mass filter to select parent ions that can be fragmented and analyzed by subsequent analysers. 

Rodil R, Moeder M (2008) Development of a method for the determination of UV filters in water samples using stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry. J Chromatogr A 1179(2) 81—88... 

The concept of peak capacity is rather universal in instrumental analytical chemistry. For example, one can resolve components in time as in column chromatography or space, similar to the planar separation systems however, the concept transcends chromatography. Mass spectrometry, for example, a powerful detection method, which is often the detector of choice for complex samples after separation by chromatography, is a separation system itself. Mass spectrometry can separate samples in time when the mass filter is scanned, for example, when the mass-to-charge ratio is scanned in a quadrupole detector. The sample can also be separated in time with a time-of-flight (TOF) mass detector so that the arrival time is related to the mass-to-charge ratio. 

The instrumental analysis for the identification of UV filters degradation products formed during the fungal treatment process was performed by means of HPLC coupled to tandem mass spectrometry using a hybrid quadrupole-time-of-flight mass spectrometer (HPLC-QqTOF-MS/MS). Chromatographic separation was achieved on a Hibar Purospher STAR HR R-18 ec. (50 mm x 2.0 mm, 5 pm, from Merck). In the optimized method, the mobile phase consisted of a mixture of HPLC grade water and acetonitrile, both with 0.15% formic acid. The injection volume was set to 10 pL and the mobile phase flow-rate to 0.3 mL/min. 

Tapwater, surface water and WWTP effluents were sampled, filtered (0.2pm) and acidified to pH 2.0. REE were separated and preconcentrated following the method described in detail by Bau and Dulski (1996). REE concentrations were determined by inductively coupled plasma mass spectrometry. 

Figure 2.15. Schematic of a quadrupole analyzer, (a) A hyperbolic cross-section (b) cross-section of cylindrical rods (c) the operating principle of a quadrupole mass filter. The x-direction pair of rods acts like a high pass filter so ion C (with low m/z) is not allowed through, and the y-direction pair of rods acts like a low pass filter and takes care of ion A (with high m/z). Only ion B having an m/z in the stable range is allowed through the quadrupole mass filter for subsequent detection. Reprinted from A. Westman-Brinkmalm and G. Brinkmalm (2002). In Mass Spectrometry and Hyphenated Techniques in Neuropeptide Research, J. Silberring and R. Ekman (eds.) New York John Wiley Sons, 47-105. With permission of John Wiley Sons, Inc.

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