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Commercial Instrument (commercial + instrument)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Rapid determination of aliphatic amines in water samples by pressure-assisted monolithic octadecylsilica capillary electrochromatography-mass spectrometry

ELECTROPHORESIS, Issue 18-19 2004
Bricio Santos
Abstract A pressure-assisted capillary chromatography-mass spectrometry method based on the use of a monolithic octadecylsilica (ODS) capillary is proposed for the determination of aliphatic amines. A 25 mM citric acid buffer containing 10% methanol is used as running electrolyte. Separation is achieved by simultaneously applying a capillary electrophoresis (CE) voltage of 13 kV and an overimposed pressure of 8 bar. The use of pressure is required to ensure stable electrospray conditions. Analysis times are reduced by using a capillary column consisting of a 30 cm long monolithic silica capillary column bound with ODS and a fused-silica capillary column also 30 cm long. The proposed method was successfully applied to the determination of low-molecular-weight aliphatic amines in tap and river water. The analysis of real samples requires cleanup and preconcentration, which can be performed automatically by inserting a minicolumn in the replenishment system of the commercial instrument. [source]

Field evaluation of ultrasonic flowmeters for measuring water discharge in irrigation canals,

IRRIGATION AND DRAINAGE, Issue 2 2009
David Lozano
mesure de débit; débitmètres acoustiques; canaux d'irrigation Abstract Measuring water flow is essential for sound irrigation management. New commercial flowmeters based on acoustic technology have become popular for measuring water discharge in open channels of irrigation schemes in Spain and various other countries. There are two main types of acoustic flowmeter: transit-time and Doppler. We tested a commercial instrument of each type (a Risonic 2000 and an Argonaut-SW, respectively) in the field throughout an entire irrigation season. The instruments were installed in rectangular cross-sections of one of the secondary canals in the B-XII irrigation scheme, Spain. The discharges tested varied from 0.1 to 4,m3,s,1. To obtain reference data, we used a propeller current meter to measure the flow velocity across the test canal sections. Both the Risonic 2000 and Argonaut-SW instruments provided measurements that were highly consistent with those obtained from the propeller meter. The Argonaut-SW, mounted at the bottom of the canal, had to be reinstalled twice during the irrigation season since it was displaced by debris dragged by the flowing water. The Risonic 2000, mounted on the canal walls, operated without interruption during the entire season. Copyright © 2008 John Wiley & Sons, Ltd. Mesurer les débits est essentiel pour une saine gestion de l'irrigation. Les nouveaux débitmètres commerciaux basés sur la technologie acoustique sont désormais bien connus pour mesurer les débits dans les canaux des périmètres irrigués en Espagne et divers autres pays. Il y a deux types principaux de débitmètres acoustiques: temps de transit et Doppler. Nous avons examiné au champ pendant toute une campagne d'irrigation un instrument commercial de chaque type (un Risonic 2000 et un Argonaut-SW). Les instruments ont été installés dans des sections transversales rectangulaires d'un des canaux secondaires du périmètre irrigué B-XII en Espagne. Les débits analysés ont varié de 0.1 à 4,m3,s,1. Pour obtenir des données de référence, nous avons utilisé un moulinet courant mesurant la vitesse d'écoulement à travers les sections du canal testé. Les deux instruments Argonaut-SW et Risonic 2000 ont fourni des mesures tout à fait conformes à celles obtenues avec le moulinet. L'Argonaut-SW, monté au fond du canal, a dû être réinstallé deux fois pendant la campagne d'irrigation car il a été déplacé par des déchets transportés par l'eau. Le Risonic 2000, monté sur les murs de canal, a fonctionné sans interruption pendant toute la campagne. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Ultraviolet photofragmentation of biomolecular ions

MASS SPECTROMETRY REVIEWS, Issue 3 2009
James P. Reilly
Abstract Mass spectrometric identification of all types of molecules relies on the observation and interpretation of ion fragmentation patterns. Peptides, proteins, carbohydrates, and nucleic acids that are often found as components of complex biological samples represent particularly important challenges. The most common strategies for fragmenting biomolecular ions include low- and high-energy collisional activation, post-source decay, and electron capture or transfer dissociation. Each of these methods has its own idiosyncrasies and advantages but encounters problems with some types of samples. Novel fragmentation methods that can offer improvements are always desirable. One approach that has been under study for years but is not yet incorporated into a commercial instrument is ultraviolet photofragmentation. This review discusses experimental results on various biological molecules that have been generated by several research groups using different light wavelengths and mass analyzers. Work involving short-wavelength vacuum ultraviolet light is particularly emphasized. The characteristics of photofragmentation are examined and its advantages summarized. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:425,447, 2009 [source]

Monitoring chloramines and bromamines in a humid environment using selected ion flow tube mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2010
Wan-Ping Hu
The selectivity and sensitivity of selected ion flow tube mass spectrometry (SIFT-MS) for individual breath analysis of haloamines has been improved by heating the flow tube in a commercial instrument to around 106°C. Data is presented showing the marked reduction in the number density of water clusters of product ions of common breath metabolites that are isobaric with the product ions from monochloramine and monobromamine that are used to monitor the haloamine concentrations. These results have direct relevance to the real-time monitoring of chloramines in drinking water, swimming pools and food processing plants. However, once the isobaric overlaps from water cluster ions are reduced at the higher temperatures, there is no conclusive evidence showing the presence of haloamines on single breath exhalations in the mid parts per trillion range from examination of the breaths of volunteers. Copyright © 2010 John Wiley & Sons, Ltd. [source]