Search results for "Ionization."

Determination of several aminoglycoside and macrolide antibiotics in animal tissues by liquid chromatography-electrospray ionization-tandem mass spec…

2008

Simultaneous determination of imidacloprid, carbendazim, methiocarb and hexythiazox in peaches and nectarines by liquid chromatography–mass spectrome…

2002

Abstract A liquid chromatographic (LC) atmospheric pressure chemical ionization mass spectrometric (MS) method is described for determining imidacloprid, carbendazim, methiocarb and hexythiazox in peaches and nectarines. The samples were extracted with ethyl acetate and anhydrous sodium sulfate. Recoveries yield for spiking samples were ranged from 64±9% (R.S.D) for carbendazim to 108±14% (R.S.D.) for hexythiazox at the concentration of 0.1 mg kg−1 (n=5). The correlation coefficients were greater than 0.998 over the range between 0.02 and 2 mg kg−1. The limits of quantitation (LOQ) were 0.02 mg kg−1 for all the pesticides. The applicability of the method to detect and quantify imidacloprid,…

Gas chromatographic separation of acetylated chlorinated phenols, guaiacols and catechols on an SE-30 quartz capillary column

1983

The Role of the Liquid Chromatography-Mass Spectrometry in Pesticide Residue Determination in Food

2008

The use of liquid chromatography (LC) in pesticide residue determination was usually limited to groups of compounds or single compounds for which no suitable gas chromatographic (GC) conditions were available. However, recent developments have significantly enlarged the LC scope in this field of analysis. One of the most important advances was the on-line coupling of efficient LC separation with mass spectrometry detectors (LC-MS and LC-MS/MS) that makes this technique an excellent method for the determination of pesticides and their transformation products in complex matrices such as food. This review considers the application of LC-MS/MS in this field. Emphasis is placed on the tandem MS …

MALDI-TOF characterization of macromonomers

1996

Methacryloyl endfunctionalized oligostyrene macromonomers were characterized by matrix assisted laser desorption ionization/time of flight (MALDI-TOF) spectroscopy and by isocratic and gradient high performance liquid chromatography (HPLC). The molar mass distribution derived by the different techniques coincide for the investigated oligomers. Mixing experiments revealed that the MALDI-TOF peak areas do not necessarily represent the mixing ratio of the components. Combination of gradient HPLC and MALDI-TOF has resolved the chemical composition of the coupling products formed by reaction of the living anion with oxygen.

Supercritical Fluid Extraction and Supercritical Fluid Chromatography of Vitamin E in Pharmaceutical Preparations

1999

An atmospheric pressure chemical ionization-ion-trap mass spectrometer for the on-line analysis of volatile compounds in foods: a tool for linking ar…

2014

An atmospheric pressure chemical ionization ion-trap mass spectrometer was set up for the on-line analysis of aroma compounds. This instrument, which has been successfully employed for some years in several in vitro and in vivo flavour release studies, is described for the first time in detail. The ion source was fashioned from polyether ether ketone and operated at ambient pressure and temperature making use of a discharge corona pin facing coaxially the capillary ion entrance of the ion-trap mass spectrometer. Linear dynamic ranges (LDR), limits of detection (LOD) and other analytical characteristics have been re-evaluated. LDRs and LODs have been found fully compatible with the concentra…

Overlapped moving windows followed by principal component analysis to extract information from chromatograms and application to classification analys…

2015

Variable generation from chromatograms is conveniently accomplished using unsupervised rather than manual techniques. With unsupervised techniques, there is no need for selecting a few peaks for manual integration and valuable information is quickly and efficiently collected. The generation of variables can be performed by using either peak searching or moving window (MW) strategies. With a MW approach, the peaks are ignored and many variables, only part of them carrying information, are generated. Thus, variable generation by MWs should be followed by data compression to generate the variables to be further used for classification or quantitation purposes. In this work, unsupervised proces…

Identification of lipid binders in paintings by gas chromatography

2001

Abstract The influence of the presence and the type of pigments in the lipid binding media of paintings were studied by gas chromatography with flame ionization detector. The drying oils were linseed stand oil, poppy oil and sunflower oil, and the pigments studied were cadmium red, cobalt blue, tin white, lead white, chalk and plaster of Paris, commonly used in paintings. The results indicate that the stearic/palmitic ratio and the presence of pigments are quite stable during ageing. However, some differences in the oleic acid/palmitic acid ratio were found, depending on the type of pigment present in the lipid binding media. These variations are related to the drying effect of the pigments…

Urban organic aerosol composition in Eastern China differs from North to South: Molecular insight from a liquid chromatography-Orbitrap mass spectrom…

2019

Particulate air pollution in China is influencing human health, ecosystem and climate. However, the chemical composition of particulate aerosol, especially of the organic fraction, is still not well understood. In this study, particulate aerosol samples with a diameter ≤ 2.5 μm (PM2.5) were collected in January 2014 in three cities located in Northeast, East and Southeast China, i.e., Changchun, Shanghai and Guangzhou, respectively. Organic aerosol (OA) in the PM2.5 samples was analyzed by ultrahigh performance liquid chromatography (UHPLC) coupled to high-resolution Orbitrap mass spectrometry in both negative mode (ESI−) and positive mode electrospray ioni…