Search results for "electrospray ionization"
showing 10 items of 275 documents
Quantitative analysis of six pesticides in fruits by capillary electrophoresis-electrospray-mass spectrometry.
2005
A method to identify and quantify six pesticide residues - dinoseb, pirimicarb, procymidone, pyrifenox, pyrimethanil, and thiabendazole - in peaches and nectarines using capillary electrophoresis-electrospray ionization-quadrupole ion trap-tandem mass spectrometry (CE-ESI-MS/MS) is described. Separation was carried out using a buffer of 0.3 M ammonium acetate at pH 4 with 10% methanol. Pesticide residues present in peach and nectarine samples were preconcentrated by solid-phase extraction using C(18), eluted with CH(2)Cl(2), concentrated to dryness, and redissolved in buffer to obtain lower detection limits. The recoveries of the analytes ranged from 58 to 99% and the relative standard devi…
Analysis of thiabendazole and procymidone in fruits and vegetables by capillary electrophoresis–electrospray mass spectrometry
2002
Abstract A capillary electrophoresis–mass spectrometry method for determining procymidone and thiabendazole in apples, grapes, oranges, pears, strawberries and tomatoes is described. Separation is achieved using a buffer of formic acid–ammonium formate at pH 3.5 with 2% of methanol. Fungicide residues present in the sample are preconcentrated by both solid-phase extraction and injection of large sample volumes into the capillary by a stacking technique, to obtain lower detection limits. Ionization is performed at atmospheric pressure in an electrospray type source and detection is carried out using positive ionization and selected ion monitoring modes. The quantitation limits are 0.005 and …
Reduction of [(C 5 Me 5 ) 2 Mo 2 O 5 ] and [(C 5 Me 5 ) 2 Mo 2 O 4 ] in Methanol/Water/Trifluoroacetate Solutions Investigated by Combined On‐Line El…
2003
Complexes [Cp*2Mo2O5 ]( Cp* =η 5 -C5Me5) and [Cp*2Mo2O4] were investigated by combined on-line electrochemical (EC) reduction and electrospray-ionization mass spectrometry (ESI-MS) techniques in a trifluoroacetic acid buffered water/ methanol solution. The reduction products at the larger negative potentials are identical for both compounds. The studies reveal the existence of a wide range of previously unknown di- and trinuclear Mo V ,M o IV ,M o III , and mixed-val
New Microbe Killers: Self-Assembled Silver(I) Coordination Polymers Driven by a Cagelike Aminophosphine
2019
New Ag(I) coordination polymers, formulated as [Ag(µ
Do electrospray mass spectra of surfactants mirror their aggregation state in solution?
2011
One important feature in the gas phase chemistry of surfactants is to ascertain whether their aggregates produced by electrospray ionization reflect those formed in the starting solution. With this aim, we have performed ESI-MS, ESI-MS/MS and ER-MS spectra of bis(2-ethylhexyl)sulfosuccinate (AOTNa) solutions in different solvents, i.e. water, water/methanol, methanol and n-hexane. The results clearly indicate that, notwithstanding the strongly different aggregation state in solution (direct micelles in water and in water/methanol, molecular dispersion in methanol and reverse micelles in n-hexane) and marked effects of the solvent polarity on the total ionic current, the surfactant aggregate…
Analysis of fumonisins B1, B2 and B3 in corn-based baby food by pressurized liquid extraction and liquid chromatography/tandem mass spectrometry
2008
A sensitive and reliable method using pressurized liquid extraction (PLE) and liquid chromatography (LC)/electrospray ionization (ESI) tandem mass spectrometry with a triple quadrupole (QqQ) analyzer has been developed for the analysis of fumonisin B(1) (FB(1)), fumonisin B(2) (FB(2)) and fumonisin B(3) (FB(3)) in corn-based baby foods. Influence of several extraction parameters that affect PLE efficiency such as temperature, pressure, solvent extraction, number of cycles and dispersant/clean-up agents were studied. The selected PLE operating method was: 3g of sample was packed into 11 ml stainless-steel cell and fumonisins were extracted with methanol at 40 degrees C, 34 atm in one cycle o…
Multiresidue analysis of organic pollutants by in-tube solid phase microextraction coupled to ultra-high performance liquid chromatography-electrospr…
2013
In this work, in-tube solid phase microextraction (IT-SPME) coupling with ultra-high-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) multiresidue analytical method has been proposed for the first time for on-line enrichment of 9 analytes included in Water Frame Directive 2000/60/EC (WFD). The device was equipped with a GC TRB-5 capillary column, used as pre-concentration loop, and two conventional six-port injection valves. Water sample and desorption solvent volumes were tested. The optimum conditions were 4mL of processed sample followed by elution with 40μL of methanol. The analytes were detected with a mass spectrometer after being ionized positively using an elect…
Analysis of carbamate and phenylurea pesticide residues in fruit juices by solid-phase microextraction and liquid chromatography–mass spectrometry
2007
A new analysis method to detect carbamates and phenylurea pesticide residues in fruit juices was developed using solid-phase microextraction (SPME) coupled with liquid chromatography-single quadrupole mass spectrometry (LC/MS) and liquid chromatography-quadrupole ion trap mass spectrometry (LC/QIT-MS). The pesticide residues present in watery matrices as fruit juices were extracted using three types of fibers: 50-microm Carbowax/templated resin (CW/TPR), 60-mum poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) and 85-microm polyacrylate. The different extraction conditions were evaluated choosing as the best parameters 90 min (time), 20 degrees C (temperature) and 1 ml (volume). After extrac…
Comparison of various liquid chromatographic methods for the analysis of avermectin residues in citrus fruits.
2001
Abstract Various liquid chromatographic (LC) techniques for analyzing avermectin (Abamectin) were compared after extraction of residues from citrus fruit samples by matrix solid-phase dispersion (MSPD). LC with UV and fluorescence detection were used as also was LC coupled to the mass spectrometer by an electrospray interface. The results obtained by the three methods were compared in terms of sensitivity and selectivity. The combination of MSPD extraction and LC with fluorescence detection have made it possible to quantify 0.5 μg kg −1 of Abamectin in 0.5 g of orange sample, with an overall average recovery of 94%. The procedure provides a simple and sensitive method for monitoring Abamect…
Nanoelectrospray with ion-trap mass spectrometry for the determination of beta-casomorphins in derived milk products.
2009
Beta-casomorphins (b-CMs) are bioactive peptides derived from casein with opioid agonist effects similar to morphine. The use of electrospray (ESI) with quadrupole ion-trap mass spectrometry (QIT-MS) for these compounds in two matrices, cheese and milk, was examined. It was compared to a liquid chromatography (LC) coupled to mass spectrometry (LC-MS), and a "soft" ionisation technique, NanoMate, with selected ion monitoring (SIM), which are unreliable for the determination of trace casomorphins in derived milk products. b-CM mass fragmentation pathways were done for the four most common b-CMs: beta-casomorphin (1-5) bovine (b-CM-5), beta-casomorphin (1-7) bovine (b-CM-7), [D-Ala2, D-Pro4,Ty…