Determination of theophylline in serum by high performance liquid chromatography/mass spectrometry with atmospheric pressure chemical-ionization (APCI HPLC/MS)

1997 ◽  
Vol 357 (3) ◽  
pp. 338-344 ◽  
Author(s):  
F. Susanto ◽  
H. Reinauer
Keyword(s):  
Mass Spectrometry ◽  
High Performance Liquid Chromatography ◽  
Atmospheric Pressure ◽  
High Performance ◽  
Chemical Ionization ◽  
Atmospheric Pressure Chemical Ionization ◽  
Liquid Chromatography Mass Spectrometry ◽  
Pressure Chemical Ionization ◽  
Pressure Chemical

scholarly journals Determination of stigmasterol hydroperoxides using high-performance liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization

2004 ◽  
Vol 22 (SI - Chem. Reactions in Foods V) ◽  
pp. S144-S146 ◽  
Author(s):  
S. Kemmo ◽  
V. Ollilainen ◽  
Lampi A-M ◽  
V. Piironen
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Peroxide ◽  
High Performance Liquid Chromatography ◽  
Atmospheric Pressure ◽  
High Performance ◽  
Chemical Ionization ◽  
Atmospheric Pressure Chemical Ionization ◽  
Liquid Chromatography Mass Spectrometry ◽  
Pressure Chemical Ionization ◽  
Pressure Chemical

A new specific method using high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the detection of stigmasterol hydroperoxides was developed. Hydroperoxides of stigmasterol were obtained by photo-oxidation (90 min) in the presence of methylene blue as a sensitizer. The separation was performed using normal-phase chromatographic conditions. The MS detection was carried out with an ion-trap mass spectrometer using atmospheric pressure chemical ionization (APCI) and positive ion mode. Stigmasterol hydroperoxides were seen to produce no protonated molecular ions [M + H]<sup>+</sup> but instead fragments representing loss of one or two water molecules [M – H<sub>2</sub>O + H]<sup>+</sup>, [M – 2H<sub>2</sub>O + H]<sup>+</sup>, loss of hydrogen peroxide [M – H<sub>2</sub>O<sub>2</sub> + H]<sup>+</sup> or loss of hydrogen peroxide and water [M – H<sub>2</sub>O<sub>2</sub> – H<sub>2</sub>O + H]<sup>+</sup>. The results showed that positional isomers of hydroperoxides had different fragmentation patterns and relative ion abundances. On the other hand anomeric isomers had more similar fragmentation. As a conclusion the method developed showed to be a useful tool for investigation the oxidation mechanism of sterols.

scholarly journals Determination of Benzoylurea Insecticide Residues in Tomatoes by High-Performance Liquid Chromatography with Ultraviolet-Diode Array and Atmospheric Pressure Chemical Ionization-Mass Spectrometry Detection

2007 ◽  
Vol 90 (5) ◽  
pp. 1395-1401 ◽  
Author(s):  
Anastasios N Markoglou ◽  
Eleftheria D Bempelou ◽  
Konstantinos S Liapis ◽  
Basil N Ziogas
Keyword(s):  
Mass Spectrometry ◽  
High Performance Liquid Chromatography ◽  
Atmospheric Pressure ◽  
High Performance ◽  
Chemical Ionization ◽  
Atmospheric Pressure Chemical Ionization ◽  
Diode Array ◽  
Pressure Chemical Ionization ◽  
Pressure Chemical

Abstract A simple and sensitive method using high-performance liquid chromatography/mass spectrometry (LC/MS) was developed and validated for simultaneous determination of 5 benzoylurea insecticidesdiflubenzuron, triflumuron, teflubenzuron, lufenuron, and flufenoxuronin tomatoes. Residues were successfully separated on a C18 column by methanolwater isocratic elution. Detection was carried out by an ultraviolet diode array detector (UV-DAD) coupled with a quadrupole mass spectrometer, using atmospheric pressure chemical ionization (APCI) in negative-ion mode. The main ions were the deprotonated molecules [MH]&lt;sup/&gt; for triflumuron, and the anions formed by elimination of hydrofluoric acid [MHHF]&lt;sup/&gt; for diflubenzuron and flufenoxuron, and [M2HHF] for lufenuron and teflubenzuron. The calibration plots were linear for both detectors over the range 0.05 to 10 g/mL, and the method presented good quality parameters. The limits of detection for standard solutions were 0.0080.01 mg/L (equivalent to 0.080.1 ng injected) for both detectors, and the limits of quantification (LOQs) were approximately 10 times lower than national maximum residue levels (MRLs). Depending on the compound and the detector, the LOQ values ranged from 0.2 to 0.4 ng injected. The optimum LC-UV-DAD/APCI-MS conditions were applied to the analysis of benzoylureas in tomatoes. The obtained recoveries from fortified tomato samples (50 g), extracted with ethyl acetate and purified by solid-phase extraction on silica sorbent, were 88100 and 92.9105 for the UV-DAD and MS detectors, respectively, with precision values (relative standard deviations) of 2.911 and 3.714, respectively. The method was applied to 12 tomato samples from local markets, and diflubenzuron and lufenuron were detected in only one sample at concentrations lower than the MRLs. The results indicate that the developed LC/MS method is accurate, precise, and sensitive for quantitative and qualitative analysis at low levels of benzoylureas required by legislation.

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