Glibenclamide in serum: comparison of high-performance liquid chromatography using fluorescence detector and liquid chromatography/mass spectrometry with atmospheric-pressure chemical-ionization (APCI LC/MS)

Abstract A liquid chromatography/mass spectrometry (LC/MS) method was developed to quantitate and confirm residues of leucomalachite green (LMG) in salmon tissue after their conversion to chromic malachite green (MG) in the extraction process. The method uses no-discharge atmospheric pressure chemical ionization (APCI) in conjunction with an ion-trap instrument to generate product-ion spectra. In the sample preparation procedure, salmon tissue is extracted with acetonitrile/buffer, the LMG residue is partitioned into methylene chloride, the LMG is converted to MG using an organic oxidizing agent, and the MG is isolated on alumina/propylsulfonic acid solid-phase extraction cartridges. The method was validated by fortifying salmon with different levels of LMG, and then detecting the residue as MG. The LC/MS conditions, including a comparison of electrospray and no-discharge APCI, were evaluated and optimized. MG was not confirmed in any of the control tissue extracts, and all fortified samples analyzed during validation met the confirmation criteria as described. In addition to providing confirmatory data, this method can provide an alternative method for quantitation of MG in salmon. The recoveries of LMG, measured as MG by this LC/MS method, at fortification levels of 1–10 ng/g were very high (86–109%), with low relative standard deviation(RSD) values (6.4–13%). The results agreed very closely with those obtained for the same extracts using an LC/VIS procedure, indicating that matrix suppression was not an issue. The presence of LMG in salmon tissue samples fortified at 0.25 ng/g was confirmed by this method, with an average recovery of 70.1% and an RSD of 12.0%. Sample extracts from fish exposed to MG were also analyzed.

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

Czech Journal of Food Sciences ◽

10.17221/10639-cjfs ◽

2004 ◽

Vol 22 (SI - Chem. Reactions in Foods V) ◽

pp. S144-S146 ◽

Cited By ~ 3

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]+ but instead fragments representing loss of one or two water molecules [M – H2O + H]+, [M – 2H2O + H]+, loss of hydrogen peroxide [M – H2O2 + H]+ or loss of hydrogen peroxide and water [M – H2O2 – H2O + H]+. 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.

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