Odd-numbered very-long-chain polyunsaturated fatty acids from the dinoflagellate Amphidinium carterae identified by atmospheric pressure chemical ionization liquid chromatography–mass spectrometry

2008 ◽  
Vol 69 (16) ◽  
pp. 2849-2855 ◽  
Author(s):  
Tomáš Řezanka ◽  
Linda Nedbalová ◽  
Karel Sigler
2005 ◽  
Vol 88 (5) ◽  
pp. 1312-1317 ◽  
Author(s):  
Sherri B Turnipseed ◽  
Wendy C Andersen ◽  
José E Roybal

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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