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Oxidative/Nitrative Stress Core Laboratory

Laboratory Director: Maret Traber, Ph.D.
Laboratory Manager: Jaewoo Choi, Ph.D.

Mass Spectrometry
Analysis of samples by HPLC-tandem mass spectrometry performed by the ONSL staff. Testing is for research purposes only and not for diagnositic use. Acceptance of our terms is needed before samples can be accepted or analyzed.


Isoprostanes are stereoisomers of prostaglandin F2-alpha and are products of free radical-induced oxidation of arachidonic acid. They are considered to be good biomarkers for oxidative stress.

Quantitation in plasma of total (free + esterified) 15-series isoprostanes, including 8-iso-PGF2 alpha, is now performed by the procedure described in Taylor et al. (2009) Analytical Biochemistry 396, 319 - 3211. Sample preparation now uses solid phase extraction, replacing the earlier liquid-liquid extraction method. The service is free to LPI investigators or at a cost of $213.64 per sample to other researchers. Arachidonic acid can also be quantified in the same sample ($68.15 per sample for outside investigators).

The assay can be used for the analysis of free isoprostanes in plasma, but this has not been validated.

The analysis of free isoprostanes and isoprostane metabolites in urine uses a novel solid phase extraction and has been published in Lipids (Taylor et al. (2008) 43, 935-946). This analysis is free to LPI investigators or at a cost of $215.06 per sample to other researches. Creatinine can also be quantified in the same sample ($16.88 per sample for outside investigators).

Submit samples and instructions for sample preparation and shipping.

25-OH Vitamin D

Serum 25-hydroxy vitamin D is considered the best biomarker for Vitamin D status. This assay is performed by a procedure presented at the American Society or Mass Spectrometry, Salt Lake City, UT, in 2010. Serum samples are subjected to solid phase extraction and 25-OH vitamins D2 and D3 are quantifiied by LC-MS/MS. The service is available free to LPI investigators and for a cost of $52.15 for outside investigators. A minimum of 0.5 mL of serum is needed for human samples, 0.1 mL for mouse samples.

Custom Analyses

Tandem mass spectrometry coupled to HPLC is a powerful tool for biomarker discovery and quantitation. The instrument, operated by ONSL staff, is available for custom analyses. Recent work includes development of methods for studying ceramides and other sphingolipids and improved sensitivity for tocopherol assay.

Solid phase extraction (SPE) can improve analytical results by producing cleaner extracts of many analytes found in biological samples. ONSL has three robots to perform SPE and can assist with development of new sample preparation methods.

Please contact Jaewoo Choi (541-737-9376 or for advice on suitability of use, scheduling, and sample preparation.

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