A Validated HPLC-MS/MS Method for Estimating the Concentration of the Ganglioside, G(D2), in Human Plasma or Serum

G(D2) is a ganglioside found in the plasma membrane of the neural crest-derived cancer, neuroblastoma. G(D2) is shed into the circulation of patients with neuroblastoma and could serve as a tumor biomarker to monitor tumor burden or response to treatment. We developed and validated a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method to quantify the D18:1-18:0 (C18) and the D18:1-20:0 (C20) lipoforms of G(D2) in human plasma and serum. Human brain derived G(D2) containing a mixture of C18 and C20 was used as the analytical standard. Samples were extracted with methanol containing dueterated-G(M1) (internal standard), and analytes were separated on a Phenomenex Kinetex C-18 column eluted with a gradient mobile phase composed of ammonium acetate buffer, methanol and isopropanol. An AB Sciex 4500 QTRAP mass spectrometer in negative ion mode was used to quantify the doubly charged G(D2) C18 and C20 lipoform precursor ions (m/z 836.8 and m/z 850.8) that both yield a product ion of m/z 290.0. The calibration curves were linear from 4-1000 ng/mL and 6-1500 ng/mL for G(D2) C18 and C20 lipoforms respectively. Inter-day and infra-day accuracy were within the acceptable validation range in plasma and serum.