A United States Pharmacopeia
reference standard of gemcitabine hydrochloride (200 mg, catalog No.
1288463) was obtained from Sigma-Aldrich. A deuterated lipid standard
mix EquiSPLASH (Avanti Polar Lipids, catalog No. 330731) was also
purchased from Sigma-Aldrich for use as a multiclass internal standard,
described in Table S1. A lysate of human
cervical cancer (HeLa) cells was purchased from Caltag Medsystems
(Buckingham, U.K., 200 μg catalog No. L013 V2) for use as a
single-cell adjacent standard. Chromatography solvents methanol (MeOH),
ethanol (EtOH), isopropyl alcohol (IPA), acetonitrile (ACN), and water
were Optima LC-MS grade and purchased from Fisher Scientific. Chloroform
used for lipid extraction was high-performance liquid chromatography
(HPLC) grade (99.5+%) and also purchased from Fisher Scientific. Dulbecco’s
phosphate-buffered saline (DPBS) was purchased from Sigma-Aldrich
(catalog No. D8537). The cell culture media was prepared, as described
by Wishart et al.25 (link),28 (link)−30 (link) More specifically,
Dulbecco’s modified Eagle’s medium (DMEM) with high
glucose (Sigma-Aldrich, Merck, U.K., catalog No. 21969035) was supplemented
with 10% fetal bovine serum (Fisher Scientific, U.K., catalog No.
11550356), 1% penicillin/streptomycin (Fisher Scientific, U.K., catalog
No. 15140122), and 2 mM l-glutamine (Sigma-Aldrich, Merck,
U.K., catalog No. 25030024).
Free full text: Click here