Xylene ar grade

Norharmane and chloroform (≥99%) were
purchased from Sigma-Aldrich (Zwijndrecht, The Netherlands) and used
without further purification. Methanol (ULC-MS grade), water (LC-MS
grade), ethanol (LC-MS grade), and xylene (AR grade) were purchased
from Biosolve (Valkenswaard, The Netherlands). Hematoxylin and Entellan
were purchased from Merck (Darmstadt, Germany), and eosin Y was purchased
from J.T. Baker (Center Valley, USA). Indium tin oxide (ITO) coated
glass slides were purchased from Delta Technologies (Loveland, USA).
A lipid standard of PS 18:0/18:1n-9 was purchased
from Avanti Polar Lipids (Alabaster, USA).

Ethanol (HPLC grade), n-hexane (HPLC grade), and xylene (AR grade) were purchased
from Biosolve (Valkenswaard, NL). Hematoxylin and Entellan were purchased
from Merck (Darmstadt, DE). Eosin-Y was purchased from J.T. Baker
(Center Valley, USA). “Pilot Blue-black” ink was purchased
from Pilot Corporation (Tokyo, JP). Yellow “Hype” highlighter
(Staples, Framingham, USA) and black “edding 3000” permanent
markers (edding, Ahrensburg, Germany) were purchased from a local
stationery story (Maastricht, NL). Thin bar, 3.05 mm, copper TEM grids
with mesh sizes of 300 (hexagonal) and 2000 (square) were purchased
from Agar Scientific, Ltd (Stansted, Essex, UK). Conductive indium
tin oxide (ITO)-coated glass slides were purchased from Delta Technologies
(Loveland, CO, USA) and were cleaned with hexane and ethanol. Mouse
kidney, rat brain, and human intestine were obtained from The Johns
Hopkins University School of Medicine and Maastricht University, respectively.
The Institutional Animal Care and Use Committees granted ethical approval
under A3272-01 and DEC 2014-085 for the mouse and rat tissues, respectively.
Human intestinal tissue was a granted ethical approval under METC
06-3-044. All organs were snap-frozen in liquid nitrogen. Cryo-sections
(10 μm thickness) were prepared with a cryostat (Leica Biosystems,
Wetzlar, DE) at −20 °C, thaw-mounted on ITO-coated glass
slides and stored at −80 °C.