Three isomers of pentane are n-pentane, iso-pentane (2-methylbutane
), and neopentane (2,2, dimethylpropane).
Colorectal carcinoma tissue and adjacent healthy colon tissue were obtained directly after tumorectomy from two patients after full informed consent and quick-frozen in 2-methylbutane
The samples were frozen in precooled 2-methylbutane
(isopentane, -80[degrees]C) for 2min and stored in liquid nitrogen until sectioned.
Following decapitation, the unfixed spinal cord was immediately removed, placed lengthwise on a flat wooden stick, and frozen by immersing in a 500 ml bath of dry ice-cooled 2-methylbutane
and stored at -80[degrees]C until OCT embedding (Sakura Tissue-Tek).
The exposure-assessment samples also showed concentrations of propane, butane, pentane, and 2-methylbutane
exceeding 100% of the lower-explosive limit (3).
The brains were removed, frozen in 2-methylbutane
(-45[degrees]C, Carl Roth, Karlsruhe, Germany) and placed in a -70[degrees]C freezer until cutting.
The root was excised 5 mm long and inserted in a plastic tube filled with freezing medium and then quickly cryofrozen in a container of isopentane (2-methylbutane
) cooled with liquid nitrogen, which provides superior cryogenic condition without Leidenfrost phenomenon (boiling of liquid nitrogen).
At postmortem, samples of liver, duodenum, and pancreas were harvested and snapfrozen by immersion in isopentane (2-methylbutane
; BDH, UK) prechilled in liquid nitrogen and stored at -80[degrees]C.
Analysis of the sample by gas chromatography and mass spectrometry showed the actual mole fraction of n-pentane to be 97.72 % with 1.6 % 2-methylbutane
as a major impurity and the balance consisting of methylcyclobutane and cyclopentane.
Fresh florets of broccoli were sliced and incubated in 37[degrees]C for 2 hours then subjected to hydrodistillation solvent extraction using a modified Likens and Nickerson apparatus with 2-methylbutane
(15 mL) as a solvent.
Hippocampi were isolated and rapidly frozen with 2-methylbutane
on dry ice.
The samples are then quickly frozen in 2-methylbutane
cooled in liquid nitrogen (-176[degrees]C).