Mtp anchorchip maldi target

2,5-Dihydroxyacetphenone (DHA) MALDI matrix, insulin, ubiquitin, cytochrome C, apomyoglobin, trypsinogen, hematoxylin stain, glycerol, and aluminum potassium sulfate were purchased from Sigma-Aldrich (St. Louis, MO). Ethanol, methanol, chloroform, acetonitrile (ACN), formic acid (FA), and acetic acid were purchased from Fisher Scientific (Pittsburgh, PA). A standard mixture of insulin (0.25 pmol/μL), ubiquitin (1 pmol/μL), cytochrome C (1 pmol/μL), apomyoglobin (2 pmol/μL), and trypsinogen (4 pmol/μL) was prepared and mixed 1:1 with a 15 mg/mL DHA solution (90/10/0.1, ACN/H₂O/FA). One microliter aliquots of this mixture were manually spotted onto a MTP AnchorChip MALDI target (Bruker Daltonics) and allowed to dry. Rat brain and rat kidney were both purchased from Pel-Freeze Biologicals (Rogers, AR) and stored at −80 °C until analysis.

Solutions of PC standards were prepared by mixing a 3 mg/ml (methanol) solution of the standard, a 50 mM of NaCl or KCl solution (water), and a 1 M 2,5-dihydroxybenzoic acid (DHB) matrix solution (methanol) in a 1:1:1 ratio. One microliter of this mixture was manually spotted onto a stainless steel MTP AnchorChip MALDI target (Bruker Daltonics, Billerica, MA) using a micropipette.
Transverse tissue sections of rat brain (BioIVT, Westbury, NY, USA) were sectioned at 10 μm thickness using a Leica CM 3050S cryomicrotome (Leica Biosystems, Buffalo Grove, IL, USA) and then thaw mounted onto indium tin oxide (ITO) coated slides (Delta Technologies, Loveland, CO, USA). The chamber temperature and object temperature were set to be −22 °C and −20 °C, respectively. Mounted tissue sections were stored at −80 °C and then dried in a dessicator for 30 minutes prior to matrix application. A DAN matrix layer was applied onto tissue using a home-built sublimation apparatus (120 °C for 7 minutes, resulting in the deposition of 1.5–2.0 mg DAN).