Polypropylene glycol ppg

Eggshells were obtained from American Dehydrated Foods Inc. (Social Circle, GA). Polypropylene glycol (PPG), ethanol, and glycerol were obtained from Sigma Aldrich (St. Louis, MO). Hydroxypropyl methylcellulose (HPMC E4M) and starch were obtained as gift samples from Colorcon (West Point, PA). Silicified microcrystalline cellulose (SMCC) was obtained from Penwest Pharmaceuticals (Patterson, NY).

A silver-109 isotope of 99.7% isotopic purity
was bought from Trace Sciences International (USA). l-Histidine
and d-ribose were purchased from Sigma-Aldrich (99% purity).
Thymidine was purchased from Alfa Aesar (99% purity). Poly(propylene
glycol) (PPG, average Mn 1000 Da) was purchased from Sigma-Aldrich.
All solvents were of HPLC quality, except for water (18 MΩ cm
water produced locally). Steel targets were machined from H17 stainless
steel. Before the LDI MS and MS imaging experiments, steel targets
were cleaned through soaking in boiling solvents: toluene (3 ×
100 mL, each plate for 30 s), chloroform (3 × 100 mL, each plate
for 30 s), acetonitrile (3 × 100 mL, each plate for 30 s), and
deionized water (3 × 100 mL, each plate for 30 s). Every plate
was dried in high vacuum (ca. 0.01 mbar, 24 h). Optical photographs
were made with the use of an Olympus SZ10 microscope equipped with
an 8 MPix Olympus digital camera and also a Canon 6D camera with a
macro-type 90 mm focal length lens.

To fabricate the membranes, Celazole S26 (PBI Performance Products, Charlotte, NC, USA) was used. It contained 25.8 wt% PBI and 1.5 wt% lithium chloride in DMAc. DMAc (99.5% Samchun Co., Pyeongtaek, Republic of Korea) and acetonitrile (MeCN, 99.5%, Duksan C&P, Daejeon, Republic of Korea) were used as solvent to dissolve PBI. Polypropylene (PP) nonwoven (Novatexx 2471, Freudenberg Filtration Technologies, Weinheim, Germany) was used as a support layer. The fabricated membranes were stored in isopropyl alcohol (IPA, 99.5%, Duksan C&P, Daejeon, Republic of Korea). As a crosslinker, $\mathrm{\alpha },{\mathrm{\alpha }}^{\prime }$ -dibromo-p-xylene (DBX, 97%, Sigma-Aldrich Co., St. Louis, MO, USA) was used. For the OSN performance test, anhydrous ethyl alcohol, acetone, methanol, and toluene were purchased from Duksan C&P (Daejeon, Republic of Korea); poly(propylene) glycol (PPG) (average Mn: 425, 725, and 1000 g/mol) was purchased from Sigma-Aldrich (St. Louis, MO, USA). The ecamsule solution was provided by Withel (Iksan, Republic of Korea).