The aqueous layer was filtered through a membrane filter (pore size 0.45 µm) prior to injection into the HPLC for chromatographic analysis.
Prior to addition, the drug solution was filter sterilized using sterile syringe driven PVDF hydrophilic membrane filter (pore size-0.22 µm).
The residues were dissolved in methanol (HPLC grade), filtered through membrane filter (pore size-0.22 µm) and analyzed by chiral HPLC.
The sieved sample was then centrifuged (20 min, at 5300 rpm and 20 °C, Avanti 30 Centrifuge, Beckman, Brea, USA) and filtered (SM 16 249 pressure filtration device, Sartorius, Göttingen, Germany; nylon membrane filter: pore size 0.45 μm, Whatman, Germany).
The sieved sample was centrifuged for 10 min at 5.300 rpm (Heraeus-Labofuge 200, Thermo Fisher Scientific GmbH, Dreieich, Germany) and filtered afterwards (SM 16249 pressure filtration device, Sartorius, Göttingen, Germany; nylon membrane filter: pore size 0.45 μm, Whatman, Germany) and analyzed for ammonium-nitrogen (NH4-N) and the volatile fatty acids (VFA) acetate, butyrate, and propionate.
The solutions were first refluxed at 150 °C for 3, 12, and 24 h followed by vacuum filtration using 1-μm membrane filter (pore size 1.0 μm, diameter 25 mm, Advantec Inc ., and the precipitate was then washed with deionized water several times and finally dried at 50 °C in vacuum oven overnight.
These plates contain bottom and top chambers with 0.4- μm membrane filter pores that do not allow GC cells to pass through but allow medium to exchange freely.
The inability of nCuO and nTiO2 to cross the membrane filter pores of 0.4 μm can be due to the tendency of NPs to form aggregates that are physically unable to pass through the membrane pores.
For in vitro cellular permeability studies, Caco2 cells or HT29 cells (2 × 104 cells/cm2) were seeded in 24-well Transwell® plates (Cornings; USA), on polyester membrane filters (pore size 0.4 µm, surface area 1.12 cm2)60.
The final sample was clarified using membrane filters (pore size of 0.45 μm and diameter of 4 mm).
Dry biomass data were determined by filtering 1 ml of cell suspension through preweighted Whatman membrane filters (pore diameter of 0.2 μm).
