Membrane Filtration - Ahlstrom Brand – ReliaDisc and ReliaPrep - Sartorius Original Cornelia Wiegand

Ahlstrom ReliaDiscTM Membranes Gridded sterile nitrocellulose membranes for use in colony counting and microbiological quality control. Non-sterile microfiltration membranes used to remove particles and microorganisms from organic solvents (PA, PTFE, RC) and aqueous solutions (CA, CN). Ahlstrom ReliaPrepTM Syringe Filters Wide variety of highest quality syringe filters for convenient sample preparation and fluid sterilization. CA and PES membranes recommended for aqueous solutions filtration; PA, PTFE and RC membranes recommended for organic solvent filtration. Many references available on special order.

Contents Depth filters versus membrane filters Membranes Syringe Filters Application Overview Microbiology, Colony Counting

Filter Types Depth Filters Filter papers are mostly made of cellulose and are characterised by high absorbency. They have high particle retention capacity and allow a large sample throughput.

Depth Filter The filter matrix consists of a three-dimensional network of fibres. Retention of particles and micro organisms mainly in the "depth" of the filter matrix by mechanical retention and adsorption. Advantage: High particle holding capacity without premature clogging. The nominal retention rate is especially influenced by the diameter of the fibres, the "compactness" of the fibre structure, and the thickness of the filter.

Depth Filter Structure Cellulose Fibre – Glass Fibre

Membrane Filters are relatively thin and made of synthetic polymers. Filter Types Surface Filters Membrane Filters are relatively thin and made of synthetic polymers. They are used for the filtration of fine particles or the collection of micro- organisms.

Surface Filter The filter matrix consists of a homogeneous "sponge-like" pore structure of high mechanical stability and pressure resistance Retention of particles and micro organisms is mainly "on or near the surface of the“ filter matrix by mechanical means. Advantage: High safety against breakthrough even at high differential pressures and pressure surges.

Surface Filter Structure Cellulose Acetate - Polycarbonate

1 µm = 0.001 mm = 0.000001m Scale of Dimensions 100 µm monkey hair 30 µm smallest particle you can see 3 µm yeast bacteria 0.01 µm virus

Cellulose Acetate (CA) High flow rates Low affinity for protein Routinely used to filter protein solutions e.g. Fetal calf serum (FCS) Bovine serum Albumin (BSA) Good resistance to certain solvents Manufactured without surfactant (SFCA) Good handling, especially when wet Autoclavable Pore size 0.2 ; 0.45: 0.65 ; 0.8; 1.2; 5 µm

Regenerated Cellulose (RC) For ultra cleaning and de-gasing solvents and mobile phase for HPLC Solvent-resistant hydrophilic membrane - Particle removal of solvents - Low non-specific adsorption - Good handling - Pore size 0.2 and 0.45µm Page 9

How to convert to RC Chemical compatibility Flow rates Non-specific binding Thermal stability Page 10

Minimizing Extractables What can cause extractables - Solubility and chemical compatibility - Particle displacement Why reduce extractables? How do you reduce extractables? HPLC certification Increase accuracy by removing unwanted particles Compatibility tested with commons solvents Page 11

Polyamide (NY) Relatively slow to moderate flow rate due to low porosity and membrane thickness (150- 200µm) - Excellent solvent resistance (Ideal for HPLC) - No surfactant required - Very low level of extractables - High non-specific affinity for proteins. - Used as an alternative to CN for blotting - Not recommended for filtering proteins e.g FCS and BSA - Autoclavable - Pore size 0.2 and 0.45µm Page 12

Polyethersulphone (PES) Fast flow rates Low extractables Low protein binding Good solvent resistance Autoclavable Good membrane for FCS Pore size 0.1; 0.2 and 0.45µm Page 13

Polytetrafluoroethylene (PTFE) PTFE is very low protein binding Has good to moderate flow rate PTFE resistant to all known solvents PTFE is hydrophobic Used for venting applications Pore size 0.2 ; 0.45 ; 1.2 and 5µm Page 14

Membrane Filtration Sterile filtration and ultra cleaning of liquids => 0.2µm Particulate removal of liquids, micro-biological reduction filtration and particulate removal of dry air and gases => 0.45µm and 0.8µm Clarification and pre-filtration => 1.2µm and 5.0µm

Membrane filtration has to become supported either by vacuum or by pressure Disc Filters and Disposables Disc membrane filters used in a disc device autoclavable device Ready to use filters have integrated membranes smal hold-up volumes available sterile or non-sterile

Vacuum glass filter holder For disc membranes Size diameter 13mm and 47/50mm

Syringe filters / CA rapid clarification or sterilization of up to 100 ml liquid volumes low unspecific adsorption fitted to a dosing syringe makes a very convenient system for dosing and sterilizing different pore size membrane filters => colour coded 0.45, 0.8, 1.2, 5.0 can be mounted directly in front of an 0.2 µm syringe filter Page 15

Syringe Filter Housing MBS (methacrylate butadiene styrene polymerisate or Cryolite) Similr to Plexiglas – good tensile strength and impact strength Non-autoclavable. Can be Gi or EtO sterilized Limited thermal resistance pH range 3 - 12 PP polypropylene Can be autoclaved or EtO sterilized Outstanding chemical compatibility Low extractables pH range 1-14

Syringe Filters, Application Overview Recommended Application Sterile Filtration Removal of microorganisms from solutions with ≤0.2um hydrophilic syringe filters: PES/CA/RC/Nylon Clarification/Pre-filtration The pre-filtration and purification of liquids with ≥0.45um hydrophilic syringe filters Chromatography-sample prep Ultra cleaning of small volume samples with chemical resistant syringe filters: RC/Nylon/PTFE Sterile venting Removal of microorganisms from gasses and air with hydrophobic 0.2um syringe filters: PTFE Medical Applications CA syringe filters for use in hospitals and pharmacies. Page 28

Volume / Diameter Volume to filter Aqueous solution, solvents Aggressive solution Up to 1 ml RC 4 mm PTFE 4mm Up to 5 ml RC 15 mm PTFE 15 mm Up to 100 ml RC,25 mm PTFE 25 mm

HPLC Sample Preparation / Chromatography

Sterile Venting Syringe filters with integrated PTFE membranes 0.2 µm Reusable filter holder 0.2 µm PTFE membranes

Competition

DMEM-Medium plus 20%FCS

Lipofundin MCT 20% +0.1 % tween

Microbiology Products Colony counting Higly symmetric membrane structure Optimized media for MF method Equipment

Cellulose nitrate membranes Uniform distribution of culture media Optimal flow and retention High recovery of microorganisms Varity of colors Varity of pach sizes