Retentate Filtration with Millicup™-FLEX Disposable Vacuum Filtration Units

The Millicup™-FLEX filter unit provides a disposable and time saving alternative to traditional glass vacuum filtration systems. The filter unit consists of a fully recyclable polypropylene funnel and a recyclable ribbed membrane support collar suitable for most filtration applications. Its unique construction enables faster flow rates compared to glass. The Millicup™-FLEX device is compatible with a broad range of chemicals and mobile phase solvents and can be used under diverse conditions, including wide temperature and pH range.

Vacuum filtration is commonly used in methods for particulate contamination analysis and contamination monitoring. For retentate techniques such as gravimetric analysis, microscopy, or X-ray diffraction (XRD) that rely on the detection of particulate matter retained on a membrane, a flat rigid membrane support is necessary. Our 47 mm stainless steel Filter Support Screen can provide such a foundation for use with the Millicup™-FLEX filter unit.

How to use Millicup™-FLEX filtration units for retentate techniques

To use the Filter Support Screen, assemble the Millicup™-FLEX filtration system according to the instructions.

1. Before placing your membrane filter, center the Filter Support Screen on the Millicup™-FLEX collar support.
2. Place the membrane filter on top of the screen and snap the funnel into place.
3. After filtration, carefully remove the filter using filter forceps and proceed according to your analytical method or standard operating procedure (SOP).

Methods for retained particulate matter

The Millicup™-FLEX device and Filter Support Screen may be employed in the following methods as well as similar methods requiring the analysis of retained particulate matter:

NIOSH 7602 Quartz 47 mm, particles retained for IR

• Step 4.b, Use the Millicup™-FLEX filter unit and the Filter Support Screen with a 0.5 µm pore size, 47 mm PVC filter to rinse the 37 mm PVC sample collection filter and collect particles.

OSHA ID 191 Asbestos

• Step 3.3.c, Use the Millicup™-FLEX filter unit and the Filter Support Screen with a tarred silver membrane to filter the sample from dissolved organic matrix (in THF) and collect asbestos material for analysis.
• Step 3.3.d, Use the Millicup™-FLEX filter unit and the Filter Support Screen with a tarred silver membrane to filter the sample from dissolved carbon interference (in 0.1 M HCl) and collect asbestos material for analysis.

ASTM D2274: Standard Test Method for Oxidation Stability of Distillate Fuel Oil (Accelerated Method)

• Step 4.1, Use the Millicup™-FLEX filter unit and the Filter Support Screen with a 47 mm, 0.8 µm pore size cellulose ester surfactant-free membrane to filter fuel sample and recover filterable insolubles.

Other methods for contamination monitoring

Many regulatory methods employ 47 mm membrane filters with standard glass, vacuum filtration setups. The Millicup™-FLEX device can be substituted for these setups in most protocols that require a 47 mm borosilicate glass filter support and glass funnel as well as some that reference stainless steel screen supports. The following methods require general filtration during one or more steps of sample preparation prior to analysis. For similar methods, please be sure to consult the Chemical Compatibility of Filter Components prior to using the Millicup™-FLEX filter unit.

EPA 3200: Mercury Species Fractionation and Quantification by Microwave Assisted Extraction, SPE, or SSE:

• Step 11.2.1.4, Use the Millicup™-FLEX filter unit and a 0.22 µm glass fiber filter to filter sample extracts
• Step 11.4.1, Use the Millicup™-FLEX filter unit to rinse 15-g cotton fiber, neutralizing its pH
• Step 11.4.4, Use the Millicup™-FLEX filter unit with a 1.0 µm filter to retain and rinse particles larger than 1.0 µm from extract
• Step 11.6.3, Use the Millicup™-FLEX filter unit in an optional filtration step to remove possible precipitate

ASTM D4382: Standard Test Method for Barium in Water, AAS Graphite Furnace

• Step 10.3, Use the Millicup™-FLEX filter unit and a 0.45 µm filter to pre-filter sample prior to analysis

ASTM D4130: Standard Test Method for Sulfate Ion in Brackish Water, Seawater, and Brines

• Step 11.1, Use the Millicup™-FLEX filter unit and 0.45 µm membrane filter to remove nucleating particles from sample