Quantitative Ashless Filter Paper — Gravimetric Filter Paper

Primary uses

• Separates a precipitate from solution in a gravimetric determination
• Can be ignited with the precipitate where the method calls for ashing
• Provides a defined filtration speed and particle-retention behaviour for a standard method

Applications

• Gravimetric determination in mining, cement and materials laboratories
• Precipitate collection and ignition workflows
• Soil, ore and digest filtration in analytical procedures
• Sample clarification where the paper itself must not contribute residue

Advantages

• Can be ignited with the precipitate, which removes a transfer step and the losses that come with it
• Offered in defined filtration-speed and retention classes that standard methods reference directly
• Circles are available in the diameters standard funnels and crucibles use, so apparatus rarely has to change

Limitations to consider

• Filtration speed and retention behaviour trade against each other: a fast paper passes fines, a slow paper takes time the laboratory may not have
• Wet strength is limited, and a torn paper mid-filtration usually means starting the determination again
• Residue after ignition, retention behaviour and filtration speed are manufacturer declarations for the specific paper, verified against its documentation
• Every numeric property — assay, purity, residual content, pore size, retention behaviour, ash content, extractables, thickness, capacity and dimensional tolerance — is a property of one manufactured item from one production line. Values are read from the manufacturer's own technical documentation for the exact item offered and confirmed at quotation, never quoted from a category page.
• A manufacturer declaration and a verified result are not the same thing. Declarations state what the manufacturer controls to; suitability inside your own method, matrix and instrument is established by your own verification. Where a result must stand up inside an accredited scope, plan that verification before the item enters routine use.

How to choose the right grade

• Take the retention and speed class from the method rather than from the current stock, because standard methods name them explicitly
• Match the circle diameter to the funnel or crucible in use, allowing for the fold the procedure requires
• Where a determination is drifting, run a paper blank before questioning the balance or the reagents
• Once a consumable is inside a validated method, changing it has a cost: the change has to be justified, trialled and documented. Continuity of the identical item usually matters more than unit price, so state the incumbent item and the property that must be matched when a second source is being qualified.
• Buyers frequently search using the catalogue name of a manufacturer they already use. Those are third-party trademarks belonging to their owners and are never used as an Allzone product identity. Where an equivalent is being considered, equivalence is assessed against the two sets of documentation and confirmed by the laboratory's own verification.
• Exact specification is confirmed against supplier documentation at quotation.

Typical grades

• Variant selection is made on the instrument, apparatus and test method rather than on a grade ladder
• Where a manufacturer operates distinct quality or cleanliness lines for the same item, the line is identified per offer
• Any declared property is read from the manufacturer documentation for the exact item offered, never assumed from a family name
• Regulatory listing, certification, food-contact status and any scheme approval belong to a specific item, facility and jurisdiction, and they change scope over time. State what your programme or customer requires at the enquiry stage so it is checked against current documentation for the offered item rather than assumed from a product name.
• These items are offered for industrial, food, feed, water, environmental and materials-testing work. Nothing here is offered, positioned or documented for medical, clinical, diagnostic or human-specimen use, and no such suitability is implied.