Our Whatman glass microfiber filter papers in grade 934-AH RTU have been pre-washed, dried (or ignited), cooled, desiccated and weighed, which eliminates the pre-treating steps that are otherwise required by the US EPA Laboratory Standard Method 2540 parts C, D, and E. These glass microfiber filter papers have fine particle retention of 1.5 µm at high flow rates to process heavy, turbid samples.

Our Whatman filter papers 934-AH family of products come in three different varieties:

• 934-AH RTU for Suspended and Dissolved Solids—pre-washed, dried, cooled, and weighed filters with certified mass loss between washing and drying steps of the lesser of less than 0.5 mg or 4% in accordance with US EPA Lab Standard Method 2540 parts C and D. (Most filters come weighed to four decimal places, however a version of the 47 mm glass microfiber filter can be measured to five decimal places if needed.)
• Ready-to-use for Volatiles—pre-washed, pre-weighed and pre-fired at 550°C aligned to US EPA Laboratory Standard Method 2540 parts C, D, and E.
• RTU Double Weigh—drying, cooling and filter paper weighing steps repeated twice for customers with the highest regulatory concern.
• Economy versions of 934-AH RTU dissolved, suspended, and volatiles testing filters are also available. These filter papers are pre-washed and dried but not weighed and do not come with barcodes.