The ash content is determined in accordance with DIN 54370: 10 g filter paper is weighed after ignition in a platinum crucible at 800 °C. Results are expressed as % of the original paperweight.
Dry bursting strength
For determination of the dry bursting strength the paper is clamped over a rubber diaphragm with an area of 10 cm2. The strain on the paper is then increased by applying increasing air pressure, until the paper bursts. The dry bursting strength in accordance with DIN 53113 is stated in KPa.
For determination of the tensile strength, a paper strip (measuring 180 x 15 mm) is subjected to vertical strain by applying increasing weight. The force expended at the moment of tearing represents the tensile strength. Results are expressed in N/15 mm.
The thickness of a paper is measured with a touch pressure device. Especially for soft and creped papers, it is important that the touch pressure is not too high. Otherwise, the papers are compressed and a falsely low thickness is obtained.
For determination of the filtration speed in accordance with DIN 53137 the duration of flow of 10 mL distilled water through a quadrant-folded, freely suspended filter circle of 12.5 cm diameter is measured. Results are expressed in seconds.
The basis weight is determined for a sample of 10 x 10 cm. It is measured in g/m2.
The Gurley test measures the time required for filtration of 100 mL air at a water column pressure of 31 mm. The sample has an area of ¼ sq. inch.
The wet strength of a paper is a measure for the mechanical stability of a paper in a wet or moist condition. For example, it can be determined as the tensile strength or the bursting strength (see above).
The retention efficiency of a filter paper is influenced by several factors. Since filter papers are deep bed filters, one usually refers to mean particle retention.
Capillary rise according to Klemm
The capillary rise according to Klemm indicates how far a strip of filter paper is moistened in 10 min when vertically dipped with one end into distilled water (20 °C)
Particle retention refers to the efficiency of filter papers in retaining certain precipitates. It is characterised by the permeability of the paper for precipitates of iron(III) oxyhydrate, lead sulfate, calcium oxalate and barium sulfate.
Selection of filter papers
filter cake ignition and quantitative determination of the residue (gravimetric analysis)
ashless filter papers
analysis of the filtrate; it is important that no interfering substances are extracted from the filter paper
ashless filter papers or glass fibre filters
mechanical removal of the filter cake from the filter, e.g. with a jet from a wash bottle or with a spatula
visualisation of small amounts of light precipitates
black filter paper (MN 220)
technical filtration or need for large cuts
technical filter papers or thick filter papers
retention of very fine precipitates
slow filter papers
retention of coarse precipitates and fast filtration
fast filter papers
filtration of strongly acidic or strongly basic liquids
glass fibre filters
filtration of aggressive liquids (e.g. strong oxidants)
glass fibre filters
need for very low metal ion blanks of the filter (e.g. for investigation of air-borne particles)
quartz fibre filters
accelerated filtration with constant retention efficiency
filtration at increased pressure or strong mechanical load (e.g. heavy filter cake).
thick technical filter papers
strongly absorbent paper, no special wet strength required
Below is a filter paper grade comparison between Macherey Nagel and Whatman.
Whatman Filter Paper Grades
Macherey Nagel Filter Paper Grades
616 md (until 07.01.2009 616)
NANOCOLOR Potassium 50 (REF 985045) has been improved. The change is introduced from LOT 45004, which is available from stock as of 20th July 2020.
The test is now produced with an integrated ammonium compensation. The modified recipe allows a simple determination of potassium in the presence of an ammonium interference up to a concentration of 200 mg/L NH4-N, which is unique in the market.
The use of the additional ammonium compensation reagent (REF 918045) is therefore no longer necessary. Additional information on this topic will be part of our upcoming water news mailing.
Please note, that the test procedure has changed.
An update of the photometers is not required.
Please find the new product information within the following link.
Note: Please save your special methods and measurement data prior to the update. More information can be found in the customer information
Macherey Nagel will leave out the blank cuvettes for the following test kits:
985003 Ammonium 3
985004 Ammonium 10
985005 Ammonium 50
985006 Ammonium 200
985008 Ammonium 100
985009 Lead 5
985012 COD 60000
985019 Chloride 200
985021 Chloride 50
985023 COD 10000
985028 COD 15000
985029 COD 1500
985035 DEHA 1
985041 Formaldehyde 8
985045 Potassium 50
985046 Formaldehyde 10
985050 organic Acids 3000
985056 Molybdenum 40
985079 Phosphate 50
985085 Starch 100
985091 Thiocyanate 50
985097 Tin 3
Test kits that require a blank cuvette even in current photometers will still be equipped with this cuvette. This applies for the following test kits:
963026 COD 160 Hg-free
985007 AOX 3
985015 Carbonate Hardness 15
985075 TOC 30
985078 TOC 300
985098 Aluminum 07
For old photometers (PF-11 etc.) asking for blank guidance is available here.
The NANOCOLOR® 500 D filter photometer is being phased out this year after more than 10 years on the market. Currently, a certain, but limited, number of devices is still available. Macherey Nagel will continue to offer support for the device. Spare parts will still be available.
The NANOCOLOR® 500 D will be replaced by the new device, the NANOCOLOR®Advance. Information is an upcoming instrument soon.