BS EN 872-2005 pdf download.Water quality Determination of suspended solids Method by filtration through glass fibre filters.
5.1 Equipment for vacuum or pressure filtration, to accommodate the selected filters (5.2).
Equipment for membrane filtration can in most cases be used for other types of filters. The plate supporting the filter needs to have sufficient permeance to allow the water to pass freely.
5.2 Borosilicate glass fibre filters
5.2.1 The borosilicate filters shall satisfy the following criteria shall not contain any binders
– shall be circular and of the appropriate diameter to fit the filtering device (5.1); shall compnse a mass per unit area of between 50 gim2 and 100 glm’;
— the loss of mass obtained in a blank test (5.2.2) shall be less than or equal to 0,017 mg/cm’ (for the more common diameter of 47 mm, this corresponds to a loss of mass less than or equal to 0,3 mg).
5.2.2 Blank test
Check the loss of mass during filtration by running the procedure in Clause 8 but using 150 ml of distilled water instead of the sample. Check each box or batch of filters separately. Carry out the test 3 times, selecting 3 filters at random, to increase the sensitivity of the test
NOTE To remove water-soluble constituents, the filters may be prewashed Individual or a small number of filters (less than 10) are prewashed by filtenng 150 ml of distilled water through the filter(s) and then drying at 105 “C for at least 1 h.
It is reconwiended to bulk•wastl filters by soaking in distilled water for several hours. The wash water is drained off and the filter dried at 105 ‘C for at least 1 h or preferably overnight before use
Glass fibre filters from different manufacturers can have somewhat different filtering characteristics, State the type of fitter used and its manufacturer in the report (see Clause 10).
5.3 Drying oven capable of maintaining a temperature of 105 ± 2 °C.
5.4 Analytical balance. capable of weighing to an accuracy of at least 0.1 mg.
5.5 Drying support of suitably surfaced material to support the filters in the drying oven (5.3), e.g. Petn
dishes.
6 Reagents
6.1 Reference suspension microcrystalline cellulose, 500 mg/L.
Shake the reference suspension (61) until it is completely uniform. With a minimum delay measure out 100 ml ± 1 ml into a 100 ml volumetric flask. Transfer the measured volume quantitatively into a 1 000 ml volumetric flask and make up to the mark with distilled water Shake the suspension well before use Prepare a fresh reagent daily
7 Sampling and sample handling
Obtain samples as described in the relevant sampling guidelines. such as EN 25667-2 and EN ISO 5667-3. Samples shall preferably be taken in bottles of transparent material. Avoid filling the bottles completely to allow efficient mixing by shaking the bottle.
Analyse samps for the determination of suspended solids as soon as possible after sampling, preferably within 4 h. Store samples which cannot be analysed within 4 h in the dark at between 1 and 5 “C. but do not allow the sample to freeze. Interpret results obtained for samples that have been stored more than 2 days with caution. Samples for the determination of suspended solids shall not be preserved by any additives
If the time period from sampling to analysis exceeds 2 days. this shall be stated in the report as well as the conditions of storage.
8 Procedure
8.1 Allow the samples to attain room temperature.
8.2 Ensure that the filters fulfil the requirements given in 5.2.1.
8.3 Allow a filter to attain moisture equilibrium with the air near the balance and wetgh it to the nearest 0.1 mg using the balance (5.4). Take care to avoid dust contaminating the filter, for example by using a desiccator.
8.4 Place the filter, the smooth side down. in the funnel of the filtering device (5.1) and connect the device to a vacuum (or pressure) line.
8.5 Shake the sample bottle vigorously and immediately transfer in one stroke a suitable volume of sample to a measuring cylinder
If the sample is obtained in a completely filled bottle, mix the sample by transferring it “back and forth between two bottles. Check that the second bottle is dry and free from contaminants before use.
Select the sample volume so that the dry residue on the filter will be in the optimum range of the determination, which is between 5 mg and 50 mg. However, avoid sample volumes exceeding 1 I. To be valid, the result shall be based on a dry residue of at least 2 mg. Read the sample volume with an accuracy of 2 % or better Sample volumes of less than 25 ml shall be determined by weighing.BS EN 872-2005 pdf download.
BS EN 872-2005 pdf download
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