Bsi bs en 00872 2005 (bs 6068 2 54 2005)

BRITISH STANDARD

Water quality —
Determination of
suspended solids —
Method by filtration
through glass fibre
filters

The European Standard EN 872:2005 has the status of a
British Standard

ICS 13.060.30

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BS EN
872:2005
BS
6068-2.54:2005


BS EN 872:2005

National foreword
This British Standard is the official English language version of EN 872:2005.
It supersedes BS EN 872:1996 which is withdrawn.
The UK participation in its preparation was entrusted by Technical Committee
EH/3, Water quality, to Subcommittee EH/3/2, Physical, chemical and
biochemical methods, which has the responsibility to:
—

aid enquirers to understand the text;

—

present to the responsible international/European committee any
enquiries on the interpretation, or proposals for change, and keep the
UK interests informed;

—

monitor related international and European developments and
promulgate them in the UK.

A list of organizations represented on this subcommittee can be obtained on
request to its secretary.
Cross-references
The British Standards which implement international or European
publications referred to in this document may be found in the BSI Catalogue
under the section entitled “International Standards Correspondence Index”,
or by using the “Search” facility of the BSI Electronic Catalogue or of
British Standards Online.
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Compliance with a British Standard does not of itself confer immunity
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This British Standard was
published under the authority
of the Standards Policy and

Strategy Committee on
21 February 2005

Summary of pages
This document comprises a front cover, an inside front cover, the EN title page,
pages 2 to 10, an inside back cover and a back cover.
The BSI copyright notice displayed in this document indicates when the
document was last issued.

Amendments issued since publication
Amd. No.
© BSI 21 February 2005

ISBN 0 580 45513 0

Date

Comments


EN 872

EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM

February 2005

ICS 13.060.30

Supersedes EN 872:1996

English version

Water quality - Determination of suspended solids - Method by
filtration through glass fibre filters
Qualité de l'eau - Dosage des matières en suspension Méthode par filtration sur filtre en fibres de verre

Wasserbeschaffenheit - Bestimmung suspendierter Stoffe Verfahren durch Abtrennung mittels Glasfaserfilter

This European Standard was approved by CEN on 17 December 2004.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.

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COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG

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© 2005 CEN

All rights of exploitation in any form and by any means reserved

worldwide for CEN national Members.

B-1050 Brussels

Ref. No. EN 872:2005: E


EN 872:2005 (E)

Contents
Page
Foreword......................................................................................................................................................................3
1

Scope ..............................................................................................................................................................4

2

Normative references ....................................................................................................................................4

3

Terms and definitions ...................................................................................................................................4

4

Principle..........................................................................................................................................................4

5

Apparatus .......................................................................................................................................................5

6

Reagents.........................................................................................................................................................5

7

Sampling and sample handling....................................................................................................................6

8

Procedure .......................................................................................................................................................6

9

Control ............................................................................................................................................................7

10

Calculation and report...................................................................................................................................7

11

Precision.........................................................................................................................................................7

Annex A (informative) Samples containing oil or other organic liquids..............................................................9
Bibliography ..............................................................................................................................................................10

2

EN 872:2005 (E)

Foreword
This document (EN 872:2005) has been prepared by Technical Committee CEN/TC 230 “Water analysis”, the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical text or
by endorsement, at the latest by August 2005, and conflicting national standards shall be withdrawn at the latest by
August 2005.
This document supersedes EN 872:1996.
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices and to ensure compliance
with any national regulatory conditions.
The evacuation of large glass vessels can cause dangerous implosions if the vessel is damaged by
scratches etc. It should be ensured that the relevant safety precautions have been observed.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark,
Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

3


EN 872:2005 (E)

1

Scope

This document describes a method for the determination of suspended solids in raw waters, waste waters and
effluents by filtration through glass fibre filters. The lower limit of the determination is about 2 mg/l. No upper limit has
been established.
Water samples are not always stable which means that the content of suspended solids depends on storage time,
means of transportation, pH value and other circumstances. Results obtained with unstable samples need to be
interpreted with caution.
Floating oil and other immiscible organic liquids will interfere (see Annex A).
Samples containing more than about 1 000 mg/l of dissolved solids can require special treatment (8.6).
NOTE 1
The result of the determination depends to some extent on the type of filter used (5.2). It is therefore recommended
that the type of filter is specified.
NOTE 2
The size distribution of particles in different samples can vary widely. Therefore there is no correlation between
results obtained with filters of different pore width and no conversion factor can be given for the conversion of results obtained
with one type of filter to another.

2

Normative references

The following referenced documents are indispensable for the application of this document. For dated references,
only the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.
EN 25667-2:1993, Water quality — Sampling — Part 2: Guidance on sampling techniques (ISO 5667-2:1991).
EN ISO 5667-3, Water quality — Sampling — Part 3: Guidance on the preservation and handling of samples
(ISO 5667-3:2003).

3

Terms and definitions

For the purposes of this document, the following terms and definitions apply.
3.1
suspended solids
solids removed by filtration under specified conditions
3.2
dissolved solids
substances remaining, after filtration and evaporation to dryness of a sample, under specified conditions
[4.25.1 of ISO 6107-2:1997]

4

Principle

Using a vacuum or pressure filtration apparatus the sample is filtered through a glass fibre filter. The filter is then dried
at 105 °C ± 2 °C and the mass of the residue retained on the filter is determined by weighing.

4


EN 872:2005 (E)

5

Apparatus

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 comprise a mass per unit area of between 50 g/m and 100 g/m ;



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).

2

2

2

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 filtering 150 ml of distilled water through the filter(s) and then drying at 105 °C for at least 1 h.
It is recommended to bulk-wash 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
filter used and its manufacturer in the report (see Clause 10).
5.3

Drying oven, capable of maintaining a temperature of 105 °C ± 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. Petri
dishes.

6
6.1

Reagents
Reference suspension, microcrystalline cellulose, 500 mg/l.

Weigh 0,500 g (oven dry basis) of microcrystalline cellulose (C6H10O5)n, the grade used for thin layer chromatography
(TLC), or equivalent, and transfer it quantitatively into a 1 000 ml volumetric flask and make up to the mark with
distilled water. Shake the suspension well before use.
The suspension may be stored for at least three months.
NOTE
The dry matter content of the microcrystalline cellulose can be determined by drying a separate sample in an oven
at 105 °C ± 2 °C.

6.2

Working reference suspension, ρ = 50 mg/l.

5


EN 872:2005 (E)

Shake the reference suspension (6.1) 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 samples 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 °C 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 weigh 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 l. 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.
8.6 Filter the sample and rinse the measuring cylinder with about 20 ml of distilled water and use this portion to
wash the filter. Rinse the inner sides of the funnel with another 20 ml portion of distilled water.
If the sample contains more than 1 000 mg/l of dissolved solids, repeat the washing of the filter with 3 portions each
consisting of 50 ml of distilled water. Take care to wash the rim of the filter.
NOTE
The filtering normally is complete within less than 1 min. However, some types of waters contain materials that block
the filter pores or reduce their width. This increases the filtering time and the results can become a function of the sample
volume. If such blocking of the filter is observed, the determination should be repeated with smaller volumes. The results should
be interpreted with caution.

Release the vacuum (or pressure) when the filter is almost dry. Carefully remove it from the funnel with a pair of
forceps having flat ends. The filter may be folded if desired. Place the filter on the drying support (5.5) and dry it in the
oven (5.3) at 105 °C ± 2 °C for at least 1 h and with a maximum of 14 h to 16 h. Remove from the oven and allow the
filter to attain equilibrium with the air surrounding the balance and weigh it as before.

6


EN 872:2005 (E)

9

Control

Repeat the test procedure (see Clause 8) using 200 ml of the working reference suspension (6.2) as the sample. The

recovery shall be between 90 % and 110 %.

10 Calculation and report
10.1 Calculation
Calculate the content of suspended solids from the expression

ρ=

1 000 × (b − a )
V

where
ρ

is the content of suspended solids, in milligrams per litre, mg/l;

b

is the mass of the filter after the filtration, in milligrams, mg;

a

is the mass of the filter before the filtration, in milligrams, mg;

V

is the volume of the sample, in millilitres, ml. If the sample has been weighed, consider 1 g as equivalent
to 1 ml.

10.2 Report

Report results below 2 mg/l as "below 2 mg/l" and other results in milligrams per litre with two significant figures.
The test report shall refer to this document and include the following:
a)

date and place of testing;

b)

identification mark of the sample tested;

c)

the manufacturer and the designation of the filter used;

d)

the result;

e)

any deviation from the procedure described in this document or any other circumstances that can have
affected the results, for example blocking of filters (see the Note in 8.6) and storage time before analysis.

11 Precision
The precision of data for the content of suspended matter, determined as specified in this document, depends mainly
on the nature of the sample rather than on the method itself. Furthermore, some influence from the particular make of
filter used cannot be excluded.
No generally valid data for the reproducibility of the results can be given since it is virtually impossible to perform an
interlaboratory study using authentic waters of relevant types with a guarantee that the subsamples are identical at
the arrival in different laboratories. Samples containing living organisms or slimy material (for example carbohydrate

polymers) that block filters are particularly sensitive to transport and testing conditions.
In an interlaboratory study (Swedish Environmental Protection Agency, 1992) 175 laboratories analysed two
samples by a method, essentially the same as in this document. Synthetic samples prepared with kaolin and
microcrystalline cellulose were used. The results summarized in Table 1 illustrate the repeatability:

7


EN 872:2005 (E)

Table 1 — Data from a Swedish interlaboratory trial
n

Sample No

nrej.

x

SR

CVR

mg/l

mg/l

%

1

171

4

961

41

4,29

2

172

3

790

36

4,72

n
nrej.

x
SR
CVR

is the number of accepted results;
is the number of rejected results;
is the total mean;
is the reproducibility standard deviation
is the reproducibility variation coefficient

In a German study, reported in 1994, the results indicated in Table 2 were obtained.
Table 2 — Data from a German interlaboratory trial
Sample

l

n

nAP

sR

CVR

mg/l

mg/l

%

x

Microcrystalline cellulose, 10 mg/l

8

32

0

9,95

0,90

9,0

Microcrystalline cellulose, 100 mg/l

8

32

0

96,6

7,53

7,8

Microcrystalline cellulose, 500 mg/l

7

26

6

499,5

17,5

3,5

Kaolin, 10 mg/l

8

30

2

9,59

0,75

7,8

Kaolin, 100 mg/l

8

32

0

92,4

6,93

7,5

Kaolin, 500 mg/l

8

31

1

463,4

27,8

6,0

Fibrous cellulose (pulp), 10 mg/l

7

28

0

10,3

0,85

8,3

Fibrous cellulose (pulp), 100 mg/l

6

24

4

102,3

9,41

9,2

Fibrous cellulose (pulp), 500 mg/l

7

28

0

474,1

64,5

13,6

Microcrystalline/kaolin, 1/1, 10 mg/l

8

31

1

9,6

0,42

4,4

Microcrystalline/kaolin, 1/1, 50 mg/l

8

30

2

49,9

0,85

1,7

Microcrystalline/kaolin, 1/1, 200 mg/l

8

32

0

195,4

6,45

3,3

l
n
nAP

x
sR
CVR

is the number of laboratories;
is the number of accepted results;
is the number of outliers;
is the total mean;
is the reproducibility standard deviation;
is the reproducibility variation coefficient

The results illustrate the reproducibility that can be expected under ideal conditions, i.e. with samples containing inert
particles of well defined sizes. Ideal conditions can, however, rarely be expected with authentic samples.

8


EN 872:2005 (E)

Annex A
(informative)
Samples containing oil or other organic liquids

Oil or other immiscible organic liquids can be retained on the filter and only partially volatilized on drying at
105 °C ± 2 °C. Where, however, immiscible oil is important and should be determined separately, the filtered, waterwashed residue should be freed from oil. This can be done by washing first with ethanol and then with hexane before
drying at 105 °C ± 2 °C. When this procedure is applied, it should be recorded with the test results as some material,
other than immiscible oil, could have been extracted.

9


EN 872:2005 (E)

Bibliography

[1]

10

ISO 6107-2:1997, Water quality — Vocabulary.

blank


BS EN 872:2005
BS
6068-2.54:2005

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