SIST EN ISO 14402:2000

• Status: Published
• Publication Date: 30-Nov-2000
• ICS: 13.060.70 - Examination of biological properties of water
• Technical Committee: KAV - Water quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2000
• Due Date: 01-Dec-2000
• Completion Date: 01-Dec-2000
• Directive: 2019-01-2991 - Pravilnik o monitoringu kakovosti tal
• Directive:

  ---

  TP255 - Pravilnik o obratovalnem monitoringu stanja tal
• Ref Project: EN ISO 14402:1999 - Water quality - Determination of phenol index by flow analysis (FIA and CFA)(ISO 14402:1999)

• Referred By: SIST EN ISO 11161:2007 - Safety of machinery - Integrated manufacturing systems - Basic requirements (ISO 11161:2007)
• Effective Date: 28-Jan-2026
• Referred By: SIST-TP CEN/TR 16950:2017 - Ductile iron pipes, fittings and accessories - Sanitary characteristics and test methods
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 13850:2016 - Safety of machinery - Emergency stop - Principles for design (ISO 13850:2015)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 11111-5:2005 - Textile machinery - Safety requirements - Part 5: Preparatory machinery to weaving and knitting (ISO 11111-5:2005)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 16230-1:2015 - Agricultural machinery and tractors - Safety of higher voltage electrical and electronic components and systems - Part 1: General requirements (ISO 16230-1:2015)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 16089:2016 - Machine tools - Safety - Stationary grinding machines (ISO 16089:2015)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 10218-2:2011 - Robots and robotic devices - Safety requirements for industrial robots - Part 2: Robot systems and integration (ISO 10218-2:2011)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 10218-1:2011 - Robots and robotic devices - Safety requirements for industrial robots - Part 1: Robots (ISO 10218-1:2011)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 12100:2011 - Safety of machinery - General principles for design - Risk assessment and risk reduction (ISO 12100:2010)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 19085-5:2017 - Woodworking machines - Safety - Part 5: Dimension saws (ISO 19085-5:2017)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 11111-1:2016 - Textile machinery - Safety requirements - Part 1: Common requirements (ISO 11111-1:2016)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 13856-2:2013 - Safety of machinery - Pressure-sensitive protective devices - Part 2: General principles for design and testing of pressure-sensitive edges and pressure-sensitive bars (ISO 13856-2:2013)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 17332:2024 - Construction products - Assessment of release of dangerous substances - Analysis of organic substances in eluates
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 19085-6:2018 - Woodworking machines - Safety - Part 6: Single spindle vertical moulding machines ("toupies") (ISO 19085-6:2017)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN ISO 14120:2016 - Safety of machinery - Guards - General requirements for the design and construction of fixed and movable guards (ISO 14120:2015)
• Effective Date: 28-Jan-2026

SIST EN ISO 14402:2000 is the SIST standard for water quality - determination of phenol index by flow analysis (FIA and CFA). It sets out two automated laboratory methods for waters of different origin, including groundwater, surface water, seep water and wastewater, and expresses the result as phenol concentration. It is aimed at laboratories and technical staff who need a repeatable way to measure low phenol-index levels in routine water testing and to document the method, calibration and report.

What does SIST EN ISO 14402:2000 specify?

SIST EN ISO 14402:2000 specifies two flow-analysis methods for determining phenol index in water: one after extraction without distillation, and one after distillation without extraction. The stated application range is 0.01 mg/l to 1 mg/l in the undiluted sample, with the range adjustable by changing operating conditions.

The document is organized into:

• Clause 3 - determination after extraction
• Clause 4 - determination after distillation
• Clause 5 - expression of results
• Clause 6 - precision and accuracy
• Clause 7 - test report
• Annex A - statistical data for precision
• Bibliography

Annex	What it covers
Annex A	Informative statistical data from an interlaboratory trial

In practice, this means the standard tells the laboratory which analytical route to use, how to run and check the system, and what to record in the report.

What are the key requirements of SIST EN ISO 14402:2000?

Clause 3 - phenol index after extraction

SIST EN ISO 14402:2000 determines phenol index by mixing the sample with 4-aminoantipyrine and potassium peroxodisulfate, extracting the colored reaction products into chloroform, and measuring the organic phase spectrometrically at 470 nm to 475 nm. This route is the one to use when the laboratory wants the extraction-based method and can handle the organic phase.

The standard says aromatic amines can cause positive bias, and that pH control after addition of reagents matters. If the sample does not reach pH 10.0 to 10.5 after reagent addition, the sample is adjusted to pH 5 to 7 before the reagents are added. In practice, that means the lab has to pay close attention to sample acidity, alkalinity and buffering, because wrong pH changes the measured response.

Clause 4 - phenol index after distillation

SIST EN ISO 14402:2000 also specifies a distillation route in which the sample is acidified with phosphoric acid, distilled in line at pH 1.4, and then reacted with 4-aminoantipyrine and potassium hexacyanoferrate(III). The colored products are measured at 505 nm to 515 nm. This route is used for steam-volatile phenolic compounds.

The standard notes that distillation at pH 4 would allow aromatic amines to distil and cause positive bias, so the method uses pH 1.4. In practice, that means the analyst selects the lower-pH distillation route to focus on volatile phenols and reduce one major source of interference.

Sampling, preservation and sample condition

SIST EN ISO 14402:2000 requires glass or PTFE sampling containers, rinsed before use with acidified water. Samples should be analyzed immediately, or acidified to about pH 2, kept dark at 2 °C to 5 °C, and analyzed within 24 h. In exceptional cases, after acidification and membrane filtration, storage up to two weeks is possible if the preservation approach is checked for the specific case.

The standard also says particulate matter may require filtration if it could clog transport tubes. In practice, this means the sample handling step is part of method selection, not an afterthought.

Reagents and apparatus

SIST EN ISO 14402:2000 requires analytical-grade reagents, degassed solutions, and fresh daily preparation for several working solutions. For the extraction method, the apparatus includes a flow injection analysis system (FIA) or a continuous flow analysis system (CFA), with a spectrometric detector at 470 nm to 475 nm. For the distillation method, the detector is set to 505 nm to 515 nm and the system includes an in-line distillation assembly heated to 155 °C.

In practice, this means the laboratory needs suitable flow-analysis hardware, not just ordinary spectrophotometry.

Calibration, blank checks and ongoing control

SIST EN ISO 14402:2000 requires at least five calibration solutions for each working range, with separate calibrations for the two working ranges. The calibration and sample measurements must use the same conditions, and the calibration function is checked again after each sample series, and at the latest after 10 to 20 samples.

The standard also requires checking the flow system and the reagent blank. If the reagent blank indicates self-condensation products, the solutions and checks are repeated. In practice, this is the quality-control backbone of the method: it confirms that the flow system and reagents are behaving properly before results are accepted.

Result calculation and reporting

SIST EN ISO 14402:2000 uses a calibration function to convert the measured signal into phenol mass concentration, with dilution factors taken into account and no extrapolation beyond the chosen working range. Results are reported to no more than two significant figures.

The test report must identify the water sample, state whether clause 3 or clause 4 was used, describe sample pretreatment, identify the instrument or flow conditions, report the result as required, and note any deviation or event that could have influenced the outcome.

Precision information

SIST EN ISO 14402:2000 points to Annex A for precision and accuracy data from an interlaboratory trial. In practice, this helps users judge how the method performed across water types and systems, especially when they need to compare routine results or set internal quality limits.

What terms does SIST EN ISO 14402:2000 define?

• Phenol index - An analytical convention for a group of aromatic compounds that form colored condensation products under the specified reaction conditions; the result is expressed as phenol concentration.
• FIA - Flow injection analysis, a flow method in which the sample is injected into a carrier stream and reacts while moving through the manifold.
• CFA - Continuous flow analysis, a flow method with continuous sample, reagent and gas bubble introduction for automated wet chemistry.
• Reagent blank - The signal obtained when water is run in place of the reagent solutions; it is used to detect self-condensation products or other reagent-related effects.
• Working range - The selected calibration and measurement interval, with separate ranges used for 0.01 mg/l to 0.1 mg/l and 0.1 mg/l to 1 mg/l.
• Phase separator - The component that separates the chloroform phase from the aqueous phase after extraction.
• Distillate - The vapor-condensed fraction collected after in-line distillation in the distillation method.

Who uses SIST EN ISO 14402:2000?

SIST EN ISO 14402:2000 is used by water-testing laboratories, environmental analysts and quality staff who measure phenol index in groundwater, surface water, seep water and wastewater. It is also relevant to operators who run FIA or CFA instruments and need to control sample preparation, calibration, interferences and reporting.

In practice, the standard supports routine monitoring, method verification and result documentation in laboratories that process large sample series at high analysis frequency.

Which standards are used with SIST EN ISO 14402:2000?

• ISO 3696:1987 - Supplies the grade 1 water used for reagent preparation, calibration and carrier solutions.
• ISO 5667-3:1994 - Gives guidance on sample handling and preservation, which the standard uses for storage and stabilization of samples.
• ISO 6439:1990 - Provides a related 4-aminoantipyrine spectrometric method after distillation, useful as a companion reference for phenol index work.

What does the SIST EN ISO 14402:2000 document contain?

SIST EN ISO 14402:2000 contains two full analytical procedures, each with principle, interferences, reagents, apparatus, sampling, procedure and calculation steps. It also includes the flow-system descriptions and example layouts in Figures 1 to 4, covering FIA and CFA arrangements for both extraction and distillation.

The document gives the reagent preparations, calibration approach, flow-system checks, blank checks and measurement sequence needed for routine operation. It also includes a regression-based calculation method and a short worked approach to reporting results in the selected working range.

Annex A collects statistical data from an interlaboratory trial, including tables for extraction with CFA, extraction with FIA, combined extraction data, and distillation with CFA.

SLOVENSKI STANDARD
01-december-2000
.DNRYRVWYRGH'RORþHYDQMHIHQROQHJDLQGHNVDVSUHWRþQRDQDOL]R),$LQ&)$
,62
Water quality - Determination of phenol index by flow analysis (FIA and CFA)(ISO
14402:1999)
Wasserbeschaffenheit - Bestimmung des Phenolindex mit der Fließanalytik (FIA und
CFA) (ISO 14402:1999)
Qualité de l'eau - Détermination de l'indice phénol par analyse en flux (FIA et CFA) (ISO
14402:1999)
Ta slovenski standard je istoveten z: EN ISO 14402:1999
ICS:
13.060.70 Preiskava bioloških lastnosti Examination of biological
vode properties of water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 14402
First edition
1999-09-01
Water quality — Determination of phenol
index by flow analysis (FIA and CFA)
Qualité de l'eau — Détermination de l'indice phénol par analyse en flux (FIA
et CFA)
A
Reference number
ISO 14402:1999(E)
ISO 14402:1999(E)
Contents Page
1 Scope .1
2 Normative references .1
3 Determination of phenol index (without distillation) after extraction .1
3.1 Principle.1
3.2 Interferences .1
3.3 Reagents .2
3.4 Apparatus .4
3.5 Sampling.6
3.6 Procedure .7
3.7 Calculation of results .8
4 Determination of phenol index (without extraction) after distillation .9
4.1 Principle.9
4.2 Interferences .9
4.3 Reagents.9
4.4 Apparatus .10
4.5 Sampling.13
4.6 Procedure .13
4.7 Calculation of results .14
5 Expression of results .14
6 Precision and accuracy.14
7 Test report .14
Annex A (informative) Statistical data.15
Bibliography.17
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
ii
©
ISO
ISO 14402:1999(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 14402 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee
SC 2, Physical, chemical biochemical methods.
Annex A of this International Standard is for information only.
iii
©
ISO
ISO 14402:1999(E)
Introduction
Methods for determination of water quality using flow analysis and automatic wet chemical procedures are par-
ticularly suitable for the processing of large sample series at a high analysis frequency.
Differentiation is needed between flow injection analysis (FIA) [1, 2] and continuous flow analysis (CFA) [3]. Both
methods include automatic dosage of the sample into a flow system (manifold) where the analytes in the sample
react with the reagent solutions on their way through the manifold. The sample preparation may be integrated in the
manifold. The reaction product is measured in a flow detector.
Phenol index is an analytical convention. It represents a group of aromatic compounds which under the specific
reaction conditions form coloured condensation products. The analytical result is expressed in terms of phenol
concentration.
This International Standard describes two methods: the determination of phenol index (without distillation) after
extraction, and the determination of phenol index (without extraction) after distillation.
It should be investigated whether and to what extent particular problems will require the specification of additional
marginal conditions.
iv
INTERNATIONAL STANDARD  © ISO ISO 14402:1999(E)
Water quality — Determination of phenol index by flow analysis
(FIA and CFA)
1 Scope
This International Standard specifies two methods for the determination of the phenol index in waters of different
origin (such as ground waters, surface waters, seep waters, and waste waters) in mass concentrations of 0,01 mg/l
to 1 mg/l (in the undiluted sample). In particular cases, the range of application may be adapted by varying the
operating conditions. Clause 3 describes the determination of phenol index (without distillation) after extraction, and
in clause 4 the determination of phenol index (without extraction) after distillation is given.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods.
ISO 5667-3:1994, Water quality — Sampling — Part 3: Guidance on sample handling and preservation.
ISO 6439:1990, Water quality — Determination of phenol index — 4-Aminoantipyrine spectrometric methods after
distillation.
3 Determination of phenol index (without distillation) after extraction
3.1 Principle
The sample is fed into a continuously flowing carrier stream and mixed with also continuously flowing solutions of 4-
aminoantipyrine and potassium peroxodisulfate. Phenolic compounds in the sample are oxidized by potassium
peroxodisulfate, and the resulting quinones react with 4-aminoantipyrine, forming coloured condensation products.
These are extracted in a flow extraction unit from the aqueous phase into chloroform. The chloroform phase is
separated by a suitable phase separator (e.g. a hydrophobic semipermeable membrane), and the absorbance of
the organic phase is measured spectrometrically in a flow spectrometer at 470 nm to 475 nm. More information on
this analytical technique is given in the references [6 to 9].
It is absolutely essential that the test described in this International Standard be carried out by suitably qualified
staff.
3.2 Interferences
3.2.1 Chemical interferences
Under the prevailing reaction conditions, aromatic amines will also form condensation products with 4-aminoanti-
pyrine, leading to positive bias.
© ISO
ISO 14402:1999(E)
Interferences can occur when the sample, after the addition of the reagent solutions, does not reach a pH of
10,0 to 10,5. In particular this may occur in the cases of strongly acidic, strongly alkaline and buffered samples. In
these cases, the sample is adjusted to a pH between 5 and 7 prior to addition of the reagent solutions.
Further information on interferences is given in [5].
3.2.2 Physical interferences arising from applying CFA and FIA
If the samples contain particulate matter, refer to 3.5 (last paragraph). Turbid samples do not cause interferences
with the determination. In the event of coloured samples, check whether the colour can be extracted with
chloroform, and determine the sample blank without the addition of reagents R1 and R2. The difference in response
between the two measurements shall be taken into account with the evaluation (according to 3.7).
The interlaboratory trial (see clause 6 and annex A) has shown that detergents in waste water can strongly
influence the determination, because the foam produced in the flow system can disturb on the one hand the steam
distillation of volatile phenols (phenol index after distillation, see clause 4, and on the other hand the phase
segmentation and phase separation procedures (phenol index after extraction, see clause 3). In general such
interferences can easily be discovered.
In the case of significant detergent content, this International Standard is only applicable for phenol mass
concentrations above 0,1 mg/l.
3.3 Reagents
Use only reagents of recognized analytical grade quality. The reagent blank value shall regularly be checked (see
3.6.3). The solutions used for the flow system shall be degassed. If not stated otherwise, it is recommended to
degas the solutions under reduced pressure, because by this procedure the solutions are simultaneously purified.
WARNING — Phenol is toxic and can easily be absorbed through the skin. Chloroform is toxic and
cancerogenic. Waste containing these substances should be disposed of appropriately.
3.3.1  Water, of grade 1 in accordance with ISO 3696
3.3.2  Potassium hydroxide, KOH
3.3.3  Sodium hydrogencarbonate, NaHCO
3.3.4  4-aminoantipyrine (4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one), C H N O
11 13 3
3.3.5  Potassium peroxodisulfate, K S O
2 2 8
3.3.6  Phenol, C H OH
6 5
3.3.7  Boric acid, H BO
3 3
3.3.8  Ethanol, C H OH, 96 % mass fraction
2 5
3.3.9  2-Propanol, C H OH, 100 % mass fraction
3 7
3.3.10  Sulfuric acid, r(H SO ) = 1,84 g/ml
2 4
3.3.11  Hydrochloric acid
, HCl, 50 % mass fraction
3.3.12  Potassium hydroxide solution, c(KOH) = 1,0 mol/l
3.3.13  Buffer solution
Dissolve in a 1 000 ml graduated flask in approximately 500 ml of water (3.3.1): 23 g of sodium hydrogencarbonate
(3.3.3), 27 g of boric acid (3.3.7), and 35 g of potassium hydroxide (3.3.2) and make up to volume with water.
The pH of the buffer solution is approximately 10,3. The solution is stable for 1 month.
© ISO
ISO 14402:1999(E)
(symbol C in Figure 1)
3.3.14 Carrier solution
Use water (3.3.1) degassed under reduced pressure.
3.3.15  4-Aminoantipyrine solution I (symbol R1 in Figures 1 and 2)
Dissolve in a 100 ml graduated flask 0,5 g of 4-aminoantipyrine (3.3.4) in approximately 50 ml of buffer solution
(3.3.13), and make up to volume with buffer solution (3.3.13).
Degas the solution, e.g. by membrane filtration.
Prepare fresh solution every day.
3.3.16  Potassium peroxodisulfate solution (symbol R2 in Figures 1 and 2)
Dissolve in a 100 ml graduated flask 5 g of potassium peroxodisulfate (3.3.5) in approximately 90 ml of water
(3.3.1), adjust to pH 11 with potassium hydroxide solution (3.3.12) and make up to volume with water.
Degas the solution, e.g. by membrane filtration.
Prepare fresh solution daily.
3.3.17  Chloroform, CHCl (symbol Org in Figures 1 and 2)
Degas the chloroform solution either by membrane filtration or for 3 min in an ultrasonic bath.
3.3.18  Phenol stock solution r
, = 1 000 mg/l
Dissolve in a 1 000 ml graduated flask 1,000 g of phenol (3.3.6) in water (3.3.1) and make up to volume with water.
Use only colourless phenol crystals.
The cooled solution (2 °C to 5 °C) is stable for one month.
3.3.19  Phenol standard solution I r
, = 10 mg/l
Pipette 1 ml of the stock solution (3.3.18) into a 100 ml graduated flask, and make up to volume with water (3.3.1).
The cooled solution (2 °C to 5 °C) is stable for one week.
3.3.20  Phenol standard solution II r = 1 mg/l
,
Pipette 10 ml of the standard solution I (3.3.19) into a 100 ml graduated flask, and make up to volume with water
(3.3.1).
The cooled solution (2 °C to 5 °C) is stable for one week.
3.3.21  Calibration solutions
Prepare the calibration solutions according to the origin of the sample and the expected concentrations by diluting
the phenol standard solution or respectively (3.3.19 or 3.3.20).
I II
Prepare a minimum of at least five calibration solutions per working range.
Proceed as follows for working ranges I and II, if using e.g. six calibration solutions:
a) Working range I, (0,1 mg/l to 1 mg/l):
Into each of a series of 100 ml graduated flasks pipette 1 ml, 3 ml, 5 ml, 6 ml, 8 ml and 10 ml respectively of
the standard solution I (3.3.19), and make up to volume with water (3.3.1).
The concentration of phenol in these calibration solutions is 0,1 mg/l, 0,3 mg/l, 0,5 mg/l, 0,6 mg/l, 0,8 mg/l and
1,0 mg/l, respectively.
© ISO
ISO 14402:1999(E)
b) Working range (0,01 mg/l to 0,1 mg/l):
II
Into each of a series of 100 ml graduated flasks pipette 1 ml, 3 ml, 5 ml, 6 ml, 8 ml, and 10 ml respectively of
the standard solution II (3.3.20), and make up to volume with water (3.3.1).
The concentration of phenol in these calibration solutions is 0,01 mg/l, 0,03 mg/l, 0,05 mg/l, 0,06 mg/l, 0,08 mg/l
and 0,1 mg/l, respectively.
Prepare fresh calibration solutions each day.
3.4 Apparatus
3.4.1 Flow injection analysis system (FIA)
The flow injection system (FIA) shall comprise the following components (see Figure 1):
a) reagent reservoirs;
b) low pulsation pump with specific pump tubing, for flowrates as shown in Figure 1, as an example;
c) displacement bottle for the feeding of the chloroform;
d) sample injector with suitable injection volumes;
e) extraction cell with phase segmentor and phase separator (e.g. hydrophobic semipermeable membrane of
PTFE).
EXAMPLES   Membrane thickness: 150 m to 200 m; pore size: 0,5 m to 2 m; porosity: 75 %.
m m m m
f) transport tubes and reaction coils, internal diameter 0,5 mm to 0,8 mm, tube connections and T-connections of
chemically inert plastic, with a minimal dead volume;
g) spectrometric detector with flow cell, of optical path length 10 mm, wavelength 470 nm to 475 nm.
h) recording unit (e.g. strip chart recorder, integrator or printer/plotter).
NOTE  In general, peak heights are measured.
i) autosampler, if required.
© ISO
ISO 14402:1999(E)
Key
C: Carrier solution (3.3.14)
R1: 4-aminoantipyrine solution I (3.3.15)
R2: Potassium peroxodisulfate solution (3.3.16)
Org: Chloroform (3.3.17)
1 Pump (flowrates in ml/min)
2 Injector
600 μl [working range 0,01 to 0,1 mg/l phenol]
200 μl [working range 0,1 to 1,0 mg/l phenol]
3 Reaction coil: 60 cm/Æ int. 0,5 mm
4 Reaction coil: 80 cm/ int. 0,5 mm
Æ
5 Extraction unit: 160 cm/Æ int. 0,7 mm
5.1 Phase segmentor,
5.2 Phase separator
6 Detector: optical pathlength: 1 cm, wavelength: 470 nm to 475 nm
7 Waste
Figure 1 — Example of a flow injection system for the determination of 0,01 mg/l to 1,0 mg/l phenol index
without distillation and with extraction (according to 3.4.1)
3.4.2 Continuous flow analysis (CFA)
The continuous flow analysis system shall comprise the following components (see Figure 2):
a) autosampler allowing a reproducible introduction of the sample or of the carrier liquid;
b) reagent reservoirs;
c) low pulsation pump with specific, chemically inert pump tubes, with flowrates as shown in Figure 2, as an example;
d) displacement bottle for the feeding of the chloroform, if required;
e) manifold with highly reproducible gas bubble, sample, and reagent introduction, with appropriate transport
systems and extraction systems, and connection assemblies, e.g. of glass, chemically inert plastics or metal,
and with appropriate separator for the separation of the organic phase from the aqueous phase;
f) spectrometric detector with flow cell, optical pathlength 0,5 cm to 5 cm, wavelength 470 nm to 475 nm
g) recording unit (e. g. strip chart recorder, integrator or printer/plotter).
NOTE 1 In general, peak heights are measured.
NOTE 2 A CFA system with an internal diameter of 2 mm is described in Figure 2. Other internal diameters (e.g.
approximately 1 mm) may also be used.
© ISO
ISO 14402:1999(E)
Key
R1 4-aminoantipyrine solution I (3.3.15) 4.2 Phase separator
R2 Potassium peroxodisulfate solution (3.3.16) 4.3 Reaction coil: 150cm/Æ int. 2 mm
Org Chloroform (3.3.17) 5 Detector: optical pathlength: 0,5 cm to 5 cm,
wavelength: 470 nm to 475 nm
1 Pump (flowrates in ml/min)
6 Segmentation gas (air)
2 Reaction coil: 40 cm/Æ int. 2 mm
7 Sample
3 Reaction coil: 40 cm/Æ int. 2 mm
8 Resample
4 Extraction unit
9 Waste
4.1 Phase segmentor
Figure 2 — Example of a continuous flow system for the determination of 0,01 mg/l to 1,0 mg/l of phenol
index without distillation and with extraction (according to 3.4.2)
3.4.3 Additional apparatus
a) Graduated flasks, 100 ml and 1 000 ml;
b) Graduated pipettes, 1 ml to 10 ml;
c) Membrane filter assembly with membrane filters, pore size 0,45 mm;
d) pH measuring device (e. g. pH electrode).
3.5 Sampling
Use glass or polytetrafluoroethylene (PTFE) containers for sampling.
Prior to use, rinse all containers and devices with which the sample may come into contact, with sulfuric acid of
pH approximately 2.
© ISO
ISO 14402:1999(E)
Analyse the samples immediately after their collection. Alternatively, adjust to a pH of approximately 2 with sulfuric
acid (3.3.10 or diluted solution) or hydrochloric acid (3.3.11 or diluted solution), store in the dark at a temperature of
2 °C to 5 °C, and analyse within 24 h.
In exceptional cases, after acidification and membrane (pressure) filtration of the sample, a storage of up to two
weeks is possible. The applicability of this preservation method shall be checked for the individual case of
examination. For more information on sample preservation, see ISO 5667-3 and [10].
Filtration of the sample prior to measurement is necessary, if there is a risk of clogging the transport tubes.
3.6 Procedure
3.6.1 Preparation for measurement
Prior to measurement, continuously run the reagent solutions C (3.3.14), R1 (3.3.15), R2 (3.3.16) and Org (3.3.17)
through the flow analysis system, wait for the baseline to stabilize, and zero the baseline.
Consider the system is ready to operate, when the baseline remains stable (no drift). A satisfying signal-to-noise
ratio should be obtained.
Verify that a signal-to-noise ratio is obtained that has no significant effect on the results.
The most frequent reasons for a poor signal-to-noise ratio are defective separator membranes or traces of water at
the walls of the cell. Traces of water adhering to the walls of the cell can be removed by rinsing the cell with ethanol
(3.3.8) or 2-propanol (3.3.9).
Monitor the blank of the reagent and control the membrane function as described in 3.6.3. Carry out the calibration
according to 3.6.4.
3.6.2 Checking of the flow system
With the measuring system adjusted to working range II, using a calibration solution (3.3.21) with a concentration of
–1
0,05 mg/l, an absorbance per 1 cm cell length of at least 0,01 cm shall be obtained. Otherwise the flow system is
not suitable, and it shall be replaced by a system which fu
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