CEN/TS 17703:2022

SLOVENSKI STANDARD
01-februar-2023
Rastlinski biostimulanti - Določevanje kroma Cr(VI)
Plant biostimulants - Determination of chromium(VI)
Pflanzen-Biostimulanzien - Bestimmung von Chrom(VI)
Biostimulants des végétaux - Dosage du chrome(VI)
Ta slovenski standard je istoveten z: CEN/TS 17703:2022
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TS 17703
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
March 2022
TECHNISCHE SPEZIFIKATION
ICS 07.080
English Version
Plant biostimulants - Determination of chromium(VI)
Biostimulants des végétaux - Dosage du chrome(VI) Biostimulanzien für die pflanzliche Anwendung -
Bestimmung von Chrom (VI)
This Technical Specification (CEN/TS) was approved by CEN on 3 January 2022 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17703:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 6
5 Chemicals . 6
6 Apparatus and materials . 7
7 Procedure . 7
7.1 Sampling and preparation of samples. 7
7.2 Preparation of analytical solution . 7
7.3 Chromatographic conditions . 8
7.4 Calibration . 8
7.5 Determination of the recovery rate . 9
8 Calculation and expression of results . 9
8.1 Calculation of chromium(VI) content . 9
8.2 Recovery rate (according to 7.5) . 10
8.3 Expression of results . 10
9 Test report . 10
Annex A (informative) Chromatographic conditions for direct detection method . 11
Annex B (informative) Chromatographic conditions for method with post-column reaction
................................................................................................................................................................... 13
Bibliography . 16

European foreword
This document (CEN/TS 17703:2022) has been prepared by Technical Committee CEN/TC 455 “Plant
Biostimulants”, the secretariat of which is held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Introduction
This document was prepared by the experts of CEN/TC 455 “Plant Biostimulants”. The European
Committee for Standardization (CEN) was requested by the European Commission (EC) to draft
European standards or European standardization deliverables to support the implementation of
Regulation (EU) 2019/1009 of 5 June 2019 laying down rules on the making available on the market of
EU fertilizing products (“FPR” or “Fertilising Products Regulation”).
This standardization request, presented as M/564, also contributes to the Communication on “Innovating
for Sustainable Growth: A Bio economy for Europe”. The Working Group 4 “Other safety parameters”, was
created to develop a work program as part of this request. The technical committee CEN/TC 455 “Plant
Biostimulants” was established to carry out the work program that will prepare a series of standards. The
interest in biostimulants has increased significantly in Europe as a valuable tool to use in agriculture.
Standardization was identified as having an important role in order to promote the use of biostimulants.
The work of CEN/TC 455 seeks to improve the reliability of the supply chain, thereby improving the
confidence of farmers, industry, and consumers in biostimulants, and will promote and support
commercialisation of the European biostimulant industry.
1 Scope
This document was developed to provide a method for verifying that hexavalent chromium (CrVI) is not
present in plant biostimulants in a concentration that exceeds the respective limits outlined in the EU
Regulation on Fertilising Products [1].
This document is applicable to all types of plant biostimulants (solid and liquid ) used in agriculture.
The method described is suitable to quantify the chromium(VI) content in plant biostimulants down to
2 mg/kg.
The results obtained from this method are strictly dependent on the extraction conditions. Results
obtained by using other extraction procedures (extraction solution, pH, extraction time, etc.) are not
comparable with the results produced by the procedure described in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
CEN/TS 17701-1, Plant biostimulants — Determination of specific elements — Part 1: Digestion by aqua
regia for subsequent determination of elements
CEN/TS 17701-2, Plant biostimulants — Determination of specific elements — Part 2: Determination of
total content of Cd, Pb, Ni, As, Cr, Cu and Zn
CEN/TS 17702-1, Plant biostimulants — Sampling and sample preparation — Part 1: Sampling
CEN/TS 17702-2, Plant biostimulants — Sampling and sample preparation — Part 2: Sample preparation
CEN/TS 17704, Plant biostimulants — Determination of dry matter
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
chromium(VI) content
amount of chromium(VI) in plant biostimulant determined after extraction with an aqueous salt solution
at pH 7,0 to 8,0
Note 1 to entry: The chromium(VI) content is reported as chromium(VI) in milligrams per kilogram (mg/kg),
expressed as the dry mass of the sample.
[SOURCE: EN ISO 17075-2:2017, definition 3.1]

According to the definition of “solid form” and “liquid form” to the current EU legislation when it is published.
4 Principle
A preliminary determination of the total chromium in aqua regia extracts by ICP-AES (CEN/TS 17701-1
and CEN/TS 17701-2) could reduce the number of the samples where the determination of
chromium(VI) is necessary because if the content of aqua regia (total) extractable chromium is lower
than the legislative limit for chromium(VI) then the determination of chromium(VI) is not necessary.
Extractable chromium(VI) is leached from the sample in phosphate buffer at pH 7,0 to 8,0. An aliquot of
the filtered extract is analysed for Cr(VI) using ion-exchange chromatography with UV-VIS detection.
5 Chemicals
All reagents used shall have at least analytical grade purity.
5.1 Extraction solution
Dissolve 22,8 g dipotassium hydrogenphosphate K HPO ·3H O in 1 000 ml water (5.7), adjusted to pH
2 4 2
8,0 ± 0,1 with phosphoric acid (5.2). Degas this solution with either argon or nitrogen (5.6) or ultrasonic
bath.
Standard practice is to make up a fresh solution each day. However, the solution can be kept for up to one
week in a refrigerator at (4 ± 3) °C but shall be warmed to room temperature and degassed prior to use.
5.2 Phosphoric acid solution
700 ml o-phosphoric acid, ρ = 1,71 g/ml, made up to 1 000 ml with water (5.7).
First add approximately 200 ml of deionised water (5.7) to a 1 000 ml volumetric flask, then add the
700 ml of o-phosphoric acid and dilute to the mark with deionised water.
5.3 Potassium dichromate (K Cr O ), dried for (16 ± 2) h at (105 ± 5) °C.
2 2 7
5.4 Chromium(VI) stock solution
Dissolve 2,829 g potassium dichromate (K Cr O ) (5.3) in water (5.7) in a volumetric flask and make up
2 2 7
to 1 000 ml with water (5.7). One ml of this solution contains 1 mg of chromium.
The solution can be kept for up to 12 months in a refrigerator at (4 ± 3) °C but shall be warmed to room
temperature prior to use.
It is also possible to use a commercial standard solution with a certified Cr(VI) concentration that can be
connected to national standards. Observe the expiry date or recommended shelf life stated by the
manufacturer.
5.5 Chromium(VI) standard solution
Pipette 1 ml of solution (5.4) into a 1 000 ml volumetric flask and make up to the mark with extraction
solution (5.1). One ml of this solution contains 1 μg of chromium.
The solution can be kept for up to one week in a refrigerator at (4 ± 3) °C but shall be warmed to room
temperature prior to use.
A stock solution of hexavalent chromium at this concentration level is an alternative available
commercially.
5.6 Argon or nitrogen, oxygen-free
Preference should be given to argon as an inert gas instead of nitrogen because argon has a higher specific
mass than air.
5.7 Distilled or deionised water, with a specific conductivity not higher than 0,2 mS/m at 25 °C.
5.8 Magnesium chloride hexahydrate (MgCl⋅6H O)
2 2
Dissolve 85,4 g in a 100 mL volumetric flask, dilute with water (5.7), close and mix thoroughly.
6 Apparatus and materials
Usual laboratory equipment and, in particular, the following.
−1
6.1 Suitable mechanical orbital shaker, (100 ± 10) min .
6.2 Conical flask, of capacity 250 ml, with stopper.
6.3 Aeration tube and flow meter, suitable for a flow rate of (50 ± 10) ml/min.
6.4 pH meter, with glass electrode.
6.5 Membrane filter, 0,45 μm pore size [polytetrafluoroethylene (PTFE) or polyamide 66].
6.6 Common laboratory glassware and pipettes.
6.7 Vacuum device, suitable for filtration of extraction solution, mobile phase, and sample extracts.
6.8 Ion-exchange chromatograph, with UV or visible detector or high performance liquid
chromatography (HPLC) with ani
...