Plant biostimulants - Determination of chromium(VI)

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.

Biostimulanzien für die pflanzliche Anwendung - Bestimmung von Chrom (VI)

Dieses Dokument wurde erarbeitet, um ein Verfahren für die Verifizierung bereitzustellen, dass sechswertiges Chrom (CrVI) nicht in einer Konzentration in Biostimulanzien für die pflanzliche Anwendung vorhanden ist, die die in der EU Verordnung zu Düngeprodukten [1] aufgeführten Grenzwerte übersteigt.
Dieses Dokument gilt für alle Arten von Biostimulanzien (in fester Form und in flüssiger Form  für die pflanzliche Anwendung, die in der Landwirtschaft eingesetzt werden.
Das beschriebene Verfahren ist geeignet, den Chrom(VI) Gehalt in Biostimulanzien für die pflanzliche Anwendung ab 2 mg/kg quantitativ zu bestimmen.
Die mit dem beschriebenen Verfahren erzielten Ergebnisse sind streng von den Extraktionsbedingungen abhängig. Ergebnisse, die mit anderen Extraktionsverfahren (Extraktionslösung, pH Wert, Extraktionszeit usw.) erzielt wurden, sind nicht mit den Ergebnissen vergleichbar, die mit dem in diesem Dokument beschriebenen Verfahren erzielt wurden.

Biostimulants des végétaux - Dosage du chrome(VI)

Le présent document a été élaboré pour fournir une méthode permettant de vérifier que le chrome hexavalent (CrVI) n’est pas présent dans les biostimulants des végétaux à une concentration dépassant les limites correspondantes indiquées dans le Règlement UE sur les fertilisants [1].
Le présent document s’applique à tous les types de biostimulants des végétaux (solides et liquides ) utilisés en agriculture.
La méthode décrite est adaptée à la quantification dans les biostimulants des végétaux de teneurs en chrome(VI) à partir de 2 mg/kg.
Les résultats obtenus avec cette méthode sont strictement tributaires des conditions d’extraction. Les résultats obtenus avec d’autres modes opératoires d’extraction (solution d’extraction, pH, durée d’extraction, etc.) ne sont pas comparables aux résultats acquis avec le mode opératoire décrit dans le présent document.

Rastlinski biostimulansi - Določevanje kroma Cr (VI)

General Information

Status
Not Published
Current Stage
5060 - Closure of Vote - Formal Approval
Due Date
02-Dec-2021
Completion Date
02-Dec-2021

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SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 17703:2021
01-november-2021
Rastlinski biostimulansi - Določevanje kroma (VI)
Plant biostimulants - Determination of chromium(VI)
Biostimulanzien für die pflanzliche Anwendung - Bestimmung von Chrom (VI)
Biostimulants des végétaux - Dosage du chrome(VI)
Ta slovenski standard je istoveten z: FprCEN/TS 17703
ICS:
65.080 Gnojila Fertilizers
kSIST-TS FprCEN/TS 17703:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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kSIST-TS FprCEN/TS 17703:2021
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kSIST-TS FprCEN/TS 17703:2021
FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 17703
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
September 2021
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 draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee

CEN/TC 455.

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.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change

without notice and shall not be referred to as a Technical Specification.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 17703:2021 E

worldwide for CEN national Members.
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kSIST-TS FprCEN/TS 17703:2021
FprCEN/TS 17703:2021 (E)
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

A.1 General.................................................................................................................................................... 11

A.2 Example of ion chromatographic conditions ............................................................................ 11

A.2.1 Mobile phase reagents ...................................................................................................................... 11

A.2.2 Instrumental conditions ................................................................................................................... 11

Annex B (informative) Chromatographic conditions for method with post-column

reaction................................................................................................................................................... 13

B.1 General.................................................................................................................................................... 13

B.2 Chromatographic system and apparatus required ................................................................ 13

B.3 Example of analytical conditions .................................................................................................. 14

Bibliography ....................................................................................................................................................... 16

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kSIST-TS FprCEN/TS 17703:2021
FprCEN/TS 17703:2021 (E)
European foreword

This document (FprCEN/TS 17703:2021) has been prepared by Technical Committee CEN/TC 455 “Plant

Biostimulants”, the secretariat of which is held by AFNOR.
This document is currently submitted to the Vote on TS.
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kSIST-TS FprCEN/TS 17703:2021
FprCEN/TS 17703:2021 (E)
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 fertilising products (“FPR” or “Fertilising Products Regulation”).

This request, presented as SR 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.
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kSIST-TS FprCEN/TS 17703:2021
FprCEN/TS 17703:2021 (E)
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 [ ].

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 1: Digestion by aqua regia

for subsequent determination of elements

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.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
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.

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kSIST-TS FprCEN/TS 17703:2021
FprCEN/TS 17703:2021 (E)
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

Seven hundred (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.
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kSIST-TS FprCEN/TS 17703:2021
FprCEN/TS 17703:2021 (E)

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.
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 anion-exchange column and UV or visible detector. It is

recommended a photo diode array detector (DAD).
6.9 Analytical balance, capable of weighing to 0,1 mg.
6.10 Syringe membrane filters of nylon of 0,45 μm for filtration of standards.
6.11 Suitable vials for HPLC.
7 Procedure
7.1 Sampling and preparation of samples

Sample in accordance with CEN/TS 17702-1. If sampling in accordance with CEN/TS 17702-1 is not

possible, details about the sampling shall be given in the test report.

Preparation of samples in accordance with CEN/TS 17702-2. For products that may d

...

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