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Electrochemical impedance spectroscopy

The Electrochemical Impedance Spectroscopy (EIS) is a technique for characterizing electrochemical systems.

The principle of this technique consists of applying a low amplitude sinusoidal signal to the electrochemical system and measuring its response at different frequencies.

In the case of an electrochemical impedance measurement applied to the aerosol generators, the test method consists of bringing the coating or varnish (container) into contact with the product which will serve as electrolyte (content).

The test is based on the application of a low alternative potential at the input, by means of a reference electrode (RE) and a counter electrode (CE) connected to a potentiostat* and the measurement of the ouput current, between the reference electrode and the working electrode (WE), which will allow the impedance (alternating current electrode) to be calculated. In this case, it is the metal aerosol can (or a container, metal bottle) which constitutes the working electrode.

In order to be able to measure an output current, it is necessary that the prodcut – the electrolyte – has a minimum conductivity. This measurement is carried out at different frequencies during the test, typically between 100 mHz and 100 kHz.

The physical model used to quantify the response to the product, the electrolyte, is a RLC model: resistance, inductance, capacity (see figure below). To quantify the quality of the coating used, we are interested by the resistance and capacity values and and their changes over time. In this goal, several measurements are carried out at regular intervals, over a period of one month, to characterize the stability of the coating to extended contact with the product.

Schéma de la spectroscopie d'impédance électrochimique

The Electrochemical Impedance Spectroscopy (EIS) is a technique that allows a rapid and reliable initial assessment of the compatiblity of a coating towards a given product. This method is complementary to storage tests for the evaluation of container-content compatibility, as it is not possible to evaluate compatibility in the gas phase with this technique.

This is an effective method to compare different varnishes between them and to anticipate faster incompatibilities. Thanks to the new generation of potentiostat*, with which the LEREM is equipped, it is possible to measure very low output signals (currents), which makes it possible to obtain a response with resistance and capacity values even with very poorly conductive formulations.

Test d'éléctrochimie

* Potentiostat: accurate device that generates and measures low electrical signals with electrodes for electrochemical studies.

Electrochemical studies include other techniques as tin rate measurements on tinplate sheets as well as corrosion current measurements by amperometry. These studies will be the subjects of a future article.


Ban of bisphenol A in food contact materials

Consequences of the ban on the intentional use of bisphenol A in food contact materials announced by DG Santé

In July 2023, at a stakeholder webinar, the EU’s Directorate-General for Health and Food Safety (DG Sante) announced a ban on the intentional use of bisphenol A (BPA) and potentially several other bisphenols. This ban is due to come into force at the beginning of 2024, with a transition period of 18 months. This ban should have an impact on the metal packaging sector, particularly through varnishes and coatings containing the targeted bisphenols.

In France, the intentional use of BPA has been banned since 1 December 2015. The ban prompted research and development of alternatives to epoxy-phenolic coatings containing BPA. Food contact material (FCM) manufacturers have made huge efforts to develop alternative coatings. However, the chemistry of new coatings applied to the internal surfaces of metal FCMs is poorly documented.  As a result, the potential hazard of chemicals migrating into foodstuffs is also unknown.

The lack of knowledge about these new types of coating, which have a shorter research history, tends to make compliance with the regulations more complex, particularly where NIAS (non-intentionally added substances) are concerned. Until now, regulations have focused mainly on the control of intentionally added substances (IAS), but the safety of FCMs in the form of final articles is becoming increasingly important.  More attention is now required for controlling the risks associated with NIAS (impurities, neoformed substances, contaminants, etc.).

A new risk assessment approach for MCDA

The collaborative work of over 20 scientists, which was published on 26 September 2023, has highlighted the need for a new conceptual approach to go beyond current risk assessment procedures for FCMs.

The authors propose to evaluate real-life mixtures, migrating (or extractable) from final articles in contact with food. This proposition includes all knowns (IAS) and unknowns (NIAS). If the result of the toxicological assessment of the mixture is positive, modern analytical techniques should be applied to elucidate it’s chemical composition, including the NIAS, in order to identify the substances responsible for the toxicity as a whole.

Interdiction du bisphénol A présentation

This and some more important topics were discussed during the CFA Technical Information Day held on Wednesday 8 November at the Maison de l’Amérique Latine in Paris with the participation of the LEREM team.


Meet us at Paris Packaging Week 2024

Paris Packaging Week 2024 Bannière

Paris Packaging Week is coming up again on 17 and 18 January in Paris. It’s a great opportunity to discover the latest innovations and trends in metal packaging sector. Our team will be present on the Comité Français des Aérosols stand V70.

Join us at Paris Packaging Week 17&18 January 2024.

📆 17 – 18 January 2024
📌Stand V70 – Paris porte de Versailles


Assessing genuine flammability hazard of halogenated species

The LEREM and INERIS, National Institute for the Industrial Environment and Risks, have carried out a study with a use case to Assess genuine flammability hazard of halogenated species for their safe processing and use.

The scientific article written by B. Tribouilloy, G. Binotto, F. Flécheux, A. Vignes and G. Marlair and published on the ScienceDirect platform is available below.

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The LEREM approval was renewed in the french official journal

The Laboratory obtained, in march 2023, the extension by the french ministry of transport of its approval for a period of 5 years in order to test and, if necessary, to approve models of packaging for the transport of dangerous materials. It has also been approved to carry out controls of the manufacturing process of packagings directly at the manufacturer. The LEREM began this activity in 1999.

The technical activities of LEREM break down, into several major sectors of comparable importance:

  • Realization of tests for the approval of packaging intended for the transport of hazardous materials.
  • Performing mechanical and flammability tests on aerosol generators and pumps.
  • Conducting content-compatibility tests by electrochemistry.
  • Study of NIAS for materials in contact with food (MCDA).
  • Technical assistance and various expertise.
  • Aerosol particle size analysis by laser diffraction.
  • Analysis of varnishes on packaging and metal aerosols.
  • Various problems on any type of packaging

Our approval activity of packagings intended for the transport of hazardous materials includes on-site manufacturing inspections of certified companies.

Download the approval (in french) :

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ADR 2023

Bannière de l'ADR 2023

The European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) established on January 1 2023 applies in 54 countries to any actor loading, transporting and unloading dangerous goods for humans or the environment (solid, liquid, gas).

The agreement evolves every odd year and adds new parts and regulations. The latest update took effect from January 1, 2023 with an obligation to apply from July 1, 2023.

The two volumes of ADR 2023 are available in PDF from the links below :

Volume 1

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Volume 2

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The importance of precision

Franck Flecheux, director at LEREM, explains innovations in its technological capabilities, as it problem-solves issues facing its members and the wider metal packaging industry

Since 1987, LEREM (Laboratoire d’Etudes et de Recherches des Emballages MétalliquesMetal Packaging Research Laboratory), founded in 1961 on the initiative of the French National Association of Metal Can Manufacturers (SNFBM), has been a non-profit association. LEREM is a member of various French technical and regulatory committees through AFNOR HO8F Committee Group, which designs and deploys solutions based on voluntary standards around the world. The French Committee of Aerosols (CFA), and at the European level, through Metal Packaging Europe (MPE), the European Industrial Packaging Association (EIPA) and the European Aerosol Federation (FEA). Based in Montataire, the organisation offers its services to its members as well as to all companies working in the metal packaging industry (mainly steel and aluminium manufacturers, food, cosmetics, industrial products and retailers) to solve the problems they may encounter in the vast field of metal packaging and its many applications.

LEREM’s routine activities

The market for metal cans is growing steadily mainly due to their durability, stability and safety. Annual European production is about 98 billion units for various applications (beverages, food, health and beauty, domestic and industrial markets), according to Metal Packaging Europe. The global market for metal packaging is steadily growing and is projected to grow 3.1% from 2020 to 2030. Metal packaging compares favourably to other types of packaging because of its physical resistance, which provides the possibility of sterilisation or stability when transporting hazardous materials. Metal packaging provides a good physical barrier that limits any contamination or “interaction” between the outer and inner sides of the container.

Finally, it is a practical and environmentally friendly solution compared to other types of packaging materials, which, importantly, can be recycled over and over again without losing their inherent properties. However, in order to guarantee these useful properties, it is necessary to strictly control the manufacturing process of the metal packaging and the quality of the final product. The most important requirements for metal packaging are physico-chemical resistance and airtightness. LEREM is at the disposal of the metal packaging industry, which it supports in :

  1. Obtaining permits for the transportation of dangerous goods
  2. Marketing safe aerosols that meet regulatory labelling (flammability and pressure resistance)
  3. Advising all members of the metal packaging industry (manufacturers, users, relevant bodies)

With the ISO 9001:2015 standard, the organisation has the capability and competence to perform the following tests :

  • Approval tests on packages intended for the transport of dangerous goods;
  • Mechanical and flammability tests on aerosol dispensers and pumps;
  • Laser diffraction particle size analysis;
  • Electrochemical and storage tests (at different temperatures) on container-contents compatibility.

LEREM has extensive experience in tests related to packaging (up to 400 litres) for the transport of dangerous goods. Back in 1997, the association obtained its first approval from the French Ministry of Transport, which is constantly updated for testing, approval of design types and production control. This expertise is based on regulatory tests such as drop tests, hydraulic pressure tests, leak tests, stacking tests, corrosion tests in accordance with RID, ADR and CLP regulations. Regarding production control, the organisation is responsible for the on- site control of the production of approved packaging, which is repeated every three years as part of the certificate renewal process (ISO 9001).

Nouveau matériel du LEREM

The firm performs flammability tests, which were regulated in 2007 in the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) and since April 8, 2008, in Directive 2008/47/EC. In France, these tests were included in the decree 2010-323 of March 23, 2010. The test method consists of:

  1. Measurement of the ignition distance for dispersed aerosols;
  2. Flammability of aerosols dispersed in an enclosed space;
  3. Flammability of aerosol foams.

This method allows, depending on the values obtained and the criteria established, to classify aerosols as “non-flammable”, “flammable” or “extremely flammable”. The study on dispersed aerosols can be supplemented with particle size analysis by laser granulometry. This analysis is an important quality control method in various industries such as paints, food and beverages, aerosols, building materials, biocide products as well as in the pharmaceutical industry. Granulometric analysis is mainly used to make sure that the final product meets consumer expectations and, most importantly, is safe for use. Mechanical tests are performed in accordance with NF H44-023 and FEA 621 standards on empty cans without valves to determine the bursting pressure.

Additionally, the mechanical strength of metal aerosol containers as well as glass or plastic containers (aerosol or not) can be determined in accordance with the FEA 623 standard and the Directive 75/324/EEC. In accordance with the draft standard FEA 647, LEREM also tests plastic aerosol cans (cold drop test, hot drop test, product test, water test, water and antifreeze test and hot air test). LEREM has the equipment and technical skills to carry out on container-contents compatibility using electrochemistry, which can be very effective in determining the suitability of steel containers or selecting appropriate corrosion inhibitors to limit the corrosion risks of certain container-content pairs.

New tool for electrochemical testing

Impedance spectroscopy is an electrochemical method of measuring the electrical resistance (impedance) of the metal/ coating interface when an alternating voltage is applied to a sample at different frequencies. This method has been used in packaging research since the 1980s, and LEREM, for its part, has been practicing this method since the early 1990s, mainly on aerosol cans. The practicality of this method for the metal packaging industry is great because it allows the detection of very small defects (sometimes even smaller than those visible with a microscope), and since this method has no destructive effect, it is possible to measure the same samples repeatedly, ie to follow their evolution over time.

Thus, mathematical models can be calibrated based on repeated measurements from very weak and very accurate electrical signals at different frequencies. Using this data, an equivalent electrical model of the RLC circuit (resistive, inductive, capacitive) can be created. Then an equivalent RLC model can be applied repeatedly at regular intervals to screen the interaction between the inner coating, the substrate, and the filled formulation of coated metal packaging cans.

This test procedure compares favourably with others (ie, storage test, pack test, etc.) as it reduces testing time, thereby speeding up time to market, and decreases the number of samples to be tested (de Vooys et al., 2012; Soares et al., 2020)1. Equipment and measurement processing systems are constantly evolving, and as LEREM strives to keep up with the latest innovations, from December 2021 the association has been equipped with brand new, state-of-the-art and more accurate (10 times more sensitive) equipment.

A new direction – analytical studies

Recently, special attention has been paid to the materials and chemicals used to produce food contact materials (FCM). At the European Union (EU) level, FCMs are subject to the framework regulation EC 1935/2004. This regulation stipulates that FCMs must not alter the organoleptic and nutritional properties of food and must not transfer their components into food in quantities that could endanger human health. This Regulation applies to all substances that can migrate from FCMs, including so-called non-intentionally added substances (NIAS).

Schéma des substances

Although EU legislation permits the presence of NIAS in FCMs, a risk assessment involving the identification and characterization of molecules migrating, as well as an assessment of exposure levels, is required. LEREM assists metal packaging manufacturers who want to ensure the safety of their materials, and carries out NIAS studies (identification, semi/quantification) using high resolution mass spectrometry techniques. The study of NIAS in FCMs will allow packaging manufacturers to confirm that their products are in accordance with current regulations and will help them comply with any regulatory changes.


Transcribed from the article “The importance of precision” of the November/December 2022 edition of the World Aerosol magazine.


Quality policy 2022

Quality policy

Mr. Paul Garcia as Chairman of the Board of LEREM and Mr. Franck Flecheux as Director of LEREM are commiting to provide the means to enforce and improve the 2022 quality policy :

Listening to customer needs

To better understand the explicit or implicit needs and expectations of interested parties. The quality, reliability, precision and speed of the Laboratory’s tests are essential elements of its brand image and reputation.

Keeping qualified staff and resources

The laboratory is made up of qualified staff and control, measurement and test equipment to meet its challenges. The laboratory also has a Quality System which has been assessed and deemed to comply with the requirements of the ISO 9001 version 2015 standard, in its field of application.

Comply with regulatory requirements

The laboratory must prevent the risks of incidents related to packaging safety through actions and relevant communications.

Sustainable waste management

Even though the laboratory generates little waste we are aware that all efforts to limit the environmental impact are important. The laboratory is committed to maintaining an approach aimed at organizing the sorting of waste and managing its evacuation to appropriate recycling or treatment channels.

Our main missions

  • Ensure the compliance of packaging intended for the transport of dangerous goods with a view to the issuance of approval certificates for packaging, in compliance with the regulations in force
  • Carry out tests for aerosol manufacturers/fillers (flammability, pressure resistance, etc.) necessary to comply with aerosol regulations and the safety of all
  • Represent the profession and defend its interests with public authorities and agencies and other professional organizations in France and Europe
  • Provide independent expertise to any applicant for any problem or technical question raised during inter-professional or legal disputes
  • Develop the commercial activity and improve the financial result

Our objectives

  • Improve the satisfaction of our customers by analyzing feedback from satisfaction questionnaires and internal quality indicators, while maintaining the same high level of requirements as in recent years
  • Ensure the safety of laboratory members at work
  • Establish a project for the evolution of the laboratory’s economic model
  • Set up the PHÉNIX research project, which is part of the OLIGO research project
  • Establish a new agreement between LEREM and SNFBM

Mr. Jean Baptiste MATHIEU is responsible for monitoring the quality system of the laboratory.

Mr. Jean Baptiste MATHIEU will also be in charge of leading and coordinating the procedures of progress.

Quality represents a commitment for each member of the laboratory. The development of quality policies, communication, risk analysis as well as the respect of the fixed objectives constitute a priority for all.

The Chairman of the LEREM Board,


The Director of the LEREM Laboratory,


The Technical and Quality manager,

Mr. Jean Baptiste MATHIEU


The Laboratory Technician and Secretary,

Ms Corinne GUYOT

papier footer LEREM 2022

Materials in contact with food products

Food contact internal coatings

In recent years, a special attention has been paid to the materials and chemicals used to produce food contact materials (FCMs).

Research is constantly underway to improve the practicality and safety of internal coatings and food contact materials to protect consumers. The Article 3 of the European Regulation 1935/2004 states that “any material or article intended to come into direct or indirect contact with food shall […] not transfer its constituents into food in quantities which might endanger human health”. This regulation applies to all substances that can migrate from FCMs – starting substances used to manufacture FCMs, as well as so-called non-intentionally added substances (NIAS).

Although EU legislation permits the presence of NIAS in FCMs, a risk assessment involving the identification and characterization of molecules migrating from the material, as well as an assessment of exposure levels, is required. This year, the European Commission re-evaluated current EU legislation on FCMs and concluded that there are “[…] potential weaknesses in the current approach to regulating FCMs”. One of the issues outlined has to do with the identification of NIAS. The problem with NIAS is that even though awareness of the topic has increased, and some studies have been done, not many molecules have yet been identified, making it impossible to accurately assess the risk, if any.

LEREM’s expertise

LEREM supports its adherents and metal packaging manufacturers who want to be proactive and ensure the safety of their materials, and offers to conduct NIAS studies (identification, semi-/quantification) using high-resolution mass spectrometry techniques. Thanks to the collaboration with LABERCA, the PhD in analytical chemistry engaged at LEREM has access to the LABERCA analytical platform, consisting of 18 different instruments. The identification of unknown substances in food contact materials carried out by LEREM will allow manufacturers to anticipate the compliance of the materials used in the packaging they will provide with future regulatory changes.

Photo d'emballages alimentaire

We participate in the FEA congress 2022

Bannière du congrès FEA 2022

The LEREM team will participate in the FEA congress 2022 in Lisbon from September 21 to 22.