Institute for Interlaboratory Studies

The independent institute organizes global interlaboratory studies on fuels, petroleum products, petrochemicals and consumer products. Studies are usually performed on commercially relevant products and involve testing on complete specifications. Any laboratory may participate using its own routine analytical methods.

Discover our annual program; 2026 program Now Available

Petroleum products

CHEMICALS
FUELS
GASES
LUBRICANTS and OILS
PETROLEUM PRODUCTS and OTHERS

Consumer products

COSMETICS AND PERSONAL CARE
LEATHER/FOOTWEAR
POLYMERS
TEXTILES
FOOD AND SKIN CONTACT MATERIAL, TOYS, DRIED PAINT

How it works

The process

Register your account

If you haven’t registered your account yet, Register first your account. After authorization by iis, you can proceed with ordering PT-products. Once already registered you can login.

Order your products

Participation in some PTs may be limited due to limited stock of products. We therefore highly recommend to apply your PT-registration as soon as possible. Dispatch costs will be calculated afterwards, this will vary per product and destination.

Product dispatch

Once your participation is confirmed, we will ship the products to the address of your choice.

Confirm product receipt

You can confirm product receipt either via your iis client account at the Proficiency tests overview or via the iis Data Reporting portal.

Report your test results

You can submit your test results via the iis Data Reporting portal.

Reports & Certificates

You will receive your Proficiency Test Report and you can download your certificates in your account. We use our protocol to run a Proficiency Test.

News Topics

December 15, 2025

Holiday update 2025-2026

Christmas and New Years Holiday Please be informed that the office of the Institute for Interlaboratory Studies will be closed from December 24, 2025, through January 4, 2026. Normal operations...

New PT Program 2026 Now Available

We’re pleased to announce that our updated Proficiency Testing (PT) program for 2026 is now live! To participate, how it works:• If you haven’t registered your account yet, Register...

Help us with new Proficiency Test ideas

Please share any ideas/suggestions you might have for setting up a new proficiency test currently not in our program. Describe as fully as possible. Thank you!

New PT ideas/suggestions

About us

Who we are

iis is an independent organization that provides various types of interlaboratory studies (proficiency tests, round robins, cross checks, collaborative trials) for analytical laboratories. The Institute is located in Spijkenisse - The Netherlands. Its clients - participating laboratories in interlaboratory studies - are found all over the world, in more than 100 countries.

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