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When a new account is requested, the shipment and billing addresses are mandatory fields to enter. This shipment and billing details are used to ship all samples and send invoices.
Unfortunately, the same shipment and billing addresses are requested again when you checkout of your shopping cart to finalize your order, but these addresses are used only in the information that is stored with the order and does not change the addresses in the account information. Please fill in a valid address the first time you order in the checkout, so the orders have the right address.

If something changes in the account shipment and/or billing addresses, the main contact of the account will see an edit option in their account and can change the shipping and billing information for your laboratory.

Participation in an iis Proficiency Test allows a laboratory to compare its own performance to those of other, similar laboratories. The presence of systematic errors and/or random errors will be revealed, which allows the laboratory to take - if it feels necessary - corrective actions to improve its performance. Furthermore, the results are compared to the requirements of internationally accepted standardized test methods (ISO, EN, ASTM or other industrial standards). Each laboratory gets a performance score (z-score) for each reported test result. Ideally, this score - given by an independent and ISO/IEC17043 accredited institute such as our organization - will prove the laboratory's good performance. Proof which can be used to convince your staff, your clients and your National Accreditation Body.

The answer is simple: "No!" iis handles all information supplied by the participating laboratories with great care and strictly confidential. No information is passed to third parties unless prior permission is received. The identity of individual participants is always maintained confidential and only known to a minimum of authorized iis personnel. Furthermore, in all reports laboratories will only be represented by a code number. The Institute is aware of the fact that participants of a proficiency test do not always wish to enclose their performance to third parties. The identity of a laboratory can only be made public by the laboratory itself.

No! The goal is to get a good impression of the quality of the normal routine performance of the laboratory. And therefore, no extra efforts should be used to reach a better performance than normal. No excessive testing, no extra quality control, no special treatment whatsoever should be used in the analysis of the PT products. Only by treatment of the PT product as if it is a routine product, the quality of the laboratory can be evaluated correctly, and when necessary, it can be improved after receipt of the PT report.

As the results of our proficiency tests are used by accreditation bodies, we - as an ISO/IEC17043 accredited organization - are not allowed to send a surplus of product in order to avoid excessive testing to get good results. However, in some cases the total amount of available bulk material is very limited. Nevertheless, the product amounts are always sufficient to perform all tests at least once.

Our institute is accredited according to ISO/IEC 17043 for a number of PTs. In the accreditation documents is a requirement that tells us to use product materials that are very realistic and like daily routine products. However, as in practice hardly ever any forbidden components (e.g. AZO-dyes, metals or pesticides) are found in for example textile, this would mean that we should use products without any contaminations at all. And that would not be suitable product material in our opinion, because we cannot evaluate laboratory performance with only 'less than' results! Therefore, we decided to use products artificially contaminated with several components, and to use each round different components with different concentrations. In this way the products are like daily routine products for some components and at the same time give useful information for other components.

The participating laboratories do not have to perform all tests that are requested. Only tests that are performed routinely by the laboratory should be reported. And the laboratory may choose to perform only the tests that are most important for the laboratory. As an ISO/IEC 17043 accredited PT provider we are not allowed to send too much product to prevent excessive testing.

If you need a PT-scheme, for instance for evaluation of supplier laboratories, laboratories of your group or similar laboratories in your own region, iis will be happy to organize such a tailor made scheme. The schemes are set up to the wishes of the client, but the set-up will always be based on international accepted protocols like ISO 5727, ASTM E691, IUPAC, JAOAC, DIN 38402 or NEN 6303. A broad range of products and product types can be handled. The tailor made interlaboratory studies may be on petroleum products or petrochemicals, but also other type of products, like soils, foodstuffs or gases.

Yes. The quality system of iis is in full agreement with ISO/IEC 17043:2010. The ISO/IEC 17043 accreditation is granted by the Dutch Council for Accreditation ('Raad voor Accreditatie', RvA) in January 2000. Our registration number is R007, see the RvA website. Please know that all PTs that iis organize follow the same protocols as the accredited PTs.

ILAC is the international organization for accreditation bodies. Since the RVA (Dutch Accreditation Council) is member of ILAC, all other ILAC members will accept the accreditations given out by the RVA. Through the existing ILAC Mutual Recognition Arrangement (ILAC MRA) other National Accreditation Boards do recognize the ISO/IEC 17043 accreditation of iis.

Regular participation to Proficiency Tests is prescribed in ISO/IEC 17025. National accreditation bodies (NAB) will audit whether your laboratory participates in relevant schemes and how the evaluation of the results is implemented in your quality system.

One has to understand that product transport is a matter of pushing (by the sender) and pulling (by the recipient). Without the assistance of the recipient, it is impossible to deliver a product, no matter how hard this is tried by the sender. Therefore the (pro-active) assistance of the receiving company is of utmost importance in order to get the product at the laboratory within an acceptable time frame. For example, import licenses need to be arranged prior to the product dispatch date.

Please report to us about the delay and test the products as usual. We will evaluate all reported results, also when reported after the deadline for submitting results.

Contact us as soon as possible. When a bottle has been broken, please do not accept the package from the courier. Please note that we will only send a replacement bottle at our cost when there is proof of the sample being broken upon receipt. This means that the consignee must report a broken bottle immediately. The consignee should take pictures of how the package and bottles looked upon arrival. We need these pictures to claim costs from the forwarders. The consignee should always mark any damage (dents, rips, leakage etc.) on the outside of the packages on the consignment note from the courier when it is delivered. Even minor damages should be reported. Please send copies of consignment notes and the pictures via email to nl.saman.iis@sgs.com

Participants are responsible for the customs clearance of the products. For some countries the receiver needs to have an import license. The import license needs to be arranged prior to the sample dispatch date. If you require us to attach documents to your parcel, we need to receive the documents at least two weeks before the sample dispatch date.

When a PT is still running it is not allowed to purchase extra product. However, as soon as the PT is finished, it is indeed possible to order retained PT products for example for training purposes or to investigate problems to determine corrective actions. All remaining PT products are retained by iis under controlled conditions and made available for the participating laboratories to be purchased. The number of remaining products is limited and varies per product. Please contact iis for more information.

A PT product should be treated and tested exactly like any other product that is tested by the participating laboratory, which is a requirement from ISO 17025 and ISO 17043. It should not receive any special treatment or attention. Excessive testing is not allowed. Only when the laboratory performs a test in duplicate routinely, the PT product may also be tested in duplicate. No extra QC, nor extra calibration may be done that is deviating from the routine procedure that is used for regular products to be tested. Also, it is not allowed to contact other participating laboratories about the test results on the PT product before the final PT report is published.

This will depend on who discovers the violation. When an external quality auditor finds the violation during a laboratory audit, without doubt a non-conformity will be raised and the certification or accreditation of the laboratory may be withdrawn. When iis finds the violation, the reported test results will not be used for evaluation and will not be published in the PT report. Also, the laboratory may be excluded from further participation in the iis' PT schemes.

Yes, multiple operators can test the PT product, but only for different tests. The PT set up is not intended for different operators performing the same test and reporting multiple test results for this test. Therefore, test results from a second or third operator will not be evaluated. Such replicate test results will have to be evaluated by the laboratory itself. One has to keep in mind that a PT product should be tested like any other regular product, without special treatment like excessive testing.

When literature reproducibilities are not available or not applicable, we summarize the group reproducibilities of the PTs from the past years to estimate a reproducibility that can be used as reference reproducibility to determine the performance. We publish them in an iis memo.

The following iis memo’s are available:

iis memo 2303 Reproducibilities of Purity and Impurities in Methanol
iis memo 2301 Reproducibility of Total Per- and Polyfluoroalkyl Subst. (PFAS) in Polymers
iis memo 2203 Reproducibility of AP and APEO in Textiles
iis memo 2201 Reproducibility of Phthalates in Leather observed
iis memo 2102 Precision data of Phosphorus Flame Retardants in polymers
iis memo 1904 Precision data of Calculated Cetane Index Four Variables in Gasoil
iis memo 1601 Precision data of Orthophenyl phenol and Pentachlorophenol in textile

This way of z-score calculation results in a simple, straight forward comparison of lab results with the reproducibility stated in the corresponding international accepted test method. It indicates how many times the standard deviation the reported result deviates from the 'true value'. Target z-scores allow evaluation of performance over longer periods using a series of PT-results.
This is impossible with z-score calculated from the standard deviation of the group of participants as the group of participants is not constant, nor is its performance. It will mean that the worse the group performs or the more variation the group has, the lower the z-score will be. This last version of the z-score based on the group results ensures that about 95% of the test results will fall within limits of ±2 and only 0.5% will fall outside 3, this by definition and thus independent from the performance of the laboratories! That is also the reason laboratories often use method repeatability for Shewart Control Charts and not the data of the control chart itself.

Please know that the z-scores of iis are calculated with the literature reproducibility. This means that a z-score within absolute 3 means the laboratory performed within the reproducibility of the method. So a z-score of 2.10 may be considered questionable, but is still within the population of the method. Please do not confuse this with z-scores calculated from the group’s reproducibility. In that case the warning signal is with a z-score above absolute 2, like is explained above.
In an iis PTs, all z-scores between -3.00 and +3.00 are considered within the variation of the method.

The average of the homogeneity test results indeed is not always in line with the average (consensus value) from the PT results. There are several reasons for this. First the goal of the homogeneity testing is very different from the goal of the evaluation of the reported PT results. In order to prove the homogeneity of the PT products, a test method is selected with a high precision (smallest variation). The accuracy (trueness) of the test method is less relevant. Secondly, the homogeneity testing is done by one laboratory only. The test results of this (ISO/IEC 17025 accredited) laboratory will have a bias (systematic deviation) depending on the test method used. The desire to detect small variations between the PT products leads to the use of a sensitive test method with high precision, which may be a test method with significant bias. Also, each test result reported by the laboratories that participate in the PT will have a bias. However, some will have a positive bias and others a negative bias. These different biases compensate each other in the PT average (consensus value). Therefore, the PT consensus value may deviate from the average of the homogeneity test. At the same time the accuracy of the PT consensus value is more reliable than the accuracy of the average of the results of the homogeneity test.

In a proficiency test the performance of the participating laboratories is evaluated, while in a collaborative trial the performance characteristics of a Standard Test Method are determined. Consequently, in a proficiency test the laboratories use their usual test methods and the determination of a reliable assigned value is the ultimate goal, while in a collaborative trial only one test method is used - being the one under investigation - and the determination of the repeatability and the reproducibility is the ultimate goal.

Certificates of Excellence and certificates of Participation are available. Only when all results reported by the laboratory are within the target reproducibility limits a certificate of Excellence may be issued.

See the 'Company Information' page.

Invoices should be paid within 30 days after receipt of the invoice. Customers with a normal payment history do not need to pay in advance. For payment terms see our General Terms and Conditions.

We prefer bank credit transfers, but credit card payment is also possible.

Yes, but only when we are informed in advance so that we can prepare an invoice in US dollars or when you pay per credit card.

The name Institute for Interlaboratory Studies (iis) is a registered tradename of SGS Nederland BV. Therefore, it is not possible to prepare invoices with iis letterhead. iis is a small, but fully independent department of the SGS Group, world's largest organization in the field of inspection, testing, analysis and certification.

When extra documents or actions are requested by the participant, additional costs may apply. See our Overview of Costs for Petroleum products here and for Consumer products here.