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What is an iRM?

In a nutshell, an iRM from White Horse Reference Materials (WHRM) is a CRM with additional characterization data for Statistical Quality Control of a laboratory’s sample analysis process.

An iRM from WHTS (designated with RM in the stock number) is a fully characterized, ISO-compliant material suitable for:

Other common terms for an iRM are Control Material, Statistical Quality Control (SQC) material, Statistical Process Control (SPC) material, QCM material (ISO Guide 80 calls them Quality Control Materials), verifier, and such.

ASTM E2972-15 "Standard Guide for Production, Testing, and Value Assignment of In-House Reference Materials for Metals, Ores, and Other Related Materials", section 3.2.2 defines the term like this:

All our CRMs and iRMs meet/exceed the ISO quality requirements for Reference Material Producers. In addition, our quality system meets the requirements of ISO 17025.

Why do you say your standards are top quality?

White Horse Technical Services (our processing division) spent years developing a 16-step proprietary production process that targets hydrogen content in titanium wire with very low pin-to-pin variance.

WHRM's superior testing protocol with proprietary equipment performs amount-of-substance measurements direct to the SI which has been shown to compare well with NIST PGAA analysis for hydrogen with very low levels of uncertainty (SA amount-of-substance standard Monte Carlo uncertainty @ 137 mg/kg was 0.034 mg/kg). N2 and O2 SI-direct characterizations are soon to follow. The direct-to-SI measurements become a primary comparison with superior accuracy (lower uncertainty) and place the use of CRMs into a secondary verification role.

All WHRMs provide traceability to the SI with either direct amount-of-substance measurements, or short links of comparison wherever possible, with rigorously derived uncertainty information. They are used for ISO compliant instrument calibration, SQC, and uncertainty estimation.

Why do you sell iRMs? How are laboratories using them?

Our WHRMs, because they are sold in larger quantities, cost less than CRMs. Because of their same high quality as our CRMs, laboratories find them an excellent choice for the maintenance of their instrument's calibration.

Laboratories are encouraged to employ iRMs for statistical process control and routine analyses while realizing a Standard Test Method to preserve the calibration on an instrument for various benefits, including harmonization among laboratories and cost.

The use of iRMs is not complicated. It is rather simple, straightforward and satisfies all accreditation requirements.

Newcomers to this practice are encouraged to examine our FAQs to aid them in the process of introducing our WHRMs into their quality system.

What is the difference between your CRMs and your iRMs?

The quality of our iRMs is identical with our CRM products, both are fully characterized.

The difference is in how they are purchased (quantity), the documentation and how they are used in your quality system.

Besides the information for use as a CRM, our WHRM documentation includes additional information helpful for instrument calibration maintenance, intermediate precision monitoring and the estimation of measurement uncertainty.

Will auditors accept iRMs for our use, and approve?

Since the use RMs are new to our niche of the market, and our company is not yet an accredited producer, you may get some resistance.

If a customer or accrediting body insists on your use of ISO 17034 accredited sources for your standards (this is NOT an ISO 17025 requirement), to aid in their acceptance simply use a combination of CRMs for calibration and WHRMs for calibration maintenance and the other uses (see our other FAQs.)

Some accreditation bodies and auditors are unfamiliar with how to verify that a laboratory has properly qualified them to meet ISO requirements for calibration. ASTM E2972 Section 6.5 and ISO 17025 (A.3.1) and associated documents explain how they are acceptable when characterized properly. (Ours are. See FAQ "How can my quality manager verify and demonstrate to an auditor that your RMs meet all ISO 17034 requirements?" for more.)

All our CRMs and iRMs meet/exceed the ISO quality requirements for Reference Material Producers. In addition, our quality system meets the requirements of ISO 17025.

For laboratories that are not ISO accredited, and those whose accreditation bodies are familiar with their use, our iRMs can be used exclusively, without a need for the more expensive CRMs, as they are fully characterized to meet all ISO Reference Material Producer requirements.

What ASTM documentation supports the use of iRMs?

E2972-15 states, in Section 4.2:

Calibration with CRMs is discouraged, when lesser expensive in-house Reference Materials (iRMs) are available with homogeneity fit for purpose. CRMs are more costly and often in limited supply.

Why don't you provide a Certificate, only an Information Document for your RMs?

Our CRMs are sold fewer bottles at a time, used for calibration of an instrument at various values in the ranges of interest. The RMs we offer have targeted values aimed at various setpoints where monitoring and maintenance of your instrument's calibration in-control status is best performed. The Information Sheet provides more information for that use.

They are marketed for a different intended purpose. WHRM SQC materials are for demonstration and maintenance of in-control status (including calibration) of a measurement process over time and to check instrumental performance, including repeatability. The laboratory is advised to purchase enough of the material to last a long time to gain a long-term perspective on their measurement performance.

The Information Sheet provides all the information required for use in the same way that a CRM is used, plus additional information helpful for SQC monitoring of the instrument's calibration in-control status with intermediate precision monitoring and the estimation of measurement uncertainty.

Are iRMs OK for use as a verifier?

Yes. The term verifier refers to how the material is employed to verify your calibration status is still in-control (providing accurate results). Various other terms are used in the industry, such as in-house reference materials (iRMs), 'Control Material', 'SPC' 'SQC', and 'QCM material', and such. We call them 'iRMs' because ASTM E2972, which addresses their production and use in the maintenance of an instrument's calibration, defines the term.

E2972-15 Section 6.1.2 states:

And Section 6.1.3:

Can I use iRMs to calibrate my instrument?

Yes, or course, that's one of their primary uses. They are employed for calibration (and/or drift correction) to establish and maintain an instrument's calibration in-control status, i.e. for Statistical Quality Control (SQC) of the measurement process.

All our CRMs and iRMs meet/exceed the ISO quality requirements for Reference Material Producers. In addition, our quality system meets the requirements of ISO 17025.

Do your CRMs and iRMs meet ISO 17025 requirements?

Yes, they meet all the requirements.

All our CRMs and iRMs meet/exceed the ISO quality requirements for Reference Material Producers. In addition, our quality system meets the requirements of ISO 17025.

Here is what ISO 17025:2017 says on this topic:

For more, see our FAQ "How can my quality manager verify and demonstrate to auditor that your RMs meet all ISO 17034 requirements?"

How can my quality manager verify and demonstrate to an auditor that your standards meet ISO quality requirements for our use?

We make it simple. Review the following requirements from ISO to verify that the documentation for any RM you consider using meets your requirements. Take special note of the questions shown in bold.

(NOTE: Although some documentation components are required for calibration use, and optional for control chart uses, for your convenience, we make sure all our CRMs and SQC RMs are fully characterized and document all the information needed for a laboratory to meet all their requirements.)

NOTE: A laboratory is advised to contact the producer for more information on any item that is not sufficiently supplied in their documentation before considering any material for use.

After evaluating the material's documented characteristics, the RM is procured, and an analysis of the material as an unknown sample on a freshly calibrated and maintained instrument is performed.

If the precision and resultant mean value of replicate measurements meets the laboratory's measurement uncertainty requirements, the material is qualified for employment.

ISO 17025 requires my test results to be traceable to the International System of Units (SI). Will they meet that requirement using WHRM's iRMs?

Our iRMs fully meet traceability requirements. ASTM E2972-15 Section 3.2.4 defines traceability like this:

Are there any other benefits to using your RMs other than the cost savings?

Our RMs (both CRMs and iRMs) have relatively low uncertainty and heterogeneity. The higher measurement process accuracy that results enables a more critical evaluation of both instrumental and manufacturing process stability.

Notable benefits are:

1. Lower inherent uncertainty in test measurement

2. Charting the test result data along with the sensitivity factor from iRM analyses can provide better clarity to view important clues to the instrument's need for maintenance, a need for other corrective action, and assist in the fine-tuning of an instrument's test method set-up parameters.

3. Charting the results of test coupons, for instance, from a manufacturing process with an instrument that has lower uncertainty in measurement enables better control over the process.

4. Conformance evaluations are enhanced with better clarity for more critical pass/fail decisions and may lower the risks involved in a lot's acceptance/rejection decision.

Why are White Horse lot numbers incorporated into the part number (with a small alphabetical character)?

This is to reduce potential confusion of values between lots. The stock number directly indicates the lot and its associate values.

White Horse Reference Materials has chosen to identify its products on a 'Series/Lot" basis. Each part number indicates the series and range of analyte concentration. For example, a titanium lot that is dosed for a targeted hydrogen value may have a P/N of "T" (for the base metal Ti) with an added character identifying its concentration range "J" (which is useful when calibrating for a max spec limit of 125ppm). The target value is aimed at exceeding a max limit by around 10%.

The full part number with its incorporated lot identifier is sufficient to uniquely identify and correlate the product with its documentation. As long as the label on the bottle matches the CRM part number shown on your documentation, then this is all the information you need to identify the RM for QA purposes.

Why aren't the values printed on the bottle label?

ISO/IEC 17034 prohibits this practice. They want you to keep the documentation close and handy for the analyst to refer to.

Although many users will hand-write the values on the label themselves, some auditors object to this practice.

I get the wrong results (bias) when I analyze your standards -why?

Our products have been well characterized and verified by our laboratory, Some by NIST, and various quality commercial laboratories.

You are likely comparing our materials with a standard from another producer. There may be several reasons for getting a difference between two standards. First, check the precision of the standard you are using to calibrate your instrument. If a group of results (min 3) has a larger variance than our samples, it could be that you need to calibrate your instrument with a minimum of 5 samples of the other material. Then, when comparing with our standards, the results should be comparable. (Unless the standard you were using has a bias.

For instance, NIST recently updated the value for SRM 2452 when they noticed a bias in their original characterization resulting from a new analysis. They published an updated value with approximately 10% change in the value. RMs that producers made using this NIST RM for one of their references may need a value revision. Check the documentation to see if this SRM or a derivative was used in its characterization. It may be biased, and the value needs updating by the producer.)

For Hydrogen bias issues, bias you see when comparing two standards may be caused by the difference between their masses.

There is a common issue with biased hydrogen results stemming from analyzing different masses of the same material using tin flux. It is recommended that you keep the mass of each sample, including calibration material within a nominal range +/- 10% (0.20-0.25g) and use at least 1.0g of tin flux to minimize this issue. (Although ASTM E1447 allows a range of 0.15-0.30g samples, many instruments experience significant bias when analyzing samples in that full mass range.)

NOTE: This bias also happens when analyzing unknown samples.

To determine the level of this bias on your instrument, analyze a series of samples from a homogeneous lot of material (use standards cut to size (as necessary) for analyses at the extremes of the STM allowable mass range of 0.15g and 0.30g and compare the average results from both extremes to determine your level of mass-range bias. The manufacturer may have additional suggestions on how to minimize the bias you experience by adjusting your instrument's internal test method parameters

Some of my results are outside of the Expanded Uncertainty range listed in your documentation. Why?

Don't worry, that is supposed to happen, sometimes. The Expanded Uncertainty is a 95% confidence interval, meaning that 95%, or 95 times out of 100, the result should be within that range, and it is normal that 5-of-100 analyses of the RM may be slightly outside that range.

WHRMs utilize the highly precise Thermal Conductivity detector technology. Many laboratories, when doing verifier analyses choose to use a multiplier of 1.5 * Uc as acceptance criteria, especially when using instruments with other detector technologies. Using this criterion lets them know when there is a high likelihood that the instrument's performance is out-of-control, and corrective action is needed.

WHRM material lots are carefully homogenized, and the expanded uncertainty is carefully established with a robust statistical evaluation.

The cause of your poor precision could also be your instrument's analytical method setup parameters (even if it was copied from a factory application note) need optimization, or it could be maintenance or repair issues. Contact us for assistance, we can help you with these issues.

I have more results out-of-tolerance with your RMs than I get with RMs from other producers. Why?

If you are new to WHRMs, and accustomed to using CRMs that document a high Expanded Uncertainty relative to 2 * the standard deviation of your results, it is likely that the Uc they publish is a simple repeatability statistic (pooling results from multiple sources which may have high variance). Your instrument may be operating poorly, and still meet the published tolerance. In addition, it may be impossible to calculate an estimated measurement uncertainty that meets laboratory or customer goals using these RMs because the published uncertainty is excessive.

ISO 17025 requires my laboratory to evaluate our measurement performance, including the validity of our measurement results. How is that done?

The primary, and most important way to do this is to routinely verify your instrument is providing accurate results within uncertainty limits that meet your laboratory acceptance criteria.

First, determine what the users of your test results expect for the uncertainty of your measurement process.

Second, gather the data from your instrument calibration verification checks, and take a statistical look at them. (Exclude those results that were qualified outliers resulting in required corrective action and re-test or re-calibration, if found necessary.) learn to estimate the measurement uncertainty of your instrument.

Third, perform an experiment to measure the variance in results of the same sample under reproducibility conditions to determine the average bias that your sample prep process introduces.

Fourth, evaluate any other potential significant sources of bias and quantify them.

Next, combine all these standard uncertainties to establish your laboratory measurement process uncertainty and see if that value falls within your laboratory's uncertainty of measurement requirement.

(This process must be performed for each test method and each measurand.)

NOTE: WHRM is working with ASTM to develop guidance to assist laboratories in this work.

Will I get a discount if I read and understood all these FAQs?

Sure, just ask... (and you don't have to understand everything... we welcome questions.)