What makes an Aircraft

"It's what's inside that counts, at the finest interstitial detail."


FAQs about our RMs

It's simple. It's no different than your acceptance procedure for any other RM.

Analyze the material and verify it results compare well with your other CRMs.

In detail:

This procedure confirms that the traceability link to the SI taken from our certificate/Information sheet is valid on your instrument.

All WHRM hydrogen RMs are primary reference standards* providing traceability to the SI with direct amount-of-substance measurements with rigorously derived uncertainty information. (Nitrogen and oxygen characterizations by this primary SI process are soon to follow.)

They are used for instrument calibration, SQC as quality control materials, interlaboratory comparison, uncertainty estimation, and used during the characterization of Certified Reference Materials.

The story: White Horse Technical Services (our processing division) spent many years developing:

  1. a proprietary production process that targets specific hydrogen content values in titanium wire with low pin-to-pin variance,
  2. a proprietary high-precision gas-dose calibration instrument providing traceability to the SI with direct amount-of-substance measurements,
  3. a proprietary standard additions method of analysis for certification, and
  4. a rigorous uncertainty evaluation protocol.

WHRM continues its research efforts to improve the quality and efficiency of its products and processes with the goal of reducing cost and increasing the breadth of its product offerings.

JCGM 200:2012 VIM3: International Vocabulary of Metrology definitions:

WHRM is a small company wich directly benefits from White Horse Tecnical Services experienced in-house R&D and production of high quality RM candidate material, and therefore has low overhead costs. Because of this, we can offer superior products competitively.

Accreditation body emphasis has been that a laboratory buy only material from accredited producers (which is not a requirement of ISO, nor dictated by ASTM). Suggesting that the quality of an RM is ensured by accreditation is misleading.

The documentation provided with an RM coupled with in-house verification are the best sources of assurance of the quality of RMs. See the FAQ “How can I be sure that an RM meets ISO 17034 requirements for use?” for more on documentation.

Accreditation bodies do not accredit individual products. An accreditation body certifies only that the producer demonstrated to their satisfaction that the producer follows their quality system documentation.

Accreditation does not mean the producer's procedures are fit for purpose. It merely shows they have a quality system that they believe conforms to ISO 17034.

The accreditors do not make CRMs and they have no experience doing so. Being accredited means only that a producer was audited and got the accreditation. It does not mean they have expertise in chemical metrology and the statistical processes needed to issue CRMs, no matter how many years they have been producing RMs or how sincerely they believe their procedures are good.

Accreditation has evolved into a marketing tool.

The production of quality RMs takes a scientist's dedication to develop and execute all necessary and proper procedures to produce products worthy of the trust of the scientific community. Scrutiny of this process is not within the capabilities or scope of an accrediting bodies' responsibility.

In the metals industry, as well as many others, the quality of an RM product is necessarily and routinely validated in each laboratory by their own instruments before use. An accreditation held by the RM producer does not directly aid the user in any significant way, as commutability is not an issue. There is no independent body that compares RMs from various sources and publishes the results.

Accreditation is not cheap, and therefore producers must pass this cost on to the market. All accredited producers have the expensive cost of accreditation built-in to the price of their products.

ISO requires a producer to provide the information we provide here in a simplified, but complete list (see *notes for optional/recommended status). For more in-depth coverage, consult ISO Guide 31:2015.

ISO Documentation requirements for CRMs:

*Mandatory for CRMs, optional for non-certified RMs such as quality control materials



****Recommended, but not spelled out as such in Guide 31

NOTE: The user is encouraged to contact the producer with questions regarding an RM before considering it for use.

After evaluating and accepting the material's documented characteristics, the RM is procured and validated in the laboratory prior to use.

Yes, they meet all the requirements.

Here is how ISO 17025:2017 states your requirements:

    "6.4 Equipment

    6.4.1 The laboratory shall have access to equipment including, but not limited to, measuring instruments, software, measurement standards, reference materials, reference data, reagents, consumables or auxiliary apparatus which is required for the correct performance of laboratory activities and which can influence the result.

    NOTE 1 A multitude of names exist for reference materials and certified reference materials, including reference standards, calibration standards, standard reference materials and quality control materials.

    Reference materials from producers meeting the requirements of ISO 17034 come with a product information sheet/certificate that specifies, amongst other characteristics, homogeneity and stability for specified properties and, for certified reference materials, specified properties with certified values, their associated measurement uncertainty and metrological traceability.

    Reference materials should be used from producers that meet ISO 17034."

For information on how our products meet ISO 17034 requirements for Reference Material Producers, see the previous FAQ"

FAQs related to iRMs

In a nutshell, a WHRM iRM* is a quality control material which is fully characterized as a CRM with additional characterization data helpful for the Statistical Quality Control of a laboratory’s sample analysis process.

*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 iRM like this:

    *in-house reference material, iRM, n-reference material with documented homogeneity that is intended for use for quality control purposes, calibration, evaluation of a calibration, or standardization whose values may have limited traceability and for which rigorously derived uncertainty information is not mandatory."

*An iRM from WHTS (designated with RM in the stock number, as in TRMHa) has full traceability with rigorously derived uncertainty and is suitable for:

Both are fully characterized, so the quality of our iRMs is identical with our CRM products,.

The difference is in how they are purchased (larger quantity for 1-2 years supply, at a discounted price), 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.

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, especially when they need long term monitoring such as with SPC.

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.

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.

E2972-15 states, in Section 4.2:

    "...there is a continuing, strong demand for reference materials (RMs) that is difficult for metrology institutes and private certified reference material (CRM) developers to meet because CRM development requires substantial investments of time and money. The metals and mining industries consume RMs and create new product and by-product compositions at high rates. They use analytical methods that provide rapid and accurate determinations, and both quality assurance and quality control can be maintained using efficient procedures provided appropriate iRMs are available."

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.

Since the use iRMs are new to our interstitial gas chemistry niche of the market, you may get some resistance.

It's simply a matter of them becoming familiar with how they are validated for use. See our other FAQs.

They are marketed for a different intended purpose. The iRMs 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 extra information for that use.

WHRM SQC materials are for the 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 1-2 years to gain a long-term perspective of their measurement process.

Our CRMs are sold fewer bottles at a time, used for calibration of an instrument at various values in the ranges of interest.

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.


The term verifier refers to how the material is employed to verify your calibration status is still in-control. 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:

    A "material demonstrated to be sufficiently homogeneous (enables) its use for a long period of time. A sufficient level of homogeneity is defined as providing repeatability variance low enough to ...(demonstrate that) ...the uncertainty goals of the test method are met on a routine basis."

And Section 6.1.3:

    "The material chosen for this purpose should be demonstrated to be stable for at least the length of time it will be used for control charts. For most metals and alloys, stability is known to be measured in years, if not decades..."

FAQs -General topics

This is to reduce potential confusion of values between lots. The stock number directly indicates the lot and its associate values. We believe that a user should not have to look at a separate lot numbers to know what the analyte values are.

WHRM has chosen to identify its products on a 'Series/Lot" basis. Each part number indicates the series and range of analyte concentration. For example: TJa is a titanium CRM that is dosed for a targeted hydrogen of "T" (for the base metal Ti) a character identifying its concentration range "J" which is useful when calibrating for a max spec limit of 125ppm, an the next character, a is the lot designation. This target value is aimed at exceeding a max limit by around 10%. If the stock number includes an RM, this designates that is an iRM product, and would be written as TRMJa.

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.

Our products have been well characterized by our laboratory, and verified 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 less than a tin flux to sample mass ratio of 3-to-1. To minimize this bias, be sure that you maintain this ratio.

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 between 0.1g and 0.3g 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.

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 outside that range.

Many laboratories, when doing verifier analyses choose to use a multiplier of 1.5 * Uc as acceptance criteria. 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.

If you have > 5-in-100 analyses that are out of the expanded uncertainty range, this poor precision would be that your instrument's analytical method setup parameters (even if it was copied from a factory application note) need optimization, or it could be caused by operator error, maintenance or repair issues.

You should expect to get, on average, 1-in-20 test results that read out of the K=2 expanded uncertainty range stated in the RM's documentation.

You may be accustomed to using CRMs that document a high Expanded Uncertainty relative to 2 * the standard deviation of your actual test results. The Uc they publish may be a simple repeatability statistic and pools results from multiple sources which have high reproducibility variance.

Note: RMs with characterizations which publish reproducibility-based uncertainty ranges will not typically present a 95%, K=2 uncertainty repeatability statistic. The laboratory should consider experimentation to establish a K=2 QC acceptance criteria for QC purposes.

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