Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Taking Measure

Just a Standard Blog

There Will Be (Precisely Measured) Blood: A Haunted House Tour Through NIST’s Spookiest Reference Materials

Several metallic envelopes with NIST labels are displayed with Halloween decorations like cobwebs, skeletons and pumpkins.
NIST makes standard reference materials — sometimes called “truth in a bottle” — for many things, but we picked a few of the most mysterious to highlight during spooky season.
Credit: R. Wilson/NIST

It’s the scariest time of year for many — with visions of ghosts, goblins and other ghastly things everywhere we look. 

Here at NIST, we’re celebrating the spooky season by looking at some of our scariest standard reference materials (SRMs). 

Labs and manufacturers use SRMs to ensure their equipment is making accurate measurements or to perform other quality control tests. That’s why they are sometimes called “truth in a bottle.” SRMs help make sure your food nutrition labels, medical tests and other measurements we rely on every day are as accurate as possible. 

While some of the things we make as SRMs are indeed scary, we make them with the strictest safety protocols, to protect both our employees and those who will buy and use the SRMs.  

Some SRMs are frozen and shipped with dry ice, making them a little extra spooky!


If you’ve seen horror movies, you know there’s usually blood. Well, we have plenty of blood deep in the bowels of our freezers on NIST’s campus in Gaithersburg, Maryland. It’s here to facilitate medical research, not to be scary! Medical research requires precise measurement and controls, so researchers rely on SRMs to test their methods.  

A small plastic vial covered with frost leans against a sparkly purple pumpkin decoration.
Researchers studying toxic metals, such as mercury, use this standard reference material to check their analytical methods.
Credit: R. Wilson/NIST

The Frozen Human Serum standard reference material has 2 milliliters of frozen human serum, the liquid component of blood that does not play a role in clotting. NIST works with blood banks or other commercial blood collection companies to get blood from paid donors to make it. Serum is pooled together from many donors to reach custom specifications. 

This SRM is used for validating measurement methods or instrument operation for health-related measurements, such as cholesterol, sodium and iron. The customers for this SRM are typically medical device manufacturers or research or clinical labs. 

The SRM for Toxic Metals and Metabolites in Frozen Human Blood contains 1.6 milliliters of blood. The SRM is made with donated human blood, and the toxic metals are prepared at a required level for the SRM. Researchers studying toxic metals, such as mercury, use this to check their analytical methods. This SRM also helps validate data from the National Health and Nutrition Examination Survey (NHANES), an ongoing study that guides national health policies. 

A metallic envelope with a NIST label is nestled alongside Halloween decorations like an animal skeleton and a sparkly pumpkin.
This standard reference material helps medical professionals accurately diagnose joint replacement failures.
Credit: R. Wilson/NIST

When a total joint replacement fails, patients often have elevated levels of the metals used in these replacements in their blood. NIST’s Trace Metals in Frozen Human Blood SRM helps medical professionals accurately diagnose joint replacement failures. This SRM is also made with donated human blood, with the precisely measured trace metals prepared at the required level for research. 


Those scary stories you see at Halloween may involve a witch or other antagonist with poison. 

One of the oldest known poisons is arsenic. While it’s deadly in high amounts, we can all be exposed to smaller quantities of arsenic through food, water or air

A metallic envelope with a NIST label and condensation is nestled alongside decorative Halloween pumpkins.
NIST arsenic standard reference materials play an important role in health research.
Credit: R. Wilson/NIST

NIST offers SRMs of human urine with arsenic at varying levels, from the middle range for the general population up to arsenic at a level found in people with arsenic poisoning. These SRMs also help validate the NHANES data. 

It may seem a little strange to pay more than $1,000 for a few vials of human urine, but this SRM plays an important role in health research. 

Cat Food 

If you see a black cat on Halloween, don’t worry; our cat food SRM makes sure that cat’s food meets standards. (That doesn’t mean the cat won’t give you bad luck though; we can’t speak to that.) 

NIST’s cat food SRM is a blend of commercially sold cat foods, and it’s ground up and blended to represent an “average” cat food. Pet food producers and regulators use it as a measurement control, so they can make sure our feline friends are getting the nutrients they’re supposed to get through food.  

Happy Spooky Season From Taking Measure 

As the classic Halloween song “Monster Mash” tells us, you never know what might be lurking if you work late at night in a lab. 

In our labs (during the day), you will find researchers hard at work making sure we have the most precise measurements possible, even if we have to freeze a little blood to make that happen. 

*No SRMs were harmed in the making of this blog post. 

About the author

Megan King

Megan King is a writer-editor at NIST and edits the Taking Measure blog. After graduating from John Carroll University, she began her career as a newspaper journalist, covering county fairs and school board meetings. Megan worked in various communications roles at the FBI for 13 years, including as a content manager and strategist for Outside of work, Megan coaches beginner ice skaters, cheers on Pittsburgh sports teams, and knits.

Related posts


I have leukemia - what will my blood say then.

Should this read "bad" luck or did you mean to say "back" luck?

(That doesn’t mean the cat won’t give you back luck though; we can’t speak to that.)

Ok so for the cat food SRM, what happens if the manufacturers you source from alter their ingredients? Do you do any independent testing of nutrients to ensure your reference isn't experiencing baseline creep?

Also I love this article!

Hi, Anne. Thank you for your kind words and your question. Here's some information from one of our researchers to answer your question:

Our SRMs (cat food included) are not meant to be the same as any or all products on the market – they are intended to be a snapshot or “average” product. If a manufacturer opts to modify their recipe a bit, this SRM generally would still be relevant as a control for their nutrient testing. That said, NIST conducts testing of our product at given intervals to ensure the levels of nutrients aren’t changing without our knowledge. We do not conduct testing of commercial products to check for their conformity with our SRM, with previous versions of their products, or with their own labels. We simply provide the standards and leave the conformance testing to the laboratory and the regulatory body (e.g., FDA).

Add new comment

Enter the characters shown in the image.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Please be respectful when posting comments. We will post all comments without editing as long as they are appropriate for a public, family friendly website, are on topic and do not contain profanity, personal attacks, misleading or false information/accusations or promote specific commercial products, services or organizations. Comments that violate our comment policy or include links to non-government organizations/web pages will not be posted.