Frequently Asked Questions

Frequently Asked Questions

These are our most frequently asked questions, covering topics such as sampling media, methods, regulatory standards, lab reports, and much more.


What are your hours of operation?

Assay Technology, Inc currently operates three facilities:

Main Office

Assay Technology
1382 Stealth Street
Livermore, CA 94551

Hours of operation: Monday through Friday, 7:30 am to 5:00 pm PST

(800) 833-1258

(925) 461-8880

Most phone calls are received in the main office. All shipments are sent from the main office.

Ohio Office

AT Labs
250 DeBartolo Place
Suite 2525
Boardman, OH 44512

Hours of Operation: Monday through Friday, 7:30 am to 4:30 pm EST

(330) 245-5240

Customers are asked to call the California office.

North Carolina Office

AT Labs (Formerly Sensors Safety Products)
6003 Chapel Hill Road
Suite 117
Raleigh, NC 27607


What is Assay Technology's holiday schedule?

Click on this link to see our holiday schedule.

Web Store

Where do I go to buy?

  • If you know what you want to order, use the Online Ordering page. You can also click “Online ordering” at the top of any page.
  • If you do not know the item number that you need, go to the product summaries page and use our simple guide. You can also search our detailed Sampling Guide for more information about which badge to use for a specific chemical.
  • If you need help ordering on the site, give us a call at (800) 833-1258, email us at, or watch our video.

Why shop online?

  • You can save 10% on all our biggest selling items, X and N boxes.
  • It’s fast, easy, and allows you to submit your order at any time.
  • You can view and choose domestic shipping options during checkout.
  • By making an account, your purchasing and shipping information can be saved and automatically filled in next time you order!

Are all items discounted online?

No. X products (boxes of 5 badges with analysis) and N products (boxes of 10 badges without analysis) are sold online at a 10% discount. Single badges (W products) and media (M products) are not discounted online.

Are all items sold online?

No. Items not sold online include:

  • Sampling media we do not manufacture: tubes, cassettes, wipes.
  • Rental pumps.
  • AT Lab testing fees that are not prepaid.
  • MNR testing and instruments.

Usually, purchasing these items requires a conversation because they are more complex than badges. We recommend calling Customer Support at (800) 833-1258 or emailing for a quote.

Prepaid Analysis

Why would I prepay for analysis?

Because it saves you time and money.

The fact of the matter is, when you buy the badge and analysis together up-front, we are offering a tremendous deal. Customers can purchase samplers with the analysis at AT Labs’ AIHA-LAP, LLC accredited laboratories already prepaid. Since both the monitor and analysis are sold at the same time, the price is significantly lower than buying them separately, and there is no additional invoice to worry about once the analysis is complete. Most samplers, including any -1 items, come with the analysis of one chemical prepaid. The -4 products come with the analysis of up to 4 chemicals prepaid. These two choices satisfy most customers’ needs.

At times, customers will need more chemicals than they have prepaid for. When this happens, you can simply request the additional chemical(s) on the lab request form and you will be billed after the report is completed. The price will vary depending on the type of analysis. The easiest way to determine the cost is often to reach out to us. However, to determine the price yourself, go to the Sampling Guide and search for your chemical. Then expand the information for that chemical by clicking on the “+” sign to see non-prepaid analysis costs.

Using Badges

Instructional video on using badges.

Slide show of the instructional video

Click here to see the slides from the instructional video on badges.

Are diffusive badges recommended for compliance sampling?

Yes. All Assay Technology personal monitors meet and/or exceed the OSHA accuracy and precision criteria for sampling and analytical methods. Samplers have been validated for performance under a wide variety of sampling conditions.

Note that OSHA does not specifically recommend or approve specific types of air monitoring products. Please read Dr Manning’s post about OSHA and NIOSH approval for more information.

Why can't some chemicals be analyzed together even though they can be collected on the same type of badge?

This question is best answered through examples:

Example 1:  The customer wants to collect and analyze total hydrocarbons and isopropyl alcohol on a single 566 badge, but customer service calls and says it can’t be done.  The customer is confused because both total hydrocarbons and IPA can be collected and analyzed on the 566.  Customer service insists total hydrocarbons is a list C chemical and IPA is a list A chemical and therefore can’t be analyzed on the same badge.

  • List A: Carbon disulfide is the primary solvent for extracting (nonpolar) chemicals from carbon.  So, hexane and xylenes are OK, but methanol and acetone are not because their recoveries are too low.  However, if you add another solvent (co-solvent) to the mix, you can add many polar chemicals to the list, including alcohols, ketones, and acetates.  At AT Labs, we use benzyl alcohol.  So, our standard solvent mixture is 97% carbon disulfide and 3% benzyl alcohol.  For most badges received, this is an excellent solvent mixture.  However, when you analyze for “Total Hydrocarbons,” you have to use a solvent mixture that doesn’t block the hydrocarbon range, which covers approximately C4 through C15.  Benzyl alcohol blocks C11 through C13, so you can’t analyze for IPA without the co-solvent, and you can’t analyze Total Hydrocarbons with the co-solvent.

Example 2 (keeping example 1 in mind):  Why is there a list B? List B contains chemicals that need a co-solvent, but are generally blocked by the benzyl alcohol. Instead of benzyl alcohol, we use n-butanol, which blocks other chemicals, but again allows the lab to include many polar and nonpolar chemicals.

On the Sampling Guide, we show which chemicals can be analyzed together in the Test Group column. All chemicals within the same Test Group can be analyzed together (unless the Test Group is blank.) The guide allows you to filter by Test Group, so you can see everything that can be analyzed together. Keep in mind that this works for other badges and chemicals as well, like amines, aldehydes, and metals.

Which Organic Vapor badge (546/566/525) should I use?

We’ve developed three different Organic Vapor monitors so that we can provide a solution for a wide range of sampling conditions. Please read our blog post on this subject in order to learn more.

Can I use badges for less than 15 minutes or greater than 8 hours?

The answer to this question will often depend on your specific sampling conditions. In general, sampling for shorter than 15 minutes can cause issues with accuracy and high reporting limits. Conversely, sampling for longer than 8 hours is often not a problem, unless you are dealing with large concentrations or certain chemicals. You can learn more by reading our blog post on this subject.

Are blanks required by the lab for the analysis of Assay Technology personal monitoring badges?

  • Media Blanks: It is not required that customers submit media blanks when using Assay Technology badges. The laboratory is always analyzing our own badges for quality control purposes. We will automatically analyze a blank monitor with every analytical batch and blank correct as appropriate.
  • Field Blanks: Field blanks are definitely recommended, but not required. These should be ordered and returned with your samples, but not exposed at any point. They monitor and correct for any background contamination that may have occurred during storage, handing, or shipping. They are especially useful for gases like nitrous oxide and ethylene oxide. Click here to learn more about field blanks.

Why are blanks required by the lab for each set of sampling tubes or cassettes I submit?

  • Media Blanks: Assay Technology does not manufacture this media, nor analyze it regularly for quality. Therefore, we require that the customer provides a blank with their samples so that the background, if any, can be corrected for. If a media blank is not provided, one will be added by our lab for a fee. We do not require that both a media and field blank be provided.
  • Field Blanks: The use of field blanks to monitor and correct for any background contamination that may have occurred during storage, handing, or shipping is recommended. Unless requested, the laboratory does not Field Blank correct results.

What is the minimum face velocity requried for the badges to function as claimed?

The badges have been tested between 15 and 150 cm/sec. We also expect that the badges will continue to function as claimed at velocities higher than 150 cm/sec.

In general, the badges should not be used in a drawer or closed cabinet, as the results would be biased low. To monitor inside these areas, use a very small fan to move the air around.

Badges can be hung in a room with normal air flow caused by air conditioning or heating units.

How do I know which media to use for sampling specific chemicals?

Please refer to Assay Technology’s Industrial Hygiene Sampling Guide for a complete listing of chemicals, and appropriate sampling media. Guidelines are based on OSHA and NIOSH sampling methods, and include media types for both diffusive and active testing.

How do temperature, humidity, etc. affect badge results?

Temperature, air velocity, humidity, pressure, and particulates can have varying effects on badge sampling. Assay Technology badges have been validated to work as claimed under normal office working conditions. For example, from our Acetic Acid badge (543) technical insert:

Effect of Temperature: Effect on result < 5% within 0 – 50 C (32 – 122 F).
Effect of Humidity: Functions as claimed within 10 – 80% RH.
Meets or exceeds OSHA requirements for accuracy: Maximum Total Error (MTE) < 25% at PEL; < 35% at STEL.

Learn more about these environmental factors by reading our blog post.

What if the badge gets wet during use?

If water gets on the badge and plugs the holes in the sampling grid, it is likely your results will be biased low because the sampling rate will be reduced.

Capacity Questions

Since Assay badges don't have a back section, like tubes or the 3M 3520 badge, how do I know if I've exceeded the capacity of my badge?

Here are a few common questions we get from thoughtful, careful customers:

  • Since Assay badges don’t have a back section, like tubes or the old 3M 3520 badge, how do I know if I’ve exceeded the capacity of my badge?
  • What is the capacity of the badge?
  • The technical insert says the capacity is 100 ppm-hr. What’s a ppm-hr?
  • The capacity is 3000 ug, but my report says the lab found 4000 ug on my badge. Isn’t that impossible?

Capacity of Diffusive Monitors (Badges)

  • For diffusive monitors, the capacity is NOT the maximum amount of chemical that can be collected.
    • Long before the badge stops being able to collect any more chemical of interest, the media inside the badge will start to collect enough chemical where the sampling rate slows. Once the sampling rate begins to slow, the exposure concentration will be biased low until the monitoring is completed. This value is far more important than when the media stops collecting any more chemical of interest.
      • Think of it like a tiny game where molecules run into an empty theater and have to find a random seat ASAP. In the beginning, the chemicals being collected find nothing but empty seats, so everyone sits right down. However, as there are fewer and fewer open chairs left, it takes longer to find an open chair. This slows the rate at which molecules come in and get seated. As the molecules keep coming, some get frustrated and float away. The capacity is the point at which the molecules start stacking up and some float off without being seated.
    • As a result, it’s possible to have more chemical on the badge than what we say the capacity is in micrograms.
  • The capacity values we list assume there are no other chemicals present.
    • If there is more than one chemical present, they will compete for space on the badge, lowering the capacity of the media for each chemical. This is not just a badge issue.
      • Let’s say a badge is going to be exposed to an environment containing toluene and benzene. While the customer may request only benzene analysis, the badge will collect all chemicals in the environment. There is no “benzene only” switch, so the toluene will cut into the capacity of the badge to collect benzene.
    • For this reason, all capacity values should be considered estimates no matter if you are sampling with a badge or tube.

It is important to use a sampling system with plenty of capacity to spare, especially with organic solvent badges. Indoor air quality projects are perfect for the TraceAirII badge because very low exposures are expected and very low reporting limits are needed. However, if a badge is going to be used all day for PEL-level exposures, the high-capacity 546 badge will often have a low enough reporting limit anyway. The 8-hour reporting limits for all chemicals on badges are in the the sampling guide.

Capacity of Badges vs Tubes

For tube sampling, the sampling rate of the monitoring is controlled by the pump. As a result, there is no change in sampling rate when the front section of the tube gets close to collecting all it can. When it does, the back section starts to collect what chemicals are breaking through and you have notification of breakthrough. So, does that mean tube sampling is much better when you are worried about capacity?

Actually, consider this: a normal tube sampling rate is 100 mL/min. The average badge sampling rates are:

  • 546: 2 mL/min
  • 566: 7 to 10 mL/min
  • 525: 50 to 70 mL/min

That means, roughly, the 546 has about 50 times the capacity of a small charcoal tube.

So, if a customer is worried about capacity, the 546 badge is 50 times better than a charcoal tube, unless you like the idea of swapping out your tubes 50 times over 8 hours to get the same capacity as the 546… and paying for the analysis 50 times, too.

Instead of a back section, the worry about capacity is engineered out of the 546 by a slow sampling rate. Even the 566 is about 10 times better than a tube. The 525 badge has about the same sampling rates as a tube, and the capacity is about the same. However, the intent of the 525 is for low exposures, like indoor air quality evaluations and for short term monitoring where capacity is not an issue.

Assay Organic Vapor Badges vs the 3M 3520

There are three ways to increase the capacity of a monitoring system:

  • Increase the amount of collection media, but keep the sampling rate the same (i.e., larger tubes, more wafers).
  • Slow the sampling rate.
  • If you can do neither of these, and are worried about capacity, you can swap in new media throughout the day, then average all the results.

Customers of the old 3M badges used the 3520 when they needed extra capacity. A second wafer was dropped into the badge, and any chemical found on the back section was multiplied by 2.2. This correction factor indicates that more than half of the chemical that made it past the first wafer is lost. Adding the second wafer is a minor help, and only increases the capacity by 2 to 3.4 times. However, the Assay 546 badge has about 8-10 times the capacity of the 3M 3520.

Reporting Limits

This isn’t magic, of course. The 546 does not reach its capacity as fast because it samples slower. The difference is, Assay can snap a ChemDiskII badge into a sampling grid with different numbers of holes: 4, 19, or 76. Of course, since the badge samples more slowly, the reporting limits are going to be higher. If a sampler gives you a reporting limit that’s too high, then it is no good to the user. But, again, if a badge is going to be used all day for PEL-level exposures, the high-capacity 546 badge will often have a low enough reporting limit anyway. The 8-hour reporting limits for all chemicals on badges are included in the sampling guide.


This is a clever little unit once you get used to it. If we say the capacity of a badge is 100 ppm-hr, then to determine the capacity as a concentration, you just divide by the number of hours you monitored. So, if you monitored for 1 hour, it’s 100 ppm-hr/1 hr = 100 ppm.  For 4 hours, it is 25 ppm. These values for the most common chemicals not collected on the organic vapor monitors are listed on the technical inserts included with each box shipped. The technical inserts are also available online.

What does sample capacity mean and why should I care?

Sample capacity is a measure of the amount or exposure of contaminant(s) that a sampler can collect without becoming saturated, leading to a biased low result.

Customers frequently want the fastest sampler possible so they can get lower reporting limits without considering the sampler’s capacity to retain the chemical it is exposed to. This is an incorrect way to sample.

Assay Technology has 3 types of Organic Vapor monitors to handle a variety of environments:

525: This super-fast sampling badge is great for IAQ, STEL, and chemicals with low PELs, <10 ppm. However, if it is exposed to 500 ppm of a chemical, its capacity will be used up over the course of the day and the results will be biased low.

566: Our most versatile badge for STEL and PEL. When asked which badge should be used, usually the answer is the 566 badge.

546: Our slowest sampling badge. The reporting limits will be higher, but the 546 is very useful when you need to monitor chemicals with very high PELs all day. If you have 750 ppm of acetone, you are below the PEL, but you risk saturating a 525 badge if you use it for 8 hours. However, the 546 badge will be fine. If the PELs are high (i.e., several hundred ppm) and you need to monitor for 8 hours, use the 546.

The sample capacity is listed on the technical insert that comes with the product. It can also be found on the website in the product page for the badge.


Where can I send my samples for analysis by an AIHA-LAP, LLC accredited lab?

In addition to being a manufacturer, Assay Technology operates two accredited industrial hygiene laboratories. If you have prepaid for the analysis, be sure to send them to our labs. The instructions sent with the badges or media will indicate which laboratory to send the badges to. However, if you send the badges to the wrong lab, we will forward the badges where they need to go, typically without extending the due date.

If you received badges from another laboratory, be sure to send them to that lab for analysis. 

What does "Store Under Refrigeration" mean?

Some of the Assay badges are marked “Store Under Refrigeration”. This leads to many questions.  Here are the answers to frequently asked questions about refrigeration:

  • When the product is shipped, it does not need to be refrigerated. However, the longest it should be in transit from Assay to you is TWO calendar days.
  • Do not ship over a weekend. If a customer places an order on a Thursday, the product has to be shipped overnight, marked to arrive Saturday, or shipped out on Monday.
  • Once the shipment is received, store in a refrigerator before use. Note: Only the 595 badge has to be shipped back cold. No other badges require refrigeration after collection if they are received by our lab within their maximum recommended holding time, which can be found on the technical insert. However, refrigeration after use is OK and will not harm the badge.
  • For a badge that is supposed to be stored under refrigeration, but was stored at room temperature or higher for a few days, we suggest using one of the badges as a field blank to correct for any background issues that may have occurred. We would also recommend using the badges within 4 weeks.

Which lab do I ship my badges/media to after use?

  • The instructions sent with the badges indicate which lab performs the analysis.
  • If you do not have the instructions, use this guide.
  • If you are not sending a badge back for analysis (e.g., a tube), call us or just send to the Ohio facility.
  • If you have one badge that goes to California and one badge that goes to Ohio, send them both to either lab. We will forward the badges where they need to go, and report them together (unless you don’t want that) without extending the due date. An exception to this is when you need a rush analysis. Then, it is very important to send the badges to the correct laboratory.

Does Assay Technology receive packages on Saturday?

Both laboratories receive samples Monday through Friday.


Can I use sampling methods other than those recommended by OSHA, NIOSH, or other government agencies?

Yes. OSHA does not require or mandate the use of a particular sampling method. Rather, OSHA and NIOSH set forth criteria for the accuracy and precision of sampling and analytical methods. An employer is obligated to select a method that meets these criteria, relative to their specific sampling conditions. Typically, these criteria for sampling at the permissible exposure limit must be within +/- 25% of the true value, at a 95% confidence level. Alternative methods, with supporting validation data to demonstrate the accuracy and precision of the methods, are acceptable for OSHA compliance monitoring.

How do I determine which sampling method is better to use?

When multiple methods are published by OSHA and NIOSH, the user should consider a number of criteria specific to the sampling situation. These include type of media preferred, analytical method, detection range, and any possible interferences. Talking with your laboratory is recommended to address other limitations or advantages of one method over another. Generally, the more current the method, the better, in that problems of earlier methods have been corrected.

Are the active sampling rates listed in methods or the Sampling Guide exact, or can I sample at variable rates?

Most active sampling methods list an acceptable range of both sampling rates and air volumes that would apply to the majority of sampling situations. Staying within these ranges is recommended to ensure the validity of the method. When variations are made, quality control data points should be obtained to demonstrate the validity of the method under the new conditions.

Can badges be used to sample formaldehyde when the source is Formalin?

In OSHA Method 1007, OSHA warns of possible sampling error when using any diffusive sampler in environments where the source of
formaldehyde exposure is formalin. Dr. Manning responded in this technical opinion, finding that the effect is minimal when using common formalin solutions containing less than 3% methanol.

How can I get copies of air sampling methods?

Both OSHA and NIOSH have sites devoted to their sampling and analytical methods. Links to the applicable methods are available on our Sampling Guide.

Pump Sampling

How to use the Buck LP-5 pump and more

How to use the Buck Basic pump and more

The error: Filter Off

The pump is trying to help you when you get the filter off message. It’s telling you that the pump is running, but the hose or media has fallen off.  More times than not, the error comes up when a customer is practicing with the pump before the sampling event.

This short video describes the error and how to clear it.

Questions about the laboratories and reading reports.

Lab Report FAQs

Go to our Lab Report FAQs.