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Meaningful results

December 1, 2015

How to get the most out of e-liquid lab testing

By John H. Lauterbach

It seems popular these days for suppliers of e-liquids to send their products to various testing laboratories for analysis. E-liquid suppliers appear to believe that having a laboratory determine the concentrations of diacetyl (often abbreviated “DA” and also known as 2,3-butanedione) and acetylpropionyl (often abbreviated “AP” and also known as 2,3-pentanedione) and sometimes acetoin (also known as 3-hydroxy-2-butanone) in their e-liquids is the right thing to do, especially if they publish the results on their websites.

What does it mean if one or more of these compounds are found or if their levels are so low that they are below the detection limits of the method used by the laboratory? Does it mean the e-liquid has more or less toxicity than the usual unflavored e-liquid consisting of glycerol (VG) and/or propylene glycol (PG) and nicotine, if used? Quite frankly, it depends on a number of factors, the most important of which is toxicity of the aerosol under the conditions it is used, including the e-cigarette device and the behavior of the person who is inhaling the aerosol. Even e-liquids composed of only VG and/or PG can yield the toxicants formaldehyde, acetaldehyde and acrolein under certain conditions (the so-called dry puff) in certain devices.

However, DA and AP, in particular, as well as some of the other aldehydes used to flavor e-liquids, have become lucrative targets for those who wish to ban or severely regulate e-cigarettes and e-liquids. Consequently, formulators of e-liquids should not use AP or DA or flavors that may decompose to those compounds when the e-liquids are subjected to accelerated aging. Assuring that does not necessarily require testing e-liquids for AP and DA. This report will tell you if, and when, you need to have your flavors and/or products analyzed, and how to get analytical data you can trust and that is business-relevant.


Those who have directed analytical chemistry laboratories –whether as part of a company that makes products or part of a commercial laborator—know that when clients “throw” samples at a laboratory, they are putting themselves in the same position as a quarterback throwing a forward pass in an American football game. Three things can happen, and only one of them—a completed pass—is good. The laboratory equivalents of incomplete or intercepted passes are all too common, and even the best laboratories get their passes intercepted. Furthermore, unlike a well-trained quarterback who has “read” the defense and knows where to throw the ball (or when to run with it), most who are submitting their e-liquids to laboratories do not have the equivalent knowledge.

Yes, bad things can happen even in the best laboratories, and unless the client is very knowledgeable about laboratory operations or has hired someone to act as his representative to the laboratories he is using to have his samples analyzed, the business value of the data he receives may be questionable. For data to have business value, you first need to know why you are having the sample analyzed and how you are going to interpret the data. Even if you are having your samples analyzed to comply with a regulatory mandate, you still need to know what the data mean, particularly if regulators can use the data you submit to bar the distribution or sale of your product. Adverse regulatory rulings can hurt your profitability just as an intercepted pass can lose a game. Unless you have the expertise in analytical chemistry and laboratory management equivalent to the skills of an experienced football quarterback, you may wish to have someone help you so your pass is not intercepted on the way to and through the laboratory.

Do I really need to have my products tested?

As of this writing, there is no regulatory mandate for the testing of e-liquids and/or e-cigarettes in the United States. Thus, it is your decision whether to have your products tested. This is a business decision, not a scientific one. The cost of testing is a direct cost, and there are indirect costs that will be discussed later. The cost of testing may become a significant part of your expenses. The laboratories you will likely use have highly skilled scientists and technicians who need competitive remuneration for their efforts. They are often using state-of-the-art instrumentation and equipment that is costly to buy and maintain. The laboratories recover these costs and get a return on their investments in people, instrumentation, equipment and facilities through the fees they charge for testing samples. Pricing of laboratory services is generally competitive so you will likely want to solicit quotations from several laboratories. Discounts are often given when sending multiple samples for the same tests at the same time, but at the end of the day, you need to ask, “Will I get business value for the price I am going to pay for having my samples tested?”

The first question you should ask at this point is, “Do I really need to have the testing done to get me the business-relevant information I need? E-liquid suppliers that are selling to retailers or directly to consumers should know the ingredients and impurities in the products they are selling. Such knowledge is part of basic product stewardship. We should not expect retailers and consumers to be experts on the safety of e-liquids. If a supplier wants to provide e-liquids that contain no detectable DA and AP, then it should insist that the vendors they use for flavors not only certify that their products do not contain DA and AP but also provide a quantitative list of the components in the flavors provided.

While flavor suppliers may balk at providing a quantitative list of the ingredients in each flavor they provide due to concerns about loss of trade secrets and lack of knowledge on the part of the supplier to understand the information provided, they should not hesitate in certifying that their flavors are free of both DA and AP, and providing experimental data to support that certification if requested. Obviously, if you doubt the veracity of the certification and intend to claim your e-liquids contain no detectable DA or AP, then it is time to have those ingredients tested.

So I have concluded I need to test, what next?

There are likely two main reasons you want to test. First, as above, you want to test the veracity of a supplier’s certifications, either because you suspect something is wrong or because you are testing the ingredients you receive just to make sure the vendor certifications you are receiving are accurate. If you want to make sure that the ingredients you are purchasing are free of DA and AP, you only need to get quotations from the laboratories that are making a market for such work, and make sure that the sample you are sending is representative of the material you want tested. This is important because some flavors may separate into a top and bottom layer on standing. The laboratory you chose should be able to advise you how to sample the bulk material and what container to use to send the sample to the laboratory. If the laboratory reports anything but nondetectable, then you have the business-relevant information you need to discuss the matter with the vendor. Second, another reason for testing is that you want to verify that your e-liquid has been properly formulated and is not changing over time. It has been known for years predating the introduction of e-liquids that aromatic aldehydes commonly used in flavors (e.g., ethylvanillin in vanilla flavors and benzaldehyde in cherry flavors) will react with PG and VG to form compounds called acetals. These acetals do not have the same hedonic characteristics as the flavorful aldehydes and will likely reduce consumer acceptance of your products.

Not all laboratories may be able to carry out the needed analyses, the analyses may be costly, and the data you receive from the laboratory may need expert interpretation. In such cases, you need to retain an expert. Such an expert is sometimes called a consultant, but if you are looking for someone to shepherd your samples through the entire process, from deciding what analyses are needed to providing you with the business-relevant information you need, you are really looking for an expert who is sometimes called a “sponsor’s representative” (SR), with you and your company being the sponsor.

The sponsor’s representative

The SR’s job is to take the worry about all aspects of testing and interpretation of test results off your back. Testing includes chemical testing but also toxicological testing, because sooner or later this is likely to be required—chemical tests may not always reflect the toxicity of an e-liquid. The SR should be experienced in laboratory management with appropriate credentials in chemistry and toxicology (e.g., DABT).

The SR starts by working with you and/or your management team to understand the business-relevant information you expect to gain through testing and data that you may be required to submit to regulatory authorities. The SR takes that information, develops a plan for what testing is really needed, selects laboratories that can do the testing and obtains quotations (cost and time for completion) for the needed testing. The SR reviews the quotations with you and makes recommendations for one or more laboratories to use.

Once you have placed the purchase order, the SR works with you and/or your staff to obtain representative samples of the ingredients and/or products to be tested and makes sure they are put in the proper containers and shipped to the laboratory. The SR (with your written authorization) communicates with the laboratory as to the safe receipt of the samples, any changes in protocols and control samples that may be needed for your samples, and also monitors the progress of the analyses, including dealing with any unexpected events that are unique to your samples.

This communication and monitoring is generally done via email and/or telephone. However, the SR may ask you for permission to visit the laboratory (at your expense) if things are not going well. The laboratory will send the data to the SR for review before it goes to you. The SR will review the laboratory’s calibration and control data that were generated during the testing of your samples to make sure that the work was done properly. He will also review the data for differences between expected results based on his knowledge of your samples and the reported results (for example, occasionally samples get out of order when they are transferred from the sample preparation laboratory to the autosampler of the gas chromatograph running the analyses). The SR will ask the laboratory to rerun any samples with suspect data.

When the SR is satisfied that the data are correct for your samples, he will turn the data over to you along with his interpretations of the data and the business relevance of the findings. The review of the laboratory data by the SR minimizes chances of erroneous data reaching your files. Yes, the SR’s review and interpretation of the data will involve costs for the SR’s time, but on the other hand, you are receiving business-relevant information, not just a set of numbers that may have no business relevance. The SR’s review of data from in vitro toxicological assays (for example, cytotoxicity assays on e-liquids) is particularly important due to the inherent variability of bioassays relative to chemical assays and the fact that results are often present as percent of control sample.

In addition to dealing with the entire analytical process and interpretation of the data into business-relevant information, a good SR should also be able to receive any ingredient information from suppliers in confidence, review that information and let you know whether those materials are satisfactory for use in your e-liquids from both chemical and toxicological perspectives. If the SR finds a problem, he will communicate that with the relevant supplier and ask for a reformulation of the material.


If you have laboratory testing of your e-liquids done without prior thought to the business relevance of the data you will receive and how you will ensure that the sampling and analysis is done correctly, you may be not only wasting your money but you may also make the wrong business decision by acting on the data. Use of a sponsor’s representative to help you determine the information you need, choosing the right testing and laboratory, ensuring data quality, interpreting the data, and converting them into business-relevant information may be a wise investment.


John Lauterbach is the owner of Lauterbach & Associates LLC, a provider of scientific and regulatory-affairs services for the tobacco and e-cigarette industries.



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