How to Think Like an Analytical Chemist | Cannabis Science and Technology

My mission in penning this collection of Cannabis Analysis columns is to passionately advocate for extra and higher testing within the hashish trade. The science whose elevated use I’m advocating for is analytical chemistry. Many of my earlier columns on spectroscopy, chromatography, and different matters have been about analytical chemistry. It is about time I backed up slightly and outlined what analytical chemistry is, and to educate my readers how to assume like one.

What is Analytical Chemistry?

Here is my definition of analytical chemistry:

“Analytical chemistry is the science of determining what chemical species are present in samples and in what amounts.”

Chemical species can encompass molecules, atoms, and ions (charged atoms or molecules). Note that I don’t embrace issues like protons, neutrons, quarks, and so on. As somebody as soon as stated: chemistry goes from the macroscopic world to the nucleus, and physics begins on the nucleus. I agree.

There are primarily two several types of chemical evaluation captured by this definition. An evaluation that determines what chemical species are current is named a qualitative evaluation as a result of the reply isn’t a quantity, however an identification. A quantitative evaluation measures the quantity of chemical species in a pattern, by definition, producing a quantity. This will usually be a focus akin to weight p.c, moles per liter, or components per million.

Cannabis evaluation then is the dedication of what chemical species are current in what quantities in hashish samples. We might argue what “cannabis samples” are, however I’ll forged a large web and say they encompass hashish plant materials, its extracts, distillates, and remaining merchandise. Essentially, something with THC, CBD, or different cannabinoids can be thought-about a hashish pattern. Here are among the analytical chemistry strategies in widespread use in hashish labs and the issues they’re used to analyze for:

• Gas Chromatography (GC) – Cannabinoids and terpenes
• High Pressure Liquid Chromatography (HPLC) – Cannabinoids
• Infrared Spectroscopy – Cannabinoids and terpenes
• Gas-Chromatography-Mass Spectrometry (GC-MS) – Pesticides
• Liquid Chromatography-Mass Spectrometry (LC-MS) – Pesticides
• Atomic Spectroscopy – Heavy metals

These are usually not all the strategies you will see in a hashish evaluation lab, however most labs may have some or all of those devices. The overwhelming majority of hashish analyses are in search of some or all of cannabinoids, terpenes, pesticides, and heavy metals. Others and I’ve written about the usage of these strategies in hashish evaluation, and they may proceed to dominate my articles going ahead (1-3).

At the start of the science of analytical chemistry over 100 years in the past, all analyses had been completed utilizing what is named moist chemistry; actually analyses utilizing beakers, flasks, take a look at tubes, and options. As time went on, devices and then computer systems had been invented to carry out these analyses, which is the place we’re right this moment. Hence, an understanding of analytical chemistry includes familiarizing oneself with matters akin to physics, optics, electronics, computer systems, laptop programming, and engineering. This is why I like analytical chemistry; it permits me to masquerade as a chemist whereas studying about new issues in all types of different fascinating fields.

Because hashish merchandise go onto or into human beings, they have to be examined earlier than they attain the purpose of buy to guarantee they’re secure. This testing might be completed in-house by hashish companies, or by third occasion labs. You can’t be on this trade with out in some unspecified time in the future coping with hashish analyses, hashish evaluation reviews, hashish labs, or hashish analyzers. The aim of this text, and maybe some subsequent ones, can be to familiarize my readers with the science of analytical chemistry so you can also make higher use of this science in your work.

We can consider any chemical evaluation as consisting of the components proven in Equation 1:

These components might be outlined as the next,

Sample: The factor being analyzed.

• Analyzer: The instrument performing the evaluation.
• Method: The set of directions carried out to full an evaluation, generally known as a Standard Operating Procedure or SOP.
• Analyst: The human being performing the evaluation. There exist automated analyzers and robots that carry out some chemical analyses, however there’s all the time a human being concerned in making ready samples, organising the analyzer, or at minimal turning the analyzer on and monitoring its work.
• Analysis: The outcomes.

Defining some additional phrases is so as:

• Analyte: The factor whose presence or quantity is being measured. In our trade analytes might be the focus of THC in a marijuana bud, the quantity of limonene in a vape pen formulation, or the components per million of a pesticide in a tincture.
• Matrix: The nature of a pattern. This contains the composition of the pattern, the concentrations of the elements current, and different variables akin to pH, strain, and temperature. For instance, the matrix of a tincture may very well be described as being that of CBD, and MCT oil, at room temperature and strain.
• Method Development: The artwork and science of growing a technique to analyze for the chosen analytes(s) in a given pattern matrix.

The Golden Rectangle of Chemical Analysis

As an analytical chemist, how do I’m going about selecting an instrument and technique to carry out the evaluation of a pattern I’m handed? I take advantage of the Golden Rectangle of Chemical Analysis as seen in Figure 1.

The phrases in Figure 1 have the next definitions in my parlance:

• Accuracy: This is one thing we’ve got outlined in earlier columns (4). Briefly, accuracy is a measure of how far off you might be from the true worth. This necessitates there exists a manner of figuring out the true worth, which is offered by commonplace samples. Accuracy is NOT the identical as precision, which is a measure of reproducibility as I’ve written earlier than (4).
• Speed: This is a measure of how a lot time an evaluation takes. In an ideal world, we’d need all of our analyses to be completed rapidly to take advantage of environment friendly use of the analyst and analyzer. There are two issues that decide the pace of a chemical evaluation. One is how lengthy it takes to put together the pattern, and the second is how lengthy it takes to run the pattern on an analyzer. For instance, in a chromatographic evaluation the pace would come with how lengthy it takes to work the pattern up for evaluation, and the period of time it takes to impact the separation on a chromatograph.
• Cost: The presence of this variable in Figure 1 is a no brainer. Of course we would like our analyses to be carried out as inexpensively as doable. There are a number of issues that decide the price of an evaluation. The first is the upfront price of the instrument itself. The price of analytical devices can differ from tens of 1000’s of {dollars} for infrared spectrometers and chromatographs to a whole bunch of 1000’s of {dollars} for GC-MS and LC-MS programs. I as soon as regarded into beginning my very own hashish evaluation lab, and decided I would want $1 million only for the devices. I didn’t trouble opening a lab. The second a part of the price of an evaluation is the upkeep and maintenance of analyzers. This can embrace the price of repairs, spare components, and consumables like chromatographic columns, pump seals, or spectroscopic mild sources. The third a part of an evaluation price is pattern preparation. Particularly for chromatographic analyses, there are vital pattern preparation prices together with vials, vial covers, syringes, filters, and solvents. Lastly, there’s the price of the labor to analyze a pattern, which incorporates the time wanted to put together a pattern and the time to really run the pattern on an analyzer.
  • Many analytical devices are costly to preserve and much more costly to repair after they break down. I strongly advocate most labs use what are known as service contracts. This is a contract you signal with the producer of your instrument that states in change for a hard and fast annual cost they may come by not less than annually, carry out routine upkeep, and make any wanted repairs at no further price. It works like an insurance coverage coverage in that it prices cash yearly, but when your instrument breaks you can be glad you’ve got the insurance coverage. I see some labs foolishly “self-insuring” by paying for upkeep and repairs as they go. This is foolish as a result of the price of fixing analytical devices is excessive. For instance, labs should pay for the time and journey prices of getting restore folks to their instrument. The instrument firm begins the clock when the restore particular person leaves their home. Companies cost a whole bunch of {dollars} per hour for journey time, there’s the price of the journey, there’s the time spent onsite, and then the price of the restore components. The latter might be 1000’s of {dollars}. Again, it’s best to have a service contract.
• Representative Sampling: This can also be one thing I’ve written about earlier than (5). By definition, once we collect a pattern, we’re taking part of a complete and then analyzing that half. An issue arises if the half isn’t the identical as the entire, main to sampling error (5). The answer to sampling error is to analyze as many samples as doable and common the outcomes (5). For this to be sensible, the analytical technique have to be quick, straightforward, and cheap. This facet of analytical strategies is considerably depending on the opposite issues listed in Figure 1, however it is crucial sufficient to benefit its personal point out. Representative sampling is a selected drawback when analyzing hashish plant materials, since it’s a heterogeneous pure materials and no two samples are alike.
• Sensitivity: This is a measure of the minimal quantity of analyte that may be detected by an analyzer. This is basically the identical as a time period you may even see in a lab report, the restrict of detection. Now, in case you are fortunate sufficient to have a considerable amount of pattern then sensitivity isn’t an situation, however when you have little or no pattern or you might be in search of an analyte in low focus, an instrument’s sensitivity can grow to be crucial. In our trade, the necessity for sensitivity varies. For instance, in marijuana bud samples the THC focus is usually current at ranges of 10% or better, so a efficiency analyzer doesn’t want to be extremely delicate. On the opposite hand, there are state legal guidelines that require the measurement of sure pesticides on the half per billion (ppb) degree. These analyses require a really
  delicate analyzer.
• Specificity: There are over 10 million chemical substances identified to humanity. Specificity is a measure of how nicely a technique distinguishes between the analyte and all the opposite stuff that is likely to be current in a pattern matrix. This property of a technique is especially necessary when coping with advanced mixtures or mixtures of issues which can be comparable, akin to terpenes. For instance, think about we try to measure the efficiency of a marijuana bud. Recall that the Total THC on this pattern is given by Equation 2:

• A technique that determines simply Total THC wouldn’t be as particular as a technique that decided each THC and THCA.
• The six parameters listed in Figure 1 work together and there are tradeoffs between them. For instance, excessive accuracy is good to have however ceaselessly comes at the price of taking extra time and being dearer. Examining many samples to decrease sampling error is nice, however that in fact drives up the associated fee, time, and complexity of analyses. A selected technique is gorgeous, akin to having an analyzer that tells you concerning the Total THC in a hemp pattern to decide legality. But in case your curiosity is in realizing concerning the different cannabinoids current, which is named a cannabinoid profile, your very particular analyzer won’t be of a lot use to you.
• Given the parameters in Figure 1, which one is most necessary, or how can we weigh the relative deserves of 1 versus the opposite? The reply to this query, like the reply to many questions in life, is it relies upon. It will depend on what you want to be taught from a pattern. That is, you’ve got to put the pattern into context. For instance, in case you are testing a marijuana bud to see if it meets your state’s allowable pesticide limits, the tactic can be completely different than if you’d like to decide the quantity of CBD in a tincture. That is, chemical analyses happen inside a context, and it is crucial to perceive what that context is earlier than making use of the Golden Rectangle of Chemical Analysis to select your technique.

The Cult of Accuracy

It is my statement that for many individuals concerned in chemical analyses, the rectangle in Figure 1 would consist solely of 1 level, and the one parameter listed can be accuracy. Their obsession with acquiring the best accuracy in any respect prices is what I name the cult of accuracy. Let me provide you with an instance.

I as soon as had an industrial consumer who employed me to develop a quantitative infrared spectroscopic technique for them. Being a superb analytical chemist, I requested them a bunch of questions to decide the context of the evaluation (asking the precise questions earlier than an evaluation to decide context is necessary, a superb matter for a future column). I made up my mind that to monitor the standard of their chemical course of an accuracy of ±10% was wanted. I subsequently developed a technique that was correct to ±5%. Pleased with myself, I offered the outcomes to the consumer. Instead of the enjoyment I believed I might engender in them, they rejected my technique as not being “accurate enough”. They demanded an accuracy of ±1%. They gave no rational motive for this, simply that they wished the evaluation to be as “accurate as possible.” Higher accuracy comes on the worth of price and pace. In this case, the infrared spectroscopic technique I developed took 2 minutes and required no pattern preparation, so it was quick, straightforward, cheap, and was easy sufficient that non-scientists might carry out the evaluation.

The gasoline chromatographic technique my consumer finally selected was correct however concerned vital pattern preparation prices in consumables together with solvents, vials, vial caps, and filters. The technique was gradual as a result of every pattern required 10 minutes of pattern preparation time plus an further 10 minutes to run the pattern on the GC. Worst of all, that they had to rent an skilled analytical chemist to carry out the tactic, preserve and run the instrument, including additional to price. They sacrificed time and cash on the altar of accuracy. There isn’t any want to do that, which is why I educate the Golden Rectangle idea in each analytical chemistry course I educate.

The ethical of the story is that context issues in analytical chemistry and armed with that data and the Golden Rectangle of Chemical Analysis, it is possible for you to to choose the perfect method for any given pattern.

References

1. Smith, B.C.. A Proposed Representative Sampling Plan for Hemp Grows. Cannabis Science and Technology. 2020, 3 (6), 24-38
2. Giese, M.W.; Lewis, M.A.; Giese, L.; andSmith, Ok.M. Method for the Analysis of Cannabinoids and Terpenes in Cannabis. Journal of AOAC International.2015, 98(6), 1503. DOI: 10.5740/jaoacint.15-116
3. Ruppel, T. D.; Kuffel, N. Cannabis Analysis: Potency Testing Identification and Quantification of THC and CBD by GC/FID and GC/MS, Perkin Elmer Application Note https://cdn.technologynetworks.com/tn/Resources/pdf/cannabis-analysis-potency-testing-identification-and-quantification-of-thc-and-cbd-by-gcfid-and.pdf (Accessed 2025-12-10).
4. Smith, B., Error, Accuracy, and Precision. Cannabis Science and Technology. 2018, 1(4), 12-16.
5. Smith, B., A Proposed Representative Sampling Plan for Hemp Grows. Cannabis Science and Technology. 2020, 3(6), 10-13.

About the Columnist

Brian C. Smith, PhD, is Founder, CEO, and Chief Technical Officer of Big Sur Scientific. He is the inventor of the BSS collection of patented mid-infrared primarily based hashish analyzers. Dr. Smith has completed pioneering analysis and revealed quite a few peer-reviewed papers on the appliance of mid-infrared spectroscopy to hashish evaluation, and sits on the editorial board of Cannabis Science and Technology. He has labored as a laboratory director for a hashish extractor, as an analytical chemist for Waters Associates and PerkinElmer, and as an analytical instrument salesperson. He has greater than 30 years of expertise in chemical evaluation and has written three books on the topic. Dr. Smith earned his PhD on bodily chemistry from Dartmouth College. Direct correspondence to: [email protected]

How to Cite This Article

Smith, B., How to Think Like an Analytical Chemist, Cannabis Science and Technology, 2025, 8(6), 6-9.