Cannabis, Cannabinoid (Hemp, THC, CBD, CBN, Marijuana) HPLC Analysis and Testing, Areas for Improvement [*Updated 8/2021]

Over the past few years we have observed an exponential growth in the number of state-level, legal businesses (in the USA) who offer Cannabis Analysis (e.g. Potency Analysis or Profiles) and/or related businesses such as Hemp Oil Extraction. Most related products which incorporate Marijuana, CBD, THC, Cannabinoids, Terpenes and/or other related compounds require formal analytical laboratory testing which should follow good laboratory practices. This article is targeted to help many of the people involved in this new analysis business (or anyone using chromatography as the analytical technique of choice for the same goals).

As a professional chromatography consultant, I have seen a large increase in the number of requests for my services to this new market. Most of these new businesses have questions about obtaining professional training, correct analysis procedures, improving reproducibility, documentation, optimizing method development, how to receive professional training in maintenance of the HPLC system(s) and need hands-on help to optimize the procedures used. Many users are not achieving acceptable results and need help finding out why. They want to know where they can take a class to learn HPLC method development and how to perform the required tests. 

These new businesses would benefit greatly from professional guidance EARLY in their setup and establishment, to improve the internal methods and procedures of analysis used. Time spent on the "front-end" of any process is always time spent wisely (in this context, knowledge and practical experience = confidence). A chromatography professional can quickly identify areas which may need improvement and/or suggest changes that can directly improve your company's accuracy, reproducibility, increase efficiency and of course, impact your bottom-line too. Focus is placed on the exact areas that will benefit you (rather than wasting time with non-targeted approaches, sales biased classes and trial-and-error approaches). 

• Please note that there are NO SCIENTIFICALLY LEGITIMATE ONE DAY, ONE WEEK or ONE MONTH LONG TRAINING CLASSES THAT CAN TEACH YOU HOW TO PERFORM HPLC METHOD DEVELOPMENT or ANALYSIS. NONE AT ALL. Most types of "Certification" offered are completely without scientific merit or value. The training needed takes many years of hands-on experience, in an industrial laboratory (not a school), to acquire just a basic level of proficiency (*Emphasis on 'Basic", not intermediate or expert). Be very cautious of anyone who claims to be able to provide you with all the training you need in a short time period.
  

Generating accurate and reproducible analytical data, esp. with HPLC, SFC or GC requires a great deal of knowledge, formal training and practical hands-on experience (not something which is taught at most university or school programs). These complex techniques require years of bench time and professional hands-on experience to learn). Shipping or selling products which contain unacceptable levels of impurities or which do not meet basic testing or regulatory qualifications could pose a health and/or liability risk. Hire people who have the needed training from industry before setting up the laboratory.

It has been my professional experience that some of the most common training areas that client's would benefit from are: GLP (Good Laboratory Practices/Procedures and SOPs) and additional instrument operational training to demonstrate proficiency in analytical chromatography. Address these areas early on and continuously update them to reduce errors and improve results. Training should continue on a regular basis to gain experience.
 
While each confidential consultation visit I have with a client may show different key issues which need to be addressed, many labs can start to improve their analytical results by addressing and improving how they address:

1. Documentation: Laboratory methods and sample analysis must be conducted using clearly written documentation. This should initially include having Standard Operating Procedures (SOPs) in place for all methods, procedures, qualification, verification and tests used. They should include SOPs, Document Control and Policy documents which also address: Training, Calibration, Maintenance, Frequency of the same, Mobile phase preparation, pH measurement, use of the balance and so on... I find that it is best to create an initial SOP Template to insure document uniformity (i.e. include such fields as: Business Name, SOP #, review/approval date(s)/names, Rev #, materials & tools needed, purpose, procedure steps, pass/fail definitions... plus any needed supporting documents).
2. Sample Preparation Methods: Be sure to document, test, review / standardize specific sample preparation methods, for each sample type. Variations in: temperature, extraction solvent or the solution(s) dissolved in, homogenization or grinding methods, mixing, times used, glass or plastic containers used may result in significant variation of the final reported results.
3. Correct Poor Reproducibility and/or Baseline Instability Issues: In chromatography analysis, if the method(s) used are not stable and reproducible, every time they are run, then little to no scientific value can be obtained from them. Methods used must follow basic good chromatography fundamentals and meet basic guidelines. Baseline noise or instability may directly impact integration results (which directly impacts reported results). Instrumentation must be operated in clean, climate controlled rooms. Failure to reproduce a result within acceptable limits (these will vary per method type) will invalidate the method used. Make sure that SOP's are followed, mobile phase solutions are made fresh each day (do not pre-mix solutions with acids and let them sit for several days before use; do not "top off" bottles), solutions should be degassed, HPLC columns are properly washed and re-equilibrated before each analysis, instruments are maintained (per a SOP) and serviced on a regular basis. 
4. Develop HPLC methods that follow good chromatography fundamentals: Retain, separate and resolve ALL peaks. Insure peak K primes are 2.0 or higher. If you have co-eluted peaks in your method, then method development is not finished. If you have ghost peaks or changing retention times, then you need to stop running samples and find out why. Be careful whose method(s) you use. A method that is "Validated" may not be scientifically valid method to use. Have the method checked by an experienced chromatographer.
   
5. Continuous Training is Required to become Proficient: To be proficient, at a basic level in chromatography, takes most chromatographers several years working in an industrial environment to gain practical hands-on time. That assumes that they have had professional training outside of college, in an industrial lab, and can demonstrate an understanding of the fundamentals of good chromatography. Note, that method development skills require a much higher level of understanding and hands-on training to acquire the needed skill set. Make sure your scientists have the needed level of training to operate, run analysis methods and troubleshoot any issues that come up (and issues will come-up, even under ideal conditions). Please do not make the mistake of thinking they will "figure it out" on their own. Hire people who already have several years of industrial chromatography experience, then provide them with additional training opportunities to advance their skills in the application areas that your business needs.  Get them help NOW, you will save money and time, plus get back on track moving forward with your project.
   

If you want to surpass your competitors and provide clients with the most accurate data, then investing in your employees professional knowledge and hands-on technical training is the fastest route to do so. This is an experience based technique where decades of practical knowledge are needed to improve your skill set. A professional can quickly provide you with practical information and show you techniques that will help you move forward. 1-2 days of on-site training often translates to nearly one years worth of knowledge. What is one-years worth of lost time worth to you?
  
Additional Resources:

• Modern HPLC Method Development Tips (PART I): 
• Modern HPLC Method Development Tips (PART II):
• EXPERT CANNABINOID HPLC Training and CONSULTING SERVICES: 

HPLC UV - VIS Wavelength Accuracy Check (" Calibration ") Notes

To verify correct detector wavelength accuracy of your HPLC UV / VIS module it is periodically necessary to measure the wavelength accuracy against know standards using an appropriate SOP ("fit for purpose"). This may be required as part of a Performance Verification (PV), Installation Qualification (IQ) or Operational Qualification (OQ). 

Wavelength accuracy may be adversely affected (or change) when an UV/VIS detector is serviced/repaired, moved, suffers a physical shock (bumped), large temperature changes occur, a lamp or other optical component is changed, a flow cell is changed, the optics become dirty or contaminated, or due to normal wear and age. The wavelength accuracy of any applicable detectors (e.g. UV, VIS, UV/VIS, DAD, PDA) should be measured on a regular basis as part of "Good Laboratory Practices" (GLP). Depending on the regulations or guidelines applied, most authorities require accuracy to be within 2 to 3 nm of a certified standard within the range used. In practice, we generally achieve accuracy of equal to or better than 0.5 nm across a range of UV / VIS wavelengths. Following good laboratory practice (GLP) requires that we establish the frequency and conditions which determine when they should be verified. Complete documentation of these wavelength checks which describe their purpose, specificity, application and detailed procedures (SOP) should be reviewed.

We present a few suggestions in how to measure the detector wavelength accuracy of your HPLC UV / VIS module. 

• Built-In Test Methods: Most instrument manufacturers incorporate one or more wavelength accuracy checks directly built into their detectors. This allows quick and accurate measurement of the detector's wavelength accuracy for one or more wavelengths in an automated fashion. Most instruments utilize built-in filters (e.g. holmium oxide) which have been treated with chemicals to provide repeatable wavelength spectra which can be used to determine the accuracy of the detector (and adjust it to within specification in most cases, too). If your instrument has one or more of these built-in test filters, then follow the manufacturer's instructions for using them to measure the wavelength accuracy of your detector. 

• Using a solution of high purity ANTHRACENE: Dissolved in an HPLC grade alcohol (i.e. Methanol ) or Acetonitrile (for low UV checks), anthracene has a lambda max of 251 nm. A solution concentration of ~ 1 ug / mL for HPLC use can be injected using a standardized method (SOP) and the area% evaluated, one-at-a-time, at several different wavelengths (for VWD or single wavelength detectors) as follows: 249, 250, 251, 252, 253 nm. Relative to the baseline, the areas should show a peak at 251 nm. If you have a scanning UV/VIS detector (aka: DAD or PDA), then you can scan all wavelengths around the 251 nm region and plot the results using just one run to obtain the same type of data.

• Using a solution of high purity CAFFEINE in HPLC grade water: Caffeine has two useful lambda maximums that we can use for wavelength accuracy checks in the ultraviolet region, 205 nm and 273 nm. We often prepare a range of solutions from 5 ug / mL to 500 ug / mL for linearity testing of UV/VIS detectors, but any of those same solutions could be used for wavelength accuracy checking (similar method as described above for anthracene).

• One of the most widely used methods requires a solution of HOLMIUM PERCHLORATE  solution (NIST). Available for purchase from many chemical suppliers, this acidic solution provides excellent signals for calibration at well documented transmittance bands (i.e. 241.1, 287.1, 361.5 nm and many others out to ~ 640 nm, depending on the solution it is dissolved in). The detector's flow cell can be filled with the solution and measurements made. The solution is also available coated onto quartz slides and is in fact what is found and used in many detectors today as part of their built-in verification. However, you can still prepare your own test solution.

Notes: A reminder that the solution used to prepare the wavelength check standard(s) in will directly affect the results obtained. If you prepare it in a solution which has strong absorbance at or near the region you test, the results obtained may be inaccurate (e.g. a test std dissolved in MeOH used to measure wavelength accuracy at 205 nm would not be an appropriate choice. A standard dissolved in ethyl acetate would obscure the UV wavelengths below its cutoff of ~ 256 nm). Make sure your SOPs state exactly which solutions are used, how they are prepared and which flow cell are used to make the measurements! Flow cells with different dimensions (i.e. path lengths, volumes) will result in different signal outputs. Different background solutions will also result in different results which can not be directly compared (invalid test). For each test, you must use scientifically appropriate methods and the same conditions to make all measurements.