Translator for HPLC HINTS and TIPS for Chromatographers

Showing posts with label Analysis. Show all posts
Showing posts with label Analysis. Show all posts

Saturday, July 11, 2020

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:

Saturday, April 2, 2016

Chromophore, Chromophores, UV Absorbing for HPLC Analysis and Detection

A compound's absorption coefficient relates to its "strength". I find it useful to know which compounds can (and cannot) be easily detected by UV/VIS and a quick analysis of their chemical groups can provide an answer. Please note that the actual measured absorbance maximums will vary depending on the solution that the compound is dissolved in. Beta-Carotene is included as a very interesting structural example because it is composed of long chains of conjugated double bonds (isoprene units) which are cyclised at each end. Here are some other popular examples:

KEY CHROMOPHORE        Absorption MAX (nm)  STRENGTH

acetylide                                    177                           medium
aldehyde (2)                                210                           strong
anthracene                                 252 & 375                strong
azido                                          190                           medium
amine                                         195                           weak
benzene                                     184 & 255                strong
β-carotene                                  450                          medium
disulfide                                      194                          medium
ether                                           185                           weak
ethylene                                     190                           medium
ketone (2)                                   190                           weak
naphthalane                              220 & 286                strong
nitrate                                        270                           weak-strong
nitrite                                         225                           weak
nitro                                           210                           strong
oxime                                         190                           medium
thiol                                            195                           weak
thioketone                                  205                           strong
thioether                                     194                           medium
conjugated ring                        varies                          strong

Notes: 

  1. Chromophore conjugation is the process that gives rise to multiple spectral peaks (or shoulders) which are very useful in qualitative identification for HPLC (Spectral fingerprinting). For more information on this topic, I recommend a very well written description of UV/VIS spectroscopy fundamentals at this link.
  2. Other interesting examples: Carbonyl (aldehyde) as found in Acetaldehyde; 293nm. Carbonyl (ketone) such as found in Acetone; 271nm.

Data supplied from "Instrumental Methods of Analysis"; Willard, Merritt & Dean; D. Van Nostrand Co. Inc., (1965).

Thursday, December 1, 2011

Adduct formation in LC-MS Analysis (esp. ESI)

Almost everything you analyze by Electrospray ionization mass spectrometry will create an adduct with something in the system. Normally, hydrogen is the most common adduct formed (M+1), but other chemicals, often in trace amounts may form adducts with your sample too. Sometimes we can take advantage of this fact and introduce our own adduct into the system (post column) to increase signal sensitivity or help us isolate one signal from another (the addition of an adduct can sometimes increase the signal seen for one species, but not the other). 

One of my favorite elements to form an adduct with is sodium (Na+). Two common forms are; sodium citrate and sodium acetate. Both have PKA’s between 3 and 6 so a variety of buffered solutions can be prepared for use. However, it is very important that we keep the concentration of sodium as low as possible so as to not clog the mass detector or suppress ionization completely (and see nothing BUT Sodium for weeks …). My suggestion is to initially prepare the buffers such that the solution is less than or equal to 3 mM in concentration. The lowest concentration should be used that yields reproducible results. Ranges from 0.1 mM to 5 mM are common. Only use the highest purity, volatile buffers (some manufacturer’s use names such as “ultra” to describe them) when preparing these ‘doping’ solutions for post-column addition and be sure and filter them through a 0.2 micron filter before use. A syringe pump can be used to deliver the solution during the run. A low flow rate should be used to infuse the adduct solution into the main inlet of the detector. Make sure you have a simple way of controlling the pump through the system (e.g. ‘On’ / ‘Off’, contact closure) so the flow can be turned off when you are not acquiring data. Be sure to not only monitor the baseline, but also measure true peak S/N values of a standard when evaluated the results (decreasing baseline noise may also mean the signal is decreasing too).

Ammonium (NH4) is another popular adduct to add to the system, often in the form of ammonium acetate. It reduces the chances of adding more sodium ions to the system (from glassware). Whichever adduct you use in your system, always start off testing as low a concentration as possible. Monitor the baseline carefully for noise and also to see if the addition of the compound is suppressing or enhancing the signal generated for your compound. Careful use of adducts in your system can provide you with another means to selectively enhance the signal of some compounds without changing the original chromatography method.

I must again emphasize to use the lowest concentration of doping agent. Proper pH control and mode choice are also very important. Use of a syringe pump for infusion, post column can help you to quickly optimize the fragmentor settings in real time.