Improved Gas Chromatographic Quantification of Acidic and Neutral Cannabinoids

Transcription

1 Improved Gas Chromatographic Quantification of Acidic and Neutral Cannabinoids Amanda Rigdon 1, Jack Cochran 1, Julie Kowalski 1, Corby Hilliard 1, Sara Minier 1 Restek, PA, USA 2 Trace Analytics, WA, USA

2 Outline Introduction to cannabis in 2016 The cannabis analytical market Why test cannabis at all? Sample Preparation A maddening mystery with a happy ending

3 Cannabis It s Everywhere! Already being sold Just legalized CBD Specific 34 states allow cannabis in some form 3 additional states have decriminalized possession

4 Medical Cannabis New Dosage Forms

5 The Cannabis Testing Industry

6 The REAL Cannabis Testing Industry Reggie Gaudino SteepHill Labs B.S. in Molecular Biology Ph.D. in Molecular Genetics Rodger Voelker OG Analytical BS Analytical Chemistry Ph.D Analytical Chemistry Chris Hudalla ProVerde Labs BS Chemistry Ph.D Chemistry Principal Apps Chemist at Waters for 13 years

7 Why Care About Cannabis Testing

8 Cannabis Testing Applications Potency LC and GC Terpenes/Terpenoids GC and LC Residual Solvents GC Pesticides LC and GC

9 Cannabinoid Biosynthetic Pathway Geranyl pyrophosphate Olivetolic acid Enzymatic Decarboxylation Oxidation CBGA CBG CBDA CBCA THCA CBNA CBD CBC THC CBN

10 The problem with GC potency testing Cannabinoids are reported as a sum of acidic/neutral analytes Majority of states require separate reporting for cannabinoid acids and neutrals.

11 Introduction to Derivatization Derivatization produces molecules that are stable under gas chromatographic conditions

12 Derivatization Method Place desired amount of solvent extract into a 2mL microvial Add internal standard if desired Evaporate to dryness under a gentle stream of N 50 C Add 50µL EtAc Add 50µL BSTFA + 1% TMCS Immediately cap vial Incubate C Cool vials and dilute with EtAc as appropriate 11 nor 9 carboxy THC

13 Method Development/Validation

14 Goals for Potency Work Evaluate GC derivatization method in authentic samples Evaluate potential sample cleanup methods Modified AOAC extraction to protonate cannabinoid acids Lighter cleanup methods to improve recoveries

15 Modified Extraction Method for Edibles Weigh 1g sample into 50mL centrifuge tube Soak 30 minutes Add AOAC QuEChERS salts and shake 1 min Add 15mL water + 1% Acetic Acid, 15mL ACN, and 2 Genogrinder balls Centrifuge 3000x g for 5 minutes Process on Genogrinder RPM

16 Modified Cleanup Method for Edibles Pipet 1mL extract into dspe tube containing 150mg MgSO 4, 25mg PSA, 2.5mg GCB Shake 2 minutes Centrifuge x g DONE!

17 Edible Cleanup Recovery and Spike Accuracy All samples spiked at low (0.50 mg/g) and high (0.99 mg/g) concentration with THCA and CBDA. Neutrals not spiked due to unknown incurred neutral levels. Cleanup recovery measured by comparing difference of all detected cannabinoids between cleaned and uncleaned extracts. Accuracy for neutrals evaluated using HPLC results from established and new method.

18 Blue Hard Candy No Cleanup dspe Cleanup CBDA THCA THC

19 Blue Hard Candy Results Cleanup Recovery Unclean Recovery Clean Recovery %Difference from Est. Method THC 110 Not Spiked Not Spiked 3.0 CBDA NA THCA NA

20 Cookie Truffle No Cleanup dspe Cleanup THC CBDA THCA

21 Cookie Truffle Results Cleanup Recovery Unclean Recovery Clean Recovery THC 113 Not Spiked Not Spiked CBDA THCA You should have used an internal standard!!

22 So what happened? Derivatized plant sample GC Results THC 13% CBG NQ THCA 9.6% CBGA NQ HPLC Results(%): THC: 0.00 THCA: 25% Calculated THCA Sum = (THC*1.13) + THCA = 24% Decarboxylation occurred during sample processing!

23 Decarboxylation During Sample Processing Duplicate sample results for plant material THC CBG THCA CBGA Plant Sample Plant Sample Duplicate THC THCA Poor duplicate precision further indicates decarboxylation during sample processing

24 Decarboxylation During Sample Processing Should affect THC values for spiked edibles Lemon Chocolate Cookie Candy Unspiked Spike Spike %RSD Sugar Sugar Dup Caramel Caramel Dup Unspiked Spike Spike %RSD

25 What about the standards? Comparison of duplicate preparations of standard curve CBD CBN This variation was observed in 5 of 7 calibrators THC CBDA THCA

26 So is a GC Method Out of the Question? Front work was promising Importance of authentic samples Early decarboxylation tests showed no issue Needs to be revisited

27 What about the sample prep method? Cookie Candy Caramel QuEChERS Established QuEChERS Established QuEChERS Established CBD ND ND ND ND ND ND CBDA ND ND ND ND ND ND CBN ND ND ND ND ND 0.01 THC THCA ND ND ND Good agreement with results from an established method and good duplicate precision point to the fact that the extraction method looks promising. More work needs to be done to evaluate cleanup methods as well as acid performance

28 Conclusions QuEChERS may be an easier and faster extraction method for cannabis edibles Method development can be complicated due to regulatory issues Work with authentic matrix is necessary to generate robust methods Verdict on the derivatization method is still unknown HPLC is easier!

29 Thank you!