GC Methods for Cannabis Safety and Potency Tes6ng

Transcription

1 GC Methods for Cannabis Safety and Potency Tes6ng Amanda Rigdon 1, Jack Cochran 1, Corby Hilliard 1, William Schroeder 2, Chris< Schroeder 2, Theo Flood 2 1 Restek, Bellefonte, PA, USA, 2 Cal- Green Solu<ons, San Luis Obispo, CA, USA

2 Outline Residual solvent analysis Mi<ga<ng matrix effects Confirma<on column Pes<cide analysis QuEChERS sample prep Recovery studies Detec<on methods Potency analysis GC vs. LC repor<ng Quan<ta<ve Bias

3 How do we measure residual solvents? Confirma<on and quan<fica<on of residual solvents in pharmaceu<cals GC- HS- FID methodology Depends on accurate repor<ng of solvents used during manufacture

4 Residual Solvents in Cannabis Concentrates Butanes Heptanes Benzene Toluene Hexane Xylene Ethanol Isopropanol Acetone

5 Introduc:on to HS- GC Par<<oning of Vola<le Analytes G = Gas Phase (headspace) S = Condensed Phase (liquid or a solid) HEAT Mass Transferred un6l Equilibrium is reached Solvent molecule Solute molecule

6 Matrix Effects Equilibrium Quan<fica<on in HS- GC depends upon the establishment of equilibrium in a par<<oning system. Difficult matrices can introduce adsorp<on effects or change par<<on coefficients of analytes of interest.

7 Introduc:on to FET- HS- GC In this example, a saltwater matrix will dras<cally decrease the par<<on coefficients of some solvents, infla<ng results unless matrix- matched standards are used.

8 Matrix Effects? The complex nature of cannabis concentrates is likely to give rise to matrix effects, which may reduce quan<ta<ve accuracy. Addi<onally, given the variety of concentrates available, solubility in solvents that do not interfere with later elu<ng analytes of interest (e.g. xylenes) may be an issue.

9 Mi:ga:ng Matrix Effects USP <467> Procedure A: Screening Dissolved sample analyte peak areas are compared to standard peak areas at cutoff Procedure B: Confirma<on Dissolved sample analyte peak areas are compared to standard peak areas at cutoff on a column with alternate selec<vity Procedure C: Quan<fica<on Dissolved sample analyte peak areas are compared to matrix- matched standard peak areas at cutoff Quan<fica<on is corrected for matrix interferences by using matrix matched standard.

10 Mi:ga:ng Matrix Effects The full evapora:on technique (FET)

11 Mi:ga:ng Matrix Effects - FET Increase par<<oning efficiency by increasing surface area of the solid sample 140 C for 30 minutes. Photos and mel3ng point data courtesy of Cal- Green Solu3ons

12 Confirma:on Columns 8/ type (G43) column ) Methanol 2) Pentane 3) Ethanol 4) Hexane 5) Benzene 6) Heptane 7) Toluene 8/9) m,p- xylene 10) o- xylene Wax- type (G16) column 4) Hexane 2) Pentane 6) Heptane 1) Methanol 5) Benzene 3) Ethanol 7) Toluene 8) p- xylene 9) m- xylene 10) o- xylene Chromatograms from EZGC chromatogram creator

13 Pes:cide Analysis

14 The QuEChERS Process Sample Homogeniza<on and Weing Reduce sample par<cle size to improve extrac<on efficiency. Use a homogenizer or cryo- mill. Wet sample so it contains > 80% water Extrac<on QuEChERS extrac<on is a liquid- liquid extrac<on that effects par<<oning using salts. This step should extract most analytes, as well as many matrix components (e.g. chlorophyll) Cleanup Matrix components are removed from the extract using either dispersive sorbents or cleanup cartridges.

15 The QuEChERS Process Extrac:on Extract Solid Matrix Water + Matrix Salt

16 The QuEChERS Process Cleanup

17 Performing a Preliminary Recovery Study Prepare spiked samples at a mid-level concentration by adding a known amount of analyte to the sample prior to extraction. Extract spiked samples Extract blank samples Spike final extract from blank samples with analyte constituting 100% recovery Analyze the pre and post-extraction spiked samples. % Recovery = Analyte area in pre- extrac<on spike Analyte area in post- extrac<on spike X 100

18 Recovery Study Requirements Use internal standards for quantificaton Use matrix-matched standards for each commodity Evaluate recoveries at low, mid, and high levels Multiple replicates at each level required Make sure to also analyze unspiked blank matrix for interferences!

19 204 pes<cides in 7 minutes! CBD? Pes:cide Analysis THC? LC- MS/MS may suffer from severe ion suppression due to co- elu<ng cannabinoids While GC- MS/MS is less prone to ion suppression, interference may s<ll occur.

20 Why Test Potency by GC? PROCESS MONITORING! GCs are less expensive to purchase, maintain, and operate Standards as less expensive Separa<on is more straighporward (fewer compounds) High CBD? High THC?

21 Mismatch between GC and LC Potency Results LC Results: 18% THCA, 1% THC GC Results: 16.8% THC: (18 * 0.877) % loss of mass in the GC inlet for THCA due to loss of carboxylic acid group.

22 Calcula:ng Decarboxyla:on Efficiency Inject equal concentra3ons THC and THCA standards (solvent or spiked matrix standards) THC Standard area = 40.2 pa*s THCA area Percent (%A THCA ) = (22.8/40.2)*100 = 56.7% THCA Standard area = 22.8 pa*s At 100% decarboxyla<on efficiency, %A THCA should be 87.7%. Decarboxyla<on efficiency = (A THCA / 87.7) *100 = 64.7% min

23 Op:mizing GC Inlet for Potency Analyses 100% decarb. efficiency 84.0% efficiency 64.6% efficiency Base deact. liner, double wool. 280 C, 20:1 split IP deact. liner w/wool. 280 C, 20:1 split min

24 Op:mizing GC Inlet for Potency Analyses 100% decarb. efficiency 91.9% efficiency 90.7% efficiency Base deact. liner, double wool. 300 C, 10:1 split Base deact. liner, double wool. 320 C, 10:1 split min

25 So Everything s Great, Right? Decarboxyla<on efficiency seems to change over <me and between commodi<es. Need to determine if the method performs consistently. Decarboxyla<on efficiency over <me with base deac<vated liner Ini<al decarb. efficiency: 82.3% Ater 6 calibra<on curves: 73.6% Ater 100 standard injec<ons: 45.8% Ater 200 standard injec<ons: 30.0%

26 Summary Either USP <467> or the full evapora<on technique are suitable for analysis of residual solvents in cannabis concentrates Matrix matched standards should be used Confirma<on should be performed on a column with alternate selec<vity QuEChERS is a proven, fast, and simple method of sample prepara<on for pes<cide analyses Co- elu<ng cannabinoids will be problema<c LC- MS/MS may suffer from ion suppression Decarboxyla<on efficiency for potency analyses must be considered. Increase efficiency by increasing inlet temperature and analyte residence <me

27 Ques6ons?