1. Scope

This method is for the testing of residual solvents in liquid samples that contain terpenes. The method utilizes low heat parameters for headspace-gas chromatography (HS-GC).
This method can be used when analyzing a variety of liquid samples for residual solvents. Liquid samples could include in-process terpene blends, isolated liquid terpenes, finished product essential oils, liquid ingredients containing terpenes and other chemical classes such as esters and aldehydes, among others.
This method can be used when analyzing liquid samples containing either naturally occurring or synthetically created terpenes for residual solvents. This method can be used regardless if the product or material analyzed contains cannabinoids.
Discussion: residual solvents can also be a contaminant in cannabinoid material, regardless of the presence of terpenes. It is suggested that the user of this method tests all of the individual components of a product containing cannabinoids for residual solvents in order to understand the source of the residual solvents.
This method may be used in conjunction with mass spectrometry (MS), flame ionization detection (FID), or other detector types as implemented and validated by the user of this standard.
This method does not cover the prevention of interferences between terpenes and residual solvents peak, which can occur depending on the detector type the user of this standard employs.
This method is applicable to volatile analytes regulated as a residual solvent. It is the responsibility of the user of this standard to understand what analytes are regulated under the appropriate AHJ.
Note: All analytes tested by this method must be demonstrated and appropriately validated by the user of this document to be performed on the user’s specific instrument.
This method can be used as the primary analysis for residual solvents or as a secondary analysis to verify a residual solvent result that was above the AHJ set action limit. It is the responsibility of the user of this standard to know the action limits associated with each analyte set by the appropriate AHJ.
This method does not discuss the procedure to calibrate the instrument for residual solvent quantitation.
This method discusses the sample preparations for liquid samples that are prepared volumetrically.
This method is not the only method that can be employed to reduce false positive residual solvent results. Interaction with oxygen has also been demonstrated to cause terpenes to undergo chemical reactions that produce residual solvents. Reducing or eliminating the oxygen in the sample may be another method a user can employ. This method will only discuss the method of reducing heat exposure during the analysis of the sample.
Units - The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Keywords

Headspace; gas chromatography; HS-GC; residual solvents; volatile organic; cannabis; quantitative; terpenes; cannabinoid; terpenoids

Rationale

This method is for the testing of residual solvents in liquid samples containing terpenes using headspace-gas chromatography (HS-GC) with either mass spectrometer or flame ionization detectors (MS or FID). Both MS and FID are being used with HS-GC in cannabis testing labs, and this standard was developed to be applicable to HS-GC independent of (and adaptable to) the type of detector used. While HS-GC is already commonly used to analyze volatile materials for residual solvents, the temperature settings of standard methods have been shown to artificially increase the levels of the residual solvents. Heat exposure can cause volatile compounds, such as terpenes and terpenoids, to undergo chemical degradation and produce residual solvents. Subsequently, the levels of residual solvents that are detected by the instrument are not indicative of the levels in the starting material. This method outlines the settings laboratories can input into the HS-GC parameters in order to reduce the temperature the starting liquid is exposed to, therefore, reducing false-positives. This method may be used to analyze a variety of residual solvents, and can be used as a primary analysis method, or a secondary method to verify results.
This method does not go into how to calibrate the instrument, or which residual solvents to analyze. This method does not propose solutions for other factors of false positive results, such as overlapping peaks, or oxidation, although these methods may produce similar results as this method. Terpene peaks may overlap with residual solvents peaks. Additionally, oxidation reactions with terpenes and terpenoids have also shown to create residual solvents. This method will not cover methods to reduce oxidation of the liquid sample.
This method only covers the sample preparation for liquid samples which can be measured volumetrically. This method is not solely applicable to terpenes and can cover other molecular compounds such as esters, alcohols, ketones, thiols, and more. This method can be utilized with samples with or without cannabinoids as long as the liquid is fluid enough to be measured volumetrically.

The title and scope are in draft form and are under development within this ASTM Committee.