Residual Solvent Testing

Residual Solvent Testing

Lime Analytical has developed a Residual Solvent Test (RST) to identify the presence of harmful solvents, impurities, and/or other added odorants and chemicals present in super-concentrated forms of Cannabis. Increasingly, more patients are seeking out super-concentrated forms of Cannabis (i.e wax, hash oil, RSO, hemp oil, shatter, amber glass, crumble, budder, etc.)

These types of concentrates are produced by using a solvent (such as butane, CO2, ethanol, propane, etc.) to extract cannabinoids and terpenoids from plant-material. Finally, heat, vacuum, and/or other methods are applied to purge out any remaining solvent from the concentrate.

To ensure that the highest quality of concentrates are being produced and made available to patients, Lime Analytical offers collectives and concentrate manufacturers a Residual Solvent Test (RST).

By testing for Residual Solvents, we are able to ensure that the producer’s concentrate process is sound, not only verifying that the producer has used a high-quality solvent, free of impurities and toxic odorants, but has also followed a proper purging process (i.e. vacuum, desiccation, etc.) Utilizing a combination of Gas Chromatography/FID, Head-space analysis, and Mass Spectrometry, SCL is able to identify all of the most commonly used solvents and trace residues of chemicals in the process of extracting cannabinoids, including:

  • Acetone
    • Butane
    • Propane
    • Pentane
    • Hexane
    • Heptane
    • Ethanol
    • Isopropanol (iso-alcohol)

As the rise of the “dab” continues to gain popularity amongst the Cannabis community, the need to ensure the highest levels of product purity and patient safety becomes paramount. There is no denying the efficiency (?) of vaporizing a concentrate, as a method for ingesting a concentrated dose of cannabinoids with very little to no carcinogenic plant-material. Many municipalities and other states that have authorized medical Cannabis for medicinal use are growing concerned with the rising trend of super-concentrates, In many cases, due to the strength in potency of these products and the negative connotations that various production methods may present, a Collective may find itself at risk of legal issues if chemical-solvent extracted concentrates are offered.

More importantly, chemical residues can have a significant impact on the health of a patient, especially over time and with repeated exposure. Our community must self-regulate to ensure that patients are receiving the highest of quality, solvent-free concentrates possible.

Residual Solvent Testing

A Residual Solvent Test (RST) has been developed by Lime Analytical for identifying the presence of impurities, solvents, and/or other added chemicals and odorants that are present in super-concentrated Cannabis forms. More patients are increasingly searching for super-concentrated types of Cannabis (i.e. budder, crumble, amber glass, shatter, hemp oil, RSO, hash oil, wax, etc.)

These kinds of concentrates are produced through using a solvent (like propane, ethanol, CO2, butane, etc.) for extracting terpenoids and cannabinoids out of plant materials. Finally, vacuum, heat and/or methods are used to purge any remaining solvent out of the concentrate.

To ensure that concentrates of the highest quality are produced and available for patients, a Residual Solvent Test is offered by Lime Analytical to concentrate and collectives manufacturers.

Residual Solvents testing allows us to ensure that the producer has a sound concentrate process, that verifies the producer has utilized a high-quality solvent that is free of toxic odorants and impurities, and also followed the correct purging process (i.e. desiccation, vacuum, etc.) Using a combination of Mass Spectometry, Head-space analysis, and Gas Chromatography/FID, SCL can identify all of the more commonly used trace residues of chemicals and solvent in the cannabinoids extraction process, including:

– Isopropanol (iso-alcohol)
– Ethanol
– Heptane
– Hexane
– Pentane
– Propane
– Butane
– Acetone

As the rise of “dab” continues to increase in popularity in the Cannabis community, it becomes paramount to ensure the highest levels of patient safety and product purity. There is no denying that the efficiency of vaporizing concentrates, as a way to ingest concentrated cannabinoids doses with no or little carcinogenic plant material. Many states and municipalities that have authorized medicinal use of medical Cannabis are becoming concerned with the growing trend of super-concentrates. Many times this is due to the potency strength of those products and the negative connations that may be presented by various production methods. This could result in a Collective finding itself at risk of legal problems if it offers chemical-solvent extracted concentrates.

Most importantly, chemical results may have a very significant impact on a patient’s health, especially with repeated exposure and over time. Our community needs to self-regulate to make sure that patients are getting solvent-free, and highest quality concentrates as possible.

Residual Solvents – Acceptable Limits

A universal standard has not been yet set for limits on the residual solvents that are contained in cannabis concentrates. Guidelines have been set by the United States Pharmacopeia (USP) for individual solvent daily exposure limits. Based on risk assessment, solvents are divided into three “classes.”

Assessment of Residual Solvent Classes

Class 1 Solvents that need to be Avoided

Environmental hazards
Highly suspected human carcinogens
Known human carcinogens

Class 2 Solvents To Be Limited

Either nongenotoxic animal carcinogens or potential causative agents of other forms of irreversibility toxicity, like teratogenicity or neurotoxicity.

Solvents that are suspected of other types of significant toxicities but that are reversible.

Class 3 Solvents That Have Low Toxic Potential

Solvents that have low toxic potential for humans; there is no health-based exposure limit necessary. [Note: There are PDEs in Class 3 residual solvents. Source of 50 mg per day or more.]

Class III solvents include Pentanes, Butanes, Propanes, Isopropanol, and Ethanol.

Currently, SC Laboratories serves cannabis industries in California and Washington, which are two markets that have different regulatory requirements when it comes to residual solvents that are contained in inhaled cannabis concentrates. In Washington, under WAC Chapter 314-55-104, parts per million (PPM) for one gram worth of finished extract may not exceed 500 PPM of gas or residual solvent. Although California does not have a statewide standard established, a limit has been set by the City of Berkeley of 400 PPM for gas or residual solvents in a one gram amount of finished extract.

“Tested/Detected” rather than “Pass/Fail”

All of the samples where there has been a request for a residual solvent test have been designated as “Tested” and is highlighted in green. On the samples where it is detected that residual solvents are in excess of 400 PPM are classified as “Detected” and then are highlighted in yellow. This 400 PPM limit represents the lowest tolerance that a regulatory body has established in a market where data from a Lime Analytical test is used for verification purposes. “Detected” is not the same thing as “Fail.”

There is no universal standard on tolerance limits, so residual solvent data is shown in PPM format without any pass/fail determination. Consumers patients or individual processors must determine what is “safe” for them.

Acceptable Limits for Residual Solvents

There has not yet been a universal standard set for limits on residual solvents in cannabis concentrates. The United States Pharmacopeia (USP) has set guidelines for daily exposure limits for individual solvents. Solvents are broken into three “classes” based on their risk assessment.

Residual Solvent Class Assessment
Class 1 Solvents to be Avoided
Known human carcinogens
Strongly suspected human carcinogens
Environmental hazards
Class 2 Solvents To Be Limited
Nongenotoxic animal carcinogens or possible causative agents of other irreversible toxicity, such as neurotoxicity or teratogenicity.
Solvents suspected of other significant but reversible toxicities.
Class 3 Solvents With Low Toxic Potential
Solvents with low toxic potential to humans; no health-based exposure limit is needed. [*NOTE—Class 3 residual solvents have PDEs. Source of 50 mg or more per day.]
* Class III solvents include Ethanol, Isopropanol, Propanes, Butanes, and Pentanes.

Lime Analytical currently serves the cannabis industries in both Washington and California, two markets with differing regulatory requirements with respect to residual solvents in inhaled cannabis concentrates. For Washington, under the WAC Chapter 314-55-104, the PPM (parts per million) for one gram of finished extract cannot exceed 500 PPM of residual solvent or gas. Although a statewide standard has not been established for California, the City of Berkeley has set a limit of 400 PPM for residual solvents or gas in one gram of finished extract.

“Tested/Detected” instead of “Pass/Fail”

All samples on which a residual solvent test has been requested are designated as “Tested” and highlighted in green. Samples where residual solvents are detected in amounts greater than 400 PPM are designated as “Detected” and highlighted in yellow. The 400 PPM limit is the lowest tolerance established by a regulatory body in a market where Lime Analytical test data is used for verification. “Detected” does not equate to “Fail”.
Due to the lack of a universal standard for tolerance limits, residual solvent data is displayed in PPM format without a pass/fail determination. Individual processors, patients or consumers must make the decision for what is “safe” for themselves.