Tag Archives: green

dSPE cleanups

The Grass Isn’t Always Greener: Removal of Purple Pigmentation from Cannabis

By Danielle Mackowsky
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dSPE cleanups
Cannabis strains used (clockwise from top left): Agent Orange, Tahoe OG, Blue Skunk, Grand Daddy and Grape Drink

Cannabis-testing laboratories have the challenge of removing a variety of unwanted matrix components from plant material prior to running extracts on their LC-MS/MS or GC-MS. The complexity of the cannabis plant presents additional analytical challenges that do not need to be accounted for in other agricultural products. Up to a third of the overall mass of cannabis seed, half of usable flower and nearly all extracts can be contributed to essential oils such as terpenes, flavonoids and actual cannabinoid content1. The biodiversity of this plant is exhibited in the over 2,000 unique strains that have been identified, each with their own pigmentation, cannabinoid profile and overall suggested medicinal use2. While novel methods have been developed for the removal of chlorophyll, few, if any, sample preparation methods have been devoted to removal of other colored pigments from cannabis.

Cannabis samples following QuEChERS extraction

Sample Preparation

Cannabis samples from four strains of plant (Purple Drink, Tahoe OG, Grand Daddy and Agent Orange) were hydrated using deionized water. Following the addition of 10 mL acetonitrile, samples were homogenized using a SPEX Geno/Grinder and stainless steel grinding balls. QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) non-buffered extraction salts were then added and samples were shaken. Following centrifugation, an aliquot of the supernatant was transferred to various blends of dispersive SPE (dSPE) salts packed into centrifugation tubes. All dSPE tubes were vortexed prior to being centrifuged. Resulting supernatant was transferred to clear auto sampler vials for visual analysis. Recoveries of 48 pesticides and four mycotoxins were determined for the two dSPE blends that provided the most pigmentation removal.

Seven dSPE blends were evaluated for their ability to remove both chlorophyll and purple pigmentation from cannabis plant material:

  • 150 mg MgSO4, 50 mg PSA, 50 mg C18, 50 mg Chlorofiltr®
  • 150 mg MgSO4, 50 mg C18, 50 mg Chlorofiltr®
  • 150 mg MgSO4, 50 mg PSA
  • 150 mg MgSO4, 25 mg C18
  • 150 mg MgSO4, 50 mg PSA, 50 mg C18
  • 150 mg MgSO4, 25 mg PSA, 7.5 mg GCB
  • 150 mg MgSO4, 50 mg PSA, 50 mg C18, 50 mg GCB

Based on the coloration of the resulting extracts, blends A, F and G were determined to be the most effective in removing both chlorophyll (all cannabis strains) and purple pigments (Purple Drink and Grand Daddy). Previous research regarding the ability of large quantities of GCB to retain planar pesticides allowed for the exclusion of blend G from further analyte quantitation3. The recoveries of the 48 selected pesticides and four mycotoxins for blends A and F were determined.

dSPE cleanups
Grand Daddy following various dSPE cleanups


A blend of MgSO4, C18, PSA and Chlorofiltr® allowed for the most sample clean up, without loss of pesticides and mycotoxins, for all cannabis samples tested. Average recovery of the 47 pesticides and five mycotoxins using the selected dSPE blend was 75.6% were as the average recovery when including GCB instead of Chlorofiltr® was 67.6%. Regardless of the sample’s original pigmentation, this blend successfully removed both chlorophyll and purple hues from all strains tested. The other six dSPE blends evaluated were unable to provide the sample clean up needed or had previously demonstrated to be detrimental to the recovery of pesticides routinely analyzed in cannabis.


(1)           Recommended methods for the identification and analysis of cannabis and cannabis products, United Nations Office of Drugs and Crime (2009)

(2)            W. Ross, Newsweek, (2016)

(3)            Koesukwiwat, Urairat, et al. “High Throughput Analysis of 150 Pesticides in Fruits and Vegetables Using QuEChERS and Low-Pressure Gas Chromatography Time-of-Flight Mass Spectrometry.” Journal of Chromatography A, vol. 1217, no. 43, 2010, pp. 6692–6703., doi:10.1016/j.chroma.2010.05.012.

flower inspect

The Organic Certification of Cannabis

By Aaron G. Biros
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flower inspect

News of potentially harmful pesticide use on cannabis grown in Colorado, along with new legislation in California that would develop guidelines for pesticide use, highlight the need to cultivate cannabis that is not only safe to consume, but also environmentally friendly. Cannabis cultivation is a rapidly expanding industry and as growers scale up their operations, the question of sustainability remains.

Chris Van Hook performing a routine inspection of a Clean Green Certified crop

Clean Green Certified is a third-party certification program that incorporates aspects of the USDA’s National Organic Program (NOP), international organic programs and sustainable farming practices. Cannabis is not eligible for USDA organic certification because it is not a federally recognized crop, so Clean Green Certified is the closest certification nationally available. More than 200 cultivators are currently Clean Green Certified in California, Oregon, Washington, Colorado and Nevada.

Chris Van Hook, attorney and founder of Clean Green Certified, started the program in 2004 out of requests from growers to certify their cannabis as organic. Van Hook has decades of experience working in environmental law and USDA organic certifications. “About 95% of the Clean Green Certification is based on the USDA’s NOP,” says Van Hook. “The Clean Green Certified cannabis farmer would be eligible for an organic certification as soon as it becomes available, so we are helping the industry get accustomed to the regulations, inspections, and audits that come with getting organically certified.”

plants clean green vert
A close-up of an outdoor Clean Green Certified crop

Getting Clean Green Certified requires an initial application. Upon inspection, Van Hook’s program examines all the inputs, including water and energy usage, nutrients, pesticides, and soil, along with inspecting the actual plants for agricultural vitality. “We follow the plants from seed to when it is harvested, checking for clean surfaces and containers, as well as drying, curing, trimming, and processing practices,” says Van Hook. “Just like organic farming, the cultivator needs to be an engaged manager and heavily involved with the plants. Much more monitoring is involved to prevent pest problems from getting out of control without using pesticides.”

flower inspect
Van Hook inspecting the flowers on an outdoor plant

The initial screening process takes into consideration traceability and legal compliance, which in cultivation and processing alike is an eligibility requirement. “We use USDA organic standards as guidance for processor facility reviews as well, which include concentrates and edibles manufacturers, breaking it down to labeling, food handling, standard operating procedures, mock recalls, and more,” says Van Hook.

“In a market so used to a lack of oversight, there definitely are some challenges, but we are bringing the necessary agricultural and food handling regulations into the cannabis industry,” adds Van Hook.

The option to grow organically and acquire a third party certification for it can benefit cultivators across the country looking to market their product as environmentally sustainable and pesticide-free.