Determination of Herbicides Paraquat, Glyphosate, and Aminomethylphosphonic Acid in Marijuana Samples by Capillary Electrophoresis

Abstract

In this work, two methods were developed to determine herbicides paraquat, glyphosate, and aminomethylphosphonic acid (AMPA) in marijuana samples by capillary electrophoresis. For paraquat analysis, sample was extracted with aqueous acetic acid solution and analyzed by capillary zone electrophoresis with direct UV detection. The running electrolyte was 50 mmol/L phosphate buffer (pH 2.50). For glyphosate and AMPA, indirect UV/VIS detection was used, as these substances do not present chromophoric groups. Samples were extracted with 5 mmol/L hydrochloric acid. The running electrolyte was 10 mmol/L gallic acid, 6 mmol/L TRIS, and 0.1 mmol/L CTAB (pH = 4.7). The methods presented good linearity, precision, accuracy, and recovery. Paraquat was detected in 12 samples (n = 130), ranging from 0.01 to 25.1 mg/g. Three samples were positive for glyphosate (0.15-0.75 mg/g), and one sample presented AMPA as well. Experimental studies are suggested to evaluate the risks of these concentrations to marijuana user.

Pesticides in cannabis: A review of analytical and toxicological considerations

“…This method was used in a study that was able to rapidly and simultaneously detect pesticides over a wide range of polarities and molecular weights, including highly hydrophilic ones. 55 This is a simple and fast separation method for highly polar pesticides that provides good resolution and recovery. The biggest drawback, however, is that the run times are short which may result in the presence of isobaric interferences, therefore reducing the method's resolution.…”

“…55 For example, current LOQs for various pesticides in the state of Oregon lie between 0.00025 and 0.005 μg/g. 55 For example, current LOQs for various pesticides in the state of Oregon lie between 0.00025 and 0.005 μg/g.…”

“…A study using capillary electrophoresis-UV detected three herbicides in cannabis. 55 This is a simple and fast separation method for highly polar pesticides that provides good resolution and recovery. Unfortunately, the LOQs (paraquat: 5 μg/g, glyphosate: 10 μg/g, AMPA:…”

“…10 μg/g) are deemed to be too high for the regulatory action limits. 55 For example, current LOQs for various pesticides in the state of Oregon lie between 0.00025 and 0.005 μg/g. Regulatory action limits lie between 0.1 and 2 μg/g.…”

Death as a Drug Side Effect in FAERS: Is Glyphosate Contamination a Factor?

“…Furthermore, we believe we have identified a class of patients suffering from chronic kidney disease who statistically and collectively exhibit a profile of symptoms that can be explained as a consequence of chronic exposure to glyphosate in the ingested food and water. Our hypothesis is based, in part, on the increasing amounts of glyphosate found in food, air [3] [4], rain [3] [5], groundwater [5], surface water [4]- [6], soil [5], seawater [7], human serum [8] and urine [9], and even in samples of marijuana [10]. Formal testing of the suspected drugs and ingested foods for glyphosate contamination can and should be done to validate our hypothesis.…”