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The growing use of cannabidiol (CBD) products by the general public is expected to result in an increase in the prevalence of CBD and the CBD metabolites in drug testing laboratories. CBD converts into tetrahydrocannabinol (THC) under acid conditions which could produce false positive results but little is known about how the presence of the urinary metabolite of CBD, 7-carboxy-cannabidiol (7-COOH-CBD) would affect urine drug testing for 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH). As the operators of the National Laboratory Certification Program (NLCP) we prepared a set of performance testing (PT) samples containing 7-COOH-CBD for cannabinoids testing at the laboratories accredited by the NLCP to investigate if 7-COOH-CBD can produce false positive results for THC-COOH during immunological screening analysis and if 7-COOH-CBD can be converted to THC-COOH. At concentrations up to 2,500 ng/mL, 7-COOH-CBD was not reactive by immunoassay in any of the four different immunoassay kits used. Additionally, we did not observe any significant conversion of 7-COOH-CBD to THC-COOH in assays used by NLCP certified laboratories. However, we did see conversion when we requested that selected laboratories retest their samples using derivatization with perfluorinated anhydrides in combination with perfluorinated alcohols or when samples containing 7-COOH-CBD were exposed to acid for an extended time.

The paper describes and evaluates a capillary-tube technic for the chamber count of circulating eosinophils. The outstaning merits of the method are ease of collection, accuracy ard reproducibility of results and the fact that counting can be deferred for hours and even days without vitiation of the accuracy. Application of this method to study of normal subjects indicates a diurnal cycle of eosinophil fluctuation, with a low at noon and a high late at night.

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