Dr. Xiaoyan Wang | Authors

Articles

Determination of 11-nor-9-Carboxy-THC in Human Urine by QuEChERS and LC-MS/MS

11-nor-9-Carboxy-THC, also known as THCA or carboxy-THC, is the main secondary metabolite of THC (the active component of marijuana) formed in the human body [1]. THCA is excreted in urine in the form of glucuronide conjugates. THCA is not psychoactive but has a long half-life of up to several days or even weeks in very heavy users, thus determination of THCA in urine plays an important role in confirmation of marijuana consumption. The Substance Abuse and Mental Health Services Administration (SAMHSA) has set the THCA cutoff concentration of confirmatory testing at 15 ng/mL. Typical sample preparation methods for THCA in urine include liquid-liquid extraction (LLE) and solid phase extraction (SPE). This application utilizes a novel sample preparation technique, QuEChERS to effectively quantitate THCA levels in human urine.

EPA Method 530: Determination of Selected Semivolatile Organic Chemicals in Drinking Water by SPE and GC/MS

Recently the US EPA published a list of 30 UCMR4 (the 4th Unregulated Contaminant Monitoring Rule) analytes which may potentially be present in tap water but are not yet subject to EPA’s drinking water standards set under the Safety Drinking Water Act. Four among the 30 UCMR4 compounds, including o-toluidine, quinoline, butylated hydroxyanisole (BHA), and dimethipin, are determined by EPA method 530 using solid phase extraction (SPE) and GC/MS detection. In this study, analytes were extracted using UCT’s divinylbenzene based sorbent (HLDVB). GC/MS SIM method with solvent standard calibration was carried out for data acquisition and analyte quantitation.

Scaled Down EPA Methods 8270 and 625: Solid Phase Extraction of 100 mL Samples or Less

The EPA has updated methods 8270 (8270E) and 625 (625.1) to both now permit the use of solid phase extraction (SPE) to analyze for semi-volatile organic compounds (SVOCs) in aqueous samples and TCLP leachates. As a result of new advancements in instrumental sensitivity, smaller sample sizes can now be utilized to obtain required method detection limits, reducing solvent and standard consumptions and overall sample preparation time. This application note describes a reliable, efficient, and cost-effective SPE method utilizing two stacked cartridges for the extraction of 100 mL water samples or less.