Liquid Chromatography/Quadrupole Ion Trap/Time-of-Flight Determination of the Efficacy of Drug Test Kits for Rapid Screening of Food

Abstract

The goal of this study was to evaluate the plausibility and accuracy of commercially available on-site immunoassay urinalysis kits for the screening of compounds of interest within food matrices. In conjunction with this study, a sensitive, robust, and reproducible analytical method, utilizing solid-phase extraction liquid chromatography/quadrupole ion trap/time-of-flight mass spectrometry for confirmation analysis, was developed. The food matrices analyzed were tomato juice, apple juice, milk, beer, white wine, ground beef, powdered milk, and all-purpose flour. Compounds fortified into the food matrices included heroin, phencyclidine, cocaine, benzoylecgonine, methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine, imipramine, doxepin, nitrazepam, diazepam, oxazepam, temazepam, alprazolam, flunitrazepam, clonazepam, and lorazepam. Standard curves were prepared for each matrix from 10 to 500 ng/ml for each analyzed compound. All liquid chromatography/tandem mass spectrometry samples were fortified with 20 microl of deuterated internal standard at 90 ng/ml. Quality control standards were prepared at 20 and 400 ng/ml, and > 90% were within 2 SD of the mean for each analyte. The test kits were found to produce up to 85% of the expected results based on concentration levels of adulterants (i-Screen in milk). This study shows that lateral-flow immunoassay test kits are plausible as a rapid, accurate, and reliable screening method in the event of adulteration of the food supply.

Fast Screening and Secure Confirmation of Milk Powder Adulteration with Maltodextrin via Electrospray Ionization−Mass Spectrometry [ESI(+)−MS] and Selective Enzymatic Hydrolysis

“…Ramos and Juárez reviewed some 25 years ago the main possible frauds in dairy products and the corresponding analytical procedures for their detection. Since then, significant advances in analytical dairy science have been achieved, mostly for protein analysis, owing to further developments in chromatography, electrophoresis, enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction − , and in particular, mass spectrometry (MS) − . A recent example with worldwide awareness was the “melamine” scandal, resulting in enormous health damages and even a number of fatalities in China, which triggered the development of new methods of trace analysis by MS , .…”