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Nguyen T.A.H.,Hanoi University of Science | Pham T.N.M.,Hanoi University of Science | Ta T.T.,Hanoi University of Science | Nguyen X.T.,Institute of Forensic Science | And 6 more authors.
Science and Justice

A simple and inexpensive method for the identification of four substituted amphetamines, namely, 3,4-methylenedioxy methamphetamine (MDMA), methamphetamine (MA), 3,4-methylenedioxy amphetamine (MDA) and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) was developed using an in-house constructed semi-automated portable capillary electrophoresis instrument (CE) with capacitively coupled contactless conductivity detection (C4D). Arginine 10 mM adjusted to pH 4.5 with acetic acid was found to be the optimal background electrolyte for the CE-C4D determination of these compounds. The best detection limits achieved with and without a sample preconcentration process were 10 ppb and 500 ppb, respectively. Substituted amphetamines were found in different seized illicit club drug tablets and urine samples collected from different suspected users. Good agreement between results from CE-C4D and those with the confirmation method (GC-MS) was achieved, with correlation coefficients for the two pairs of data of more than 0.99. © 2015 The Chartered Society of Forensic Sciences. Source

Tran S.C.,National Institute for Food Control NIFC | Le H.T.H.,National Institute for Food Control NIFC | Thai-Nguyen T.H.,Hanoi University of Pharmacy
Acta Alimentaria

A modified QuEChERS method was developed and validated for determination of pesticide multi-residues in green tea by liquid chromatography tandem mass spectrometry. Lead acetate was fi rst time used together with primary secondary amine and graphite carbon black to eliminate tannin, caffeine, and other pigments in tea and thus reduced the matrix effects. The method was compared to the original QuEChERS method as well as A.O.A.C. QuEChERS method. For accurate quantifi cation, the matrix matched calibration technique was used. The method showed good performance in the concentration range from 0.01 to 1 mg kg-1. All pesticides could be quantifi ed at and lower than 0.01 mg kg-1. Recoveries were from 70 to 120% and repeatabilities were <15% RSD depending on the compounds. © 2015 Akadémiai Kiadó, Budapest. Source

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