A precise and feasible HPLC method has been developed for the analysis of amphetamine (AMPH), methamphetamine (MAMPH) and methylenedioxymethamphetamine (MDMA, ecstasy) in human urine. A chromatographic run on a C8 Genesis (150 mm x 4.6 mm, 5 microm) column maintained at 30 degrees C lasts about 17 min, using a mobile phase composed of ACN (12%) and a pH 2.5 phosphate buffer (88%) containing 0.3% triethylamine. Mirtazapine was used as the internal standard. Good linearity was found in the 100-2000 ng/mL concentration range for AMPH and MAMPH and in the 12-2000 ng/mL concentration range for MDMA. The pretreatment of urine samples was carried out by means of a careful SPE procedure on C2 cartridges. The extraction yields were very satisfactory for all analytes, with average values greater than 97%. The leading conditions allowed the determination of AMPH, MAMPH and MDMA with satisfactory precision and accuracy. The method has been successfully applied to the determination of the analytes in urine of AMPH users.
We have studied by electrical and optical methods the properties of the defects to possibly identify which ones affect the luminescence of the material. We have characterized Er-doped Si samples grown by the Liquid Phase Epitaxy (LPE) method, a relatively simple and inexpensive technique, by means of photoluminescence (PL), cathodoluminescence, EXAFS and deep level transient spectroscopy. The optical methods reveal the presence of two emission bands which coincide with the lines labelled D1 and D2, attributed to dislocations. Since line D1 fortuitously coincides within a few meV with the energy of the transition 4 I 15/2 3 4 I 13/2 of Er 3 , it could at least partially cover the Er-related emission. Furthermore, as Er and O could both interact with dislocations, the dislocation optical activity might be influenced by their presence and play a significant role in the material overall luminescence.
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