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We have investigated electrical properties of n-GaPN layers grown by molecular-beam epitaxy with an rf-plasma source using sulfur and tellurium as dopants. The electron concentration in n-GaPN was about 10 times lower than that in n-GaP. Desorption of dopants from the grown surface by impinging N atoms may be one of the possible causes for the reduced electron concentration. In addition, electron mobilities in GaPN were restricted by ionized impurity scattering even at room temperature (RT). N atoms at N-related levels could trap the electrons, and these ionized N could act as a Columb scattering center for free electrons even at RT.

Dedicated with friendship to Joe Richmond on the occasion of his 60 th birthday.

Nicotine (NC) and its related compounds (cotinine (CN), nornicotine (NN), anatabine (AT) and anabasine (AB)) were simultaneously enantioseparated by CE using a capillary with amino groups and sulfated beta-CD as a chiral selector. The optimum running conditions were found to be 30 mM acetate buffer (pH 5.0) containing 8% sulfated beta-CD with an applied voltage of +15 kV at 30 degrees C using direct detection at 260 nm. Using a capillary coated with amino groups, the EOF migrates toward the positive pole. However, when sulfated beta-CD was added to the BGE, it was found that the EOF migrated toward the negative pole due to ionic adsorption of sulfated beta-CD to amino groups on the capillary inner wall. All the cationic analytes migrated as anions, suggesting that they formed stable anionic complexes with sulfated beta-CD. With this system and a simple pretreatment with mini-cartridges, NC alkaloids in five cigarette samples were enantioseparated. As a result, each of the compounds except for CN was detected. In the case of NC, only (S)-NC was detected (more than 99.9%), but in the case of NN, AT and AB, the ratios of (S)-isomer to total isomers were in the ranges 58-70, 81-85 and 59-65%, respectively. On the other hand, only NC was detected in cigarette smoke and the ratio of (S)- and (R)-NCs was 96:4. The amounts of NC alkaloids in cigarettes suggest that the production of (R)-NC resulted from racemization due to the high temperature/burning of the cigarette.

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