Colorimetry in Chemical Analysis
Colorimetric Methods of AnalysisIncluding Some Turbidimetric and Nephelometric Methods. By Dr. Foster Dee Snell. Dr. Cornelia T. Snell. Third edition. Vol. 2: Inorganic. Pp. x + 950. (New York: D. Van Nostrand Co., Inc.; London: Macmillan and Co., Ltd., 1949.) 90s. net.
A Monitor Calibrator as a Portable Tool for Determination of Luminescent Compounds
A monitor calibrator has been tested as a portable, available, and cost-effective tool for the detection of luminescence. Prospects of this device as an all-sufficient analog of an analytical fluorometer have been outlined. Its ability to determine luminescent compounds was demonstrated by the example of rhodamine 3B and fluorescein. The determination is based on simultaneous impulse irradiation of a fluorescent sample with the incorporated continuous-spectrum light emitter in the visible and near UV ranges and registration of the luminescence. The appropriate cuvettes for the analysis and the device sealing film were chosen. The lowest relative detection limit for the developed approach was <inline-formula> <tex-math notation="LaTeX">$0.03~\mu $ </tex-math></inline-formula>mol L<sup>−1</sup> for rhodamine 3B and <inline-formula> <tex-math notation="LaTeX">$0.01~\mu $ </tex-math></inline-formula>mol L<sup>−1</sup> for fluorescein; the lowest absolute detection limits were 0.01 and 0.002 nmol for rhodamine 3B and fluorescein, respectively. Using the proposed approach, it was possible to determine the luminescent compounds in tap water.
Influence of inducers and inhibitors on the metabolism in vitro and neurochemical effects in vivo of MDMA.
(S)-(+)- and (R)-(-)-3,4-methylenedioxymethamphetamine (MDMA) were metabolized in vitro by rat liver microsomes via N-demethylation to 3,4-methylenedioxyamphetamine (MDA). Whereas no difference was found in the biotransformation of the two enantiomers in the male rat or in the phenobarbital (PB) treated animals of either sex, more than twice as much MDA was formed from (S)-(+)- than from (R)-(-)-MDMA in the untreated female rat. Although 3-methylcholanthrene (3MC) pretreated rat liver microsomes were less active than those from the untreated rats of the same sex, they formed more MDA from (+)- than from (-)-MDMA. The enantioselective metabolism thus appears to be associated with the relative abundance of individual cytochrome P-450 isozymes. (S)-(+)- and (R)-(-)-MDMA.HCl (20 mg/kg) were about equipotent in depleting serotonin (5-HT) levels in the frontal cortex at 3 hrs and 1 wk following oral administration to female rats. Pretreatment of rats with SKF-525A attenuated and that with PB enhanced the 5-HT depleting potential of either isomer at 3 hrs. The 5-HT depleting potency of (+)-MDMA was significantly greater than that of its (-)-antipode at 3 hr in PB pretreated, but not in SKF-525A pretreated animals. The results suggest that the neurochemical effects of MDMA are caused by the formation of an active metabolite in vivo, and since both enantiomers were N-demethylated in vitro to approximately the same extent by PB pretreated rat liver microsomes, the active metabolite may be other than MDA.