A liquid chromatography-mass spectrometry method for nicotine and cotinine; utility in screening tobacco exposure in patients taking amiodarone

A liquid chromatographic mass spectrometric (LC-MS) assay for the quantification of nicotine and cotinine in human specimens was developed. Human serum and urine (100 μL) were subjected to liquid-liquid extraction. For glucuronidated cotinine, serum was alkalinized and hydrolyzed before extraction. The dried samples were reconstituted and run using gradient flow reverse-phase liquid chromatography with MS detection. The ions utilized for quantification of nicotine, cotinine and milrinone (internal standard) were 162.8, 176.9 and 211.9 m/z, respectively. The mean recoveries were over 80% for cotinine and nicotine with excellent linearity between nominal concentrations and peak area ratios, over a wide concentration range. The percentage coefficient of variation and mean error of the inter- and intra-day validations were <15% for nicotine and cotinine. Analysis of serum from cardiac patients receiving amiodarone suggested that a number of patients were either active smokers or exposed to second-hand smoke. Significant concentrations of nicotine and cotinine were measured in the urine of a known smoking volunteer. The method was highly specific, sensitive and applicable as a tool in detecting and monitoring the passive exposure to tobacco smoke using small specimen volumes (0.1 mL).     

Thermodynamic properties and ordering in liquid NaK alloys

The thermodynamic activities of sodium and potassium were determined by vapour-phase absorption spectrophotometry of atomic resonance lines. Both components exhibit significant positive deviations from ideality. Excess Gibbs energies computed from the activity data were combined with available heat-of-mixing data to yield values for excess entropies. The entropy of mixing which was found to be ideal in the sodium-rich liquid alloys provides no support for the earlier speculations about the existence of Na₂K molecules therein. The partial molar excess entropy of sodium in dilute solution in potassium was found to be surprisingly large and negative for a system of this type. A plausible model, involving sodium-sodium pairing, is proposed to account for the loss of configurational entropy.     

Photodegradation of Ethylene/Propylene/Polar Monomers Co‐ and Terpolymers. I—Prepared by Group 4 Catalyst Systems

The photooxidative degradation behavior of polyethylene, its copolymers (propylene/polar monomers) and terpolymers, synthesized by a group 4 catalyst system, has been studied by Fourier transform infrared spectroscopy and confirmed with scanning elecrton microscopy for morphological changes. The kinetics of photodegradation has also been studied. Surface damage caused by polychromatic (≥290 nm) at 55°C in air is presented in different micrographs. The rate of photodegradation is very fast in terpolymers containing polar monomers as compared with copolymers and polyethylene. Morphological study of these photodegraded samples showed a very good relation with photodegradation results.