Gerald P. Morie

Determination of nitrate and nitrite in mixtures with a nitrate ion electrode

Abstract A rapid method for the determination of nitrate and nitrite ions is described. The potential of a mixture of nitrate and nitrite was measured with a nitrate ion selective electrode. The nitrite in the mixture is then oxidized to nitrate with permanganate in acid solution, and the potential of the oxidized solution is also measured with the electrode. The fundamental equations for the response of the nitrate ion electrode to nitrate ion in the presence of interfering ions were used, and a new equation was developed for calculating the original nitrate concentration of the mixture. The absolute errors for solutions of known concentrations (2.5–100 p.p.m. each) were 1.8 p.p.m. nitrate and 2 p.p.m. nitrite. When the results are calculated by computer, five determinations can be performed in 30 min. The method was applied to the determination of the oxides of nitrogen in cigarette smoke as nitrite and nitrate after dissolution in basic solution.

Evaluation of thermal analysis equipment for the determination of vapor pressure and heat of vaporization

Abstract A rapid, relatively simple method for determining vapor pressure and heat of vaporization on small amounts of organic compounds is described. A DuPont 900 differential thermal analyzer (DTA), a Perkin—Elmer Model DSC-1B differential scanning calorimeter (DSC), and a Thomas—Hoover (TH) melting point apparatus were evaluated in this work. Vapor pressure data for a wide variety of organic liquids were obtained by measuring the boiling points of the liquids at pressures ranging from 20 to 735 torr. A computer was used to rapidly plot the experimental data. The average deviations of boiling points from the literature values were 2.3°C for the DTA 1.2°C for the DSC, and 1.5°C for the TH. The vapor pressure data were used to solve the Haggenmacher equation for heat of vaporization (Δ H v ). The deviations of the experimental values for Δ H v . from the literature values were 5.5%, 8.3%. and 3.3% for the DTA, DSC, and TH methods, respectively.

Parameters Affecting the Selective Filtration of Certain Tobacco Smoke Components

Abstract The purpose of this investigation was to attain a better understanding of the selective removal of certain compounds from cigarette smoke by filters. A gas chromatographic method for the determination of selected semivolatile smoke compounds was developed. The method, which utilizes a 160 m glass capillary column, was used to determine the efficiency of filters for the removal of these selected semivolatile compounds. A correlation was found between the selective filtration of these compounds from cigarette smoke and their distribution coefficients [Kd = (g compound/g filter)/ (g compound/cm3 air)] between air and various filter materials. In addition, a correlation was found between the physicaI and chemical nature of certain smoke compounds and their selective filtration. Previous work indicated that if a compound is to be selectively removed from tobacco smoke by a filter, [1] a significant portion of that compound should be in the vapour state as it passes through the filter and [2] the compound should have an affinity for the filter material. The relative rate of vapourization (Rv) was used as a measure of 1., and the totaI solubility parameter (d) was taken as a measure of 2. Values for the vapourization rate were calculated from the product, vapour pressure (P), molecular weight (M), and diffusion coefficient (D), (Rv = kPMD1/2). The correlation of Rv and δ with the selectivity (Sx) of cellulose acetate filters for smoke compounds is described by Sx = b0 + b1δ + b2δ (1n Rv), where b0, b1, and b2 are constants. This equation may be used to predict the selective filtration of semivolatile compounds from cigarette smoke.

Spectrophotometric Determination of Textile Lubricants that Contain Poly(oryethylene) Surfactants

A method for the rapid determination of lubricants on textile fibers was developed. The method is applicable for most textile lubricants that contain a constant percentage of one or more nonionic surfactants. The surfactants con taining poly(oxyethylene) moieties react with ammonium tetrakis(thiocyanato) cobalt(II) (ATTC) to give a blue, water-insoluble complex that is extracted into dichloromethane and measured spectrophotometrically. To determine the amount of lubricant on cellulose acetate fibers, 2 g of the fibers and 25 ml of water are placed in an ultrasonic bath for 5 min. Twenty ml of the ATTC solution and 20 ml of the extract are added to a separatory funnel. Ten ml of dichloromethane is added; the complex is extracted; the absorbance of the dichloromethane solution is read at 620 nm on a spectrophotometer; and the amount of lubricant is read from a calibration curve. The standard deviation at the 95% confidence level is ± 0.07% lubricant. Five samples may be analyzed by this method in less than 1 h.