An instrumental method for rapid determination of carbonate and total carbon in solutions

Abstract

estimating the intersection point and the positioning of the sample cell in the Dewar flask. It should be noted that the correction factors for tryptophan and tyrosine are 1.00 because the molar absorptivities are quite small at the wavelengths being used and the solutions are dilute.The measured intensity ratio of the two components of a mixture is a function of the wavelength of excitation, of the wavelength at which emission is measured, and of the sensitivity of measurement of the individual components. This assumes that the decay times of the two components are sufficiently different that an analytically useful logarithmic decay curve results. Note that the mixture of tryptophan-tyrosine is easily resolvable even though the ratio of decay times is only 4.6. The concentration ratio of the components in a two-component mixture can vary considerably if the analyst is willing to sacrifice sensitivity and accuracy of measurement of one or both of the components.Several other uses of the measurement system should be mentioned. Phosphorescence decay times greater than 0.2 second can be simply measured by measuring the slope of the logarithmic decay curve for the component in concern.It is also simple to check the purity of any phosphorescent molecule by verifying the linearity of the logarithmic decay curve. It should, however, be pointed out that non-exponential decays have been observed for some pure organic phosphors (8-10). For example, the authors have failed to obtain exponential decays for high purity benzyl alcohol and toluene in absolute ethanol.

A versatile method for the rapid and accurate determination of carbon by high temperature combustion1

“…Peak heights and areas per unit volume or weight of sample reached stable levels at temperatures above 900°C. These observations agree with the results of Van Hall et al (1963) for an aqueous solution of acetic acid. Thus small variations in the temperature of the furnace do not affect the results obtained by using combustion at 950°C.…”

“…Menzel and Vaccaro 1964) or high temperature combustion (e.g. Van Hall et al 1963;Armstrong et al 1971;Sharp 1973;Gordon and Sutcliffe 1973). Both dissolved and particulate organic carbon can be determined by wet combustion, but some doubt has been cast on the completeness of the oxidation (Sharp 1973).…”

“…If necessary, the tube can be cooled between the side opening and the furnace by evaporation of water from an asbestos line tied around the tube with its ends in a container of water. The gaseous products of combustion are carried by the flow of oxygen to a catalyst zone (cobalt oxide supported on long-fiber asbestos: Van Hall et al 1965) about 10 cm long, supported by platinum net rolls at both ends. The level of water vapor in the gas passing through the furnace is stabilized with a simple condenser (2'-5OC) which can be drained automatically through a constant level water lock.…”

“…High temperature combustion methods are usually designed for the determination of either dissolved (Van Hall and Stenger 1967;Gordon and Sutcliffe 1973;Sharp 1973) or particulate (commercial CHN analyzers) organic carbon. However, even these limited methods are susceptible to contamination, too time consuming, too insensitive, or require special skill for operation (see Wangersky 1975).…”

New techniques for analysis of organic pollutants in drinking water

“…In waters were developed to determine the total-organic carbon (TOC) In samples (3,4). More recently, methods have been developed to concentrate and determine the organic compounds present In drinking waters (5,6,7).…”