Atomic emission characteristics of a premixed acetylene-nitrous oxide, total consumption flame.
It is well known that most of the burners presently used to produce high temperature, premixed flames have the tendency to be discouragingly wasteful of the sample solution, often bringing only a small fraction of the amount used into the flame. This paper reports on the construction and performance of a highly efficient total consumption burner that produces a nonturbulent acetylene-nitrous oxide flame from premixed gases. The eighteen flame emission detection limits tabulated for a select group of elements compare favorably with the best values heretofore reported in the literature, and the apparent freedom of alkaline earth emission from phosphate interference indicates the total consumption flame here described to be less subject to chemical interference than is the conventional diffusion flame. The relatively low cost burner that has been developed is convenient to operate and can be quickly assembled from commercially available components.
Recent Trends in Analytical Atomic Absorption Spectroscopy
Atomic absorption spectroscopy is reviewed especially as to the effect of developments in the past few years on analytical applications. Sources and sampling devices are given special attention. Atomic absorption, flame emission, and atomic fluorescence are compared as to their detection limits and their applicability to analysis. It is shown that the three methods are in many ways complementary rather than competing. The potentialities of resonance spectroscopy are examined and instrument systems utilizing resonance methods are described.
On value preserving and growth optimal portfolios
Abstract. In a discrete-time financial market setting, the paper relates various concepts introduced for dynamic portfolios (both in discrete and in continuous time). These concepts are: value preserving portfolios, numeraire portfolios, interest oriented portfolios, and growth optimal portfolios. It will turn out that these concepts are all associated with a unique martingale measure which agrees with the minimal martingale measure only for complete markets.