Abstract

The method of changing parameter in photometry has been introduced to allow the determination of a substance in the presence of a strongly interfering unknown matrix. The theory of this method is now discussed in detail. The discussion is illustrated by the case of the determination of calcium in a strongly interfering matrix of HCl and LaCl₃, using an atomic absorption flame photometer. The derivations are, however, general enough to apply to any photometric method, and even to some nonphotometric methods having the same formal dependence on a changing parameter. It is shown that a changing parameter can be sensitive enough to prove the existence of interference, while not being sensitive enough to evaluate such an interference. It is also shown that even a very considerable interference can be difficult to detect and to evaluate.

Standards for Photometry

G. A. W. Rutgers
Appl. Opt. 10(12) 2595-2599 (1971)

Optical properties of atmospheric particles: complete parameter sets obtained through polar photometry and an improved inversion technique

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Appl. Opt. 33(30) 7187-7199 (1994)

The Photometry of Solar Eclipse Phenomena

Clayton H. Sharp, S. McK. Gray, W. F. Little, and H. J. Eckweiler
J. Opt. Soc. Am. 23(7) 234-245 (1933)

The Beginnings of Photometry

W. E. Knowles Middleton
Appl. Opt. 10(12) 2592-2594 (1971)

Light Distribution Photometry in Japan

Y. Kurioka
Appl. Opt. 10(12) 2600-2606 (1971)