Abstract

An automatic photoelectric analyzer, the counterpart of infrared process-stream analyzers, has been developed for recording the concentration of an ultraviolet-absorbing component in a nonabsorbing mixture of liquids or gases. Radiation sources, filters, and phototubes are interchangeable to provide various monochromatic radiations, or a simple monochromator can be attached to provide any wavelength from 220 to 1200 mμ. The concentration range of the analyzer can be selected by choice of interchangeable cells of lengths from 0.001 to 7.5 in., and by choice of shutters of various absorbance ranges in an optical balancing system. The absorbance range is usually restricted to values between 0.01 and 0.2. Sustained high accuracy is achieved by employing a ratio-detecting, phototube bridge circuit that eliminates erroneous readings caused by source fluctuations, and by employing an automatic standardizing system that periodically restores the initial calibration of the instrument and compensates for drift caused by fouling of windows of the sample cell and for other commonly encountered drifts. High concentrations, on the one hand, or concentrations in parts per million, on the other, can be recorded, and several typical applications are listed.

© 1955 Optical Society of America

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References

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  1. L. G. Glasser, J. Electrochem. Soc. 97, 201C (1950).
    [Crossref]
  2. N. M. Mohler and J. R. Loofbourow, Am. J. Phys. 20, 499 and 579 (1952).
    [Crossref]
  3. L. G. Glasser and D. J. Troy, J. Opt. Soc. Am. 42, 652 (1952).
    [Crossref]
  4. H. H. Landolt and von R. Börnstein, Physikalisch-chemische Tabellen, (Julius Springer, Berlin, 1923), fifth edition, Vol. 2, p. 893.
  5. International Critical Tables (McGraw-Hill Publishing Company, Inc., New York, 1929), Vol. 5, 268 and 326.
  6. Catalog of UV Spectrograms, American Petroleum Institute, Res. Proj. 44, Carnegie Institute of Technology, Pittsburgh, Pennsylvania.
  7. R. A. Friedel and M. Orchin, Ultraviolet Spectra of Aromatic Compounds (John Wiley and Sons, Inc., New York, 1951).

1952 (2)

N. M. Mohler and J. R. Loofbourow, Am. J. Phys. 20, 499 and 579 (1952).
[Crossref]

L. G. Glasser and D. J. Troy, J. Opt. Soc. Am. 42, 652 (1952).
[Crossref]

1950 (1)

L. G. Glasser, J. Electrochem. Soc. 97, 201C (1950).
[Crossref]

Börnstein, von R.

H. H. Landolt and von R. Börnstein, Physikalisch-chemische Tabellen, (Julius Springer, Berlin, 1923), fifth edition, Vol. 2, p. 893.

Friedel, R. A.

R. A. Friedel and M. Orchin, Ultraviolet Spectra of Aromatic Compounds (John Wiley and Sons, Inc., New York, 1951).

Glasser, L. G.

Landolt, H. H.

H. H. Landolt and von R. Börnstein, Physikalisch-chemische Tabellen, (Julius Springer, Berlin, 1923), fifth edition, Vol. 2, p. 893.

Loofbourow, J. R.

N. M. Mohler and J. R. Loofbourow, Am. J. Phys. 20, 499 and 579 (1952).
[Crossref]

Mohler, N. M.

N. M. Mohler and J. R. Loofbourow, Am. J. Phys. 20, 499 and 579 (1952).
[Crossref]

Orchin, M.

R. A. Friedel and M. Orchin, Ultraviolet Spectra of Aromatic Compounds (John Wiley and Sons, Inc., New York, 1951).

Troy, D. J.

Am. J. Phys. (1)

N. M. Mohler and J. R. Loofbourow, Am. J. Phys. 20, 499 and 579 (1952).
[Crossref]

J. Electrochem. Soc. (1)

L. G. Glasser, J. Electrochem. Soc. 97, 201C (1950).
[Crossref]

J. Opt. Soc. Am. (1)

Other (4)

H. H. Landolt and von R. Börnstein, Physikalisch-chemische Tabellen, (Julius Springer, Berlin, 1923), fifth edition, Vol. 2, p. 893.

International Critical Tables (McGraw-Hill Publishing Company, Inc., New York, 1929), Vol. 5, 268 and 326.

Catalog of UV Spectrograms, American Petroleum Institute, Res. Proj. 44, Carnegie Institute of Technology, Pittsburgh, Pennsylvania.

R. A. Friedel and M. Orchin, Ultraviolet Spectra of Aromatic Compounds (John Wiley and Sons, Inc., New York, 1951).

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Figures (9)

Fig. 1
Fig. 1

Automatic photoelectric analyzer.

Fig. 2
Fig. 2

Schematic diagram of automatic photoelectric analyzer.

Fig. 3
Fig. 3

Automatic photoelectric analyzer showing removable subassemblies.

Fig. 4
Fig. 4

Light gate subassembly. The cam on the right in the analytical beam provides an absorbance range of 0.168.

Fig. 5
Fig. 5

Response of a type 935 phototube to the energy transmitted by a filter comprising 1 cm of 800 g/l NiCl2 in H2O, Corning Glass Code Nos. 9863 and 5330.

Fig. 6
Fig. 6

Change in absorbance of glass plate light gate in unpolarized light vs angle of incidence.

Fig. 7
Fig. 7

Various types of sample cells. Lower left: thin cell, 0.001-0.250 in., employing shim stock as a window spacer. Upper left: 1 2 -in. cell for cold samples, employing double windows, and dry-gas blanketing. Upper right: 1 1 2 -in. cell. Lower right: low-volume cell employing rectangular glass tubing.

Fig. 8
Fig. 8

Variation of sensitivity of ratio-detecting phototube bridge with applied potential using type 935 phototubes and 405-mμ wavelength.

Fig. 9
Fig. 9

Analyzer application nomograph for liquids, gases and vapors. Indicates the concentration that will read full scale on an analyzer whose absorbance range is A, and cell length in cm is b, for various values of absorptivity (molecular extinction coefficient). Concentration ranges for liquids, in units of percent/wt, are approximations obtained by multiplying the reading of gas concentration by 4.1×10−5 M/ρ, where M is the molecular weight of the analyzed component, and ρ is the density of the solution. To convert concentrations in mole/l to percent by volume at 760 mm Hg pressure and 25°C, multiply by 2540.

Tables (1)

Tables Icon

Table I Filter combinations for isolating spectrum lines of mercury arcs (for use with an ultraviolet-sensitive Type 935 phototube).