Hitachi, Ltd.

Hitachi, Ltd. Hitachi Instrument Eng.

Seigo Kamitake

Konosuke Oishi

Yoshio Maeda

Koichi Matsumoto

Koichi Uchino

Hideo Yamada

Masao Hashimoto

An absorption profile indicative of a relation in atomic absorption spectroscopy between the absorbance of a desired element and time has a constant half-width independent of the concentration of the desired element in a sample, and hence the half-width of absorption profile with respect to the desired element can be previously determined from data which is obtained by the measurement of a standard sample. In an atomic absorption spectrophotometer herein disclosed, the half-width of absorption profile is previously determined in the above-mentioned manner, and the true peak value of an absorption profile obtained by measuring a sample which contains the desired element at a high concentration, is calculated using the time width of this absorption profile at a predetermined absorbance and the previously-determined half-width.

Atomic absorption spectrophotometer

Monochromatic light emitted from a monochromator is split into two light beams. These light beams are detected by a photodetector and converted into corresponding electric signals after having been transmitted, respectively, through a sample to be analyzed and a reference placed in the respective beam paths. The signal corresponding to the light beam transmitted through the sample and the signal corresponding to the light beam transmitted through the reference are converted into digital signals which are subsequently stored in respective digital storages or memories. The signal corresponding to the light beam transmitted through the reference is compared with a value in a predetermined range. The resultant value is then converted into an analog signal for operating a sensitivity regulator thereby to adjust the sensitivity of the photodetector. Thus, the signal corresponding to the light beam transmitted through the reference (reference light signal) is so controlled as to lie in a predetermined range. From the digital signals stored in the digital memory, ratio between the sample light signal and the reference light signal is arithmetically calculated by a digital processor unit for determining the transmittance of the sample. Since the reference light signal is prevented from significant variation and the calculation of the signal ratio is effected on the basis of digital technique, the measurement accuracy is remarkably enhanced.

Spectrophotometers with digital processing

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Katsuta, Japan

Seigo Kamitake