At present, in the world, it is generally divided into three types according to the instrument structure of the ultraviolet-visible spectrophotometer: single beam, double beam and double wavelength.

(1) Single beam spectrophotometer

Commonly used single-beam visible spectrophotometers are 721, 722, 723, 724, 727, etc. Commonly used ultraviolet-visible spectrophotometers are 751G, 752, 753, 754, and 756M. The Du70 and Pu8700 models abroad are also single-beam spectrophotometers *

Single beam refers to the light emitted from the light source, passing through the monochromator and other series of optical components, passing through the absorption cell, and finally shining on the detector, it is always a beam of light. It only has a monochromatic beam (the beam can only alternate through the reference solution and the sample solution), a cuvette, and a photoelectric converter. When working, a light path passes through the Dobby solution first, and then through the sample solution to measure the light intensity.

The single beam spectrophotometer is characterized by simple structure and low price, and is mainly suitable for quantitative analysis. The measurement result is greatly affected by the fluctuation of the power supply, and it is easy to bring large errors to the measurement result. Therefore, they are restricted in position. Generally speaking, it is not suitable to use single-beam ultraviolet-visible spectrophotometers in the pharmaceutical industry with higher requirements, quality inspections, etc.

(2) Dual-beam spectrophotometer

Common dual-beam UV-visible spectrophotometric juices are mainly 710, 730, 7MMc, 760cRT,

TYt880 type, TY8500 type, TU-1901 type, TU-1 coffee type, UVL2t0 type, UV / see -1 type, UY21 nagging type, t is L763 type, t positive / -2450 type, t eight / -3101 type, U-3400 type, Lambda9 blood type, Lilnbda9 type, CaV5 type, CgY6 coffee type, Cav500 type, etc.

The two-beam spectrophotometer is an ultraviolet-visible spectrophotometer with two monochromatic lights. Its optical path design is basically similar to the single-beam spectrophotometer. The difference is that a light cutter is added between the monochromator and the absorber. Its function is to divide a light beam into two Cambodian lights of equal intensity alternately at a certain frequency, so that one path passes through the reference solution and the other path passes through the sample solution. . The detector then alternately receives the reference signal and the sample signal. After the received optical signal is converted into an electrical signal, it is amplified by the preamplifier, and further demodulated, amplified, compensated, etc., and finally displayed by the display system. Its optical path system.

(3) Dual-wavelength spectrophotometer

The dual-wavelength spectrophotometer uses two monochromators, which can simultaneously obtain two monochromatic lights with different wavelengths, and its optical path. The light emitted by the light source is separated by the two monochromators to monochromatic light with wavelengths of 4: and 4z Through the chopper, the two beams of light are alternately irradiated to the same absorption cell containing the sample test solution at a certain time interval, and the detector shows the transmittance or absorbance of the test solution at wavelengths 4 and 42. The dual-wavelength spectrophotometer can not only measure high-concentration samples and multi-component mixed samples, but it is more sensitive and selective when determining turbid samples than single-wavelength determination. In dual-wavelength measurement, two wavelengths of light pass through the same absorption cell, pJ to eliminate errors caused by different absorption parameters, different positions, dirt, and preparation of reference solutions, which can significantly improve the accuracy of measurement.

Half Metal Ball Pens

Half Metal Ball Pens, Semi-metal Ball Point Pens

JNY International Trade Co., Ltd , http://www.jny-stationery.com