UV VIS Spectrophotometer Basic Theory - By Hengky Kusniar
ANALYTICAL CHEMISTRY
UV VIS SPECHTROPHOTOMETER
A. DATE
Wednesday, the 11th of May 2018
B. OBJECTIVES
To determine the concentration of Fe(II) in sangobion using UV VIS spectrophotometer
C. BASIC
THEORY
Iron in sangobion
can be found as Iron (II) gluconate C12H24FeO14, (Mr = 448,156 g/mol). The
basic principle to determine the concentration of Fe(II) in based on the
formation of colored complex of Fe(II) with orthofenantroline that can
optimally absorb visible light at 500 – 530 nm wavelengths. The amount of light
absorbed will be correlated with the quantity of analyte and it is accordance
with the Lambert-Beer Low.
A spectrophotometer is an instrument that measures the amount
of photons (the intensity of light) absorbed after it passes through sample
solution. With the spectrophotometer, the amount of a known chemical
substance (concentrations) can also be determined by measuring the
intensity of light detected. Depending on the range of wavelength of light
source, it can be classified into two different types:
·
UV-visible spectrophotometer: uses
light over the ultraviolet range (185 - 400 nm) and visible range (400 -
700 nm) of electromagnetic radiation spectrum.
·
IR spectrophotometer: uses
light over the infrared range (700 - 15000 nm) of electromagnetic radiation
spectrum.
In visible spectrophotometry, the absorption or the transmission of a certain substance can be determined by the observed color. For instance, a solution sample that absorbs light over all visible ranges (i.e., transmits none of visible wavelengths) appears black in theory. On the other hand, if all visible wavelengths are transmitted (i.e., absorbs nothing), the solution sample appears white. If a solution sample absorbs red light (~700 nm), it appears green because green is the complementary color of red. Visible spectrophotometers, in practice, use a prism to narrow down a certain range of wavelength (to filter out other wavelengths) so that the particular beam of light is passed through a solution sample.
D. REFERENCES
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