[1S] UNIT 4 Analytical Techniques & Automation

Four Major Disciplines of Analytic Techniques

Is the distance between 2 successive peaks and it is expressed in terms of nanometer (nm)

<400 nm = 400-700 nm = >700 nm =

The longer the wavelength, the ___________ the energy

The higher the frequency, the _______ the energy

Planck’s formula

BEER’S LAW Concentration of the unknown substance is ________ ________ to the absorbed light (absorbance or optical density) and ________ ________ to the amount of transmitted light.

T/F: A solution transmits light corresponding in wavelength to its color, and usually absorbs light of wavelengths complementary to its color

Which wavelength would be absorbed strongly by a yellow-colored solution? a. 450 nm c. 600 nm b. 585 nm d. 650 nm

A blue-colored solution would show highest transmittance at: a. 475 nm c. 585 nm b. 525 nm d. 620 nm

Parts of the Spectrophotometer

Parts of the Spectrophotometer

LIGHT SOURCE: CONTINUUM SOURCE Tungsten

LIGHT SOURCE: CONTINUUM SOURCE Deuterium & Xenon

LIGHT SOURCE: LINE SOURCE Mercury-vapor lamps

Which of the following light source provides wavelengths of light that fall under the infrared region? a. Mercury b. Xenon c. Deuterium d. Silicon Carbide

Which of the following light source provides wavelengths of light that fall under the infrared region? a. Mercury b. Xenon c. Deuterium d. Silicon Carbide

PARTS OF SPECTROPHOTOMETER Minimizes unwanted stray of light Prevents entrance of scattered light on the monochromator system

ENTRANCE SLIT • Any wavelength outside the band transmitted by the monochromator • Causes absorbance error

ENTRANCE SLIT • Limits the maximum absorbance that a spectrophotometer can achieve • Most common cause of lost linearity at high analyte concentration

PARTS OF SPECTROPHOTOMETER It isolates specific or individual wavelength of light

PARTS OF SPECTROPHOTOMETER Kinds of Monochromator

PARTS OF SPECTROPHOTOMETER Controls the width of the light beam (bandpass)

PARTS OF SPECTROPHOTOMETER Furthermore, a bandpass can be described as the ________________.