CHAPTER ONE
AN INTRODUCTION TO SPECTROSCOPIC METHOD OF ADDITIONAL NOTE
ANALYSIS
Spectrophotometer and Beer-Lambert Law
PROPERTIES OF ELECTROMAGANIC RADIOATION
Electromagnetic (EM) radiation is light, Whereby, consist of electric wave
and magnetic wave perpendicular with each other
Properties of EM are frequency, ν (Hz, s-1), wavelength, λ (cm-1) and
velocity, c (ms-1). The velocity of EM is 3.0 x 108 m/s. Similar to wave.
c = νλ
The elementary particle of EM is known as photon. Thus, EM is not
continuous but discrete. Each photo carries a pack of energy (∆E).
ℎ𝑐
∆E = hν = 𝜆
and h is Planck Constant, 6.63 x 10-34 Js
Other properties of EM are Reflection, Refraction, Diffraction and
Deflection
ELECTROMAGENIC SPECTRUM
, SPECTROSCOPIC MEASSUREMENT
Spectroscopy is the study of any compound interact with EM and the
interaction is interpreted for quantitative or qualitative measurement.
Spectrometer is the instrument use spectroscopic principle to analyze and
substance. The principle is based on Beer-Lambert Law
BEER – LAMBERT LAW
The Theory
The Law the amount of EM absorb (absorbance, A) by any chemical
system is proportional to the solution’s molar absorptivity, the
concentration of solute and pathlength travel by EM in the solution.
𝐴 = 𝜀𝑏𝑐
A is absorbance (no units), which is the amount of EM is absorbed by the
substance.
ε is the molar absorptivity with units of L mol-1cm-1 (formerly called the
extinction coefficient)
b is the path length of the sample, usually expressed in cm
c is the concentration of the compound in solution, expressed in mol L-1.
However, spectrometer does not measure the absorbance directly. Its use
the transmittance, T. By definition, T is the amount of light that
“successfully” passes through the substance and comes out the other side.
𝐼 𝐼
𝑇 = 𝐼 , or %𝑇 = 𝐼 𝑥 100
0 0
Io is the incident EM and I is the transmittance EM
The relationship between A and T is
1 𝐼0
𝐴 = 𝑙𝑜𝑔10 = 𝑙𝑜𝑔10
𝑇 𝐼
𝐼0
𝜀𝑏𝑐 = 𝑙𝑜𝑔10
𝐼
Unfortunately, Beer-Lamber Law has its limitation. The correct term is
Beer-Lamber Law Deviation. The deviation means the standard calibration
will deviate from straight line. There are three reasons for this deviation.
First is concentration. This is the fundamental limitation, where the sample
concentration must be very low. I f not the individual particles of analyte
AN INTRODUCTION TO SPECTROSCOPIC METHOD OF ADDITIONAL NOTE
ANALYSIS
Spectrophotometer and Beer-Lambert Law
PROPERTIES OF ELECTROMAGANIC RADIOATION
Electromagnetic (EM) radiation is light, Whereby, consist of electric wave
and magnetic wave perpendicular with each other
Properties of EM are frequency, ν (Hz, s-1), wavelength, λ (cm-1) and
velocity, c (ms-1). The velocity of EM is 3.0 x 108 m/s. Similar to wave.
c = νλ
The elementary particle of EM is known as photon. Thus, EM is not
continuous but discrete. Each photo carries a pack of energy (∆E).
ℎ𝑐
∆E = hν = 𝜆
and h is Planck Constant, 6.63 x 10-34 Js
Other properties of EM are Reflection, Refraction, Diffraction and
Deflection
ELECTROMAGENIC SPECTRUM
, SPECTROSCOPIC MEASSUREMENT
Spectroscopy is the study of any compound interact with EM and the
interaction is interpreted for quantitative or qualitative measurement.
Spectrometer is the instrument use spectroscopic principle to analyze and
substance. The principle is based on Beer-Lambert Law
BEER – LAMBERT LAW
The Theory
The Law the amount of EM absorb (absorbance, A) by any chemical
system is proportional to the solution’s molar absorptivity, the
concentration of solute and pathlength travel by EM in the solution.
𝐴 = 𝜀𝑏𝑐
A is absorbance (no units), which is the amount of EM is absorbed by the
substance.
ε is the molar absorptivity with units of L mol-1cm-1 (formerly called the
extinction coefficient)
b is the path length of the sample, usually expressed in cm
c is the concentration of the compound in solution, expressed in mol L-1.
However, spectrometer does not measure the absorbance directly. Its use
the transmittance, T. By definition, T is the amount of light that
“successfully” passes through the substance and comes out the other side.
𝐼 𝐼
𝑇 = 𝐼 , or %𝑇 = 𝐼 𝑥 100
0 0
Io is the incident EM and I is the transmittance EM
The relationship between A and T is
1 𝐼0
𝐴 = 𝑙𝑜𝑔10 = 𝑙𝑜𝑔10
𝑇 𝐼
𝐼0
𝜀𝑏𝑐 = 𝑙𝑜𝑔10
𝐼
Unfortunately, Beer-Lamber Law has its limitation. The correct term is
Beer-Lamber Law Deviation. The deviation means the standard calibration
will deviate from straight line. There are three reasons for this deviation.
First is concentration. This is the fundamental limitation, where the sample
concentration must be very low. I f not the individual particles of analyte
