BY

S.MATHAN KUMAR

VMKVEC, SALEM

A = ε b c

A Æ absorbance (-)

ε Æ molar absorbtivity with units of L mol-1

cm-1

b Æ path length of the sample (cuvette)

c Æ Concentration of the compound in

solution, expressed in mol L-1

Transmittance, T = I / I0,

Absorbance,

Æ

%T = 100 T

A= log10 I0 / I

A= log10 1/T

A = 2 - log10 %T

•Amount of light that a sample absorbs.

•Beam of monochromatic light

•Measuring the intensity of light reaching a

detector

EFFECT S OF CONCENTRATION TRANSMISSION OF LIGHT SOURCE

ABS OF LIGHT

• Deviations in absorptivity coefficients at

high concentrations(> 0.01M) due to

electrostatic interactions.

• Scattering of light due to particulates in

the sample

• Fluoresecence or phosphorescence of the

sample

• Changes in refractive index at high analyte

concentration

• Non-monochromatic radiation

BIO CHEMISRTY ANALYS

CELL COUNTING(FLUROSCENCE COUNTING)

Electrolyte

Like

ISOTON III

Oscilloscope

Sensing Zone

Neutrophil

Cell Counting principle

Oscilloscope

Cross section of

RBC aperture

(60x50 micron)

Oscilloscope screen

RBCs

PLT

+ -

Lymp

Mono

Eos

Neut

Baso

ADC Signal Processor

Lamp

CHAMBER

Sample Sensor & PRE-AMP

Absorbance= log 10 ( VR / Vs ) Where VR = Reference voltage

Vs = Sample voltage

Derivation