This document presents an overview of fluorimetry. It discusses that fluorimetry is the measurement of emitted fluorescence light. When certain substances are exposed to light, they emit visible light or radiation, known as fluorescence. Fluorescence occurs immediately after light absorption and stops when the light is removed. Phosphorescence is delayed fluorescence that continues after light removal. Fluorimetry works by exciting substances from their singlet ground state to a singlet excited state, then measuring the wavelength of light emitted as they return to the ground state.

1. PRINCIPLES OF
FLUORIMETRY
PRESENTED BY:
ANJALI RARICHAN
FIRST YEAR M.PHARM
DEPT. OF PHARMACY
PRACTICE
GRACE COLLEGE OF
PHARMACY

2. FLUORIMETRY
 Fluorimetry is defined as the measurement of
the emitted fluorescence light.

3.  When a beam of light is incident on certain
substances they emit visible light or
radiations. This is known as fluorescence.
 Fluorescence starts immediately after the
absorption of light and stops as soon as the
incident light is cut off.
 The substances showing this phenomenon
are known as fluorescent substances.

4.  When light radiation is incident on certain
substances they emit light continuously even
after the incident light is cut off.
 This type of delayed fluorescence is called
phosphorescence.
 Substances showing phosphorescence are
phosphorescent substances.

5. PRINCIPLE
 Fluorescence is the phenomenon of emission
of radiation when there is transition from
singlet excited state to singlet ground state.
 Wavelength of absorbed – Excitation
wavelength.
 Wavelength of emitted – Emission
wavelength.
 These two are specific for a given substance
under ideal condition.

6. VARIOUS ELECTRONIC STATES IN
FLUORIMETRY
 Singlet ground state : A state in which
all electrons in a molecule are paired.
 Doublet state : A state in which
unpaired electrons is present.
 Triplet state : A state in which unpaired
electrons of same spins present.
 Singlet excited state: A state in which
electrons are unpaired out of opposite
spin.

7.  To achieve transition from excited state to
ground state there are the possibilities:
 Collisional deactivation : in which the entire energy is
lost due to collisional deactivation and no radiation is
emitted.
 Fluorescence : Apart of energy is lost due to vibrational
transition and the remaining energy is emitted as uv/visible
radiation of longer wavelength .
 Phosphorescence : The emission of radiation when
electrons undergo transition from triplet state to ground
state.
 Intersystem crossing : At favourable conditions like low
temperature and absence of oxygen there is transition from
excited state to triplet state.

8. JABLONSKI DIAGRAM

9. EXAMPLES OF FLUORESCENT
SUBSTANCES
 Organic solutions such anthracene or stilbene dissolved
in benzene or toluene
 Calcite, Rubies, Emeralds, Diamonds. willemite, esperite,
uranium, uranyl cation, autunite or andersonite, and, hyalite
opal, ruby,europium.
 Atmospheric aurora.
 Common materials that fluoresce
 Vitamin B2 fluoresces yellow.
 Tonic water fluoresces blue due to the presence of quinine.
 Highlighter ink is often fluorescent due to the presence of pyranine.
 Banknotes, postage stamps and credit cards often have fluorescent
security features.

10. • V
COMMENT ON THERAPY