Instrumental Analysis Dr. - PowerPoint Presentation

Slide1

Instrumental Analysis

Dr.

Hisham

E

Abdellatef

Instrumental analysis

The use of instrument

Instrumental analysis

Spectral

Measure

EMR

that is

Absorbed

Scattered

Emitted by analyte

electro-analytical Measure the electric properties of analyte Potentiometry Amperometry Conductometry Electrogravimetry Voltammetry Polarography Coulometry

SeparatoryHPLC GC Electrophosis ….

1. Spectral methods

Absorptiometry

Radio wave absorption (NMR)

Microwave absorptiometry

Thermal

absorptiomety

(thermal analysis)

IR

UV-

visibble

X-ray absorptiometry

At least 4 main components

Source of EM

radation

Monochromator

(filter, prism or grading to emit narrow wavelength band)

Cell that contain the sample

Detector measure the intensity of radiation after passing to sample

1- Nuclear magnetic resonance (NMR)

Absorption of energy in radio frequency region is sufficient to cause a spinning nucleus in some atoms to move to a different spin state in the presence of magnetic field

NMR give information about the nature of each type of

hydrogen

and the type of environment each of these types of hydrogen Can be used to deduce the number and types of different nuclei of the groups attached to the atom containing the nucleus studied. (Qualitative analysis)

Low resolution

High resolution

2- Thermal analysis

Thermal

analysis is used to characterize materials by measuring physical and reactive properties as a function of temperature.  Temperature range becomes one of the most important criteria. 

Used for: Quantitative and qualitative analysis

Decomposition mechanisms of the

analyte

3- Infrared spectrometry

IR radiation Cause

rotation and vibration changes Function group analysis = qualitative analysis

Ethyl Alcohol C2

H

6

O

Dimethyl

Ether C

2

H6O

Factors affecting atom vibration Type of bond , C- C , C=C , C≡C

Type of atoms attached to carbon C- H, C-C, C-I

Hyperdization Sp, Sp2, Sp3Conjugation , lead to decrees in frequency

4000-1000

cm-1 known as the functional group region, and

<

1000 cm-1 known as the fingerprint region

4- U.V – Visible spectrophotometry

Electron absorb energy and transferred to higher level

used for quantitative analysis of atoms or molecules

Effect

of substitution on light absorption

pH of the solvent

Temperature

Reagent concentration

Reaction time

Stability of the reaction product

Factors affecting light absorption

Solvent

0.1 M

HClMethanol 0.1 M NaOH Maximum absorption

240 247265

642

652

710

ɛ

9710

12850

10740

Solvent 0.1 M HClMethanol 0.1 M NaOH

Maximum absorption 240 247265 642652

710ɛ9710

1285010740

5. X-ray absorption

X- ray cause excitation of electrons from

inner orbital (near the nucleus) to unoccupied outer orbital.Energy of x-ray is sufficient to ionize the analyte. (remove the electron from atom or molecule) give information related to

atoms not molecule.Qualitative analysis

X-ray Processes: when an X-ray strikes an atom…

Application

X- ray microscopic analysis : X- ray fluorescence X-ray photoelectron spectroscopy :(XPS) measure empirical formula, chemical state

and electronic state of the elements

2. Scattered radiation

Tyndall Scattering

Raman and Rayleigh spectroscopy

Tyndall

Used to determine

size and density of particles in colloids It cause reflection of incident radiation from the surface of the particles

Ultramicroscope

Raman and Rayleigh spectroscopy

Occur when

dimension of scattering particles are less than 5% of the wavelength of the incident radiationThe light scattered from a molecule changed based on the structural characteristics of the molecular bondsRoman spectroscopy is used to detect high frequency phonons,

magnons and electronic excitation

The detector respond to

decease the intensity of the incident

radiation = Turbidimetry The measurement is analogous to absorption measurements

Turbidimetry

If the intensity of the

scattered radiation

is measured =

nephelometry

Differ in placement of the detector

Both are used with Tyndall to quantitative assay turbid solution

Refractometry

Used to measured the RI (composition and purity of the substance)