University of Salahaddin

College of Science
Department of Chemistry
Course Book
Instrumental Analysis for fourth Stage
M.Sc. in Chemistry
Ph.D. in Chemistry
Academic Year: 2010-2011
Assist. Prof. Dr. Kamal Mustafa Mahmoud
E-mail: dr.kamal@uni-sci.org
or kamal_k58@yahoo.com
Mob: +964 (0) 750 454 6198
(Academic Year 2010-2011)
 Grading
Number of Units = 8
Theory:
• Three term exams 20 points
• Quizzes 05 points
• Final exam 50 points

Practical:
• Term exam 10 points
• Oral Presentation & seminars 05 points
• Final exam 10 points
• Total (Theory + Practical) 100 points
 Course Program

• Ch. 1: Introduction to instrumental methods

• 1A: Terms associated with chemical analysis.
• 1B: Classification of instrumental techniques.
• 1C: General considerations in evaluating:
• Precision and Accuracy, Errors in
instrumental analysis, some statistical expressions,
• Sensitivity and Detection limits for
instruments, Signal to noise ratio, etc.
 Course Program
Ch. 2: Molecular spectroscopy:
2A: Properties of light, nature of electromagnetic radiation.
2B: Interaction between light and a mater.
2C: UV, Visible and IR spectroscopy; principles, techniques and applications.
2D: Beer's- Lambert law.
2E: Sensitivity enhancement by Beer's law.
2F: Instrumentation:
2F1: Radiation sources.
2F2: Cells and sampling devices.
2F3: Wavelength selectors, Filters and monochromators.
2F4: Detectors.
2F5: Readout modules.
2G: Deviation from Beer's law:
2G1: Instrumental deviations.
2G2: Chemical deviations.
2H: Turbidimetry and Nephelometry.
 Course Program
• Ch. 3: Molecular emission spectroscopy:
• 3A: Principles, Energy transition levels when a molecule
gains energy.
• 3B: Requirements for fluorescence:
• 3B1: Structural rigidity.
• 3B2: Temperature and solvent effects.
• 3B3: Effect of pH (Chemical quenching).
• 3B4: Instrumentation: Filter fluorimeter;
Spectrofluorimeter.
• 3C: Phosphorescence and Chemiluminescence's
spectroscopy; Theory, instrumentations and
• Applications.
 Course Program
Ch. 4: Atomic spectroscopy:
4A: Principles: Band spectra and line spectra.
4B: Atomic emission.
4C: Radiation sources:
4C1: Flame.
4C2: Electrical Arc and Spark.
4D: Flame photometry:
4D1: Flame, types of fuels and oxidants, flame zones.
4D2: Mixing of fuels and oxidants, total combustion method.
4D3: Instrumentation.
4E: Effect of Temp. in atomic absorption.
4F: Atomic absorption:
4F1: Flame, premixed type.
4F2: Radiation source in atomic absorption (H.C.L.).
4F3: Compares between flame photometry and atomic absorption.
4F4: Applications of flame photometry and atomic absorption:
4F4-1: Direct calibration.
4F4-2: Standard addition techniques.
4G: Interferences of atomic spectroscopy:
4G1: Spectral interferences.
4G2: Ionization.
4G3: Chemical reactions inside the flame.
4G4: Self absorption.
 Course Program
• Ch.5: Automatic and continuous methods of analysis:
• 5A: Importance of automatic analysis.
• 5B: Classifications.
• 5C: Continuous methods of analysis:
• 5C1: flow Injection analysis (FIA).
• 5C2: Continuous flow analysis (CFA).
•
• 5D: Flow injection analysis (FLA):
• 5D1: Instrumentation.
• 5D2: Dispersion.
• 5D3: Detectors.
• 5D4: Applications.
 Course Program
• Ch.6: Electrochemical methods of analysis:
• 6A: Potentiometric methods:
• 6A1: Oxidation- Reduction processes.
• 6A2: Electrochemical cells.
• 6A3: Reference electrodes.
• 6A4: Indicator electrodes.
• 6B: Voltammetry.
• 6C: Polarography.
• 6D: Conductometry.
• Ch.7: Nuclear and X-ray methods.
• Ch.8: Thermal methods of analysis.
 References:
1- Principles of Instrumental Analysis. By: Skoog.

2- Instrumental methods of Analysis. By: Willard et.al.

3- Instrumental analysis. By: Ewing.

4- Chemical Instrumentation. By: Strobel.

5- Fundamentals of Analytical Chemistry. By: Skoog and

West.

6- Undergraduate Instrumental Analysis. By: James W.

Robinson.
 Analytical Chemistry
Deals with methods for Identification of one or more of the
components in a sample of matter and the Determination of the
relative amounts of each.

Qualitative analysis “Identification” Quantitative

Classical: color, indicators, boiling points, odors. analysis
Instrumental: chromatography, electrophoresis, “Determination”
physical property (spectroscopy, electrode
potential)

Classical methods: mass or volume Instrumental techniques:

1. Gravimetric methods 1.Spectroscopy
2. Volumetric methods 2.Electrochemistry
3.Chromatography
 Distinction between Techniques and
Methods

• Techniques Methods Procedures

• Analytical Techniques: is a fundamental scientific

phenomenon that has proved useful for providing
information on the composition of substances.
• Analytical Methods: is a specific application of a
technique to solve an analytical problem.
 Types of Instrumental Methods:
• Property • Example Method
• Radiation absorption • Absorption spectroscopy
(photometry,
spectrophotometry, NMR, ESR)
• Radiation emission • Emission spectroscopy
(fluorescence, phosphorescence,
luminescence)
• Radiation scattering • Turbidity, Raman
• Radiation refraction • Refractometry
• Radiation diffraction • X-ray, electron
• Radiation rotation • Polarimetry
 Types of Instrumental Methods:
• Electrical potential Potentiometry
• Electrical charge Coulometry
• Electrical current Voltammetry- amperometry,
polarography
• Electrical resistance Conductometry
• Mass Gravimetry
• Mass-to-charge ratio Mass spectrometry
• Rate of reaction Stopped flow, FIA
• Thermal Thermal gravimetry, calorimetry

• Radioactivity Activation, isotope dilution

 How to choose an analytical
method?
• Speed
• Convenience
• Availability of equipment
• Number of analyses
• Amount of sample that can be sacrifice
• How reproducible? - Precision
• How close to true value? – Accuracy
• How small a difference can be measured? - Sensitivity
• What range of amounts? – Dynamic Range or linear range
• How much interference? - Selectivity
 Precision - Indeterminate or random
errors
This term is used to describe the reproducibility of the results

∑ (Xi - X-)2
Absolute standard deviation: s = √
N-1

Variance: S2
S

Relative standard deviation: RSD = ― x 100

X-

Standard deviation of mean: sm =

 Accuracy- Determinate errors
(personal, method, instrumental)
• It is refers to the closeness of a measurements to its
true or accepted values, Xt, and express in terms of
errors.
• Absolute error, E = Xi – Xt (Xi = observed or
experimental value; Xt = accepted or theoretical
value)
• Relative Error = Xi – Xt/ Xt X 100

• Recovery℅ = Amount found/ Amount taken X 100 or

= Xi / Xt x 100
 Sensitivity
• The sensitivity, S, of analytical method or instrument
may be defined as the ratio of the change in the
response, to the change of the quantity (i.e.
concentration);
d Signal
• S= c + Signalblank
dc
• Calibration sensitivity = mC + Signalblank

• Note: Larger slope of calibration curve m, more sensitive

measurement .
 Detection Limit
• Is the lowest concentration level that can be
determined to be statistically different from an
analyte blank.

• Minimum signal: Signalmin = Av. Signalblank + ksblank

( s is standard deviation of blank)

• From statistic, k = 3 or more (at 95% confidence

level)
• or D.L. = Blank read + 3s
 Dynamic Range
At detection limit we can say confidently
analyte is present but cannot perform reliable
quantitation.
Level of quantitation (LOQ): k=10
Limit of linearity (LOL): when signal is no longer
proportional to concentration.

LOL
Dynamic range: 10² to > 10⁶
LOQ
 Selectivity
No analytical method is completely free from interference
by concomitants. Best method is more sensitive to
analyte than interfering species (interferent).
Matrix with species A&B: Signal=mAcA + mBcB+ Signalblank
mB
Selectivity coefficient: kB,A=------
mA
k’s vary between 0 (no selectivity) and large number (very
selective).
 Calibration methods
Basis of quantitative analysis is magnitude of
measured property is proportional to
concentration of analyte
Signal α[x] or Signal =[x]+ Signalblank

Signal – Signal blank

[x]=
m
 Calibration curves (working or
analytical curves)
Dynamic Range
Instrument
Response LOQ o
(signal) o
DL LOL
o
o Slope m
o
Signalblank
[X]

Regression equation: y = a + m X
a = intercept = y- - mX-
m = slope = ∑ (Xi – X-)(yi –y-) ⁄ ∑ (Xi – X-)2
 Example :

0.0 (blank) 0.05

0.9 0.15
2.0 0.24
3.1 0.33
4.1 0.42

*ppm = μg per ml or mg per L

(μg ⁄ ml or mg ⁄ l)
 Define Variance and Covariance:
Σ (xi - x-)² Σ (x - x -)(y - y-)
Sxx= Sxy = i i
N–1 N–1
x = 2.02 y = 0.238

(2.02² + 1.12² + 0.02² + 1.08² + 2.08²) 10.828

Sxx = = =2.707
4 4

Sxy= (-2.02 х -0.188) + (-1.12 x -0.088) + (-2.02 x 0.002) +…

4
= 0.9562 = 0.23905
4
 Define Variance and Covariance:
Sxy
Slope: m = = 0.23905 =0.0883
Sx 2.707
b = y- – mx-

Intercept: = 0.238 - (0.0883´ 2.02)

= 0.0596

Calibration expression is

Absorbance = 0.0883[Analyte (ppm)] + 0.0596

The End of Lecture