1. Introduction: Analytical Chemistry
NURSAKINAH MAT HAZIR

2. OUTLINE OF CHAPTER Types & Steps in analysis
Review the terms: Moles, molarity and concentration.
Review other forms of expressing concentration
i) ppm
ii) ppt
iii) ppb
iv) %(w/w)
v) %(w/v)
vi) %(v/v)

3. What is Analytical Chemistry?
“Analytical Chemistry is what analytical
chemists do.”
--- C. N. Reilley
Chemical analysis is more than just detecting or determining the general composition or a specific component of a sample.
It is the resolution or interpretation of a given problem.

4. What is Analytical Chemistry?
Chemical analysis
determination of the chemical composition or chemical make up as well as the quantity of each composition presence in a sample
E.g: The chemical analysis of a blood sample involves the determination of its iron content, its alcohol content, or perhaps its drug content as well as how much each of the composition presence in the blood sample.
E.g: The chemical analysis of a water sample involves the determination of its mineral content, its pollutant content, and its dissolved oxygen content and the percentage of each constituents.

5. What is actually involve in CHEMICAL ANALYSIS?
Chemical analysis procedures involve two areas; the GOAL of the analysis and the METHOD used in the analysis.
The GOAL of the analysis can be classified into QUALITATIVE or QUANTITATIVE analysis:
QUALITATIVE: Analysis conducted to identify what are the constituents present in the sample (identification of the sample component)
QUANTITATIVE: Analysis to determine how much of each constituent present in the sample.

6. 􀂾 Qualitative Analysis
determination of chemical identity of the species
􀂾 Quantitative Analysis
determination of the amount of species or analytes, in numerical terms. Hence, Math is heavily involved.
􀀹 In order to perform quantitative analysis, typically one needs to complete qualitative analysis.
􀀹 One needs to know what it is and then select the
means to determine the amount

7. Qualitative analysis is what. Quantitative analysis is how much.
©Gary Christian, Analytical Chemistry, 6th Ed. (Wiley)

8. WHAT HAPPEN TO OUR RIVER?

9. Why it is important?
Analytical chemists must use a systematic approach to obtain the required information from samples.
This approach consists of a series of steps and processes.
Let we see the step in analytical analysis.

10. Step in chemical analysis….
NOV 2005
Understanding and defining the problem
Familiarize with background of problem and history of sample
Literature search
(selecting the analytical procedures)
Sampling
(obtain and store sample)
Preparation and pretreatment of sample

11. Analysis (perform measurement and compare results with standards)
Apply required stastitical tecniques
Verify results
Reporting

12. 1. Understanding and Defining Problem
The goal of every chemical analysis is to obtain the required information within a period of time acceptable to the customer.
Many problem do not require complete identification and many cases require only a general classification.
It is important for the analyst to determine the information required by the client.
For example, in water analysis, only the total hardness is required rather than the concentration of individual Ca2+ and Mg2+ ion concentration is not necessary.

13. 2. Sample History and Background of the Problem
Should know the origin of the sample.
Sample history include information on how, where, and when the sample were collected, transported and stored.
Analyst will use the sample history to maximize advantage in solving the problem.

14. 3. Literature Search
Literature search is essential to find an appropriate procedures.
Patents or commercial literature usually help in determination of the composition of industrial materials.
Others:
- book
- review articles
- standard organization :
i) Association of official Analytical Chemists (AOAC)
ii) Food and Drug Administration (FDA)
- electronic media

15. 4. Sampling
APR 2007
OCT 2007
Definition: Process of selecting representative material from the lot and storing the sample.
The suitable sampling method differ from one substance to another depending on homogeneity.
Homogeneous: Substance that has the same composition throughout the sample.
Heterogenous: Substance that has different composition from one reagent to another reagent.
Proper procedure must be used to store both samples and standards.
All sample must be properly labeled and recorded.

16. 5. Sample Preparation and Pretreatment
APR 2007
Step of sample preparation involved bulk materials:
1. Bulk sample must be reduced in size to obtain a laboratory sample of several grams.
2. From which a few grams to milligrams will be taken to be analyzed (analysis sample).
3. The size reduction may require taking portions (eg, two quarters) and mixing, in several steps, as well as crushing and sieving to obtain a uniform powder
for analysis.

17. Why sample pretreatment is important?
Laboratory samples are often subjected to physical or chemical pretreatment where it is converted to a form that is suitable for the measurement.
During pretreatment:
i) reduce and remove interferences
ii) adjust analyte concentrations to a range suitable for measurement
iii) produce species from analyte that have quantitatively measurable properties.

18. 6. Analysis
Analysis: Incorporates the measurement of the concentration of the analyte in replicates and comparing with standards.
Replicate measurement: the practice of taking multiple readings.
The replicate measurements are necessary to obtain the measurement uncertainty.
The uncertainty important as it indicates the reliability of the measurements.

19. ii) EXTERNAL STANDARDIZATION iii) INTERNAL STANDARDIZATION
Suitable standardization methods should be selected to ensure the precision and accuracy of results.
i) CALIBRATION CURVE – A graph of detector response as a function of analyte concentration.
ii) EXTERNAL STANDARDIZATION
iii) INTERNAL STANDARDIZATION
iv) STANDARD ADDITION - Addition of a known quantity of analyte to a real sample undergoing analysis.
v) BLANKS – A blank contains the reagents and solvents use in analysis, but no analyte.
vi) CONTROL CHARTS
APR 2006

20. 7. Reporting and Interpretation
Deliver a clearly written, complete report and their limitations.

21. HOMEWORK Turn to page 17 (Analytical Chemistry, 5th Ed. Gary
D. Christian, Wiley, New York, 1994.) and please answer
all questions.
This is your tutorial question !!! It not required you to
Submit this homework to me…. But if I ask you to explain
Later on.. I do hope you can… thank you.

22. PREFIX NOTATION
Main measures such as gram and meter are given prefix number for the power of ten.
Exponential
Prefix name
Symbol
1012
tera T
109
giga G
106
mega M
103
kilo k 10 -
10-1
deci d
10-2
centi c
10-3
milli m
10-6
micro
10-9
nano n
10-12
pico p

23. CONCENTRATION UNITS
Concentration : the quantity of solute in a specified volume or mass of solution or solvent.
The concentration of solutes can be expressed in various ways.
Name
Component measured by
Total sample measured by
Abbreviation
Units used
Molarity
Number
Volume M
Mol L-1
Molality
Weight m
Mol kg-1
Percent composition
Weight-to-weight
w/w
%(w/w)
Weight-to-volume
w/v
%(w/v)
Volume-to-volume
v/v
%(v/v)

24. DEFINITION Molarity (M) : No of moles of the solute in 1L of solution.
M = no.mol solute
no.L solution
Molality (m) : No of moles of the substance per kilograms of the solvent.
m = no.mol solute
kg solution

25. Continued…. Analytical molarity Species molarity
There are 2 versions of molarity
Analytical Molarity: The total number of moles of the solute in 1L of solution.
For example, a HCl solution that has an analytical concentration of 1.0 M can be prepared by dissolving 1.0 mol or 36.5 g of HCl in water and diluting to exactly 1.0 L.
Species Molarity (Equilibrium molarity) : The number of moles of a particular species in 1L of a solution at equilibrium.
The concentration unit is usually written in bracket, [H+],means the concentration of H+.
Species molarity

26. Continued…. Species Molarity
For example, the species molarity of HCl in a solution with an analytical molarity of 1.0M is 0.0 M because HCl is entirely ionized into H+ and Cl- ions and essentially no HCl molecules as such present in the solution.
CHCl = M
[HCl] = M
[H+ ] = M
[Cl-] = M

27. You should calculate this…….
What is the molarity of a solution of 0.60 g NaCl in 100 mL of solution?
Given, MW NaCl = 58.5g/mol.

28. Example: Saline water concentration
Typical seawaters contain sodium chloride, NaCl as much as 2.7 g per 100 mL. (a) What is the molarity of NaCl in the saline water ? (b) The MgCl2 content of the saline water is M. Determine the weight (grams) of MgCl2 in 50 mL of the saline water ?

29. Solution: (a) What is the molarity of NaCl in the saline water ?
MW of NaCl = = g/mol
No.of mol of NaCl in 100 mL saline water = 2.7 g
58.44 g/mol
= mol
Molarity of saline water = no.mol = mol = 0.46 M
L (100/1000) L

30. Continued……….
(b) The MgCl2 content of the saline water is M. Determine the weight (grams) of MgCl2 in 50 mL of the saline water ?
MW of MgCl2 = (35.45) = g/mol
Weight of in 50 mL of saline water
= (M x V) x MW
= M x (50/1000) x g/mol
= 0.26 g

31. DEFINITION
Weight percent, %w/w = mass of solute x weight of solution
Volume percent, %v/v = volume of solute x volume of solution
Volume percent, %w/v = mass of solute x volume of solution

32. DEFINITION
Parts per million (ppm) is grams of solute per million grams of total solution.
ppm = mass of solute x
mass of solution
Parts per billion (ppb) is grams of solute per billion grams of total solution.
Parts per trillion (ppt) is grams of solute per trillion grams of total solution.

33. Common unit to express content
Expression
Abbreviation
Units
w/w
w/v
v/v
Parts per million
ppm
µg/g
µg/mL
nL/mL
mg/kg
mg/L
µL/L
Parts per billion
ppb
ng/g
ng/mL
nL/L
µg/kg
µg/L

34. Example: Percent Composition
A solution contains KI per liter solution. Calculate the concentration in
% (w/v)
% (w/w)
Given the density of the solution at 25oC is g/mL.

35. Solution……
(a) Volume percent, % (w/v) = mass of solute x volume of solution
= g x
1000 mL
= 11.85% (w/v)
(b) weight percent, % (w/w) = mass of solute x weight of solution
= g x 1mL x
1000 mL g
= 10.99% (w/w)

36. Example: Conversion of ppb to molarity
An aqueous solution contains 56 ppm SO2. Calculate the molarity of the solution.
Solution:
MW of SO2 = (16) = 64 g/mol
56 ppm = 56 mg/L = (56 x 10-3 g / 64 gmol-1)/L solution
= 8.75 x 10-4 M