1.1 introduction of analytical chemistry

7/28/2019 1.1 Introduction of analytical chemistry

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ANALYTICAL CHEMISTRY(SSCK 1203)

Analytical Chemistry andInstrumentation Panel

Department of ChemistryFaculty of Science

UTMSkudai


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INTRODUCTION TO

ANALYTICAL CHEMISTRY(PART 1)

ANALYTICAL CHEMISTRY

- A branch of chemistry that deals withthe separation, identification &determination of analytes (components) ina sample

-It involves the application of a range oftechniques and methodologies to obtainand assess qualitative, quantitative andstructural information on the nature ofmatter.


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Clinical analysis

Analysis of blood, urine, feces, cellular fluids, etc (foruse in medical diagnosis)

Pharmaceutical analysisEstablishment of physical properties, toxicity,metabolites, quality control, etc (medicine/drugs)

AREAS OF ANALYTICAL CHEMISTRY

Environmental analysis

Monitoring of pollutants, soil and water analysis,pesticides, etc (environment quality) Forensic analysis

Analysis related to criminology, DNA finger printing,finger print detection, blood analysis (crime detectionand court testimonies)

Industrial quality controlRequirements of companies for product quality . Bioanalytical chemistry and analysis

Detection and/or analysis of biological components(eg proteins, DNA, RNA, carbohydrates, etc)


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ANALYTICAL CHEMISTS IN INDUSTRY - INTERFACES

Other

chemists

Colleges

Universities

Health&

Safety

Production

plants

Contract

labs

Management

Professional

organizations

StatisticiansGovernment

agencies

Engineers

Suppliers

Sales

&Marketing

Life

scientists

Technical reps

In field

Peers,

Supervisors

Lawyers

Analytical

chemist


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Attributes of a good Analytical Chemist

Knows and has skill in the methods and instrumentsused for analysis

Understands the principles of analysis (able to applyand modify analytical methods to solve a particularproblem)

Able to evaluate and interpret results of an analysis

Able to develop, validate, verify and apply newmethods of analysis

Validate: Prove that the method works and define itslimitations (ie. sample type, detection limits,

interferences, concentration, sensitivity, etc)Verify: Ensure that analysts are able to obtain correct

results using the method (in the laboratory)


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Analyte: the substance to be identified, detected, or

separated in some manner Sample : representative of the population or gross sample Matrix: all other constituents in a sample except for the

analyte

CHEMICAL ANALYSIS

QualitativeAnalysis

Instrumental& Chemical

methods

How much?What?

No obvious dividing line

Classical (Wet)Methods

InstrumentalMethods

An analysis to identifythe material(s) present

in a sample

An analysis to determinethe amount of a material is

present in a sample

QuantitativeAnalysis


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Quantitative Analysis

Complete Analysis - amount ofeach constituent of

the sample is determined Ultimate Analysis - amount ofeach element in a

sample is determined regardless of the actualcompounds present

Partial Analysis - amount of a certain selected

constituent in a sample is determinedClassification of constituents in a sample

Major (> 1%) Minor (0.11%) Trace (< 0.1%) Ultra trace (A few ppm or less)

What do these statements mean?? As in urine (0.1 ppm) ? Caffiene in coffee (10 %v/v)

? H2SO4 in rain (0.0001 M) ? Ca in mineral water (42 mg/L)

? Vitamin C in supplementary tablets (12 mg/tablet)


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(1) Gravimetric MethodsMeasure the mass of theanalyte or a compoundchemically related to the

analyte

(2) Volumetric MethodsMeasure the volume of asolution containingsufficient reagent to react

with the analyte (eg.titration, gas analysis)

Classical Methods (1) Separation/ChromatographicMethods

Measure the peak areas of theseparated components of a sample

(2) Spectroscopic MethodsMeasure the interaction betweenthe analyte and electromagneticradiation or the production ofradiation by an analyte

(3) Electroanalytical Methods

Measure an electrical property (egpotential, current, etc) which ischemically related to the amountof analyte

Instrumental Methods

Classification of Analytical Methods


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Separation of Analytes- Extraction, filtration,

distillation, Precipitat-ion, etc (Simple physicalprocedures)

Quantitative Analysis- Titration- Gravimetric analysis

Qualitative Analysis

- Boiling & Melting pt,color, odor, density,reactivity, refractiveindex, etc

Classical Instrumental

Separation of Analytes- Chromatography,

Electrophoresis- Spectroscopic separation

Quantitative Analysis- UV-Vis spectrometry- Atomic absorption spectro.- Atomic emission spectro.- Conductivity (pH, ISE)

Qualitative Analysis- X-ray spectrometry- Infrared spectroscopy (IR)- Mass Spectrometry (MS)- Nuclear magnetic resonance

Classification of Techniques


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Molarity (M) Formality (F) Normality (N) Molality (m) Part per thousand (ppt) Parts per million (ppm) Parts per billion (ppb) Percent concentration (%w/w, %w/v, %v/v)

EXPRESSIONS OF CONCENTRATION

Concentration is the amount of solute in aknown amount of solution

Concentration = Amount of soluteAmount of solution


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Molarity (M) = # moles solute# liters ofsolution

This unit describes what exists at equilibrium

Formality (F) = # moles solute# liters ofsolution

This unit describes how to make a solution, notwhat exists at equilibrium (aka analytical molarity)

Molality (m) = #moles of solute

#kilograms ofsolvent


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Eg. 0.100 N Na2CO3 solutionThe solution contains 0.100 equivalents Na2CO3

Rxn with H+ : CO32- + 2H+ H2O + CO21 L solution contains 0.1 equivalents Na2CO3

0.10 equivalent Na2CO3 0.050 mol Na2CO3

Normality (N) = # equivalents solute# liters of solution

Equivalents = Weight equivalent weightEquivalent weight = formula weight nwhere, n is the number of e or H+ ions or OH- ions

N = (Formality) x (#electrons transferred) or= (Formality) x (#H+ neutralized) or= (Formality) x (#OH- neutralized)


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Parts per thousand (ppt ) = g solute

103 g solution

Parts per million (ppm) = g solute

106 g solution(mg mL-1) = mg solute

Liter solution

For dilute aqueous solutions,1 ppm = 1 g solute 106 mL solution

= 1 g solute mL solution = 1 mg/L

Parts per billion (ppb) = g solute109 g solution

For dilute aqueous solutions,1 ppb = 1 g solute 109 mL solution

= 1 ng solute mL solution = 1 ng/L


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Weight percent = Weight of solute x 100%

(%w/w) Weight of solution Volume percent = Volume of solute x 100%

(%v/v) Volume of solution

Weight-volume = Weight of solute x 100%

(%w/v) Volume of solution

Commercial aqueous reagents are usuallysold in (%w/w)

Example: 37% is labeled on a HCl reagentbottle. This means that it contains 37 g HCl per100 g solution


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Density = mass of substance

volume of substance(g mL-1 is the most usual unit for density)

Specific Gravity= Mass of substance

Mass of equal volume of water

= Density of substanceDensity of water

Specific gravity is more often used incommercial reagents than density(The temperature must be specified)


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Example: Describe the preparation of 250mL of 0.100 M Na from reagent grade NaOH[Known MW: NaOH = 40, Na= 23.00]

1. Calculate the weight (g) of NaOH that isequivalent to the required moles of Na insolutionCalculations ???

PREPARATION OF SOLUTION

2. Weigh ??? g of solid (generally 0.1 mg,ie up to 4 decimal places in grams)

3. Dissolve in water, transfer (quantitativelywith rinsings) to a 250 mL volumetricflask, and dilute to the mark


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DILUTION OF SOLUTION

The moles solute in concentrated (1) solutionequals the moles in dilute (2) solution

M1 V1 = M2 V2

Example: Describe the preparation of50 mL of 0.100 M NaOH solution froma 0.5 molar solution

Calculations

How to ???Glassware requirement: ?? mL pipetand ?? mL volumetric flask

1.1 introduction of analytical chemistry

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