ERT 207 ANALYTICAL ERT 207 ANALYTICAL CHEMISTRYCHEMISTRY

Alina Rahayu MohamedPPK Bioproses

Universiti Malaysia Perlis

Lecture 17th July 2008

1.INTRODUCTION

Topics to be covered:1.1 INTRODUCTION TO METHODS IN

ANALYTICAL CHEMISTRY1.2 STEPS IN QUANTITATIVE

ANALYSIS

1.INTRODUCTION

Analytical chemistry deals with chemical characterization of matter on 2 questions:

What is it?(qualitative) How much is it?(quantitative) Applications of analytical chemistry:

agricultural, clinical, environmental. Specifically, blood glucose level in

diabetics, carbon monoxide content in public air etc.

1.1 INTRODUCTION TO METHODS IN ANALYTICAL CHEMISTRY

Q1: How do you carry out tests for qualitative analysis?

A: By performing selective chemical reactions or use instrumentation.

For example (by chemical reaction), AgNO3 added to a dissolved sample, producing a white precipitate. This indicates the presence of chloride ions qualitatively.

• Why?• Because Ag+ and Cl- reacts to form AgCl that produces the

white precipitate • or example (by chemical reaction), AgNO3 added to a dissolved

sample, producing a white precipitate. This indicates the presence of chloride ions qualitatively.

• Why?• Because Ag+ and Cl- reacts to form AgCl that produces the

white precipitate.

Q2: How do you carry out tests for quantitative analysis?

A2: Nowadays, we use instrumentation. Because, the results are more accurate.

For example, testing of banned substances at the Olympic Games. There are 3 phases in the analysis.

• Phase 1: Fast screening phase

• Phase 2: Identification phase

• Phase 3: Possible quantification

Fast screening phase: • Urine samples are tested rapidly for the

presence of classes of compounds different from normal samples. Techniques use: gas chromatography (GC), liquid chromatography (LC).

• If samples have unknown compounds, that may or may not be prohibited, therefore further testing is needed for identification purpose.

Using techniques such as gas chromatography-mass spectrometry (GC-

MS).

Identification phase:

• Q3: What happens during this procedure of using Gas Chromatography- Mass Spectrometry (GC-MS)?

• A3: Complex mixtures are separated by GC. Then, detetected by MS that gives molecular structural data on the compound.

Possible Quantification:

• Q4: Why need this step?

• A4: Some compounds must be quantified precisely. Meaning that, exact amount of compound must be determined. Therefore, we can verify whether the substance is present is present at low level (permissible level) or high level (unpermissible level)

• Thank you.