Analytical Chemistry. Introduction. Chemistry is a branch of science. There are different branches to Chemistry: Organic Chemistry Inorganic Chemistry Physical Chemistry Analytical Chemistry. Organic. Inorganic.
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Chemistry is a branch of science.
Chemical Analysis: is the determination of the quality and quantity of the substance.
Analytical Chemistry: is concerned with the chemical characterization of matter, both qualitative and quantitative.
Analytical chemistry plays an important role in nearly all aspects of chemistry.
There are many fieldsthat depend on analytical chemistry. For ex.,
Deals with the identification of elements, ions and compounds in a sample (we may be interested in whether only a given substance is present).
1. Elemental Analysis
2. Identification of sample structure to be analyzed
Deals with the determination of how much of one or more constituent is present.
There are two kinds of quantitative analysis:
y + x = p
2. Instrumental AnalysisComparing Between Qualitative Analysis and Quantitative Analysis
1. A chemical analysis is usually performed on only a small portion of the materiel to be characterized.
2. The material to be characterized can be:
* In the case of biological fluids, the condition which the collected sample must undergo are very important. Forex.,the patient should fast for a number of hours before a blood test.
* Blood samples may be analyzed as whole blood or separated to yield plasma and serum.
Serum: is the fluid separated from the clotted blood.
Plasma:is the fluid separated from the unclotted blood.
The difference is that plasma contains fibrinogen.
3. Handling and storing samples: Certain precautions must be taken to prevent alternation or contamination of the sample. For ex., storing the sample in the proper light, temperature and container.
* The stability of samples must be considered. For ex.,preservations added to the blood must not interfere with the sample.
- Measure the size of the sample to be analyzed. For ex., volume and weight of sample. It is important that a level of accuracy and precision is required.
- Solid samples are often analyzed on a dry basis and must be dried in an oven (110ْ – 120 ْ) for 1-2 hours.
- To measure the sample we weigh the crucible containing the sample after weighing the crucible alone. Then we subtract the second from the first.
2. Dissolving the sample:
- Solid samples must be dissolved.
- Inorganic materials can be dissolved in various acids or in water.
- Organic materials must be dissolved in organic solvent.
3. Fusing the sample:
- The sample must be fused with a compound to obtain a mixture.
4. Chemical separation/ Masking of interference:
- In this step it is required to separate chemicals by selective methods or specific methods.
A child who has been poisoned by a substance cannot wait long enough until the nature of the poison has been detected. That is why a high level of speed must be required in a method.
2. Accuracy and precision needed:
Finding the amount of sugar in a soda drink does not require a method of high accuracy and precision. Unlike analyzing toxic constituents such as lead and mercury that require accurate and precise methods.
Accuracy: is the degree of agreement between a measured value and a true value.
Precision: is the degree of agreement between replicate measurement of the same quantity and does not necessarily imply accuracy.
3. Tools/ Instruments available.