Introduction to Analytical Chemistry

Concept, and terms and definition

Analytical Chemistry

Science that focuses on determining the composition and structure of matter, involves separating, identifying, and quantifying a substance, and playing a crucial role in various fields like forensics, pharmaceuticals, and environmental monitoring.

Qualitative Analysis

reveals the identity of the elements and compounds in a sample.

Analytical Chemistry

Science that focuses on determining the composition and structure of matter, involves separating, identifying, and quantifying a substance, and playing a crucial role in various fields like forensics, pharmaceuticals, and environmental monitoring.

Qualitative Analysis

reveals the identity of the elements and compounds in a sample.

Quantitative Analysis

indicates the amount of each substance in a sample.

Classical/Wet Procedure

are used to perform the analysis and there is no use of any mechanical or instrumental except on an analytical balance.

Instrumental Procedure

use of instrument for some sort either to make a critical measurement to perform analysis.

Gravimetric Methods

determine the mass of the analyte or some compound chemically related to the analyte.

Volumetric or Titric method

measure the volume of a solution. Combination of quantitative and qualitative methods.

Electroanalytical Methods

to measure electrical properties such as potential (voltage), current, resistance, and quantity of electric charge.

Spectroscopic or Optical Methods

explore the interaction between electromagnetic radiation and analyze atoms or molecules or the emissions of radiation by analytes.

1. Picking method

factors need to be considered in the selection of process are: Accuracy Required, Cost Analysis (Total investment), Number of sample to be analyzed, Time required for analysis, Skill required, Complexity of the sample, Number of components in the sample

2. Acquiring the sample

Sampling is the process of collecting a small mass of material whose composition accurately represents the bulk of the material from which it was taken. To produce meaningful information, an analysis must be performed in a representative sample.

3. Processing the sample

Sometimes no sample processing is required prior to the measurement step such as pH of the water sample can be measured directly. Sample needs to be processed in a variety of different ways.

4. Eliminating Interference

Need to eliminate substance from the sample that may interfere with the measurement step.

5. Calibration and Measurement

An analytical result depends on a final measurement of a physical or chemical property (X). ideally, the measurement of the property is directly proportional to the concentration (CA)

6. Calculating Results

Analyte concentrations from experimental data need to be calculated.

7. Evaluating Results by Estimating Reliability

Analytical results are incomplete without an estimate of their reliability. Some measure of the uncertainties associated with computed results need to be provided.

Analyte

constituent of the sample which is to be studied by quantitative measurement or identified qualitatively.

Assay

A highly accurate determination, usually of a valuable constituent in a material of large bulk. Also used in the assessment of the purity of a material.

Background

the proportion of a measurement which arises from sources other than the analyte itself.

Blank

A measurement or observation in which the sole is replaced by a simulated matrix, the conditions otherwise being identical to those under which sample would be analyzed.

Calibration

A procedure which enables the response of an instrument to be related to the Mass, volume or concentration of analyte in a sample.

Concentration

Amount of a substance present in a given mass or volume of another substance. The abbreviations w/w, w/v and v/v are sometimes used to indicate whether the concentration quoted is based on the weights or volumes of the two substances.

Constituent

A component of a sample

Major Constituent

> 10 %

Minor Constituent

0.01 to 10%

Trace

1 to 100 ppm(0.00010.01%)

ultra trace

< 1 ppm

Detection Limit

the smallest amount or concentration of an analyte that can be detected by a given procedure and with a given degree of confidence.

Determination

a quantitative measure of an Analyte with an accuracy of considerably better than 10% of the amount present.

Equivalent

That amount of a substance which, in a specified chemical reaction, produces, acts with or can be indirectly equated with one mole (6.023x1023) of hydrogen ions.

Estimitation

A semi quantitative measure of the amount of analyte present in a sample, i.e. an approximate measurement having an accuracy no better than 10 of the amount present.

Interference

effect which alters or obscures the behaviour of analysis in an analytical procedure.

Internal Standard

A compound or element added to all calibration standards and samples in a constant known amount.

Masking

the treatment of a sample with reagent to prevent interference worth the response of the analyte by other constituents of the sample.

Matrix

The remainder of the sample of which the analyte forms a part

Method

the overall description of the instructions for a particular analysis.

Primary Standard

A substance whose purity and stability are particularly well established and with which other standards may be compared.

Procedure

A description of the practical steps involved in an analysis.

Reagent

A chemical used to procedure a specified reaction in relation to an analytical procedure.

Sample

A substance or portion of a substance about which analytical information is required.

Sensitivity

The change in the response from an analyte relative to a small variation in the amount being determined. The sensitivity is equal to the slope of the calibration curve, being constant if the curve is linear.

Standard

The pure analyte or a substance containing an accurately known amount of it which is used to calibrate an instrument or to standardize a reagent solution.

Standard addition

A method of quantitative analysis whereby the response from an analyte is measured before and after adding a known amount of that analyte to the sample.

Standardization

Determination of the concentration of an analyte or reagent solution from its reaction with a standard or primary standard.

Technique

The principle upon which a group of methods is based.

Validation of Methods

Analyzing standards which have an accepted analyte content, and a matrix similar to that of the sample.