Introduction to Analytical Chemistry

Analytical Chemistry

The science that focuses on determining the composition and structure of matter, involving separating, identifying, and quantifying substances.

Quantitative analysis

Indicates the amount of each substance in a sample.

Qualitative analysis

Reveals the identity of the constituents (elements and compounds) in a sample.

Gravimetric methods

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

fields you can use ANACHEM

Medicine

Environmental monitoring

Food

Forensic analysis

Pharmaceuticals

Bioanalytical chemistry and analysis

Volumetric methods

Methods used to measure the volume of a solution containing sufficient reagent to react completely with the analyte.

Sampling

The process of collecting a small mass of a material whose composition accurately presents the bulk from which it was taken.

Instrumental Procedures

Use of instruments to make a critical measurement or to perform the entire analysis.

Electroanalytical methods

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

Spectroscopic or Optical Methods

Methods used to explore the interaction between electromagnetic radiation and analyte atoms or molecules or the emission of radiation by analytes.

Equivalent

That amount of a substance which, in a specified chemical reaction, produces, reacts with or can be indirectly equated with one mole (6.023 x 10^23) of hydrogen ions.

Calibration

The process of determining the proportionality constant (k) is an important step in most analyses.

Estimation

A semi-quantitative measure of the amount of an analyte present in a sample, i.e., an approximate measurement.

Eliminating Interferences

The process of removing substances from the sample that may interfere with the measurement step.

Classical/Wet Procedures

Methods used to perform the analysis without the use of any mechanical or electronic instruments.

Accuracy required

The degree of closeness of measurements to the actual (true) value.

Cost of analysis

The total investment required for conducting the analysis, with a lesser investment being preferable.

Number of samples to be analyzed

The quantity of samples that can be analyzed, with a higher number generally being better.

Time required for analysis

The duration needed to complete the analysis, with a shorter time being preferable.

Skill required

The level of expertise necessary to perform the analysis.

Complexity of the sample

The degree of difficulty in analyzing a sample based on its composition.

Number of components in the sample

The total distinct substances present within the sample.

Processing the sample

The steps taken to prepare a sample for measurement, which may include physical and chemical changes.

Calibration and Measurement

An analytical results depends on a final measurement of a physical or chemical property.

Analytes

Constituent of the sample which is to be studied by quantitative measurements or identified qualitatively (portion of a sample)

Assay

A highly accurate determination, usually of a valuable constituent in a material of large bulk, e.g. minerals and ores. Also physiologically active constituent of a pharmaceutical product.

Background

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

Interference

An effect which alters or obscures the behavior of an analyte in an analytical procedure. It may arise from the sample itself, from contaminants or reagents introduced during the procedure or from the instrumentation used for the measurements.

Internal Standard

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

Masking

Treatment of a sample with a reagent to prevent interference with 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 (known samples).

Procedure

A description of the practical steps involved in an analysis.

Reagent

A chemical used to produce 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.

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 (your analyte is impar with the 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 measurement which arises from sources other than the analyte itself. Individual contributions from instrumental sources, added reagents and the matrix can, if desired, be evaluated separately.

Blank

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

Calibration

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

Concentration

The amount of 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 weighs or volume of the two substances.

Constituent

A component of a sample.

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 (considerable amount).

A component of a sample:

a. major >10%

b. minor 0.01-10%

c. trace 1-100ppm (0.0001-0.01%)

d. ultratrace <1ppm

Determination

A quantitative measure of an analyte with an accuracy of considerably better than 10% of the amount present.