1. The document defines reagents as substances added to cause or test for chemical reactions. It describes analytical reagents which are used for qualitative or quantitative analysis and lists organizations that establish purity levels. 2. Types of analytical reagents are described including those for chemical analysis, indicators, and instrumentation. Laboratory reagents are compounds used to detect or measure other substances through color changes. 3. The key difference between primary and secondary standards is that primary standards are more pure and less reactive while secondary standards are less pure and more reactive. Primary standards are used to standardize secondary standards.

1. Reagent
Mrs.Poonam Sunil Aher (M.Pharm, PhD)
Assistant Professor
Sanjivani College of Pharmaceutical Education and Research
(Autonomous),
Kopargaon, Ahmednagar-423603 (M.S.), INDIA
Mobile: +91-9689942854

2. • Definition of Reagent:
• In chemistry, a reagent or analytical reagent is a substance or
compound added to a system to cause a chemical reaction, or
test if one occurs.

3. Types of Reagents
• 1. Analytical Reagent
• 2. Laboratory Reagent

4. Analytical Reagent
• Analytical reagent is a class of chemical reagents for analytical testing with being able to provide
molecules, ions or radicals in the qualitative or quantitative analysis, and the reaction product being
precipitated or colored compound or fluorescent substance and so on.
• Indicator, titrant and Instrument Analytical Reagents also fall into this category. The most
important feature of the analysis reagent is the sensitivity and selectivity, even if the number of the
test substance is little or the ion concentration is also small, the reagent can also be used for
identification or quantitative determination
• The American Chemical Society (ACS) and the American Society for Testing and Materials
(ASTM) are two organizations that establish the purity levels for a product to be labelled as
reagent-grade.

5. Classification of Analytical Reagents
1.Reagents for chemical analysis: testing items for the chemical reaction analysis.
2.Baseline reagent: a pure compound for direct formulation of the standard solution and the standard
solution in the volumetric calibration.
3.Indicator: reagent used to indicate the end of the titration reagent and can be classified into pH
indicator, redox indicator, adsorption indicator, metal indicator and fluorescent indicator, etc
4.Analysis reagent of Instrument: high-purity compounds dedicated to instrumental analysis.
5.Spectroscopically pure reagents: spectroscopically pure compound, often expressed in the SP;
reagents for spectral analysis.
6.Chromatography pure reagents: reagents dedicated to analysis by gas chromatography and liquid
chromatography analysis.
7.Deuterated reagents: reagents dedicated to the nuclear resonance instrument analysis.

6. Laboratory Reagents
• In analytical chemistry, a reagent is a compound or mixture used to
detect the presence or absence of another substance, e.g. by a color
change, or to measure the concentration of a substance, e.g. by
colorimetry. Examples include Fehling's reagent, Millon's reagent,
and Tollens' reagent.

7. • Uses of Reagents
1.Reagents are commonly used in laboratories for a variety of tests. Collins reagent, for
example, is used to convert alcohols to aldehydes and ketones.
2.Reagents are often used to indicate the presence of compounds by causing colour
changes to indicate presence.The presence of proteins can be detected using Millon’s
reagent. Fehling’s reagent, for example, can detect the presence of carbohydrates or
ketones and distinguish between the two functional groups. The presence of proteins,
as indicated by the presence of tyrosine residues, causes the solution to turn reddish-
brown when Millon’s reagent is added.
3.One of the most common applications of reagents in everyday life is drug testing.
While most kits, such as those used to test for common drugs, are simple to use and
involve observing whether a colour change occurs.

8. Primary standard
• A primary standard solution is a solution with a high purity and less
reactivity. It is a compound of sufficient purity from which a standard
solution can be prepared by direct weighing of quantity of it and make
defined volume of solution.

9. Examples of primary standard
• 1. Acid base titration: sodium carbonate, sodium tetraborate,
potassium hydrogen phthalate, potassium hydrogen iodate
• 2. Complexometric Titration: pure metals such as zinc , magnesium,
copper, manganese and salts, copper sulfate, sodium tetraborate act
as primary standard
• 3. Precipitation Titration: silver, silver nitrate, sodium chloride,
potassium chloride and potassium bromide
• 4. Oxidation and reduction Titrations: potassium dichromate,
potassium bromate, potassium iodate, arsenic oxide, sodium oxalate
and pure iron

10. Secondary Standard
A secondary standard is not that pure and is chemically reactive than
primary standards. It is a substance which is used for standardization
and whose content has been found by comparison against a primary
standard.
Examples: NaOH, Potassium permagnate

11. Difference between primary and secondary
Primary standard Secondary standard
1. It is high pure compound 1. It is less pure than primary standard
2.It is preserve or store in pure state 2. It is store at room temperature
3. Less reactive 3. More reactive
4. Not hygroscopic 4. More hygroscopic
5. It required specific storage conditions 5. It require laboratory storage conditions
6.It is used to standardise secondary
standard
6. It is used for analytical experiments
7. It is highly stable 7. It is less stable than primary standard