Page 32 - Feed Lab

Reagents and Chemicals Suguna Management System Ver 1.0 / SOP / FQL /P1 - 04 Page 4 of 6

reducing agents (SnCl ), special care should be
STORAGE OF STANDARD SOLUTION 2
taken while weighing them. In case of chemicals
In any analytical laboratory it is essential to maintain like CaCl weigh them quickly in the presence of a
2
stocks of solutions of various reagent: some of these drying agent. In such cases do not use glazed
will be of accurately known concentration (i.e. standard paper for weighing, better use a watch glass. This
solutions) and correct storage of such solutions is
imperative. is more important in case of strong oxidizing
reagents for they may burn the paper.
FPrimary standard reagents must be dried in an oven
Solutions may be classified as:
o
o
FReagent solutions which are of approximate at 100 C - 110 C for at least 1-2 hours before their
concentration; use. Drying overnight is preferred. After drying the
container with the chemical (or the reagent bottle)
FStandard solutions which have a known should be placed quickly in a dissector and
concentration of some chemical;
covered with a stopper or watch glass. After
FStandard reference solutions, which have a known cooling, immediately weigh the exact quantity
concentration of a primary standard substance. needed for making the solution.

FStandard solutions, which have a known Note: Some chemicals may need different
concentration (determined either by weighing or temperatures for drying than mentioned above. Some
by standardization) of a substance other than a of the hydrated salts may be dried, although less
primary standard. efficiently, in a good desiccators.
FThe IUPAC Commission on Analytical CHEMICALS
Nomenclature refers to (3) and (4) respectively as
Primary Standard Solutions and Secondary Different Grades of Chemicals
Standard Solutions. FMost of the chemical manufacturers produce
genuine quality of chemicals with good assay. At
the same time, it is needless to say that some profit-
1. Primary and Secondary Standard Solutions:
FAlkaline solutions, hydrogen fluoride react with minded companies are damaging the scientific and
glassware's. Such solutions are stored in plastic research programs with their low quality products.
bottles. FIn such conditions, a researcher or an analyzer
must be aware of the different grades of chemicals.
FSodium Oxalate, Ammonium phosphate and
Ammonium Molybdate and some other reagents The following is the grade with various levels of
react with glass. purity in descending order.
FSome solutions are affected by light (iodides) Analytical Grade (AR)
liberate iodine because of photochemical action. Guaranteed Grade (GR)
Such type of reagents is stored in brown bottles.
Laboratory Grade (LR)
FMany of the chemicals used in a laboratory should Commercial Grade (CR)
be handled with utmost care both in their original
state and in the form of their solutions. Chemical For precise chemical analysis and for the preparation of
bottles marked with the words; Poison, Danger, primary standard solution GR grade chemicals are
preferred, for qualitative and for the preparation of
Caution, Fuming, Inflammable or some other reagent for other applications where precision and
warnings should be handled with utmost discretion
quantitative estimations are not carried out.
and care.

FSome chemicals absorb water very fast (like CaCl ) Storage of chemicals
2
and others are strong oxidizing (Na 0 ) and FStore acids and bases in separate locations, near
2
2

Prepared by : Approved by :
22 Director - Technical