b. Nanogram Solvents. These solvents are highly purified for electron capture
gas liquid chromatography (GLC) techniques such as pesticide residue analysis and
c. Liquid Scintillation Chemicals. These are specifically formulated to meet
the needs of scintillometric radioisotope counting techniques.
d. Spectrophotometric Solvents. These solvents contain low levels of
contaminants and give reproducible absorption curves throughout the entire spectrum.
Organic laboratory chemicals are of suitable purity for most research work and
for general laboratory purposes such as standard and reagent prepa- ration.
Specifications are usually determined by melting or boiling point.
CHEMICALLY PURE GRADE
Chemicals that are chemically pure grade (CP) cannot be used as standards in
either the clinical laboratory or in research without first being analyzed. There are no
set specifications for this grade of chemical and the quality varies from manufacturer to
manufacturer. This grade of chemical is usually satisfactory for most reagents used in
the chemical laboratory.
UNITED STATES PHARMACOPEIA AND NATIONAL FORMULARY GRADES
The United States Pharmacopeia (U.S.P.) or the National Formulary (N.F.) sets
forth the specifications for the chemicals that are assigned the above listed grades. The
specifications for this grade of chemical state that the impurities present may not be of
such concentration as to be harmful to one's health. This grade of chemical is usually
unsatisfactory for use in preparing standards or reagents. It should only be used in
PURIFIED, PRACTICAL, OR PURE GRADES
There are no definite specifications for these grades of chemicals; they should
not be used in the preparation of standards or reagents.
TECHNICAL OR COMMERCIAL GRADES
The purity of this grade of chemical is dependent upon the ease with which a
certain impurity is removed. This grade of chemical is only suited for industrial use.