March–April 2009
Official USP Reference Standards Catalog 21
HOW TO READ PRODUCT LISTINGS
Column 1 (Catalog Number): Catalog number currently
assigned to each Reference Standard and Authentic Substance.
Please include this number in your order.
Column 2 (Description): Product description as designated
in USP–NF, the product label, and/or the Drug Enforcement
Administration Control Schedule, as applicable. The quantity
of material per container follows the name in parentheses. (All
materials are in single containers unless otherwise specified.)
Column 3 (Current Lot): Current lot designation of each
official item being distributed as of the date of this catalog.
If the current lot is blank, the item is not in distribution.
Column 4 (Purity Value): Assigned purity value as it
appears on the Reference Standard or Authentic Substance
label. Code interpretations for the basis of purity assignments
are as follows:
Basis
Code
Interpretation
(ai)
(dr)
(an)
(fb)
(ig)
(sf)
as is
dried
anhydrous
free base
ignited
solvent free
Column 5 (Change Code): Code that identifies any change
in USP Reference Standards status or information since the
Jan.–Feb. 2009 official catalog. Code interpretations are
as follows:
Change
Code
Interpretation
1
2
3
4
5
6
7
8
9
New Reference Standard
New lot
Change in package size or description
Correction of typographical error
New catalog number—use for all orders
Previous lot no longer official; only
current lot to be used
Valid use date of previous lot extended
Change in catalog number and/or name,
see cross-reference section
Discontinued
Column 6 (Previous Lot/Valid Use Date): Lot designations for recent lots no longer being distributed. The indicated
month and year in parentheses indicate the date (last day of
the month) through which that lot was valid as an official USP
Reference Standard (e.g., “F- 1 (06/00)” means lot F- 1 is no
longer being distributed, but was considered official through
June 30, 2000).
Column 7 (CAS Number*): Chemical Abstracts Service
number, when available, for USP Reference Standards and
Authentic Substances. For mixtures, typically, the CAS
number of the analyte of interest is listed.
Column 8 (Price): List price of the Reference Standard.
CAS numbers are provided for informational purposes only,
and their listing in the USP Reference Standards Catalog does
not indicate official designation of any CAS number to a salt,
isomer, hydration state, or other chemical form of any specific
Reference Standard or Authentic Substance.
Search the latest USP Reference Standards e-catalog and order online at www.usp.org.
