Cat #

The alpha-numeric catalog number for a particular product. Data tables are organized first in alphabetical order using the alpha identifier of the catalog number, and second in numerical order using the numeric identifier of the catalog number (e.g., A47, B153, B438, C194, etc.). In most cases, data tables do not list kits, protein conjugates, dextran conjugates, gel and blot stains, ChromaTide nucleotides and FluoSpheres polystyrene microspheres.


Molecular weight (MW) for the anhydrous compound, except in a few cases for which the exact degree of hydration has been determined and is specified in the name of the product. We caution that products may not be completely anhydrous upon receipt, even if they are represented in this form by the chemical structure and MW value. For compounds isolated and sold in salt form, MW is inclusive of counterions unless noted otherwise. In some cases (e.g., nucleotide derivatives, some peptides and proteins), the exact salt form has not been established, and consequently the MW value is approximate, denoted by a preceding "approximately" symbol (~). In general, we recommend measuring the absorbance of a solution and calculating concentration with the extinction coefficient rather than using these MW values.


Recommended storage conditions for products. Abbreviations are as follows:

A Material may be air sensitive
AA Air sensitive, use under a N2 or Ar atmosphere
D Desiccation recommended
DD Desiccation required
F or FF Store at ≤–20°C
L Protect material from long-term exposure to light; may be exposed to light for short periods of time
LL Protect material from light at all times
MIXED Contains components with incompatible storage requirements; store components separately as indicated
NC Storage conditions are not critical; store at ≤25°C
RO Store at ≤6°C; if frozen, AVOID FREEZE-THAW CYCLES
RR Store at 2–6°C; DO NOT FREEZE
RT Store at room temperature or below (2–25°C); DO NOT FREEZE
UF Store at ≤–70°C

Many products may remain at ambient temperature for short periods of time (e.g., during shipment) without any loss of product performance, but should be stored as indicated upon arrival. Storage information is also printed on all product container labels.


Recommended solvent for preparing stock solutions of at least 1 mM. Recommendations are based on the best knowledge and experience of our technical staff, but have not necessarily been tested. If a pH is indicated, the product generally ionizes and should be dissolved in aqueous buffer in the specified pH range. Abbreviations for solvents are defined below (see Solvent).


The longest-wavelength (unless noted otherwise) absorption maximum (in nanometers) in the solvent listed in the column headed Solvent.


Molar extinction coefficient (in cm–1M–1) determined at the wavelength listed in the column headed Abs. Values above 10,000 cm–1M–1 are rounded to the nearest 1,000. In most cases, extinction coefficients have not been rigorously determined, and the values may vary somewhat among production lots.


Fluorescence emission maximum (in nanometers) in the solvent listed in the column headed Solvent. Em values are generally not corrected for instrument response characteristics, resulting in small variations when compared to measurements in other laboratories. Considerable environment-dependent variation of Em occurs for some products; when known, this is indicated with a footnote.


Solvent used for acquisition of spectroscopic data, including Abs, EC and Em. Solubility of the product in this solvent is not necessarily any greater than is required to obtain an absorption spectrum (i.e., 10 µM or less). In some cases, it is necessary to prepare a stock solution in a different solvent and then to dilute the sample into the indicated solvent to measure spectra. Refer to the column headed Soluble for recommended solvents for preparing stock solutions. Abbreviations are as follows:

CHCl3 Chloroform
DMF Dimethylformamide
DMSO Dimethylsulfoxide
H2O Unbuffered water
EtOAc Ethyl acetate
EtOH Ethanol
pH 7 pH 7 aqueous buffer
H2O/DNA Spectra measured for probes bound to DNA in aqueous solution
MeCN Acetonitrile
MeOH Methanol
THF Tetrahydrofuran

Data for ion indicators are usually listed for aqueous solutions both with and without the target ion. The indicator dissociation constant for the target ion, in most cases determined in our R&D laboratories, is listed in a separate column headed Kd or for pH indicators, pKa.


Catalog numbers or references to footnotes indicating products that are generated by enzymatic or chemical conversion of the parent compound in the course of standard applications.


Extensions to the listed data, identified by numbers (1, 2, etc.). For example, in cases where a product exists in two forms (e.g., substrate/enzymatic product, free/bound, unreacted/reacted), data for one form is listed in the table and for the other form in a footnote. Other spectroscopic parameters reported in some footnotes include fluorescence quantum yields (QY) and excited state lifetimes (tau; units = seconds ×10–9 = nanoseconds). We do not routinely determine QY and tau for our products, but include this data in the footnotes when it is known.