1. Specialty Chemical
Manufacturing Expertise
Since 1928
GFS Chemicals
Analytical Reagents
& Solutions
2006-2007 PRODUCT CATALOG
2. pH Reference
Buffers
and Primary
Standards
ANALYTICAL REAGENTS&SOLUTIONS
pH Reference Buffers used with confidence for all ucts but also new unit sizes,
GFS Chemicals’ pH Buffers are applications because stan- including bulk containers, and
manufactured from the finest dardization is performed case pricing. Certificates of
high-purity water and reagent using the most trusted instru- Analysis are provided with
grade chemicals. They are ments in the business – Orion, every shipment and include
standardized at 25°C against Beckman-Coulter, and Hanna, NIST Traceability.
NIST reference materials to a to name a few. For simplicity,
tolerance of 0.01 on Buffers all common buffers are the Primary Standards
4.00, 7.00, and 10.00 and to a same price regardless of pH Even with the automation of
tolerance of 0.02 on all other or if color coded. This catalog so many lab methods, it
buffer ranges. Our buffers are features not only new prod- remains essential to verify
analytical standard solutions.
For over 75 years, GFS
Chemicals has provided pri-
mary standards to support
analytical chemists worldwide
with traceability as well as the
confidence that their results
are accurate.
GFS continues to support
chemists performing such
titrations as acid-base, redox,
complexometric, and many
others. Following is a list of
many common primary stan-
dards manufactured by GFS.
Throughout the catalog, many
others are listed and we wel-
come inquiries for your
unique standards.
3. For acid-base: diphenylguani- involving the formation of
dine, constant boiling perchlo- complex ions.
ric acid, potassium acid
phthalate, potassium bi- Of several substances which
iodate, sulfamic acid, and can be used as standard solu-
tris-hydroxymethyl- tions in such analyses, sodi-
aminomethane. um ethylenediamine-
tetraacetate (EDTA) is one of
ANALYTICAL REAGENTS&SOLUTIONS
For redox titrimetry the fol- the most satisfactory in that it
lowing are listed as primary forms highly stable complex
standards: ceric ammonium ions with calcium, magnesium
nitrate, ferrous ethylenedi- and numerous other metals. A
ammonium sulfate, electrolyt- solution of disodium dihydro-
ic iron, potassium bi-iodate, gen ethylenediaminetetra-
potassium dichromate, and Find these items by name in acetate (pH 5.5) is usually
sodium oxalate. the alphabetical listing in this used as the standard solution.
catalog. For more information,
For complexation titrimetry request GFS Chemicals publi- The most common of such
(EDTA): calcium carbonate, cation No. 497, Standard titrations is the determination
disodium dihydrogen ethyl- Substances and Solutions (see of calcium and magnesium, as
enediaminetetraacetate dihy- page facing inside back cover). in analysis of waters for hard-
drate, and magnesium iodate ness, or of limestone. The
tetrahydrate. Complexometric end-point may be detected in
Titration Reagents various ways, the most com-
Other specially prepared pri- A spectacular advance in ana- mon utilizing the dyestuff
mary standards include sodi- lytical chemistry was the Eriochrome Black T. This
um chloride for argentimetric introduction of ethylenedi- dyestuff has the unique prop-
titrations; and cobalt sulfate aminetetraacetate as a stan- erty of itself forming a com-
for volumetric and colorimet- dard solution in titrations plex ion with magnesium. On
ric analyses. titration, the EDTA first unites
pH Values of Buffers at Various Temperatures
25 o 0o 5o 10 o 20o 30o 40o 50o 60o 70o 80o 90o
1.68 1.67 1.67 1.67 1.67 1.68 1.69 1.71 1.72 1.74 1.77 1.79
4.01 4.00 4.00 4.00 4.00 4.02 4.03 4.06 4.08 4.13 4.16 4.21
6.86 6.98 6.95 6.92 6.87 6.85 6.84 6.83 6.84 6.85 6.86 6.88
7.00 7.11 7.08 7.06 7.01 6.98 6.98 6.97 – – – –
9.18 9.46 9.40 9.33 9.23 9.14 9.07 9.01 8.96 8.92 8.89 8.85
10.01 10.32 10.25 10.18 10.06 9.97 9.89 9.83 – – – –
4. with the calcium and metals with EDTA.
magnesium ions in
solution and then Three primary stan-
pulls the magnesium dard materials are
away from the available for titrimet-
dyestuff-magnesium ric work with EDTA.
complex resulting in a Ordinary reagent
color change from red grade calcium carbon-
ANALYTICAL REAGENTS&SOLUTIONS
to blue. The titration ate contains sufficient
is carried out at a pH magnesium to make it
of 10 and yields the unacceptable as a pri-
sum of the calcium mary standard but a
and the magnesium special, low-magne-
present. sium grade is avail-
able, Item# 337. About
Aqueous solutions of the only good
Eriochrome Black T primary standard
do not keep and magnesium
another indicator, Calmagite, tion of certain blue dyes, thy- compound is magnesium
was introduced for the EDTA molphthalein or bromthymol iodate tetrahydrate, described
titration of calcium plus mag- blue, gives a somewhat more in 1962 by Lindstrom and
nesium. The color change of satisfying color change at the Stevens; this material is avail-
Calmagite at the end-point is end-point. able as Item# 348. Disodium
also from red to blue but the Dihydrogen Ethylenediamine-
colors are clearer and the The end-point with Calcein tetraacetate Dihydrate, the
end-point sharper. Aqueous may be detected also by the reagent used to prepare EDTA
solutions of this indicator are disappearance of the fluores- solutions, is itself a good pri-
stable indefinitely. Carried out cence under ultraviolet illumi- mary standard when properly
under slightly different condi- nation of the calcium salt. prepared, item #365.
tions, pH 12, and with the Calcein is prepared by the
indicator Calcein, calcium action of formaldehyde and
alone may be determined in iminodiacetic acid on fluores-
the presence of even large cein. It is typical of a class of
amounts of magnesium. This indicators known at “metalflu-
procedure may be applied to orochromic” indicators.
the determination of calcium
in water and in limestone. Another indicator of this class
Calcein modified by the addi- is Calcein Blue
(ß-methyl-umbelliferonemeth-
ylene- iminodiacetic acid)
which is useful in the titration
of copper, cobalt and other
11. High-Purity
Quaternary
Ammonium
Salts
ANALYTICAL REAGENTS&SOLUTIONS
HPLC and processes and protocols that examples and broader appli-
Analytical Grade Quats have stringent purity require- cations include:
As a chemical manufacturer ments; this includes suitabili- • Bu4NOH (TBA hydroxide) -
serving analytical labs world- ty for use as polarographic supporting electrolyte;
wide, the addition of product electrolytes and/or HPLC phase-transfer catalyst;
lines targeted directly to that applications. Both methanolic titrant
market is one of our top prior- and aqueous hydroxide solu- • Bu4N(H2PO4) (TBA phos-
ities. Hundreds of GFS prod- tions feature: phate) - ion-pair chromatog-
ucts fit this product profile, • very high alkalinity raphy; buffering medium
and two groups deserve spe- • very low chloride • Me4NCl (TMA chloride) -
cial mention: ultrapure (99.99 • virtual freedom from alkali USP/NF polarographic test
to 99.9999%) materials and metal impurities reagent; catalyst; inhibitor
standard solutions, (for exam- • low ash • Me4NOH (TMA hydroxide) -
ples, see pp. 96-97) and synthetic intermediate;
Quaternary Ammonium salts The EARG line fully comple-
precipitant; etchant; catalyst
and solutions (QUATS). ments the traditional GFS
• Et4NPF6 (TEA hexafluo-
QUAT line, which has found
widespread industrial and rophosphate) - fluoriding
GFS has a long history with agent; biocide precursor
QUATS; our production of commercial use. Some key
tetraalkylammonium perchlo-
rates reflects the company’s
dominant market position in
perchloric acid and inorganic
perchlorate salts. The GFS
QUAT line now includes
Electrometric and Analytical
Reagent Grade (EARG) prod-
ucts.
The EARG line of high purity
QUATS have characteristic
properties that are of particu-
lar interest to chemists and
technicians dealing with
12. Many other products are
available in various purities,
and we make custom formula-
tions on a regular basis.
The chemical literature
reflects a broad and ongoing
interest in QUATS, including
ANALYTICAL REAGENTS&SOLUTIONS
the perchlorate salts. Electro-
analytical studies of
tetraethylammonium perchlo-
rate solutions have elucidated
the nature of cation adsorp-
tion at mercury electrodes.1
A wide range of tetrabutyl-
ammonium perchlorate solu-
tions have been examined for
conductometric and dielectric
behavior.2 Electronic conduc-
tion has also been used to
study the behavior of the
nitrobenzene anion radical in
the presence of tetrabutylam-
monium perchlorate in solid
nitrobenzene.3
In the final analysis, it’s all
part of the greater product
selection and personal service
that you’ve come to expect
from GFS.
1. Journal of Electroanalytical
Chemistry 1989, vol.270 pp. 381-393.
2. Acta Chemica Scandanavia 1989,
vol.43, pp. 103-115.
3. Bulletin of the Chemical Society of
Japan 1989, vol.62, pp. 3413-3416.