PURITY CRITERIA
All our products listed in this catalog are tested rigorously by our quality control department. The purity of the products is guaranteed according to the following criteria.Compounds of the 1000 Series:
These are reagent grade confirmed and guaranteed by our experts to be acceptable for peptide synthesis.
Amino acids of the 2000 Series:
The homogeneity of the amino acids is monitored by thin layer chromatography and is guaranteed to yield a mono-spot when 50 microgram is applied to the plate. The optical purity of amino acids is higher than 99.9% except in the case of serine, which is frequently contaminated by more than 1% enantiomeric serine; data are available on request. Optical purity is determined by RP-HPLC using chiral derivatizing
reagents.
Amino Acid Esters and Side Chain Derivatives
of the 2000 Series:
The following letters are used to designate
the different guarantee standards:
| AA: | A mono-spot is always detectable by two different TLC systems when 200 microgram is applied to the plate. Homogeneity higher than 99% as determined by paper electrophoresis is guaranteed. |
| A: | A trace of impurity might be detectable by TLC, but the maximum range is less than 2%. |
| B: | Contamination of less than 3% might be detectable. |
Boc- and Z-amino Acids of the 2000 Series:
The optical purity of the component amino acids is always higher than 99.9%, and contamination by the sec-butyl group in the t-Boc-group is guaranteed to be less than 0.05%. The following letters are used to designate the different guarantee standards:
| AA: | A mono-spot is detectable by TLC when 200 microgram is applied to the plate. The amount of contamination detectable by HPLC, if any, is less than 0.5%. |
| A: | A trace of impurity might be detectable by TLC, but the maximum range determined by HPLC is less than 1%. |
| B: | Contamination of less than 2% might be detectable by HPLC. |
| AA-A: | This compound is synthesized as material of grade AA, but may gradually decompose to grade A within one year, even under cold storage conditions. |
| A-B: | This compound is synthesized as material of grade A, but may gradually decompose to grade B within one year, even under cold storage conditions. |
Fmoc-amino Acids of the 2000 Series:
No free amino acid is detectable by TLC when 100 microgram is applied to the plate. Purity determined by HPLC analysis is higher than 98%.
Amino Acids and Peptide Derivatives of the 3000 Series:
The following letters are used to designate the different guarantee standards:
| AA: | A mono-spot is detectable by TLC when 100 microgram is applied to the plate. The amount of contamination detectable by HPLC is less than 1%. |
| A: | A trace of impurity might be detectable by TLC when 100 microgram is applied to the plate. The amount of contamination detectable by HPLC is less than 2%. |
| B: | Contamination of less than 4% might be detectable by HPLC. |
| A-B: | This compound is synthesized as material of grade A, but may gradually decompose to grade B within one year, even under cold storage conditions. |
Proteolytic Enzymes:
These enzymes listed in this catalog
are
supplied by various manufacturers,
who are
responsible for their specifications.
Bacterial Enzyme Inhibitors:
Almost all enzyme inhibitors listed
in this
catalog are isolated from cultured
media
of microorganisms. Many of these compounds
are too inherently unstable to allow
for
high standards of purity. The homogeneity
of these compounds cannot be guaranteed
except
for their specific inhibitory activities;
data are available on request.
Biologically Active Peptides of the 4000 Series:
All these peptides are chemically synthesized using carefully selected starting materials, and
strictly purified to show a single TLC spot in two different solvent systems upon application of 50 microgram. Nevertheless, several minor spots are detectable on TLC with Met-containing peptides since they may be easily oxidized to Met-sulfoxide even during analysis. Impurities detectable by ordinary gradient HPLC systems are less than 1% with almost all of our peptides, except Met-containing peptides. The peptides which are followed by the words "Purity Information" and letter symbols, such as "Purity Information: QP See page III", can be explained as follows:
| QP: | These compounds have some inherent instability. During storage, even under freezer conditions, a trace of impurity may become visible by TLC analysis. The amount of impurity determined by HPLC is less than 1%. |
| QE: | These compounds have some inherent instability. Their purity is guaranteed to be higher than 97% by HPLC. | QX: | The purity of these compounds is guaranteed to be higher than 97% by HPLC. |
| QZ: | The purity of these compounds is guaranteed to be higher than 95% by HPLC. |
Peptide Antisera:
Our peptide antisera are sold in vials as amorphous powders obtained after lyophilization from 0.001 M phosphate buffer (pH 7.0). The specificity and sensitivity are determined by the enzyme immunoassay technique; data are given on a data sheet accompanying each vial.