Per definition, a sterile product does not harbor any living organisms on its surface. The degree of sterilization is described by a residual probability of contamination. This probability is expressed as SAL (Sterility Assurance Level). Thus, a SAL value of 10-6 indicates the presence of one non-sterile item among 106 (1,000,000) sterilized items.
Sterile products are required whenever the presence of germs may have a negative effect; for example, in preventing the contamination of sensitive samples or avoiding incorrect test results in microbiology, contamination of cell cultures, etc.
Thermostable substances (glycoproteins) from the outer membrane of bacteria and other microorganisms can cause fever in humans and impair the growth of cell cultures.
Absence of pyrogen prevents endotoxin-based contamination in drug manufacture, cell culture and medical laboratories.
Bacterial DNA-free (E. coli):
DNA is found in the cells of all living entities, and it is the carrier of all genetic information. The highly sensitive PCR technique enables the detection of individual molecules.
The presence of DNA could lead to false positive results for different applications involving DNA. Note: Autoclaving does not remove traces of DNA
Free of human DNA:
To eliminate this potential source of contamination, the consumables are tested for the presence of human DNA. Even a single human cell (e.g., skin particles) would be detected in the test. To avoid contamination, manufacturing is virtually fully automated and monitored by staff wearing protective clothing.
Contamination with human DNA could lead to false positive results especially in the analysis of human DNA. This is particularly critical in the areas of diagnostics and forensics.
DNases are enzymes which degrade DNA.
DNase contamination can influence DNA analysis.
RNases are enzymes that degrade RNA. These enzymes are extremely resistant and cannot be subsequently removed from consumables. (They are even resistant to autoclaving and irradiation.)
RNase-free products are an absolute must in the field of molecular biology because RNA is highly sensitive and can be destroyed very quickly by RNases.
ATP is a part of all living cells; therefore, its presence can indicate biological contamination.
The test procedure for the quantitative and qualitative detection of ATP is already an integral part of hygiene monitoring, e.g., in the pharmaceutical industry. Non ATP-free lab products would be indicated immediately in this very sensitive test.
Free of PCR inhibitors:
PCR - the replication of DNA - has developed into one of the most important and commonplace molecular biology methods. It is used in basic biological research as well as in medical diagnostics, genetic counseling and quality analysis. However, there are also substances (inhibitors) that may impair the PCR reaction considerably. Lab products must therefore be demonstrably free of PCR inhibitors.
It is essential that consumables used for PCR reactions contain no impurities that could adversely affect the reaction. This is particularly crucial for the amplification of minute quantities of genetic substances and for quantitative PCRs.
*The suffix or word „free“ in the context of the purity grades means, testing showed conformity within the detection limits (see certificate of purity)