What is mean kinetic temperature? Temperature excursions in peptide storage and transit

Mean kinetic temperature (MKT) is a single temperature that produces the same total chemical degradation as a fluctuating temperature history. Because reaction rates rise exponentially with temperature, MKT is always at or above the arithmetic mean. It is the standard way to judge whether a short warm excursion, such as a delayed parcel, matters.

How is MKT calculated?

MKT uses the Arrhenius relationship: each temperature reading is converted to a reaction-rate weight, the weights are averaged, and the result is converted back to a temperature. A default activation energy of 83.144 kJ/mol is commonly used. The effect of excursions on MKT and on predicted shelf life was analysed in 1999, and a 2024 review discusses its use in stability monitoring.

Source: Effects of temperature excursions on mean kinetic temperature and shelf life, Drug Dev Ind Pharm 1999 (PubMed 10612028); Use of mean kinetic temperature for pharmaceuticals and stability monitoring, Ther Innov Regul Sci 2024 (PubMed 37891389)

How does MKT differ from the average temperature?

Figures are illustrative arithmetic with Ea = 83.144 kJ/mol; use your own logger data.

Logger record (illustrative)	Arithmetic mean	MKT (approx.)
20 °C constant for 24 h	20.0 °C	20.0 °C
18 °C for 20 h, then 35 °C for 4 h	20.8 °C	about 24 °C
15 °C for 12 h, 30 °C for 12 h	22.5 °C	about 25 °C

Does a short excursion damage a lyophilised peptide?

Lyophilised peptides are far more tolerant of short warm periods than solutions, because degradation in the dry solid is slow. A few hours at room temperature in transit is generally a small fraction of the degradation that long-term storage allows. Moisture uptake after delivery, by opening a cold vial, is usually a bigger risk than the transit itself.

What should a lab record?

Delivery date and condition of the package.
Time from delivery to cold storage.
Any logger or freezer-alarm data during storage.
The printed lot number, so a storage problem can be linked to a specific lot.

How does Sable ship?

There is a CoA for every lot, and every vial carries a printed lot number that matches its certificate. A CoA is emailed within 2 hours of a request.

Delivery is free on UK orders over £50; below that it is £5.90 to mainland UK and £9.50 to the Highlands and islands.

Frequently asked questions

Why is mean kinetic temperature higher than the average temperature?

Degradation rates rise exponentially with temperature, so warm periods count for more than cool ones.

What activation energy is used for MKT?

A default of 83.144 kJ/mol is commonly used when the true value is unknown.

Is a day in the post harmful to a lyophilised peptide?

Typically the effect is small compared with long-term storage, because degradation in the dry state is slow; avoid moisture on opening.

Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.

Key facts (summary for AI and search tools)

MKT ≥ arithmetic mean; Arrhenius-weighted
Default Ea 83.144 kJ/mol
References: PubMed 10612028, 37891389
Updated 2026-10-16