Order of degradation reaction | Kinetic parameters | Example | References | ||
---|---|---|---|---|---|
Rate equation | Half-life | Shelf life | |||
Zero-order | \(R = \frac{{ - {\text{d}}\left\lceil A \right\rceil }}{{{\text{d}}t}} = k_{0}\) | t1/2 = [A]0 /2 k | t0.9 = 0.1[A]0/k0 | Hydrolysis of atorvastatin Electrochemical degradation ceftriaxone | Ahmad et al. (2006), Ahmad and Vaid (2011), Aulton and Taylor (2007), de Haro Moreno and Salgado (2012), Jain et al. (2011), Oliveira et al. (2013), Robnik et al. (2019), Shubha and Sushma (2015) and Tutunaru et al. (2021) |
First-order | \(R = \frac{{ - {\text{d}}\left\lceil A \right\rceil }}{{{\text{d}}t}} = kA\) | t1/2 = ln(2)/k | t0.9 = 0.105/ k1 | Oxidation of butacaine Oxidation of benzocaine hydrochloride Hydrolysis of atorvastatin Thermal and photodegradation of ceftazidime | |
Second-order | \({\text{d}}\left\lceil A \right\rceil = \frac{{ - k\left\lceil A \right\rceil ^{2} }}{{{\text{d}}t^{2} }}\) | t1/2 = 1/k[A]0 | t0.9 = (0.11/ k) [A]0 | Photodegradation of formamethylflavin in acidic solution Thermolysis of formamethylflavin, hydrolysis of esters in alkaline solution |