Table III.

Stability of Ceftizoxime in Human Serum and Urine (n = 5)

Matrix	Stability types	Concentration (nominal, ng/mL)	Concentration (measured, ng/mL)	Accuracy (RE, %)	RSD (%)
Serum	Short-term (at room temperature for 4 h)	7.5	7.22	−3.7	4.0
		750	738	−1.7	4.7
		7,500	7,442	−0.8	2.2
	Auto-sampler (24 h)	7.5	7.00	−6.6	4.1
		750	717	−4.4	2.7
		7,500	7,166	−4.5	3.4
	Freeze–thaw (3 cycles)	7.5	7.60	1.4	5.9
		750	765	2.1	3.3
		7,500	7,570	0.9	1.1
	Long-term (60 days)	7.5	7.42	−1.1	2.9
		750	740	−1.2	1.7
		7,500	6,786	−9.5	0.8
Urine	Short-term (at room temperature for 24 h)	1.50	1.41	−5.9	3.3
		6.00	5.62	−6.3	1.1
		40.0	37.9	−5.3	0.4
	Auto-sampler (24 h)	1.50	1.55	3.1	1.7
		6.00	5.94	−1.0	2.0
		40.0	39.3	−1.8	1.9
	Freeze–thaw (3 cycles)	1.50	1.38	−8.1	2.0
		6.00	5.68	−5.3	2.3
		40.0	38.7	−3.3	5.6
	Long-term (56 days)	1.50	1.63	8.9	2.4
		6.00	6.30	5.0	2.6
		40.0	39.5	−1.3	1.7