Table 1

Mass balance of lidocaine solutions after various stressed degradations

Area
Peaks	Retention time (minutes)	Relative retention	Without stressed degradation	Acidic degradation	Alkaline degradation	Oxydative degradation	Heat degradation	Photolyse degradation*
Peaks	Retention time (minutes)	Relative retention	Without stressed degradation	HCl 30% 85°C 48 hours	NaOH 1M 85°C 48 hours	H₂O₂ 30% 48 hours	85°C 48 hours	254 nm 24 hours
Lidocaine	11.68	1.00	14 112 820	13 271 413	12 901 779	12 680 895	14 400 257	/
1	2.42	0.21				655 944		/
2	3.75	0.32				14 449		/
3	4.01	0.34				67 051		/
4	4.32	0.37				65 209		/
5	4.66	0.40		1 058 815	38 077			/
6	7.08	0.61				15 983		/
7	8.64	0.74		17 057				/
Mass balance			14 112 820	14 347 285	12 939 856	13 499 531	14 400 257	/
% degradation				6%	9%	10%	0%†	/

*Photolyse degradation was carried out and no degradation product was detected. A significant evaporation concentrated samples, therefore the results are not presented in the mass balance.
†No degradation was observed for heat degradation. The higher peak surface found is due to the increase of the concentration, probably caused by the evaporation of the solvent.