Table 2.

Mean recoveries of LT3 and HT4 peptides in plasma samples.

	HT4		LT3
	Mean	CV (%)	Mean	CV (%)
Digestion recovery	89.5	2.8	103.3	7.7
SPE extraction recovery	48.1	3.4	63.6	10.5
Ionization recovery	50.8	8.1	47.9	6.6
Total recovery	21.8	4.6	31.3	6.4

Mean recoveries were determined by measuring the peak area ratio of HT4 and LT3 peptides from a cetuximab digest spiked at 200 µg/mL, before and after incubation with trypsin, SPE extraction and confronted to peak area ratios from a pure solution. Means are from 3 experiments. CV: Coefficient of variation.