Development and Validation of an ELISA at Acidic pH for the Quantitative Determination of IL-13 in Human Plasma and Serum

Table 6

Stability assessment of endogenous IL-13 in human plasma. Two different human plasma samples (3.75 and 1.16 pg/mL of endogenous IL-13) were stored undiluted under different temperatures and time periods or subjected to freeze and thaw cycles. Recovery of IL-13 concentration was calculated using the concentration measured at Day 1 (T0) as a reference value.

	Storage conditions	Mean recovery (%)	Range of recovery (%)
Short-term stability	25^∘C, 1 week	77.2	72.3–81.9
	4^∘C, 1 week	82.3	74.0–94.3
	−20^∘C, 1 month	80.7	77.4–83.3
	−80^∘C, 1 month	76.1	73.9–78.2
Freeze/thaw stability	3 cycles at −20^∘C	92.2	73.6–112.5
	3 cycles at −80^∘C	96.6	84.3–105.5