Fig 2. Results from matrix interference assessment.

A standard solution (final concentration 240pg/ml) was spiked with either phosphate-buffered saline or a set of serial dilutions of a pooled sample (“uL of sample added”) composed of blubber cortisol extracts from four individuals to make a final equivalent volume of 240ul. The concentration of cortisol contributed from the pooled sample (neat = ± 398.5pg/ml) was subtracted from each sample-spiked measurement so its contribution would be factored out of the assessment. Little to no evidence of matrix interference was observed (r² = 0.012, p = 0.78).