Detection of carboxyhemoglobin (COHb) in thin films of 50 μL of human and bovine blood <i>in vitro</i> with spectrograms from the SCiO pocket molecular sensor.

<p><b>A</b>. Representative spectrograms of human blood with varying fractional content of COHb, produced by adding pure CO gas to heparinized blood. Hemoximeter measured COHb is indicated, expressed as % of total hemoglobin, as are the wavelengths of interest in the analysis (775 nm, 875 nm and 925 nm). The multiple traces of the same color indicate repeat scans of the same sample, to indicate reproducibility. <b>B</b>. Regression analysis of spectrometric model [COHb] = f(850nm spectrogram signal-775 nm spectrogram signal)/925 nm signal and hemoximeter measured COHb levels in human and <b>C</b>. bovine blood, based on creation of an index relating differences in spectrogram signals at 875 and 775 nm relative to an isobestic wavelength of 925 nm (see text). <b>D</b>. Modified Bland-Altman bias plot of errors in SCiO estimates of [COHb] % based on the regression equation relating SCiO index value and hemoximeter measured [COHb]. Dashed lines show 95% confidence limits for the regressions.