Effect of optimization on spectrum quality and reproducibility.

a<p>Values reported are the means of 20 replicates ± the standard deviations of the mean. Data were analyzed by t test (α = 0.05).</p>b<p>Values reported are the average correlation coefficients of 20 replicates ± the standard deviations of the correlation coefficient.</p><p>Before and after optimization values for each bacterium followed by different numbers of asterisks are significantly different.