Skip to main content
. 2008 Mar 1;9:133. doi: 10.1186/1471-2105-9-133

Table 2.

A fragment of mass and intensity peaks lists of 2 samples, illustrating the "missing data" problem.

A)


Sample 1 Sample 2


Mass (Da) Intensity (A.U.) Mass (Da) Intensity (A.U.)
? 1193.6166 756021
? 1194.5728 191048
1194.6477 175777 1194.6477 271465
1197.1376 126487 ?
? 1197.6611 124472
? 1198.5193 162275
1198.7047 3154774 1198.7047 2435350


B)


Sample 1 Sample 2


Mass (Da) Intensity (A.U.) Mass (Da) Intensity (A.U.)
0 1193.6166 756021
114322 1194.5728 191048
1194.6477 175777 1194.6477 271465
1197.1376 126487 80604
0 1197.6611 124472
0 1198.5193 162275
1198.7047 3154774 1198.7047 2435350

A) Missing data problem. It appears that the signal intensity from of a peptide mass of 1193.6166 Da in sample 2 is not matched with an intensity of the peptide mass from another sample 1 and vice versa the intensity of peptide mass of 1197.1376 Da of sample 2 is not observed in sample 1.

B) More reliable comparison including background noise signal by recording all the peaks with intensities between the baseline and the S/N threshold in a "noise peaks" file.

A.U. = arbitrary units