Matrix interferences may be caused by contaminants co-extracted from the sample. The
extent of matrix interferences will be source- and matrix- specific. If interferences occur in
subsequent samples, modification of the mobile phase or some additional cleanup may be
necessary.
3.4 In Procedure 1, acetaldehyde is generated during the derivatization step if ethanol is
present in the sample. This background will impair the measurement of acetaldehyde levels below
0.5 ppm (500 ppb).