Developing Methods
User Information 113
Matrix Effects
The composition of the sample matrix can affect the amount of
analyte that escapes into the headspace. Adding an inorganic
salt to aqueous samples increases the concentration of organic
molecules in the headspace by making them less soluble in the
sample matrix, increasing sensitivity. For nonaqueous but
water-miscible systems, dilute the sample with water. This
decreases the solubility of most organic molecules in the sample
and increases their concentration in the headspace.
Matrix effects are important when developing external
standards. The composition of the matrix in the standard
should closely resemble that of the sample, or accuracy suffers.
The effect of the matrix on a standard can be compensated for
by using the standard addition method or by quantifying results
using MHE.
medium_standard.book Page 113 Tuesday, February 17, 2004 10:14 AM
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