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Matrix effect in manual injection - 2005/11/28 18:03
Not True. the matrix can have asignificant effect on manual (or automatic!) injections. Consider the case of the solvent based calibration solution and the aqueous sample as an extreme. The solvent will evaporate in the injector very quickly (not instantaneously!) and the calibrants will then be free to evaporate and enter the column system. The water will evaporate very slowly (comparitively) and will hold back the analyte evaporation and transport to the column. The solvent vapour will probably be half the volume of the injector liner and will give a small kick in the injection pressure and probably a minor change in split ratio to that which was set. The water vapour will probably be 2 or 3 times the volume of the injector liner and produce anomalous effects on the inlet pressure and wierd changes to the split ratio.
And this is just the injector end - the differences in "solvent effect" at the front of the column and any hydrolysis, hydration or decomposition effects on various analytes all mean that the sample matrix cannot be ignored for this extreme case. Care should also be taken with less extreme cases.
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