spatial-distribution interference

in flame spectroscopy
Interference which may occur when changes in concentration of concomitants affect the mass flow rates or mass flow patterns of the analyte species in the flame. If they are caused by changes in volume and rise velocity of the gases formed by combustion, in extreme cases manifesting themselves by changes in the size and/or shape of the flame, they are non-specific and are called flame-geometry interferences.
Orange Book, p. 171