Only in the presence of higher ascorbic acid than 150 lg L1 the decrease of the sensitivity is significantly observed, and the working range is narrowed.
As a result, the same or slightly lower sensitivity is achieved for matrix-matched calibration solutions.
Since ascorbic acid is especially a natural ingredient of the natural fruit juices as
well as wine and beer, it can be considered that beverage samples have their own suitable matrix modifier for the selective determination of especially Sn(IV).
It should be pointed only that obviously matrix matched standard solution should be used for calibration, which mean that ascorbic acid should be added to all aqueous standard solutions to ensure the same sensitivity for total Sn determination.
In this case, the slope of standard addition curve for beverages like wine and beer can be accepted to be approximately equal to those of aqueous standard solutions matched with ascorbic acid.