The use of a six-way valve controlled by the mass spectrometer to switch between the 'Blank Route' and the 'Sample route' significantly reduced the amount of operator intervention during analysis (and therefore the possibility of operator error), and greatly increased analysis reliability. Prior to its incorporation into this method, additional data processing was required to mathematically determine the start and end of the blank and the sample, involving finding the largest increase in the 2nd differentiation of the Savitzky-Golay smoothed total ion current (TIC) spectrum over a 12 second interval. (The now definite switch between the 'Blank Route' and 'Sample Route' may be seen to occur at exactly 3 minutes in Figure ). Furthermore, the entire system was able to remain under the pressure of the nitrogen gas flow, removing abnormally intense measurements in the first few seconds of sample analysis due to a low nitrogen flowrate entering the APCI inlet.