Figure 4. Positive ion mode paper spray mass spectra for rapid detection of metaldehyde in raw water samples (supplied by Northumbrian Water) whereby a volume of ~10 μL of the sample was deposited onto the paper substrate and ionized in the open environment by application of an electric potential of +3.5 kV.

Abberton Raw was analyzed according to (a) the ‘normal PS-MS’ method and (b) with reactive PS-MS. Similarly for Chigwell Raw, ‘normal PS-MS’ analysis is shown in (c) and reactive PS-MS in (d). Inserts (i) & (ii) are the MS/MS CID mass spectra for the protonated metaldehyde ion at m/z 177 from each water sample analyzed using the reactive methodology.