Answer:

1. Usage of portable gas chromatography-mass spectrometry (GC-MS) is an important capability that has been available commercially for a long time. 

There are many methods used to screen and detect CWAs and TICs in the some field. These methods range from simple color tests capable of detecting different functional groups of the CWA or TIC molecule, to advanced methods such as gas chromatography-mass spectrometry (GC-MS) that can identify and even quantify the specific chemical composition of the CWA or TIC substance. That is why it is necessary to look to those two.

2. In the mass spectrum, the heaviest ion is likely to be the molecular ion. A few compounds have mass spectra which don't contain a molecular ion peak, because all the molecular ions break into fragments.

Different in the strength of the magnetic field, ions of different mass can be focused progressively. The highest mass ion in a spectrum is normally considered to be the molecular ion.