This technical note illustrates the NCI capabilities of the ISQ 7000 single quadrupole GC-MS system, with detection limits as low as 100 attograms OFN on-column. An appropriate balance of ion source temperature and reagent gas flow rate is required to have a suitable abundance of high mass ions as well as satisfactory peak asymmetry. For applications involving silylated compounds careful consideration needs to be given to optimization of source temperature, in order to avoid excessive fragmentation of higher mass ions and excessive peak tailing. For most applications however, ion source temperatures between 200 and 250 °C, and methane flow rates between 1 and 2 mL/min provide a good balance between sensitivity and robustness.
