Final answer:
True, GC detectors can have sensitivities in the order of nanograms, which allows for very low levels of substance detection. Some detectors can be destructive, but whether this is a drawback depends on the requirements of the analysis.
Step-by-step explanation:
The statement B. Typical GC detectors sensitivities are in the order of nanograms is true. Gas chromatography (GC) is a common analytical technique used in many laboratories for the separation and analysis of compounds. Detectors in GC systems are designed to respond to substances passing through the column, and the truly sensitive ones can indeed detect substances in the nanogram range. While some detectors like the flame ionization detector (FID) and the thermal conductivity detector (TCD) are non-destructive and can be used for subsequent analysis, others such as the mass spectrometer (MS) detector can indeed be considered destructive because they utilize processes that alter or destroy the sample.
It is important to choose the right detector based on the application and the sensitivities required. In many applications, the fact that a detector is destructive is not a drawback, because the detailed information obtained (like mass spectra) is essential and worth the destruction of the sample. Others may require the sample to be recovered post-analysis, in which case a non-destructive detector would be preferred.