RITS System Description

A RITS system in its fullest form consisted of 2 GCs and 3 separation columns (channels), each loaded with a unique packing material for the measurement of N2O, CFC-12, CFC-11, CH3CCl3, and CCl4, with dual-channel redundancy for N2O and CFC-11. N2 was the carrier gas used on the chlorocarbon solvent (B) channel, while the two N2O channels (A and C) used a 5% mixture of CH4 in Argon (called "P5") as the carrier gas. The RITS system is summarized by channel in Table 2. A description of the RITS system analytical technique can be found at the in situ monitoring page.

 
 
Table 2: RITS System Channel Summary
RITS
Channel		 Gas
Chromatograph		 Carrier
Gas		 Column
Packing
Material		 Detector Measureable
Compounds
A Hewlett-Packard 5890 P5 Porasil B Electron
Capture		 N2O, CFC-12, CFC-11
B Hewlett-Packard 5890 N2 OV-101 Electron
Capture		 CFC-11, CFC-113,
CH3CCl3, CCl4
C Shimadzu P5 Porapak Q Electron
Capture		 N2O, SF6
 
 

Figure 1. Chromatograms from each of the three RITS channels. These plots are all from the same calibration sample injection -- the first sample injection of the new millenium (GMT) at CMDL's Samoa observatory.

 
 

Figure 2. The RITS system at Niwot Ridge. Shown from left to right are the data-recording system, analog-to-digital converter boxes, Hewlett-Packard GC (housing channels A and B), and the Shimadzu GC (housing channel C). On the wall above the system is the environmental stream intake manifold. Cylinders holding calibration gases, P5 and N2 carrier gases, and pnuematic air (for driving the stream select valve) are out of the picture to the right.