Oxygen sensitive detectors

Graphite-Vespel (15% 85%) 350°C upper temperature limit general-purpose use in capillary columns recommended for MS or oxygen-sensitive detectors, also compatible with other detectors, such as FID and NPD most reliable leak-free connection proper installation requires a finger-tight turn on the nut, then an additional quarter-turn with a wrench the ferrule hole must match the column o.d. exactly to ensure a leak-free seal not reusable. 

Lipid hydroperoxides are also generated in singlet molecular oxygen mediated oxidations and by the action of enzymes such as lipoxygenases and cyclooxygenases. Chemiluminescence (CL) arising from lipid peroxidation has been used as a sensitive detector of oxidative stress both in vitro and in vivo . Several authors have attributed ultra-weak CL associated with lipid peroxidation to the radiative deactivation of O2 and to triplet-excited carbonyls (63, 72) (equations 35 and 36) " . It has been proposed that the latter emitters arise from the thermolysis of dioxetane intermediates (61, 62) (equation 35), endoperoxide (73) (equation 37) and annihilation of aUtoxyl, as well as peroxyl radicals ... 

FLOW REQUIREMENTS. The carrier gases used are nitrogen or argon containing methane at 5 - 10% of the total volume. The methane reduces the concentration of metastable argon and promotes thermal equilibrium of the electrons. The ECD is/is not a flow-sensitive detector. Many believe that column bleed and traces of oxygen in the carrier gas are responsible for flow and temperature dependence. It is prudent to see if the system is dependent. 

More information about this technique is given in Section 5.3. A variety of other detectors were used in Py-GC, such as NPD, which is practically a modified FID, PID and ECD, which are very sensitive detectors for specific classes of compounds, and AED [38aj. With an AED detector, it is possible for example to monitor in parallel eluting compounds that contain carbon, hydrogen, oxygen, nitrogen, and sulfur. 

A sensitive method for the flow injection analysis of Cu + is based on its ability to catalyze the oxidation of di-2-pyridyl ketone hydrazone (DPKH) by atmospheric oxygen. The product of the reaction is fluorescent and can be used to generate a signal when using a fluorometer as a detector. The yield of the reaction is at a maximum when the solution is made basic with NaOH. The fluorescence, however, is greatest in the presence of HCl. Sketch an FIA manifold that will be appropriate for this analysis. 

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