Chemiluminescent detector

Detector Chemiluminescence following post-column reaction. A1 mM solution of Ru(2,2 -hip3o-idine)3 in 50 mM sodium sulfate (continuously sparged with helium) was oxidized to Ru(2,2 -bipyridine)3 using a Princeton Applied Research Model 174A polarographic... 

Detector Chemiluminescence following post-column reaction. The column effluent mixed with the reagent pumped at 1.4 mL/min and the mixture flowed to the detector. (Reagent was 0.25 mM bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate (TDPO, Wako, Oseika) emd 37.5 mM hydrogen peroxide in MeCN ethyl acetate 50 50.)... 

Detector Chemiluminescence following post-column reaction. A 1 mM solution of Ru(2,2 -bipyridinels in 50 mM sodium sulfate (continuously sparged with helium) was oxidized to Ru(2,2 -bipyridine)3 " using a Princeton Applied Research Model 174Apolarographic analyzer with a platinum gauze working electrode, a platinum wire auxilituy electrode, and a silver wire reference electrode. The Ru solution pumped at 0.3 mlVmin mixed with the column effluent in the flow cell of the detector, a fluorescence detector with the li t source removed. 

Obviously, the chromatographic principles are the same in process and laboratory GCs and they are built up in a very similar way. Standard detectors are in each case the thermal conductivity detector (TCD), which is a universal detector for all components, and the flame ionization detector (HD), which is a specific detector for hydrocarbons. To detect sulfur gases selective detectors like an electrochemical detector, chemiluminescence detector and, most important, flame photometric detector (FPD) are used. Gaseous fuels hke natural gas, synthetic gases, and blends are complex mixtures that cannot completely be separated in a single column. Two or more different columns must be combined. To monitor the fuel quality a quasi-continuous analysis is necessary this means that very short cycle times must be realized. To do so, high-boiling components are removed... 

MSFIA-CL manifold for the determination of trace levels of orthophosphate in waters. Detector chemiluminescence detector (flow-through solid-phase optical sensor-i- photosensor module) HC holding coil PMT photomultiplier RC reaction coil V solenoid valve. 

Reference methods for criteria (19) and hazardous (20) poUutants estabHshed by the US EPA include sulfur dioxide [7446-09-5] by the West-Gaeke method carbon monoxide [630-08-0] by nondispersive infrared analysis ozone [10028-15-6] and nitrogen dioxide [10102-44-0] by chemiluminescence (qv) and hydrocarbons by gas chromatography coupled with flame-ionization detection. Gas chromatography coupled with a suitable detector can also be used to measure ambient concentrations of vinyl chloride monomer [75-01-4], halogenated hydrocarbons and aromatics, and polyacrylonitrile [25014-41-9] (21-22) (see Chromatography Trace and residue analysis). 

Fig. 2. Schematic of the fraction of chemiluminescence time profile observed in a flowing stream detector (71). See text.

Several new oxalates have been developed for use ia analytical appHcations. Bis(2,6-difluorophenyl) oxalate (72) and bis(4-nitro-2-(3,6,9-trioxadecylcarbonyl)phenyl) oxalate (97) have been used ia flow iajection and high performance Hquid chromatography (hplc) as activators for chemiluminescence detectors. These oxalates are generally more stable and show better water solubiUty ia mixed aqueous solvents yet retain the higher efficiencies ( ) of the traditional oxalates employed for chemiluminescence. 

The flame-photometric detector (FPD) is selective for organic compounds containing phosphoms and sulfur, detecting chemiluminescent species formed ia a flame from these materials. The chemiluminescence is detected through a filter by a photomultipher. The photometric response is linear ia concentration for phosphoms, but it is second order ia concentration for sulfur. The minimum detectable level for phosphoms is about 10 g/s for sulfur it is about 5 x 10 g/s. 

Fig. 14-4. Schematic diagram of chemiluminescent detector for NO2 and NO. PMT, photomultiplier tube.

Figure 14.2 Schematic diagram of the cliromatographic system used for the analysis of low concenti ations of sulfur compounds in ethene and propene VI, injection valve V2, column switcliing valve SL, sample loop R, restriction to replace the column SCD, sulfur chemiluminescence detector.

The System described in the previous section has been extended with a sulfur chemiluminescence detector (SCO) for the detection of Sulfur compounds (32). The separated fractions were thiols + sulfides + thiophenes (as one group), benzothio-phenes, dibenzothiophenes and benzonaphtho-thiophenes. These four groups have been subsequently injected on-line into and separated by the GC unit. Again, no overlap between these groups has been detected, as can be seen from Figure 14.20, in which the total sulfur compounds are shown and from Figure 14.21 in which the separated dibenzothiophenes fraction is presented. The lower limit of detection of this method proved to be 1 ppm (mg kg ) sulfur per compound. 

In the chemiluminescence-based HPLC detection system, illustrated schematically in Figure 6, the oxalate ester and hydrogen peroxide are introduced to the eluent stream at postcolumn mixer Mj, which then flows through a conventional fluorescence detector with the exciting lamp turned off or a specially built chemiluminescence detector. The two reagents are combined at mixer Mj, rather than being premixed, to prevent the slow hydrolytic reactions of the oxalate ester. 

Using a chemiluminescence detector with 60-pL sample cell. 

These results encouraged further efforts in the development of the peroxyoxalate chemiluminescent method for HPLC-detectors. 

The product gases were continuously analyzed for NO and NO2 using a chemiluminescent analyzer, and discontinuously for N2O, N2, CO, CO2 and O2 by GC equipped with a thermal conductivity detector and an electron capture detector, specifically for the N2O analysis, using a Poraplot Q column and a molsieve 5A column for separation. 

Supercritical fluid chromatography (SEC) was first reported in 1962, and applications of the technique rapidly increased following the introduction of commercially available instrumentation in the early 1980s due to the ability to determine thermally labile compounds using detection systems more commonly employed with GC. However, few applications of SEC have been published with regard to the determination of triazines. Recently, a chemiluminescence nitrogen detector was used with packed-column SEC and a methanol-modified CO2 mobile phase for the determination of atrazine, simazine, and propazine. Pressure and mobile phase gradients were used to demonstrate the efficacy of fhe fechnique. 

---