Chemiluminescence detector

The combination of FI gas-diffusion separation with chemiluminescence has produced selective methods for the determination of chlorine and chlorinated species. Hollowell ct al.[33] determined chlorine dioxide by a chemiluminescent reaction with luminol, following a gas-diffusion separation. A T-spiral flow cell was mounted directly in front of the photomultiplier to maximize the detection of the light emission. Potential interferences from transition metals were removed by the gas-diffusion process, since they do not pass 

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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. 

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. 

SCD Sulfur chemiluminescence detector (flame and flameless) Ozone-induced CL... 

QF Quartz tube flame atomiser chemiluminescence detector ... 

J.S. Beckman and K.A. Congert, Direct measurement of dilute nitric oxide in solution with an ozone chemiluminescent detector. Methods 7, 35-38 (1995). 

J.K. Robinson, MJ. Bollinger, and J.W. Birks, Luminol/H202 chemiluminescence detector for the analysis of nitric oxide in exhaled breath. Anal. Chem. 71, 5131-5136 (1999). 

Many sophisticated analytical techniques have been used to deal with these complex mixtures.5,45,46 A detailed description is not possible here, but it can be noted that GLC, often coupled with mass spectrometry (MS), is a major workhorse. Several other GLC detectors are available for use with sulfur compounds including flame photometer detector (FPD), sulfur chemiluminescence detector (SCD), and atomic emission detector (AED).47 Multidimensional GLC (MDGC) with SCD detection has been used48 as has HPLC.49 In some cases, sniffer ports are provided for the human nose on GLC equipment. 

Savchuk et al. [331] used GC with an open tubular column and a chemiluminescence detector to determine sulfur-containing organic compounds in amounts down to 0.1 ppt in seawater. 

Sievers Instruments. Gas-phase chemiluminescence detector http / / www.SieverInst.com/... 

As shown schematically in Figure 1, a gas-phase chemiluminescence detector consists of a reaction chamber, inlets for the analyte and reagent gas streams, a vacuum pump to lower the pressure in the reaction chamber (typically to a few torr), and a transducer such as a photomultiplier tube (PMT) to monitor the light produced in the reaction. The reagent gas, usually present in large excess, reacts with a trace concentration of analyte to produce an excited product that subse-... 

Figure 1 Schematic diagram of a generalized gas-phase chemiluminescence detector.

Optimization strategies and a number of generalized limitations to the design of gas-phase chemiluminescence detectors have been described based on exact solutions of the governing equations for both exponential dilution and plug-flow models of the reaction chamber by Mehrabzadeh et al. [12, 13]. However, application of this approach requires a knowledge of the reaction mechanism and rate coefficients for the rate-determining steps of the chemiluminescent reaction considered. 

The chemiluminescent reaction of SO with ozone is the basis of the sulfur chemiluminescence detector (SCD) [23] discussed later in this chapter,... 

Gas chromatography is one of the most powerful analytical techniques available for chemical analysis. Commercially available chemiluminescence detectors for GC include the FPD, the SCD, the thermal energy analysis (TEA) detector, and nitrogen-selective detectors. Highly sensitive detectors based on chemiluminescent reactions with F2 and active nitrogen also have been developed. 

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