DNPH-cartridges

In another intercomparison using TDLS, several DNPH methods, the 1,3-cyclohexanedione diffusion scrubber, and the enzymatic method were compared using both spiked samples and ambient air. The TDLS was used as a standard for comparison. For ambient air measurements, results obtained with the 1,3-cyclohexanedione diffusion scrubber were about 30% higher than those obtained with TDLS, whereas results for the enzymatic method were about 35% lower. The DNPH cartridge measurements were quite variable, which may... 

Sirju, A.-P., and P. B. Shepson, Laboratory and Field Investigation of the DNPH Cartridge Technique for the Measurement of Atmospheric Carbonyl Compounds, Environ. Sci. Technol., 29, 384-392 (f 995). 

Samplers for vapors in cell/chamber exhaust DNPH cartridges for formaldehyde Tenax TA or alternative sorbent for VOCs When using Tenax TA tubes for VOCs, max volume restricted to 5L... 

Figure 1.2-2. Different types of sampling devices for aldehydes, phenols and MDI, 1 = Tenax tube with gas meter and pump 2 = DNPH cartridge 3 = MDI cartridge 4 = Muencke absorber with gas meter and pump.

The aldehydes and ketones can be collected in several different ways. One of the most common is the use of solid sorbents such as silica gel, Florisil, or C,x cartridges that are coated with DNPH (e.g., see Lipari... 

Benning, L and A. Wahner, Measurements of Atmospheric Formaldehyde (HCHO) and Acetaldehyde (CH3CHO) during POPCORN 1994 Using 2,4-DNPH Coated Silica Cartridges, J. Atmos. Chem., 31, 105-117 (1998),... 

Figure 3. LC chromatogram of carbonyls collected on a DNPH-impregnated silica gel cartridge. Peak identities 1, DNPH 2, formaldehyde 3, acetaldehyde 4, acrolein 5, acetone 6, propionaldehyde 7, x-acrolein 8y crotonaldehyde 9, butyraldehyde and 10, benzaldehyde. (Reproduced with permission from reference8. Copyright 1992.)...

The DNPH derivatives may also be extracted by solid-phase extraction (liquid-solid extraction). The sorbent cartridge is conditioned with 10 mL of dilute 1 M citrate buffer solution (1 25 dilution) and 10 mL of saturated NaCl solution. The cartridge is then loaded with the extract and the derivatives eluted with acetonitrile. 

Trace acetone in water may be determined by a fast HPLC method (Takami et al., 1985) aqueous sample passed through a cartridge packed with a moderately sulfonated cation-exchange resin charged with 2,4-dinitrophenylhydrazine (DNPH) DNPH derivative eluted with acetonitrile and analyzed by HPLC with a 3-mm ODS column. 

Alternatively, a measured volume of air drawn through a prepacked cartridge coated with acidified DNPH the DNPH derivative of acetone eluted with acetonitrile and measured by HPLC-UV as above (U.S. EPA Method TO-11, 1988). 

Air drawn through a cartridge containing silica gel coated with acidified DNPH derivative eluted with acetonitrile and determined using isocratic reverse phase HPLC with UV detection at 360 nm (U.S. EPA 1988, Method TOll) recommended flow rate 1 L/min sample volume 100 L. 

TO-11 DNPH-coated adsorbent cartridge elution with acetonitrile HPLC analysis Formaldehyde... 

Millipore Corporation. 1992. Waters Sep-Pak DNPH-Silica Cartridge. Care and use manual. Milford, MA Waters Chromatography Publications. 

Styrene and cyclohexene by reactions with O3 during sampling. Roberts et al. reported formation of monoaromatics, w-alkanes, and aldehydes when Tenax was exposed to O3. Unsaturated compounds adsorbed on Tenax have been observed to react with nitrogen oxides, CI2, and O3 to produce a mixture of OxHCs. ° Decomposition of the Tenax by O3 can also occur to produce benzaldehyde, phenol, and acetophenone however, graphitized carbon sorbents appear more robust. " Interferences of O3 with carbonyl sampling by 2,4-DNPH-coated cartridges include depletion of the 2,4-DNPH, degradation and formation of carbonyl hydrazones, and formation of unknown 2,4-DNPH products. 

Druzik, C. M., Grosjean, D., van Neste, A., and Parmer, S. S., Sampling of atmospheric carbonyls with small DNPH-coated C18 cartridges and liquid chromatography analysis with diode array detection, Int. J. Environ. Anal. Chem., 38, 495-512, 1990. 

For sampling, air is sucked through cartridges coated with a DNPH solution (see Fig. 1.2-2). Ready-to-use cartridges are now commercially available or can be prepared as described by Zhang et al. (1994a 1994b). Air samples are typically collected for I - 3 h... 

Air samples were collected on Tenax TA (60-80 mesh) (0.5-1.0 1 total volume at a flow rate of 50 ml/min). The analysis of Tenax tubes was carried out using a GC/ MS-system (Hewlett-Packard 6890) or a GC/FID-system (Hewlett-Packard 5890) with a 25-m HP-5 column, each equipped with a thermal desorber - cold trap injector (Perkin Elmer ATD 400). Identification of the compounds was based on a PBM library search. Moreover, mass spectra and retention data were compared with those of reference compounds. The monoterpenes and sesquiterpenes were sampled on active charcoal (NIOSH standard, SKC 226-01, 60-80 1 total volume at a flow rate of 0.5 1/min). The terpenes were extracted by use of carbon disulfide under constant shaking for 1 h and analyzed via GC/FID. Aldehydes were trapped on filter cartridges coated with dini-trophenylhydrazine (DNPH) (Macherey Nagel). The dinitrophenylhydrazone derivatives were extracted with acetonitrile and analyzed via HPLC/UV. 

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