Detectors nitrogen-phosphorus

The neutral Rb atoms that have evaporated from the heated rubidium silicate react with the cyano (or phospho for P detection) radicals, the Rb ions are neutralized on 

The optimized detector gas flow rates are different for N and P detection and also from that of the FID. Formation of CH radicals is suppressed in the NPD. The NPD is a selective detector for N- and P-containing compounds and the MD is about lOpgN and 5 pg P. Other detector characteristics can be found in Table 2.4. The NPD is used, for example, for pesticide determination in food and environmental applications. 

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Hint To distinguish these compounds without elemental composition or standards for GC retention time, split the GC effluent to a FID, a nitrogen-phosphorus detector, and the mass spectrometer, simultaneously. Using this splitter system, it is easy to determine if the GC peak contains nitrogen. Also, the analyst can differentiate between azobenzene and benzophenone by using the methoxime derivative. 

Methyl parathion was determined in dog and human serum using a benzene extraction procedure followed by GC/FID detection (Braeckman et al. 1980, 1983 DePotter et al. 1978). An alkali flame FID (nitrogen-phosphorus) detector increased the specificity of FID for the organophosphorus pesticides. The detection limit was in the low ppb (pg/L). In a comparison of rat blood and brain tissue samples analyzed by both GC/FPD and GC/FID, Gabica et al. (1971) found that GC/FPD provided better specificity. The minimum detectable level for both techniques was 3.0 ppb, but GC/FPD was more selective. The EPA-recommended method for analysis of low levels (<0.1 ppm) of methyl parathion in tissue, blood, and urine is GC/FPD for phosphorus (EPA 1980d). Methyl parathion is not thermally stable above 120 °C (Keith and Walters 1985). 

EC = electrical conductivity detector ECD = electron capture detector FPD = flame photometric detector GC = gas chromatography HPLC = high performance liquid chromatography NPD = nitrogen phosphorus detector TID = thermionic detector UV = ultraviolet spectroscopy... 

GC nitrogen-phosphorus detector (NPD), flame photometric detector (FPD), electron capture detector (BCD), flame ionization detector (FID), mass-spectrometric detector (MS)... 

Gas chromatograph equipped with a nitrogen-phosphorus detector... 

Hewlett-Packard Model 5890 gas chromatograph with capillary split/splifless inlet with nitrogen-phosphorus detector equipped with a Model 7673A autosampler... 

Hewlett-Packard Model 5890 gas chromatograph equipped with a nitrogen-phosphorus detector Hewlett-Packard Model 3396 or 3396A integrator Hewlett-Packard Model 6890 or 7673A autosampler RTX-1 fused-silica column (100% polymethylsilox-ane), 30 m x 0.53-mm i.d., 0.5- um film thickness, Restek Corporation (Bellefonte, PA, USA)... 

Gas chromatograph equipped with a nitrogen-phosphorus detector Water-bath electrically heated, temperature 45 °C... 

Nitrogen-phosphorus detector 290 °C (for imibenconazole), 260 °C (for imibenconazole-debenzyl)... 

Varian 3400 gas chromatograph with split/splitless injector and nitrogen-phosphorus detector (GC/NPD)... 

Hewlett-Packard 5890A Series II with HP-7673A autosampler and nitrogen-phosphorus detector. HP-17 fused silica, 10 m x 0.53-mm i.d., 2.0-p.m film thickness... 

Cabbage, cantaloupe, cauliflower, citrus fruit, cottonseed, cucumber, mustard greens, nutmeats, pome fruit, stone fruit, summer squash, tomatoes, soil, and water Gas chromatograph with nitrogen-phosphorus detector... 

Gas chromatograph, equipped with a nitrogen-phosphorus detector Glass chromatography column, 19 x 300 mm with Teflon stopcock Glass wool (Pyrex)... 

Nitrogen-phosphorus detector, 300 °C Helium carrier gas, 20 mLmin ... 

Water samples are acidified and extracted with solvent (Kawamura and Kaplan 1983 Muir et al. 1981). Clean-up steps may be used (Kawamura and Kaplan 1983). Methylene chloride is often used as the extracting solvent, and it may interfere with the nitrogen-phosphorus detector. In this case, a solvent-exchange step is used (Muir et al. 1981). Analysis by GC/NPD or GC/MS provides specificity (Kawamura and Kaplan 1983 Muir et al. 1981). Accuracy is acceptable (>80%), but precision has not been reported. Detection limits were not reported, but are estimated to be 0.05-0.1 pg/L (Muir et al. 1981). Detection limits at the low ppt level (ng/L) were achieved by concentrating organophosphate esters on XAD-2 resin. The analytes were solvent extracted from the resin and analyzed by GC/NPD and GC/MS. Recovery was acceptable (>70%) and precision was good (<10% RSD) (LeBel et al. 1981). 

Acrylonitrile in both biological and environmental samples is most commonly determined by gas chromatography with a nitrogen-phosphorus detector (GC/NPD) (Page 1985), gas chromatography/flame ionization detection (GC/FID) (EPA 1982a), or gas chromatography/mass spectroscopy (GC/MS) (Anderson and Harland 1980). Infrared spectroscopy (Jacobs and Syrjala... 

GC = gas chromatography MS = mass spectrometry NPD = nitrogen-phosphorus detector. 

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