Nitrogen-specific analyses, capillary

Analysis of dimethyl- and diethylamine in air may be performed in accordance to NIOSH Method 2010 (NIOSH 1984, Suppl. 1989). About 3-30 L of air at a fiow rate of 10-1000 mL/min is passed through a silica gel (20/40 mesh, 150 mg front and 75 mg back) sorbent tube. The analytes are desorbed with dilute sulfuric acid in 10% aqueous methanol (3-h ultasonication) and injected into a GC equipped with a FID. A packed column, 4% Carbowax M over 0.8% KOH on Carbosieve B (60/80 mesh) was used in the NIOSH laboratory. A nitrogen-specific detector may be used for amine analysis instead of an FID, using a DB-5 fused-silica capillary column. This method may be applied for the analyses of other aliphatic amines in air and also for certain ethanolamines (NIOSH 1984, Suppl. 1989, Method 2007). Alternatively, ethanolamines may be analyzed by NIOSH Method 3509 (NIOSH 1984, Suppl. 1989). These compounds present in air (5-300 L of air) are... 

As shown in Fig. 3, nitrogen adsorption isotherms of CMK-1 feature well-pronounced capillary condensation steps similar to those of ordered mesoporous silicas and indicative of high degree of mesopore size uniformity. The isotherms reveal that the CMK-1 carbon has high nitrogen BET specific surface area (1500-1800 m g ), and large total pore volume (0.9-1.2 cm g ) [14]. The adsorption capacity is comparable or larger than that of MCM-48 template. The pore-size analysis (calibrated BJH analysis) shows that typical CMK-1 has uniform mesopores about 3 nm in size, which is accompanied by a certain amount of micropores when sucrose is used as the carbon source. 

VX may be analyzed by GC techniques using a flame photometric or a nitrogen-phosphorus detector operated in the phosphorus-specific mode. A fused-silica capillary column may be used for GC analysis. It may be identified and analyzed... 

As GC techniques became more refined and were generally accepted, due to the superior separation and resolution potential of modern capillary columns, they took preference, especially in the analysis of PAH in car exhaust emissions and air particulates. In combination with an FID-detector, which, in contrast to the UV-detectors used frequently in HPLC analysis, has a nearly uniform response factor for hydrocarbons, or coupled to mass spectrometry, this technique must now be considered the method of first choice for a reliable and reproducible determination of PAH traces in a wide range of matrices. The introduction of more sensitive (photo-ionisation detector - PID) and specific detectors, such as the nitrogen-phosphorus (NPD)... 

As indicated above, lead-free gasolines currently contain substantial amounts of compounds such as methyl t-butyl ether (MTBE) as octane rating improvers, and various methods for the analysis of these compounds in a complex hydrocarbon matrix have been proposed. The method currently favored is the use of an oxygen-specific detector. This is a modified FID first suggested by Schneider and colleagues in 1982. The effluent from the capillary column in the carrier gas (nitrogen with a small amount of hydrogen) passes into a small capillary coil of platinum/iridium electrically heated to 1150°C. Under these conditions, hydrocarbons are cracked, i.e., completely broken down to carbon and... 

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