Methylene Chloride | ScienceGate

Abstract The analysis of aromatic amines, particularly benzidines, at trace levels in environmental media has been difficult because of the lack of suitable deactivated capillary column stationary phases for gas chromatography. This report describes the use of an improved type of column as well as a method for the analysis of anilines and benzidines in water, wastewater and sewage samples. Extraction procedures are applicable to a wide range of compounds that are effectively partitioned from an aqueous matrix into methylene chloride, or onto a solid-phase extraction cartridge. The extracted analytes are also amenable to separation on a capillary gas chromatographic column and transferable to the mass spectrometer. These contaminants are converted to their N-trifluoroacetyl derivatives. Aniline and some substituted anilines, and 3,3’-dichlorobenzidine and benzidine were determined in 24-h composite industrial water, wastewater, primary sludge and final effluent samples at concentrations from 0.03 up to 2760 µg/L.

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Comparison of Sorption and Extraction Methods for Recovery of Trace Organics from Water

Water Science & Technology ◽

10.2166/wst.1983.0139 ◽

1983 ◽

Vol 15 (6-7) ◽

pp. 149-159 ◽

Cited By ~ 11

Author(s):

V C Blok ◽

G P Slater ◽

E M Giblin

Keyword(s):

Solvent Extraction ◽

Methylene Chloride ◽

Extraction Methods ◽

Liquid Extraction ◽

Standard Mixture ◽

Liquid Liquid Extraction ◽

Trace Organics ◽

Tenax Gc

Several commercially available adsorbents were compared with solvent extraction methods for their utility in recovering trace organics from water. The adsorbents examined included Amberlite XAD-2, XAD-4 and XAD-8, Ambersorb XE340 and XE348 and Tenax-GC. All were found to produce high artifact levels, even after extensive clean-up, making them unsuitable for the analysis of trace organics in water. Quantitatively, Likens-Nickerson or continuous liquid-liquid extraction with méthylene chloride gave better recoveries than the adsorbents. Qualitatively, extractive methods were preferred as they yielded much lower levels of impurities than the adsorbents. These methods of recovering trace organics were evaluated using a standard mixture of compounds added to the water at a level of 55 µg/l. Likens-Nickerson extraction gave comparable recoveries of this mixture at 55 µg/l and 11 µg/l.

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Henry's constants and mass transfer coefficients of halogenated organic pollutants in an air stripping packed column

Water Science & Technology ◽

10.2166/wst.1998.0263 ◽

1998 ◽

Vol 38 (6) ◽

pp. 287-294 ◽

Cited By ~ 4

Author(s):

Pen-C. Chiang ◽

Chung-H. Hung ◽

J. C. Mar ◽

E. E. Chang

Keyword(s):

Mass Transfer ◽

Methylene Chloride ◽

Packed Column ◽

Transfer Coefficients ◽

Chlorinated Organic Compounds ◽

Air Stripping ◽

Mass Transfer Coefficients ◽

Equilibrium Partition ◽

Henry's Constants ◽

Chlorinated Organic

Both Henry's constants and volumetric mass transfer coefficients (KLa) of eight priority chlorinated organic compounds including 1,1-dichloroethene, methylene chloride, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and 1,4-dichlorobenzene in an air stripping packed column were investigated in this study. The liquid and gas phase EPICS (Equilibrium Partition in Closed System) and direct calculating methods were applied to determine the Henry's constants of VOCs. The interference of co-solute on Henry's constants was also investigated. Experimental results indicated that decrease in Henry's constants of VOCs was observed in the presence of humic acid but no apparent effect on Henry's constants was detected when there was NaCl and surfactant in solution. Four different configurations of packing media including Intalox Saddle, Super Intalox Saddle, Telleret, and Hedgehog made of polypropylene were respectively packed in the air stripping tower and investigated in the study. The dependence of hydraulic loading, air-water ratio, and configurations of packing media on mass transfer coefficients of VOCs was discussed.

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