W. Wilson Pitt

Nonpulsing reagent metering for continuous colorimetric detection systems

Abstract A method has been developed for metering liquid reagents without variations in flow rate for continuous colorimetric detection systems. The reagent is forced from a storage chamber by hydraulic head or by gas overpressure, and flow control is achieved by resistance in the delivery line which may be either capillary tubing and/or a needle valve. Continuous flow of the reagent reaction mixture through the colorimeter is achieved by using a water aspirator. Such a system is now employed routinely in a continuous carbohydrate analyzer in which concentrated sulfuric acid and a 5% phenol solution are continously metered and mixed with the effluent from an anion-exchange resin column that separates the carbohydrates in physiological samples.

The determination of stable organic compounds in waste effluents at microgram per liter levels by automatic high-resolution ion exchange chromatography

Abstract A high-resolution anion exchange analyzer was adapted for determination of u.v.-absorbing compounds in water at μg 1 −1 levels. The samples were concentrated prior to analysis by vacuum distillation and freeze-drying. Seventy-seven peaks were obtained from a municipal primary sewage effluent; each constituent was present at less than 100 μg 1 −1 . Thirty-eight peaks were obtained from a municipal secondary sewage effluent, with each constituent at less than 20 μg 1 −1 . Thirteen compounds have been identified as relatively stable to primary treatment. The concentrations of compounds in industrial primary and secondary effluents were estimated at up to 1 mg 1 −1 ; the secondary treatment caused little degradation. Chromatograms of the effluents appear to depend upon sewage plant operating conditions as well as upon the type of feed sent to the treatment plant.

Characterization of organics in aqueous effluents of coal conversion processes

Abstract High-resolution liquid chromatography is being applied to the characterization of refractory organic compounds present in coal conversion streams at concentrations as low as a few micrograms per liter. The chromatographic system, which was previously developed for the analysis of the molecular biochemical constituents in human body fluids, is capable of analyzing for compounds that are u.v.-absorbing and/or oxidizable with sulfatoceric acid. Aqueous samples from various coal-liquefaction experiments have been collected, concentrated when necessary, and chromatographed. The chromatographic fractions have then been subjected to a multiple-analytical identification procedure utilizing, in sequence, UV-spectrometry, gas chromatography, and mass spectrometry. With this procedure, 18 organics were identified and 15 were quantified in the effluent from the product scrubber of a bench-scale hydrocarbonization unit. In addition, numerous unknown constituents have been characterized with respect to gas chromatographic and mass spectrometric properties.

Centrifugal elution chromatography with eluate monitoring

Abstract The feasibility of using centrifugal, multicolumn elution chromatography in conjuction with eluate monitoring is being studied. A preliminary prototype system has as many as four columns mounted in a spinning rotor that passes through a stationary photometric detection station. Cuvette windows at the terminal end of each chromatographic column allow photometric monitoring of each column eluate as it passes through the detector. The monitor is capable of associating a given output signal with the appropriate chromatographic column using suitable digital logic. The photometric output can be recorded by a conventional strip-chart recorder or via a computer by printed tabulations. In the present mode of operation a common sample is introduced simultaneously to each column with a single eluent stream being used for all columns. Preliminary tests have been directed toward establishing the best rotor design for hydrodynamic stability and overall operability. The system is being considered for the assay of several serum proteins from a single serum sample utilizing affinity chromatography.