Wayne H. Griest

Analysis of methylphosphonic acid, ethyl methylphosphonic acid and isopropyl methylphosphonic acid at low microgram per liter levels in groundwater

A method is described for determining methylphosphonic acid, ethyl methylphosphonic acid and isopropyl methylphosphonic acid, which are hydrolysis products of the nerve agents VX (S-2-diisopropylaminoethyl O-ethyl methylphosphonothiolate) and GB (sarin, isopropylmethyl phosphonofluoridate). The analytes are extracted from 50 ml groundwater using a solid-phase extraction column packed with 500 mg of silica with a bonded quaternary amine phase, and are eluted and derivatized with methanolic trimethylphenylammonium hydroxide. Separation and quantitation are achieved using a capillary column gas chromatograph equipped with a flame photometric detector operated in its phosphorus-selective mode. Two independent statistically-unbiased procedures were employed to determine the detection limits, which ranged between 3 and 9 micrograms/l, for the three analytes.

Influence of carbonaceous particles on the interaction of coal combustion stack ash with organic matter

Stack ash samples were fractionated by aerodynamic size, and the largest particle size fraction was separated into constituent particle type subfractions. Comparison of the mineral, magnetic, and carbonaceous particles showed that coked coal is responsible for the sorptivity of the large particle size fraction for carbon-14 labeled benzo(a)pyrene ((/sup 14/C)BaP) and for low solvent extraction recoveries. Elevated levels of organic matter and surface area also are contributed by the carbonaceous particles. In contrast, solvent extraction recoveries of polar degradation products of (/sup 14/C)BaP are attributable more to the mineral and magnetic particles and to exposure of the ash to light and oxygen. Analysis of bulk ash samples may not fully reflect the true organic composition of stack ash. 27 references, 1 figure, 4 tables.

Determination of munitions components in water by resin adsorption and high-performance liquid chromatography—electrochemical detection☆

Abstract A method has been developed for the determination of several munitons components (nitro-organic compounds) in environmental waters. The method is based on Porapak resin adsorption of the munitions components from aqueous samples. Following desorption with acetone, the nitro compounds are measured by high-performance liquid chromatography with electrochemical detection at a gold—mercury electrode, which is maintained at −1.0 V vs. a silver—silver chloride references electrode. This technique provides a high degree of selectivity and sensitivity for these compounds in actual samples. Detection limits approach 1 μg/1 for many components.

Combustion as the principal source of carbonaceous aerosol in the Ohio River Valley

Organic and elemental carbon and a number of carboxylic acids and n-alkanes were measured in aerosol samples collected at three sites in the Ohio River Valley between October 1980 and August 1981. Approximately 100 filters were analyzed for organic and elemental carbon for each site. For the 11-month period organic and elemental carbon comprised about 19 percent of the total aerosol mass with about two-thirds of the carbon as organic. Regression analysis showed that the principal source of organic carbon was combustion. The measurements of the specific organic compounds indicated a weak biogenic component to the organic aerosol.

Carbonaceous particles in coal combustion stack ash and their interaction with polycyclic aromatic hydrocarbons

Carbonaceous particles consisting of uncombusted coal, coal coke, and intermediates are concentrated in the large particle size fractions (>14 μm) of stack ash. Although they do not constitute a major portion of the ash, they appear to contribute significantly to the interaction of fly ash with organic matter. The carbonaceous particle-enriched fractions are more sorptive, have higher levels of organic matter, and exhibit higher specific surface areas than mineral or magnetic particle-enriched subfractions. Extraction recoveries of organics from fly ash appear to be limited mainly by the carbonaceous particles.

Characterization of insoluble fractions of TNT transformed by composting

Soil contaminated with explosives was supplemented with carbon-14 labelled 2,4,6-trinitrotoluene ([sup 14]C-TNT) and was composted in a field static pile composting experiment. After 90 d of composting, the distribution of carbon-14 ([sup 14]C) activity in fractions from acetonitrile extraction ([open quotes]free[close quotes] fraction, 1.2% of the initial [sup 14]C-activity) and filtration ([open quotes]insoluble-particle[close quotes] fraction, 17.9%), alkaline hydrolysis ([open quotes]insoluble-hydrolyzable[close quotes] fraction, 56.8%), and combustion of the residue ([open quotes]insoluble-nonhydrolyzable[close quotes] fraction, 4.7%) showed that the bulk of the [sup 14]C-activity, and presumably transformed product(s) of the [sup 14]C-TNT, accumulated in a nonextractable, but hydrolyzable fraction. Repetitive aqueous leaching of the compost and also ultraviolet light irradiation followed by leaching suggest that the insoluble fraction of transformed TNT should not be released appreciably by the action of acid rain or sunlight. 16 refs., 11 figs., 2 tabs.

Supercritical fluid extraction of chemical warfare agent simulants from soil

Chemical warfare agent simulants are efficiently recovered from 2-ppm spikes in 1 g of Rocky Mountain Arsenal Standard Soil using methanol-carbon dioxide (5:95) at 300 atm for 2 min at 60 degrees C. Recoveries (n = 3) were 79 +/- 23% for dimethylmethylphosphonate, 93 +/- 14% for 2-chloroethylethyl sulfide, 92 +/- 13% for diisopropylfluorophosphate and 95 +/- 17% for diisopropylmethylphosphonate. Recoveries are higher than, but less precise than those achieved from a 5-min ultrasonic micro-scale extraction using methanol. Much less laboratory waste is generated than the current standard organic solvent extraction method (33 g of soil shaken with 100 ml of chloroform).

Evaluation of Micellar Electrokinetic Capillary Chromatography for the Separation and Detection of Normal and Modified Deoxyribonucleosides and Deoxyribonucleotides

Abstract Micellar electrokinetic capillary chromatography allows high resolution separations with very small sample volume requirements. Deoxyribonucleotide oligomers can be resolved on the basis of chain length, nucleic base sequence, and base modification. Sensitivity for dideoxyribonucleosides in the -presence of a 1,000-fold excess of deoxyribonucleosides is ca. 12 pg with on-column UV absorbance detection.

Determination of explosives and some metabolites of TNT in biological and environmental samples by liquid chromatography on a mixed-mode C18-anion column

Abstract This method employs a ternary gradient generated from (1) a 90:10 water:methanol solution that is 0.015 M in potassium phosphate at pH 5.1; (2) methanol; and (3) acetonitrile to separate fifteen explosives, byproducts, and metabolites of 2,4,6-trinitrotoluene (TNT) on a C18/anion exchange stationary phase. TNT, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), six reduction metabolites and three oxidation metabolites of TNT have been separated and quantitated in a single chromatographic run. Because of the anion exchange character of the stationary phase, the anionic TNT metabolite 2,4,6-trinitrobenzoic acid also may be separated and quantitated using this method. Quantitation limits generally lower than 1 ppm have been established by a systematic certification procedure. The performance of the mixed mode separation method combined with diode array ultraviolet absorbance detection has been demonstrated with samples derived from both biological ...

Microscopic identification of carbonaceous particles in stack ash from pulverized-coal combustion

Abstract Carbonaceous particles were separated from the 21–150 μm mass median aerodynamic diameter particle size fraction of two stack ashes collected from two electric power generation plants fuelled with pulverized coal. Scanning electron and light microscopy were used to examine loose particles and polished particle sections mounted in epoxy resin for morphology and internal structure. Several distinct types of carbonaceous particles were identified, ranging from uncombusted macerals of optically isotopic fusinite, to optically anisotropic coked products derived from vitrinite and exinite. The latter displayed complex porous internal structures containing mineral inclusions. X-ray diffraction spectra demonstrated a graphite carbon composition contaminated with quartz and mullite, which is consistent with the results of energy-dispersive X-ray fluorescence spectra.