Octadecyl (C-18) bonded to porous silica has been evaluated for the solid-phase extraction (SPE) of organic compounds from water. Excellent performance was deduced from average recovery of >85% for pesticides and polycyclic organic materials present In contrived water samples at 1-10 ng/mL. Extraction results showed effective performance of the SPE when 1-100 mL of water was passed through small columns containing 40-100 mg of 40-µ C-18 bonded porous silica at flow rates as high as 250 bed volumes/mln. The adsorbed compounds were removed by collecting 60-100 µ of either ethyl acetate or benzene eluate. The unique feature of this research Is the combination of small water volumes, fast flow rates, small columns, and small eluate volumes that obviate solvent removals prior to GC analysis, while still retaining all the other advantageous features of SPE. Excellent performance was also confirmed In tests of environmental waters where the results based on SPE agreed with those based on accepted classical extractions.
15 431 448 20 431 431 acetic acid-chloroform mixture.In almost all cases, 5 ml. of the solvents tested were miscible with 20 ml. of acetic acid-chloroform.Recovery of peroxide was quantitative when as little as 20% by volume of acetic acidchloroform was present in the solvent mixture. It should therefore be possible to determine peroxide groups on polymers and other organic solids if the solution of the material is compatible with the minimum amount of acetic acid-chloroform required for the reaction of the peroxide with iodide.Attempts to determine di-ferf-butyl peroxide by using HC1 to increase the acidity were unsuccessful. Ten milligrams of this peroxide gave a pale yellow 2 hours after solution in 1 to 1 HC1 and the addition of KI.
Selected organic components in samples collected from monitoring wells and from surface water are shown to follow definite areal, vertical, and temporal trends in concentration. Atrazine (2‐chloro‐4‐[ethylamino]‐6‐[isopropylamino]‐s‐triazine), alachlor (2‐chloro‐2′ ,6′ ‐ diethyl‐N‐[methoxymethyl]acetanilide) and dieldrin (1,2,3,4,10,10‐hexachloro‐exo‐6,7‐epoxy‐1,4,4a,5,6,7,8,8a‐octahydro‐1,4‐endo, exo‐5,8‐dimethanonaphthalene) were measured in 64, 35, and 35 water samples, respectively. The atrazine amounts ranged from < 0.01 to 88 µg/liter. Peak concentrations were observed in shallow well water downgradient from irrigated fields at the end of the irrigation season. The areal and vertical distributions of atrazine are closely associated with those of nitrate‐nitrogen (NO3‐N), which was measured as an indicator of deep percolation from irrigated croplands. However, temporal variations in atrazine concentrations suggest that it is a nonconservative constituent of ground water. Alachlor and dieldrin amounts were extremely low, being less than 0.1 µg/liter in all but one water sample which was taken from a well located in an excessively well‐drained area. Dissolved organic carbon (DOC) was measured in 95 water samples and the amounts ranged from 0.2 to 4.8 mg/liter. Maximums occurred in shallow wells and there were no seasonal associations with either atrazine or NO3‐N. The DOC data suggest percolation from the unsaturated zone and partial removal from solution during vertical transport within the saturated zone.
Steam dlstlllatlon, solvent extraction, and ion exchange procedures have been employed to isolate volatile organlc ackls, bases, and neutral compounds from process waters generated durlng the retortlng of oil shale. Gas chromatography was used for the analysis of the Isolated components and for the dlrect analysis of the process waters. The use of these multiple isolation and analyses procedures has resulted In the determlnatlon of the foilowlng compounds wlth the amounts In ug/mL given in parentheses: 12 C2 to C,o aliphatlc acids (26 to 450); phenol (21); pyridine (5); five methyl substttuted pyrldlnes (3 to 19); aniline (2); isoquinoline (2); four C, to C, n-alkylamlnes ( 2 to 10); three C, to C, n-aikylnltriies ( 1 to 21); benzonltrlie (3); formaldehyde (500); acetaldehyde (2); propanone (16); and butanone (6). The advantages of steam dlstiliatlon and ion exchange for the isolation and eventual anaiysls for water containlng complex mixtures of volatile acidic, basic, and neutral organlc components are described.The retorting of oil shale leads to a process water containing a complex mixture of acidic, basic, and neutral organic compounds. Raphaelian and Harrison ( 1 ) have identified 160 different components and Pellizzari and his colleagues (2,3) have reported qualitative and quantitative data for 97 organic compounds in oil shale process waters. These researchers used solvent extraction and purge and trap procedures to isolate the organic compounds from the process water. These procedures are efficient for nonpolar, low solubility compounds ( 4 5 ) but are less effective for polar components especially those having high solubility in water. These hydrophilic compounds are frequently isolated by less general, but potentially more efficient procedures, such as distillation (6-1 l ) and ion exchange (1 2,13).Steam distillation, using standard procedures (6, 7), has been investigated thoroughly for the isolation of fatty acids and phenols from wastewaters and other aqueous samples. It has also been shown to be efficient for neutral hydrophilic compounds (8,9). Direct distillation of aqueous samples has also been successful for neutral components (10) and for volatile amines ( 1 1 ) . Other basic components have not been investigated but distillation procedures should be generally applicable to all polar, acidic, and basic organic compounds of reasonable volatility.Polar organic compounds that form anions and cations in water can also be isolated by ion exchange procedures and recent reports (12,1#3) suggest general applicability to organic acids and bases.An alternative to isolating the organic compounds is the direct analysis of process water using gas chromatography (GC) with stationary phases that are tolerant of the water matrix. This procedure is effective if the concentrations of the organic compounds are near or above 1 ppm and other organic and inorganic components in the water do not cause rapid deterioration of the GC column used for the separation.Our analysis of oil shale process waters using the iso...
A method of producing CaSO4:Dy thermoluminescent mini-dosimeters was reported in 1986 by B W Wessels for determination of the in vivo absorbed dose in radioimmunotherapy, a field in which absorbed dose gradients are important. These dosimeters, which undergo dissolution when used in a liquid environment, showed a sensitivity loss of up to 30% after 4 days of immersion in our tests. Moreover, several studies have shown that biocompatibility problems can occur during in vivo studies in animals. This paper describes the production and testing of a new type of thermoluminescent mini-dosimeter obtained by microextrusion of a mixture of LiF:Mg,Cu,P polypropylene and plastic adjuvants. These dosimeters, in the form of long 400 microm diameter filaments, can be cut to the desired length. The production process allows an LiF:Mg,Cu,P load of up to 50%. Results obtained in external irradiation indicate that these new miniature LiF:Mg,Cu,P dosimeters have good sensitivity (about 1.6 times that of CaSO4:Dy mini-TLDs), homogeneous response within a production batch (mean +/-4%), response stability in water (0.7% of variation in sensitivity after 2 weeks of immersion) and stability in aqueous solutions at different pH. LiF:Mg,Cu,P mini-dosimeters appear to be highly promising for internal dosimetry, and evaluation is in progress in animals.
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