Unidentified Organic Compounds Research Articles

Tannic Acid Content in the Cultured Diatom Skeletonema costatum (Greville) Cleve 1873, Isolated from the Romanian Black Sea Waters

Skeletonema costatum is a dominant species in the spring phytoplankton composition of the Romanian Black Sea coastal waters. The species was isolated during a spring bloom and maintained in laboratory conditions for the past 10 years. The biomass was obtained by culturing the species in growth medium for diatoms under continuous light and shaking for four days. The biomass was harvested by vacuum filtration and lyophilized. The tannic acid content was determined by the HPLC method in the methanolic etract of S. costatum biomass. The tannic acid content was 0.46% (4.6 mg tannic acid/g biomass). Also, the chromatogram showed the presence of other separate, but unidentified organic compounds, which may contribute to its therapeutic potential. Our results justify further research to highlight S. costatum antioidant and antimicrobial activity.

The Perron Gold Deposit, Archean Abitibi Belt, Canada: Exceptionally High-Grade Mineralization Related to Higher Gold-Carrying Capacity of Hydrocarbon-Rich Fluids

The Perron deposit, an Archean orogenic gold deposit located in the Abitibi belt, hosts a quartz vein-type gold-bearing zone, known as the high-grade zone (HGZ). The HGZ is vertically continuous along >1.2 km, and is exceptionally rich in visible gold throughout its vertical extent, with grades ranging from 30 to 500 ppm. Various hypotheses were tested to account for that, such as: (1) efficient precipitating mechanisms; (2) gold remobilization; (3) particular fluids; (4) specific gold sources for saturating the fluids; and (5) a different mineralizing temperature. Host rocks recorded peak metamorphism at ~600 °C based on an amphibole geothermometer. Visible gold is associated with sphalerite (<5%) which precipitated at 370 °C, based on the sphalerite GGIMFis geothermometer, during late exhumation of verticalized host rocks. Pyrite chemistry analyzed by LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) is comparable to classical orogenic gold deposits of the Abitibi belt, without indication of a possible magmatic fluid and gold contribution. Comparison of pyrite trace element signatures for identifying a potential gold source was inconclusive to demonstrate that primary base-metal rich volcanogenic gold mineralization, dispersed in the host rhyolitic dome, could be the source for the later formation of the HGZ. Rather, nodular pyrites in graphitic shales, sharing similar trace element signatures with pyrite of the HGZ, are considered a potential source. The most striking outcome is the lack of water in the mineralizing fluids, implying that gold was not transported under aqueous complexes, even if fugacity of sulfur (−6) and oxygen (−28), and pH (~7) are providing the best conditions at a temperature of 350 °C for solubilizing gold in water. Fluid inclusions, analyzed by solid-probe mass spectrometry, are rather comparable to fossil gas composed mostly of hydrocarbons (methane and ethane and possibly butane and propane and other unidentified organic compounds), rich in CO2, with N2 and trace of Ar, H2S, and He. It is interpreted that gold and zinc were transported as hydrocarbon-metal complexes or as colloidal gold nanoparticles. The exceptional high content of gold and zinc in the HGZ is thus explained by the higher transporting capacity of these unique mineralizing fluids.

Natural Attenuation and Anaerobic Benzene Detoxification Processes at a Chlorobenzene-Contaminated Industrial Site Inferred from Field Investigations and Microcosm Studies.

A five-year site investigation was conducted at a former chemical plant in Nanjing, China. The main contaminants were 1,2,4-trichlorobenzene (TCB) reaching concentrations up to 7300 μg/L, dichlorobenzene (DCB) isomers, monochlorobenzene (MCB), and benzene. Over time, these contaminants naturally attenuated to below regulatory levels under anaerobic conditions. To confirm the transformation processes and to explore the mechanisms, a corresponding laboratory microcosm study was completed demonstrating that 1,2,4-TCB was dechlorinated to 1,2-DCB, 1,3-DCB, and 1,4-DCB in approximately 2%/10%/88% molar proportions. The DCB isomers were dechlorinated via MCB to benzene, and, finally, benzene was degraded under prevailing sulfate-reducing conditions. Dechlorination could not be attributed to known dechlorinators Dehalobacter or Dehalococcoides, while anaerobic benzene degradation was mediated by microbes affiliated to a Deltaproteobacterium ORM2, previously associated with this activity. Unidentified organic compounds, possibly aromatic compounds related to past on-site production processes, were fueling the dechlorination reactions in situ. The microcosm study confirmed transformation processes inferred from field data and provided needed assurance for natural attenuation. Activity-based microcosm studies are often omitted from site characterization in favor of rapid and less expensive molecular surveys. However, the value of microcosm studies for confirming transformation processes, establishing electron balances, assessing cocontaminant inhibition, and validating appropriate monitoring tools is clear. At complex sites impacted by multiple compounds with poorly characterized transformation mechanisms, activity assays provide valuable data to incorporate into the conceptual site model to most effectively inform remediation alternatives.

Effects of gas–wall partitioning in Teflon tubing and instrumentation on time-resolved measurements of gas-phase organic compounds

Abstract. Recent studies have demonstrated that organic compounds can partition from the gas phase to the walls in Teflon environmental chambers and that the process can be modeled as absorptive partitioning. Here these studies were extended to investigate gas–wall partitioning of organic compounds in Teflon tubing and inside a proton-transfer-reaction mass spectrometer (PTR-MS) used to monitor compound concentrations. Rapid partitioning of C8–C14 2-ketones and C11–C16 1-alkenes was observed for compounds with saturation concentrations (c∗) in the range of 3 × 104 to 1 × 107 µg m−3, causing delays in instrument response to step-function changes in the concentration of compounds being measured. These delays vary proportionally with tubing length and diameter and inversely with flow rate and c∗. The gas–wall partitioning process that occurs in tubing is similar to what occurs in a gas chromatography column, and the measured delay times (analogous to retention times) were accurately described using a linear chromatography model where the walls were treated as an equivalent absorbing mass that is consistent with values determined for Teflon environmental chambers. The effect of PTR-MS surfaces on delay times was also quantified and incorporated into the model. The model predicts delays of an hour or more for semivolatile compounds measured under commonly employed conditions. These results and the model can enable better quantitative design of sampling systems, in particular when fast response is needed, such as for rapid transients, aircraft, or eddy covariance measurements. They may also allow estimation of c∗ values for unidentified organic compounds detected by mass spectrometry and could be employed to introduce differences in time series of compounds for use with factor analysis methods. Best practices are suggested for sampling organic compounds through Teflon tubing.

The influence of solvent and pH on determination of the light absorption properties of water-soluble brown carbon

Brown carbon (BrC) is a class of unidentified organic compounds that efficiently absorb solar radiation in the ultraviolet (UV) wavelengths, and its effects on climate are poorly understood. Measurement of the light absorption properties of BrC in liquid extracts is a commonly used BrC analytical method, but the optical characteristics of water-soluble BrC may be affected by pH and solvent. In this work, we investigated the effects of concentration, pH, and solvent on water-soluble BrC from ambient aerosols, biomass burning, diesel exhaust, and a humic substance standard. The results showed that pH can affect the light absorption properties of water-soluble BrC, whereas concentration had little effect, except low concentrations dissolved in methanol. Therefore, the pH of humic-like substances (HULIS) should be adjusted to the same value as water-soluble carbon (WSOC) for calculating the light-absorption contribution of HULIS to WSOC. The light absorptivity of water-soluble BrC dissolved in methanol was higher than that in water. Considering the pH and concentration effects, extraction of WSOC with a particle: water ratio of 0.25 mg/mL is proposed as well as to get a reference pH for light absorption analysis.

Quantification of nitroaromatic compounds in atmospheric fine particulate matter in Hong Kong over 3 years: field measurement evidence for secondary formation derived from biomass burning emissions

Environmental context Nitroaromatic compounds constitute an important portion of brown carbon and thereby contribute to the light-absorbing properties of atmospheric aerosols. We report their abundance in Hong Kong over 3 years and show that they were mainly associated with aged biomass burning particles. Knowledge of the abundance and sources of nitroaromatic compounds could assist in evaluating their contribution to brown carbon and in apportioning secondary organic aerosols from biomass burning sources. Abstract Biomass burning is a major source of atmospheric aerosols on both global and regional scales. Among the large number of unidentified organic compounds related to biomass burning, nitroaromatic compounds (NACs) have drawn attention because of their UV light-absorbing ability. In this study, an analytical method based on liquid chromatography–mass spectrometry was used to quantify a group of NACs (nitrophenol, methylnitrophenols, dimethylnitrophenol, nitrocatechol and methylnitrocatechols) in aerosol samples. The nitrocatechol–metal complex interference, sample matrix effects, sample stability, precision and reproducibility were investigated. The method detection limits ranged from 0.10 to 0.23ngmL–1 and the recoveries for the target NACs were in the range of 96–102%. The method was applied to a total of 184 ambient PM2.5 samples (particulate matter of 2.5µm or less in aerodynamic diameter) collected at an urban site in Hong Kong over 3 years (2010–2012). The NACs quantified showed a distinct seasonal variation with higher concentrations in autumn and winter (3.6–21.0ngm–3), coinciding with more biomass burning activities coming from the regions west and north-east to Hong Kong, and lower levels during spring and summer (0.3–3.8ngm–3). The good correlations between NACs and levoglucosan (R=0.82), a known biomass burning tracer compound, support the common origin from biomass burning. Moderate to good correlations between NACs and nitrate suggest that they might be products of secondary formation processes involving the same precursor gases (e.g. NOx). Additional lines of circumstantial evidence were also found and presented in the paper to support secondary formation derived from biomass burning as the main contributing source of NACs.

Oxalate minerals on Mars?

Small amounts of unidentified organic compounds have only recently been inferred on Mars despite strong reasons to expect significant concentrations and decades of searching. Based on X-ray diffraction and reflectance spectroscopic analyses we show that solid oxalic acid and its most common mineral salts are stable under the pressure and ultraviolet irradiation environment of the surface of Mars, and could represent a heretofore largely overlooked reservoir of organic carbon in the martian near-surface. In addition to the delivery to Mars by carbonaceous chondrites, oxalate minerals are among the predicted breakdown products of meteoritic organic matter delivered to the martian surface, as well as any endogenic organic carbon reaching the martian surface from the interior. A reinterpretation of pyrolysis experiments from the Viking, Phoenix, and Mars Science Laboratory missions shows that all are consistent with the presence of significant concentrations of oxalate minerals. Oxalate minerals could be important in numerous martian geochemical processes, including acting as a possible nitrogen sink (as ammonium oxalate), and contributing to the formation of “organic” carbonates, methane, and hydroxyl radicals.

Seasonal survey of copper-complexing ligands and thiol compounds in a heavily utilized, urban estuary: Elizabeth River, Virginia

Concentrations of thiol compounds, copper-complexing ligands, and total dissolved copper were followed over the course of 1 year (October 2002 until September 2003) in the Elizabeth River, Virginia to evaluate seasonality. Copper-complexing ligand concentrations were determined by competitive ligand equilibration-adsorptive cathodic stripping voltammetry (CLE/ACSV). Thiol detection was carried out by high performance liquid chromatography (HPLC) and calibration using a suite of nine thiol compounds (cysteine, glutathione, mercaptoacetic acid, 2-mercaptoethanesulfonic acid, 2-mercaptoethanol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptosuccinic acid, and monothioglycerol). Total dissolved copper concentrations reached a January low of 13.1 nM to a June high of 24.7 nM and were found to vary seasonally with higher concentrations occurring from June to September. With a low of 26 nM during April to a high of 56 nM in October, copper-complexing ligand (average log K′ CuL of 12.0 ± 0.2) concentrations displayed a similar seasonal pattern to that of total dissolved copper. Free cupric ion concentrations remained below 1.5 pM for a majority of the year except during March, April, and December when values reached pM levels greater than 1.5. Six of the nine thiol compounds surveyed were detected in the Elizabeth River samples and ranged in concentration from below detectable concentrations (< 5 nM) to individual highs ranging from 25.3 to168.5 nM. The thiol compound concentrations displayed a clear seasonality fluctuating at below detection limits during November to February then increasing with increasing surface water temperatures from March to July. CLE/ACSV was used to assess whether or not the suite of thiol compounds detected by HPLC could contribute to the copper-complexing ligand pool. Conditional stability constants for each one of six thiol standards (average log K′ CuL ∼ 12.1 ± 0.5) were found to be statistically equivalent to the naturally occurring copper-complexing ligands (average log K′ CuL ∼ 12.0 ± 0.2). This suggests that these thiol compounds could act as copper-complexing ligands in natural samples and could contribute to the copper-complexing ligand pool detected by CLE/ACSV. This study involving seasonality of copper-complexing ligands and thiols in an industrialized, urban estuary underscored several points that have to be substantiated in future research efforts including copper-complexing ligands sources and the role that thiol compounds as well as other unidentified organic compounds play in the copper-complexing ligand pool.

The tunicate Salpa thompsoni ecology in the Southern Ocean. II. Proximate and elemental composition

Detailed determination of Salpa thompsoni elemental composition has been carried out on specimens collected in the Eastern Bellingshausen Sea and at the northern edge of the Weddell Gyre during austral autumn (April and May) of 1996 and 2001. More than 170 Antarctic tunicates S. thompsoni were analysed to determine wet weight (WW), dry weight (DW), ash-free dry weight (AFDW) and elemental composition (C, N content, proteins, carbohydrates and lipids) of different sizes and stages. Dry weight comprised 6.4% (aggregate form) to 7.7% (solitary form) of the WW. AFDW amounted to ~44% of the DW. Carbon and nitrogen contents (Carbon: 17–22%, Nitrogen: 3–5% of the DW) of both aggregate and solitary forms were found to be high relative to data reported in the literature. Although some unidentified organic compounds are not included in our carbon budget, the findings of this study show higher than previously reported nutritional values of S. thompsoni. In spite of this, a shift from a krill-dominated towards a salp-dominated ecosystem would have dramatic consequences for organisms at higher trophic levels.

Relationships between contaminant levels in marine sediments and their biological effects on embryos of oysters, Crassostrea gigas

Abstract-Surface sediment samples from 10 coastal locations were analyzed with respect to their physical and chemical characteristics as well as their biological quality. The toxicity of the decanted fresh and freeze-dried sediments and of their elutriates was assessed by bioassays with embryos of the oysters Crassostrea gigas. The concentration inhibiting normal embryogenesis in 20% of the larvae (EC20) was used as a measure of toxicity and compared with the physical and chemical properties of the sediments and elutriates by principal components analysis. Decanted whole sediments were one to four orders of magnitude more toxic than their elutriates because the latter have lower contaminant concentrations. The biological effects of decanted whole sediment depended mostly on the levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs), while in the case of the elutriates, the toxicity was mainly correlated with the concentrations of total ammonia and of dissolved organic carbon (DOC). Freeze-dried sediments and their elutriates were up to one order of magnitude more toxic than fresh sediments and elutriates, respectively, presumably because the freeze-drying procedure increases pollutant bioavailability or causes a release of unidentified organic compounds having toxic effects.

Evidence of perchlorate (ClO4-) reduction in plant tissues (poplar tree) using radio-labeled 36ClO4-.

Phytoremediation of perchlorate (ClO4) by poplar trees Populus deltoidex nigrawas investigated using small cuttings growing in hydroponic Hoagland solution and plant tissue cultures, consisting of spherical photosynthetic cell aggregates (i.e. nodules) developing in Murashige and Skoog culture medium. Both plants and nodules were grown under a 16 h/8 h photoperiod cycle and under sterile conditions. Degradation experiments, performed by the incubation of pregrown plants and nodules in the presence of 36Cl radio-labeled ClO4- (25 mg L(-1)), showed a reduction of the initial ClO4- concentration in the solution of about 50% after 30 d of incubation. Analysis of the distribution of radioactivity in different plant fractions indicated that 27.4% of the total was translocated to the leaves, while 66.9% remained in the solution. Very little radioactivity (less than 3.0%) was detected in the other parts of the plants. 32.0% of the radioactivity recovered in the solution was shown to consist of 36Cl- and 68.0% of nontransformed 36ClO4-. The radioactivity recovered in the leaf extracts was distributed as chloride (36Cl-) (1.6% of the total), chlorite (36ClO2-) (2.4%), chlorate (36ClO3-) (4.8%), nontransformed 36ClO4- (21.6%), and an unidentified organic compound (1.4%). The radioactivity recovered in the solution containing submerged nodules consisted of 36Cl- (6.4% of the total), 36ClO3- (1.3%), and nontransformed 36ClO4- (51.5%). Radioactivity detected in the nodule extracts was distributed as 36Cl- (2.0% of the total), 36ClO2- (5.2%), 36ClO3- (6.4%), 36ClO4- (22.7%), and an unidentified organic compound (0.5%). These results provide evidence of perchlorate reduction inside poplar tree tissues. 36ClO4- is partially reduced to 36ClO3-, 36ClO2-, and 36Cl-.

Application of total-reflection X-ray fluorescence spectrometry and high-performance liquid chromatography for the chemical characterization of xylem saps of nickel contaminated cucumber plants

Total-reflection X-ray fluorescence (TXRF) spectrometry, reversed-phase (RP) and size–exclusion (SE) high-performance liquid chromatography (HPLC) methods were applied for the characterization of low-volume xylem sap of control and nickel contaminated cucumber plants growing in hydroponics containing urea as the sole nitrogen source. In these saps collected for 1 h, Ca, K, Fe, Mn, Ni, Zn, as well as malic, citric and fumaric acids were determined. The SEC measurements showed that macromolecules were not detectable in the samples. Nickel contamination had minimum impact on the organic acid transport, however, the transport of Zn, K and Fe was reduced by 50, 22 and 11%, respectively. This observation supports the results of our earlier experiments when nitrate ions were used as the sole nitrogen form. At the same time, the fresh root weight and the volume of the collected xylem sap increased by 36 and 85%, respectively. Therefore, nickel addition seemed to decrease the urea toxicity of the plants. By pooling the eluting fractions of the SEC column, which were 10-fold concentrated by freeze-drying, the series of the resulted samples were analyzed by the TXRF spectrometry and RP-HPLC. The three organic acids could be identified in only one of the fractions, which contained Fe and, in the case of the contaminated plants, Ni in detectable concentration. However, considerable parts of these two elements and Mn, as well as practically the total amounts of Cu may be transported by unidentified organic compounds in the xylem.

Receptor model and emissions inventory source apportionments of nonmethane organic gases in California's San Joaquin valley and San Francisco bay area

The chemical mass balance (CMB) receptor model was applied to the nonmethane organic gas (NMOG) database acquired during the San Joaquin Valley Air Quality Study (SJVAQS)/Atmospheric Utility Signatures—Predictions and Experiment (AUSPEX) Regional Model Adaptation Project (SARMAP). During SARMAP, the major contributors to NMOG were vehicle exhaust, liquid gasoline, gasoline vapor, oil production, acetone and unidentified organic compounds. Oil production was the major contributor to NMOG in the southern SJV during the morning hours, ranging from about one-third to one-half of the total NMOG. Contributions of oil production were lower during the afternoon due to increased ventilation, and larger contributions from secondary organic compounds. In the afternoon, the combined fraction of acetone and unidentified or unexplained (difference between calculated and measured mass) NMOG, which is mostly of secondary origin, accounted for about half of the total NMOG at receptor sites. Only the Yosemite and Giant Forest sites showed significant contributions from biogenic emissions. The fact that CMB did not detect significant contributions from biogenic sources in samples collected from sites in the SJV where estimated biogenic emission rates exceed those of either Yosemite or Giant Forest, suggests that biogenic emissions are overestimated in the SARMAP inventory. Source contribution estimates for total motor vehicle emissions averaged 75 and 70% of the total measured NMOG in urban areas during the 0800–1000 and 1200–1400 sampling periods, respectively, compared to the average daily emission inventory contribution of 44%. These results support recent studies which indicate that motor vehicle emissions have been seriously underestimated.

Systematic Observations of Methanol and Other Organics in Comet P/Swift-Tuttle: Discovery of New Spectral Structure at 3.42 μm

We present a detailed study of the 3.4-μm "cometary organics feature" in Comet P/Swift-Tuttle (1992 XXVIII). The study is based on spectra acquired from Kitt Peak and Mauna Kea Observatories on UT 1992 November 8, 9, 12, 13, 26, and 27, during which time the heliocentric distance decreased from 1.12 to 0.99 AU. Two distinct components are present, cometary methanol (CH 3OH), and another as yet unidentified organic volatile responsible for an emission feature centered at ∼3.424 μm. We obtain a CH 3OH abundance of 4.3 ± 0.5% relative to H 2O, revising our previously reported value of 7 ± 1%. The revisions result from improved data analysis, inclusion of additional P/Swift-Tuttle observations, and use of corrected CH 3OH g-factors. The unidentified feature consistently accounted for one-half of the flux contained in the 3.4-μm feature and exhibited a heliocentric dependence consistent with a volatile parent species, in agreement with conclusions based on observations of several recent comets. We present the first echelle spectrum of this feature (resolving power λ/Δλ ≈ 8000), which reveals spectral structure in the form of a pronounced peak centered at a rest frequency of(2920.24 ± 0.09) cm -1. We suspect this to be representative of asymmetric CH 2 (or CH-X) vibrational stretching in some as yet unidentified organic compound. Our results indicate the presence of an additional abundant form of volatile carbon in comets. If the unidentified band(s) possess g-factors similar to those of the adjacent methanol bands, the inferred abundance of the unidentified emitting species would be comparable to that of methanol.

Biological removal of organic nitrogen and fatty acids from metal-cutting-fluid wastewater

The anaerobic, anaerobic/aerobic (anaerobic followed by aerobic) and straight aerobic treatments of a simulated metal-cutting-fluid wastewater were evaluated in terms of the removal of organic nitrogen (primarily alkanolamines and heterocyclic compounds) and fatty acids, the two major constituents of many water-based metal-cutting fluids. The organic nitrogen was not well adsorbed on activated carbon but was degraded through the anaerobic/aerobic or straight aerobic treatment. It was also found that an acclimation period was necessary before the organic nitrogen could be anaerobically degraded. 2-Methylhexanoic, heptanoic, 3,5,5-trimethylhexanoic and benzoic acid, which were found in the wastewater, were degraded well both anaerobically and aerobically. The wastewater also contained a group of unidentified organic compounds that consisted of five gas chromatographic peaks (probably branched C 8–C 10 fatty acids or their esters). These unidentified organics were partially degraded and persisted in the effluents, contributing to the non-biodegradable portion of organics. Several low molecular weight fatty acids (acetic acid, propanoic acid, 2-methylpropanoic acid, butanoic acid, 3-methylbutanoic acid and pentanoic acid) were produced during the periods when the influent chemical oxygen demand (COD) loading was varied to study the response of an anaerobic reactor to the variation. The anaerobic/aerobic treatment produced an effluent similar to that of the straight aerobic treatment with respect to fatty acid concentrations.

Biotransformation of chlorinated aliphatic solvents in the presence of aromatic compounds under methanogenic conditions

Transformation of carbon tetrachloride (CT) and tetrachloroethylene (PCE) was studied under methanogenic conditions, in the presence or absence of toluene, ethylbenzene, phenol, and benzoate. Microbial inocula for the experiments were derived from three groundwater aquifers contaminated by jet fuel or creosote. CT and PCE were reductively dechlorinated in all the examined cases (CT to chloroform [CF]; PCE to trichloroethylene [TCE], trans-l,2-dichloroethylene [DCE], and vinyl chloride [VC]). In the aquifer microcosms, the electron donors used for the reductive transformations were most likely the unidentified organic compounds present on aquifer solids, or storage materials in microorganisms. Alternatively, molecular hydrogen from the anaerobic incubator atmosphere could have been used. The addition of benzoate caused a decrease in rates of dechlorination if benzoate was transformed. Phenol and ethylbenzene were not degraded and did not influence the transformation of CT or PCE. Toluene, in most of the studied cases, had no influence on reductive dechlorination of either CT or PCE. Only in microcosms derived from a JP-4 jet fuel-contaminated aquifer did the anaerobic degradation of toluene occur simultaneously with reductive dechlorination of PCE, suggesting that toluene might possibly have been used as an electron donor for reductive transformation of chlorinated solvents.

Toxicity and physiological disposition of sodium- p-N-glycolylarsanilate : II. Absorption, excretion, and metabolism in the chicken

Sodium p-N-glycolylarsanilate administered orally to chickens is excreted to the extent of 95% within 16 hours after the second of two doses given 8 hours apart, and 99% is excreted within 88 hours. The arsenical excreted by these birds appears to be 98.5% unchanged drug and 1.5% arsanilic acid. The arsenic of intramuscularly administered glycolylarsanilate is excreted at almost the same rate, but about 28% is split to arsanilic acid. The only tissue in which glycolylarsanilate accumulates to any extent is liver, and the residue in this tissue is indistinguishable from the unchanged drug. This conclusion is based on a rat excretion experiment. Tissue residues of glycolylarsanilate following a 9-week feeding period at 60 g/ton are only nominal, and, if subject to a 5-day withdrawal period, become virtually zero. There is evidence that chickens receiving arsenite parenterally convert it, as least in part, to an unidentified organic compound. Comparing the excretion data on SNGA presented herein with that of Moody and Williams (1962), it may be concluded that SNGA administered orally to chickens is excreted more rapidly than arsanilic acid, acetylarsanilic acid, or 4-hydroxy-3-nitrophenylarsonic acid.

Studies on utilization of sulfate sulfur for growth of the chicken.

Summary1. Addition of 0.5% sodium sulfate to a diet low in sulfur stimulated growth of the young chicken. 2. When Na2S35O4 was fed for a period of 1 week, approximately 23% of the S35 ingested was incorporated into the tissues. Most of the S35 was recovered as sulfate-S35. However, about 19% was present as taurine-S35, 6.6% as unknown organic compounds and barely detectable amounts as sulfur amino acids. Two weeks after Na2S35O4 feeding a larger proportion of S35 was present in the carcasses as taurine and unidentified organic compounds and 1.5% of the S35 in the chickens was accounted for as cystine and methionine. It was concluded that there is a physiological requirement for sulfate per se and that dietary sulfate promotes growth primarily by providing sulfur for this purpose. 3. Taurine was found to be the major sulfur constituent of the water-soluble portion of feathers.