Lead and antimony from bullet weathering in newly constructed target berms: Chemical speciation, mobilization, and remediation strategies.

Understanding lead (Pb) and antimony (Sb) speciation associated with the weathering of bullets at shooting ranges is essential for identifying species migration potential to local watersheds and for assessing the overall toxicity of shooting range soils. In the present study, we fired 2000 5.56 mm bullets into newly constructed and instrumented target berms composed of well-characterized test soils (sand, sandy loam, loamy sand, silt loam) and collected berm pore water runoff and soil samples over five summers (2011 to 2015). We tracked the chemical transformations of Pb and Sb released during bullet weathering as a function of time and soil properties. During 2014 summer, an amendment of ferrous chloride (FeCl2) with a calcium carbonate (CaCO3) buffer was added to a subset of the berms of each soil type to test this remediation strategy. Bulk speciation analysis coupled with micro-scale spectroscopic methods show that both Sb(III) and Sb(V) species are present in soil solution depending on the soil matrix type, but Sb(III) was not observed after 9 months of weathering. In general, Sb was found to be more mobile than Pb, attributable to the relatively low solubility of the dominant Pb phases present in the crust forming around bullet fragments and within soil. The oxidation of Pb(0) resulted in a mixture of lead oxide, lead carbonate, and lead sorbed onto iron(III) oxides. We found a higher degree of metal(loid) mobilization (higher dissolved metal concentrations) in the berms made from the sandy soils. In contrast, silt loam soil was found to be more effective at immobilizing metal(loid)s. Furthermore, we observed that an iron-oxide type amendment may be effective at further reducing Pb and Sb runoff. Results from this study provide insight into the fate and transport of metal(loid)s within small arms target ranges and address a potential method for metal(loid) immobilization.

Surface complexation studied via combined grazing-incidence EXAFS and surface diffraction: arsenate on hematite (0001) and (10-12).

X-ray diffraction [crystal-truncation-rod (CTR)] studies of the surface structure of moisture-equilibrated hematite reveal sites for complexation not present on the bulk oxygen-terminated surface, and impose constraints on the types of inner-sphere sorption topologies. We have used this improved model of the hematite surface to analyze grazing-incidence EXAFS results for arsenate sorption on the c (0001) and r (10-12) surfaces measured in two electric vector polarizations. This work shows that the reconfiguration of the surface under moist conditions is responsible for an increased adsorption density of arsenate complexes on the (0001) surface relative to predicted ideal termination, and an abundance of "edge-sharing" bidentate complexes on both studied surfaces. We consider possible limitations on combining the methods due to differing surface sensitivities, and discuss further analysis possibilities using both methods.

Pb(II) distributions at biofilm-metal oxide interfaces.

The distribution of aqueous Pb(II) sorbed at the interface between Burkholderia cepacia biofilms and hematite (alpha-Fe(2)O(3)) or corundum (alpha-Al(2)O(3)) surfaces has been probed by using an application of the long-period x-ray standing wave technique. Attached bacteria and adsorbed organic matter may interfere with sorption processes on metal oxide surfaces by changing the characteristics of the electrical double layer at the solid-solution interface, blocking surface sites, or providing a variety of new sites for metal binding. In this work, Pb L(alpha) fluorescence yield profiles for samples equilibrated with 10(-7) to 10(-3.8) M Pb(II) were measured and modeled to determine quantitatively the partitioning of Pb(II) at the biofilm-metal oxide interface. Our data show that the reactive sites on the metal oxide surfaces were not passivated by the formation of a monolayer biofilm. Instead, high-energy surface sites on the metal oxides form the dominant sink for Pb(II) at submicromolar concentrations, following the trend alpha-Fe(2)O(3) (0001) > alpha-Al(2)O(3) (1102) > alpha-Al(2)O(3) (0001), despite the greater site density within the overlying biofilms. At [Pb] > 10(-6) M, significant Pb uptake by the biofilms was observed.

Anterior tibialis tendon ruptures: an outcome analysis of operative versus nonoperative treatment.

Ruptures of the anterior tibialis tendon are a rare clinical entity. Case reports in the literature reveal a total of 28 cases. Unfortunately, because of the limited discourse in the orthopaedic literature, there are few guidelines regarding the treatment for these injuries. This study analyzes the treatment of 16 anterior tibialis tendon ruptures. Eight patients in this group had operative treatment of their ruptures, and eight patients had nonsurgical treatment of their ruptures. The average follow-up for the operative and nonoperative patients were 6.68 years and 3.86 years, respectively. The Foot and Ankle Outcome questionnaire provided by the American Academy of Orthopaedic Surgeons and an outcome-based foot score described by Kitaoka et al. were used as the methods of analysis. Our outcome results show no statistically significant difference between operative and nonoperative treatment in anterior tibialis tendon ruptures. The lack of statistical difference between operative and nonoperative groups may be a reflection of the age bimodality present in this study. Elderly low demand patients were treated nonsurgically and young active patients were treated operatively. Therefore, despite a lack of statistical difference present in the outcome of both groups, we still maintain the need to repair/reconstruct anterior tibialis tendon ruptures in young active patients with high functional demands. The deficits present in the nonoperative group, we believe, would not be well tolerated in a young high functional demand patient. Nonsurgical management is an appropriate alternative in low demand elderly patients.

Determination of aliphatic amines in air by on-line solid-phase derivatization with HPLC-UV/FL.

An easy, rapid, and efficient method using on-line solid-phase derivatization in HPLC is developed for the trace determination of aliphatic amines in air. Some fundamental studies on stop-flow, on-line, solid-phase derivatizations in HPLC are also investigated, such as optimization of the reaction detection HPLC system and band broadening. Air is sampled with silica gel tubes from different sites, including sewage areas, fish cleaning and processing rooms, and an organoleptic lab of the U.S. Food & Drug Administration (FDA). The trapped amines are desorbed with an acidic aqueous-organic solution, followed by pH adjustment of the eluates to pH 10. The resulting solution is directly injected into an on-line, precolumn, solid-phase derivatization and reversed-phase HPLC-UV/FL system, not requiring any further sample workup steps. The percent derivatizations are as high as 88 +/- 5% (n = 3) for primary amines, and 75 +/- 4% (n = 3) for diethylamine under optimized conditions (60 degrees C for 10 min). The recoveries for all amines are above 90%. The method is validated by a single-blind, spiked experiment with 1.1-4.4% relative standard deviation (RSD) in the range of 15-47 ppm. These results are confirmed by a GC-FID method performed in another lab. Amines are quantitated via calibration plots, with final concentrations from 0.02 to 0.38 mg/m3 air. It is suggested that this newer approach for the determination of amines and polyamines, using polymeric solid-phase reagents on-line, precolumn in HPLC, should prove generally successful for other amines and other sample types in the future.

Determination of N-n-propylnorapomorphine in serum and brain tissue by gas chromatography-negative ion chemical ionization mass spectrometry.

A method for the determination of the neuroactive compound N-n-propylnorapomorphine (NPA) in biological tissues is described. Isolation of NPA from serum or brain tissue was achieved via liquid-liquid extraction from phosphate-buffered tissue extract (0.25 M, pH 7.2) into ethyl acetate. The NPA, along with a [2H7]NPA analogue serving as internal standard, was converted to the corresponding bis(trifluoroacetyl) ester by treatment with excess trifluoroacetic anhydride at 75 degrees C. The electrophoric derivatives were analyzed by fused-silica capillary gas chromatography-mass spectrometry in the negative ion chemical ionization mode. Selected ion monitoring of the [M-CF3CO]- ions of derivatized NPA (m/z 390) and internal standard [2H7]NPA (m/z 397) permitted the quantitation of NPA in serum and brain samples obtained from rats treated with either free NPA or the prodrug methylenedioxy-NPA (MDO-NPA). Calibration was conducted down to a practical limit of assay sensitivity, at 0.50 ng NPA per ml of serum and 0.50 ng NPA per g of brain. The relative standard deviation for replicate serum samples spiked at 20 ng/ml was 4.2% (n = 5) and for brain samples at 10 ng/g, it was 3.6%. This method revealed differences in the free NPA brain/serum ratios in rats treated separately with the stereoisomers R-(-)-MDO-NPA and S-(+)-MDO-NPA.

Mass spectrometry of electrophore-labeled nucleosides. Pentafluorobenzyl and cinnamoyl derivatives.

Three structurally similar deoxynucleosides (thymidine, O4-ethylthymidine, and 2'-deoxyuridine) were studied by mass spectrometry as pentafluorobenzyl, cinnamyl, or mixed derivatives. The purpose of the work was to define the usefulness of such derivatives for structural elucidation of deoxynucleosides. The compounds were ionized in three ways: electron capture negative ion, positive ion chemical ionization, and electron impact. For each of the derivatives examined, the combined spectra were well suited for structural elucidation purposes.

Aporphines 65: chemical, microbial synthesis and characterization by gas chromatography/mass spectrometry of (R)-(-)-10-hydroxy 11-methoxy-N-n-propylnoraporphine, a potential metabolite of N-n-propylnorapomorphine.

The title compound has been synthesized by a multistep sequence from (R)(-)-morphine, and compared with the product obtained by microbial O-demethylation of (R)- and (S)-10,11-dimethoxy-N-n-propylnoraporphine (N-n-propylnorapomorphine dimethyl ether). The comparison was based on an analysis of the trifluoroacetyl derivatives of the microbial products and the synthesized compounds using gas chromatography/mass spectrometry in the electron impact mode. Examination by gas chromatography/electron impact/mass spectrometry of the trifluoroacetyl derivatives of 11-hydroxy-10-methoxyaporphine (apocodeine, 3) and 10-methoxy-11-hydroxyaporphine (isoapocodeine, 5) has revealed their excellent chromatographic resolution, and the preferential loss of the methyl group as in 3 [M-15]+ or the trifluoroacetyl group from the 10-position of the aporphine ring as in 5 [M-97]+. Characteristic fragmentations of these isomeric aporphines were used to confirm their structures and were compared with the spectra of authentic synthetic samples.

Stereospecific microbiological 10-O-demethylation of R-(-)-10,11-dimethoxyaporphines.

The microbiological O-dealkylation of (+) and (-) 10,11-dimethoxyaporphine and the corresponding N-n-propyl analog 10,11-dimethoxy-N-n-propylnoraporphine utilizing the fungus Cunninghamella elegans (ATCC 9245) was found to proceed with regioselectivity for the 10-position, and with a high degree of substrate stereospecificity for the 6a R(-)enantiomer. Only the (R) 10-demethylated products were isolated i.e. (R) iosapocodeine and (R) N-n-propylnor-isoapocodeine. The products were confirmed by comparison with their GC/MS spectra.