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PubMed2006

Statistical evaluation of an analytical IC method for the determination of trace level perchlorate.

Trace level perchlorate analysis in water initiated a new development in the Ion Chromatography (IC) technology. Maintenance of a low detection limit may be highly affected by the operating conditions of the IC system. In this paper the homoscedasticity of the IC system within the calibration concentration range, the effect of the system drift on the calibration curve and the effect of the self regeneration suppressor (SRS) current on the detection limit were investigated. The experimental results were evaluated by statistical methods such as the Cochran test and the lack of fit test. The detection limits were obtained by two ways. One through method detection limit (MDL) and the other through detection limit from the calibration curve (DTC). The Cochran test results revealed the homoscedasticity of the IC system. The effect of system drift on the calibration curve was noticed by the lack of fit test. MDL yielded a lower but less reliable detection limit than DTC. An acceptable detection limit can be achieved under the lower SRS current (100 mA).

Chromatography↗
PubMed2004

Measurement of perchlorate in water by use of an 18O-enriched isotopic standard and ion chromatography with mass spectrometric detection.

Currently, the most promising analytical methodology for low-level determination and confirmation of perchlorate (ClO4-) in drinking water is ion chromatography followed by electrospray ionization mass spectrometric detection (IC-ESI-MS). However, there are still potentially limiting situations that must be considered when analyzing real world samples by IC-ESI-MS. They are: (1) co-elution of contaminants with fragment ions having the same m/z as ClO4-, (2) high background counts at the m/z of interest leading to a subsequent decrease in signal-to-noise, (3) gradual loss of sensitivity occurring over time as the sampling cone and/or ion optics of the mass spectrometer are fouled, and (4) suppression of gas phase ion formation (ionization suppression) that can occur if high concentrations of contaminants co-elute with ClO4-. An internal standard whose response, on the column and in the electrospray, is similar to that of ClO4- would give the highest degree of accuracy possible in situations 3 and 4 listed above. Commercially available NaClO4 that was enriched with oxygen-18 was evaluated for its potential as an internal standard. The level of oxygen-18 (18O) enrichment was verified, the stability of the enriched ClO4- in aqueous solutions was determined, and method performance parameters such as method detection limits, accuracy, precision and ruggedness using the enriched ClO4 as an internal standard were determined. Internal and external calibration yielded similar results with respect to calibration, detection limits, and short-term precision. However, the enriched isotopic internal standard showed superior results with respect to ruggedness and percent recovery of spikes in ground water and synthetic water samples.

Chromatography, Liquid↗
PubMed2005

The perchlorate anion is more effective than the trifluoroacetate anion as an ion-pairing reagent for reversed-phase chromatography of peptides.

The addition of salts, specifically sodium perchlorate (NaClO4), to mobile phases at acidic pH as ion-pairing reagents for reversed-phase high-performance liquid chromatography (RP-HPLC) has been generally overlooked. To demonstrate the potential of NaClO4 as an effective anionic ion-pairing reagent, we applied RP-HPLC in the presence of 0-100 mM sodium chloride (NaCl), sodium trifluoroacetate (NaTFA) or NaClO4 to two mixtures of synthetic 18-residue peptides: a mixture of peptides with the same net positive charge (+4) and a mixture of four peptides of +1, +2, +3 and +4 net charge. Interestingly, the effect of increasing NaClO4 concentration on increasing peptide retention times and selectivity changes was more dramatic than that of either NaCl or NaTFA, with the order of increasing anion effectiveness being Cl- << TFA- < C104-. Such effects were more marked when salt addition was applied to eluents containing 10 mM phosphoric acid (H3PO4) compared to 10 mM trifluoroacetic acid (TFA) due to the lesser starting anion hydrophobicity of the former mobile phase (containing the phosphate ion) compared to the latter (containing the TFA- ion).

Anions↗
PubMed2005

Perchloric acid-soluble protein regulates cell proliferation and differentiation in the spinal cord of chick embryos.

The role of perchloric acid-soluble protein (PSP) was investigated in chick embryos. Fluorescently labeled anti-chick liver (CL)-PSP IgG was injected into the yolk sac in ovo at embryonic day 3, and became localized in neuroepithelial cells. Within 12 h, morphological changes were observed in 37.5% of anti-CL-PSP IgG-injected embryos, and the neuroepithelial cells formed a wavy line. No significant changes were observed in embryos injected with non-immune IgG or PBS. Increased expression of PCNA and decreased expression of neuronal class III beta-tubulin were observed in the spinal cord after anti-CL-PSP IgG injection. These results suggest that PSP controls the proliferation and differentiation of neuroepithelial cells in chick embryos.

Animals↗
PubMed2004

In utero and lactational exposure of Long-Evans rats to ammonium perchlorate (AP) disrupts ovarian follicle maturation.

Ammonium perchlorate (AP) is a powerful oxidizer manufactured almost exclusively for the aerospace industry. AP salts are also used in airbags, flares, fertilizers, enamels and paints. As a result of widespread industrial use, AP has become a persistent environmental contaminant of drinking water in several U.S. states. AP ion disrupts the trapping of iodide as well as facilitates the discharge of unorganified iodide from the thyroid gland. Such disturbances in thyroid hormone concentrations during critical periods of development are then known to cause profound reproductive and developmental defects, since thyroid hormones modulate both follicular development and steroidogenesis and affect estrogen metabolism and receptor. This study was designed (1) to determine whether exposure to a low or high concentration of AP (LAP, HAP) exerts detrimental effects on follicle maturation in the Long-Evans hooded rat and (2) to determine whether the modulatory effects of AP can be ameliorated by levo-thyroxine sodium (T4) supplementation. Animals were treated via deionized drinking water on GD 7-21 with LAP (0.4 mg/kg/day) or HAP (4.0 mg/kg/day). Half of each group was also given T4 supplements via drinking water on GD 7-21. Female pups were sacrificed on postnatal days 24/25, and the ovaries were excised, fixed for histology and analyzed. The analysis included a count, measurement and classification of preantral and antral follicles in the greatest cross-sectional area of the ovary. The results indicated that treatment with the HAP significantly reduced the number of preantral follicles <50,000 microm2 and the total number of antral follicles in the <50,000, 50-100,000 and >100,000 microm2 size classes. In ovaries treated with the LAP, we observed no significant decrease in preantral follicles of any size class and only a significant reduction in the largest antral follicles. T4 only circumvented the effect on the number of small preantral and antral follicles; however, a significant diminution in the antral follicle number persisted in the mid-sized (HAP) and large (LAP, HAP)-sized classes. These data support the hypothesis that AP reduces the number of preantral and antral follicles in certain size classes in rats exposed during a critical period of development, and that T4 can attenuate the effects of AP on small preantral and antral follicles, but not on medium or large antral follicles. (T35ES007292 & ES08342.).

Administration, Oral↗
PubMed2005

Vibrational spectral studies of L-citrullinium perchlorate.

Infrared and Raman spectra of L-citrullinium perchlorate crystals have been recorded at room temperature. The vibrational assignments of the observed wavenumbers are proposed on the basis of group theoretical analysis. The presence of carbonyl group indicates that the molecule exists in the ionic form. The shifting of stretching and bending wavenumbers indicates the presence of extensive hydrogen bonding in the crystal. The anion fundamentals however continue to be degenerated. This suggests that its symmetry is not affected in the crystal.

Citrulline↗
PubMed2005

Use of starch and potato peel waste for perchlorate bioreduction in water.

The cost of carbon substrates for microbial reduction of perchlorate (ClO(4)(-)) is central to the success and competitiveness of a sustainable bioremediation strategy for ClO(4)(-). This study explored the potential application of starch in combination with an amylolytic bacterial consortia and potato peel waste for ClO(4)(-) bioreduction. We obtained a potent amylolytic bacterial consortium that consisted of a Citrobacter sp. S4, Streptomyces sp. S2, Flavobacterium sp. S6, Pseudoxanthomonas sp. S5, Streptomyces sp. S7, and an Aeromonas sp. S8 identified by 16S rDNA sequencing. ClO(4)(-) concentration substantially decreased in purified starch medium inoculated with the amylolytic bacterial consortium and Dechlorosoma sp. perclace. Potato peel waste supported ClO(4)(-) reduction by perclace with the rate of ClO(4)(-) reduction being dependent on the amount of potato peels. Over 90% ClO(4)(-) removal was achieved in 4 days in a single time point experiment with 2% (w/v) potato peels waste. ClO(4)(-) reduction in a non-sterile 0.5% potato peel media inoculated with perclace occurred with an initial concentration of 10.14+/-0.04 mg L(-1) to 2.87+/-0.4 mg L(-1) (71.7% reduction) within 5 days. ClO(4)(-) was not detected in the cultures in 6 days. In a non-sterile 0.5% potato media without perclace, ClO(4)(-) depletion occurred slowly from an initial value of 9.99+/-0.15 mg L(-1) to 6.33+/-0.43 mg L(-1) (36.63% reduction) in 5 days. Thereafter, ClO(4)(-) was rapidly degraded achieving 77.1% reduction in 7 days and not detected in 9 days. No susbstantial reduction of ClO(4)(-) was observed in the sterile potato peel media without perclace in 7 days. Redox potential of the potato peel cultures was favorable for ClO(4)(-) reduction, decreasing to as low as -294 mV in 24 h. Sugar levels remained very low in cultures effectively reducing ClO(4)(-) and was substantially higher in sterilized controls. Our results indicate that potato peel waste in combination with amylolytic microorganisms and Dechlorosoma sp. perclace can be economically used to achieve complete ClO(4)(-) removal from water.

Bacteria↗
PubMed2005

Iodine-deficient vegetarians: a hypothetical perchlorate-susceptible population?

Recent risk assessments of environmental perchlorate have been subject to much debate. A particular concern is whether appropriate susceptible sub-populations have been identified. Iodine-deficient pregnant women, especially vegetarians, have been proposed as such a potential susceptible sub-population, but there is no evidence of iodine deficiency in the US population and the adequacy of iodine nutrition has not been studied in US vegetarians. To understand the possibility that US vegetarians might be iodine deficient, we reviewed the prevalence, demography, and lifestyle characteristics of US vegetarians as well as the world literature on iodine nutrition in vegetarians. Our findings indicate that strict vegetarians and vegans, who comprise probably less than 0.1% of the US population, have higher education, higher incomes, and healthier lifestyles than the general population. Field studies indicate that vegetarian diets need not lead to iodine deficiency and vegans may suffer excess iodine intake. It is remains uncertain whether there are iodine-deficient vegans or pregnant women in the US. Of more general concern is whether the 10-fold default uncertainty factor is needed for intraspecies (i.e., within human) variability to protect such hypothetical susceptible sub-populations.

Diet, Vegetarian↗
PubMed2002

Kinetics and mechanism of Ru(III) and Hg(II) co-catalyzed oxidation of D-galactose and D-ribose by N-bromoacetamide in perchloric acid.

Kinetics of oxidation of reducing sugars D-galactose (Gal) and D-ribose (Rib) by N-bromoacetamide (NBA) in the presence of ruthenium(III) chloride as a homogeneous catalyst and in perchloric acid medium, using mercuric acetate as a scavenger for Br(minus sign) ions, as well as a co-catalyst, have been investigated. The kinetic results indicate that the first-order kinetics in NBA at lower concentrations tend towards zero order at its higher concentrations. The reactions follow identical kinetics, being first order in the [sugar] and [Ru(III)]. Inverse fractional order in [H(+)] and [acetamide] were observed. A positive effect of [Hg(OAc)(2)] and [Cl(minus sign)] was found, whereas a change in ionic strength (mu) has no effect on oxidation velocity. Formic acid and D-lyxonic acid (for Gal) and formic acid and L-erythronic acid (for Rib) were identified as main oxidation products of reactions. The various activation parameters have been computed and recorded. A suitable mechanism consistent with experimental findings has been proposed.

Acetamides↗
PubMed1997

Short term storage of samples containing monoamines: ascorbic acid and glutathione give better protection against degradation than perchloric acid.

In order to study the protection of monoamines from degradation during short-time storage, the effect of three different antioxidants on the degradation of dopamine, dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5-HIAA) was analyzed after 5 and 20 h. The results showed that dopamine was still quite stable after 20 h storage at room temperature, but that about 95% of 5-HIAA had disappeared. The best protection against degradation of all three substances was achieved when 15% v/v of a solution containing 1-2 mM ascorbic acid or 40 mM glutathione was added to the sample, resulting in near 100% protection after 20 h. Perchloric acid actually accelerated the degradation of 5-HIAA.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Effect of water content in perchloric acid on the non-aqueous potentiometric titration of nitrogen-containing compounds.

In the United States Pharmacopeia (USP), 0.1 N perchloric acid in acetic acid volumetric solution (hereafter HClO4 VS) used for non-aqueous titration has specified a water content between 0.02 and 0.05%. Preparing this titrant with such a narrow range of water content is very time consuming, precludes the use of commercially available titrants, and, consequently, prompted an investigation to try and expand the range up to 0.5%. In this study, the titrimetric results obtained using HClO4 VS containing more water were very close to those obtained using the USP specified titrants. A maximum assay difference of 0.7% in the titrations of three selected nitrogen-containing compounds, clonidine hydrochloride, dipyridamole, and adenosine were observed. The titrimetric results obtained using these titrants were also precise with RSDs of not more than 0.4%. Therefore, a wider range of water content in HClO4 VS between 0.02 and 0.5% is suggested for the USP potentiometric titration of nitrogen-containing compounds.

Indicators and Reagents↗
PubMed2001

Development and validation of a nonaqueous titration with perchloric acid to determine sparfloxacin in tablets.

A simple, rapid and inexpensive method for the determination of sparfloxacin in tablets is described. The procedure is based on the use of volumetric dosage in a nonaqueous medium in glacial acetic acid with 0.1 M perchloric acid. The method validation yielded good results and included precision and accuracy. It was also found that the excipients in the commercial tablet preparation did not interfere with the assay.

Anti-Infective Agents↗
PubMed2000

Vibrational spectroscopic studies on ion solvation of lithium perchlorate in propylene carbonate + N,N-dimethylformamide mixtures.

The infrared (IR) and Raman spectra are reported for solutions of lithium perchlorate in propylene carbonate (PC), N,N-dimethylformamide (DMF) and PC + DMF mixtures. The band splittings of symmetric ring deformation for PC and O=CN deformation for DMF suggest that there is a strong interaction between lithium cations and solvent molecules. The solvent molecules have been assigned to two types, the free and complexed molecules. By a comparison of the intensity for the corresponding bands, it has been concluded that Li+ cations are preferentially solvated by DMF molecules in the LiClO4/PC-DMF solutions. This has been explained by the difference in values of donor number.

Carbonates↗
PubMed2002

Ion-molecule interactions in solutions of lithium perchlorate in propylene carbonate + diethyl carbonate mixtures: an IR and molecular orbital study.

FTIR spectra have been recorded and analyzed for solutions of lithium perchlorate in propylene carbonate (PC), diethyl carbonate (DEC), and PC + DEC mixtures. It has been shown that the carbonyl stretch bands for PC and DEC are very sensitive to the interaction between Li+ and the solvent molecules. They split with addition of LiClO4, indicating a strong interaction of Li+ with PC and DEC through the oxygen group of PC and both oxygen and ether oxygen atoms of DEC. In conjunction with molecular orbital calculation, the optimized geometries of solvation are given. In addition, solvent separated ion pairs and contact ion pairs were observed in LiClO4/DEC solutions, and no preferential solvation of Li+ in LiClO4/PC + DEC solutions were detected.

Carbonates↗
PubMed2002

Infrared spectra of permanganate anions in potassium perchlorate matrices: vibrational anharmonicity, effective symmetry and vibrational mode mixing effects.

Fourier transform infrared spectra of MnO4- anions isomorphously isolated in potassium perchlorate matrices were recorded at room and low temperature (LT, approximately 100 K). On the basis of the detected second-order vibrational transitions involving the dopant species nu3 mode components, anharmonicity constants and harmonic eigenvalues for these modes were calculated. Despite the fact that, rigorously speaking, the appearance of the spectra of dopant permanganate anions may be explained in terms of a Cs site symmetry, the nu3 stretching region resembles an approximate A1+E splitting (characteristic for a local C3nu or even higher symmetry), which is not expected, even within the latent symmetry approach. We explain such spectral patterns on the basis of vibrational mode mixing (a 'Fermi-like' resonance) of the MnO4- nu1 mode with the nu3, site-group component. With the results of degenerate case stationary perturbation theory, we show that in the present case the Fermi-like resonance is predominantly responsible for the observed spectral features. The appearance of the region of second-order vibrational transitions in the spectra of dopant permanganate anions may be better explained in terms of the (rigorous) crystallographic Cs site group (corresponding to the crystallographic Pnma space group), instead of the 'latent' (effective) symmetry site group C2nu (corresponding to the latent symmetry space group Imma).

Manganese Compounds↗
PubMed2001

Regeneration of perchlorate (ClO4-)-loaded anion exchange resins by a novel tetrachloroferrate (FeCl4-) displacement technique.

Selective ion exchange is one of the preferred treatment technologies for removing low levels of perchlorate (ClO4-) from contaminated water because of its high efficiency and minimal impact on water quality through the addition or removal of chemicals and nutrients. However, the exceptionally high affinity of ClO4- for type I anion-exchange resins makes regeneration with conventional NaCl brine extremely difficult and costly for practical applications. The present study entails the development of a novel regeneration methodology applicable to highly selective anion-exchange resins. Tetrachloroferrate (FeCl4-) anions, formed in a solution of ferric chloride and hydrochloric acid (e.g., 1 M FeCl3 and 4 M HCl), were found to effectively displace Cl04- anions that were sorbed on the resin. A mass-balance analysis indicated that a nearly 100% recovery of ion-exchange sites was achieved by washing with as little as approximately 5 bed volumes of the regenerant solution in a column flow-through experiment There was no significant deterioration of the resin's performance with respect to ClO4- removal after repeated loading and regeneration cycles. Thus, the new methodology may offer a cost-effective means to regenerate ClO4- -loaded resins with improved regeneration efficiency, recovery, and waste minimization in comparison with conventional brine regeneration techniques.

Anion Exchange Resins↗
PubMed2003

Complete degradation of perchlorate in ferric chloride and hydrochloric acid under controlled temperature and pressure.

Despite favorable thermodynamics, the reduction of perchlorate (ClO4-) is kinetically limited in aqueous media because of its high activation energy. In this paper, a new methodology has been presented for degrading ClO4- in an FeCl3-HCl solution at an elevated temperature (< 200 degrees C) and/or pressure (approximately 20 atm). Results indicate that the rate constant for the pseudo-first-order reaction between ClO4- and ferrous Fe(II) (in excess) increased nearly 3 orders of magnitude when the temperature was increased from 110 to 195 degrees C, and a complete reduction of ClO4- occurred in < 1 h at 195 degrees C in the FeCl3-HCl solution. The activation energy of the reaction was calculated to be about 120 kJ/mol. Additionally, a flow-through reactor was constructed based on the batch kinetic measurements, and a nearly complete degradation of ClO4- was observed under continuous-flow mode. Because the FeCl3-HCl solution has been successfully used in regenerating selective anion-exchange resins sorbed with ClO4- during water treatment, this new methodology offers a cost-effective means to degrade ClO4- while not altering the chemical properties of the FeCl3-HCl regenerant solution so it can be reused, eliminating the production of secondary wastes.

Anion Exchange Resins↗
PubMed2005

Sorption and desorption of perchlorate and U(VI) by strong-base anion-exchange resins.

This study investigated the sorption affinity and capacity of six strong-base anion-exchange (SBA) resins for both uranium [U(VI)] and perchlorate (ClO4-) in simulated groundwater containing varying concentrations of sulfate (SO4(2-)). Additionally, desorption of U(VI) from spent resins was studied to separate U(VI) from resins with sorbed ClO4- for waste segregation and minimization. Results indicate that all SBA resins investigated in this study strongly sorb U(VI). The gel-type polyacrylic resin (Purolite A850) showed the highest sorption affinity and capacityfor U(VI) butwasthe least effective in sorbing ClO4-. The presence of SO4(2-) had little impact on the sorption of U(VI) but significantly affected the sorption of ClO4-, particularly on monofunctional SBA resins. A dilute acid wash was found to be effective in desorbing U(VI) but ineffective in desorbing ClO4- from bifunctional resins (Purolite A530E and WBR109). A single wash removed approximately 75% of sorbed U(VI) but only approximately 0.1% of sorbed ClO4- from the bifunctional resins. On the other hand, only 21.4% of sorbed U(VI) but approximately 34% of sorbed ClO4- was desorbed from the Purolite A850 resin. This study concludes that bifunctional resins could be used effectively to treatwater contaminated with ClO4- and traces of U(VI), and dilute acid washes could minimize hazardous wastes by separating sorbed U(VI) from ClO4- prior to the regeneration of the spent resin loaded with ClO4-.

Anion Exchange Resins↗