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PubMed1988

Dealing with spills of hazardous chemicals: some nitrosamides.

Spills of N-methyl-N-nitrosourea, N-ethyl-N-nitrosourea, N-methyl-N-nitrosourethane and N-ethyl-N-nitrosourethane can be decontaminated using a mixture of ethanol and saturated aqueous sodium bicarbonate solution. Spills of N-methyl-N-nitroso-p-toluenesulphonamide, N-methyl-N'-nitro-N-nitrosoguanidine and N-ethyl-N'-nitro-N-nitrosoguanidine can be decontaminated with a solution of sulphamic acid in 2 M-hydrochloric acid. In all cases the nitrosamides are completely destroyed and only non-mutagenic reaction mixtures are produced.

Chromatography, High Pressure Liquid↗
PubMed1989

Assay of antipyrine and its main metabolites 3-hydroxymethylantipyrine, norantipyrine and 4-hydroxyantipyrine in urine.

Two assay methods for antipyrine (AP) and its main metabolites 3-hydroxymethylantipyrine (3-HMA), norantipyrine (NORA) and 4-hydroxyantipyrine (4-HA) in urine samples have been compared. Method I involved a 3 h incubation at 37 degrees C with beta-glucuronidase, whereas method II used acid hydrolysis with 3 M hydrochloric acid to convert NORA glucuronide to the aglycone and 24 h incubation at 37 degrees C with beta-glucuronidase for hydrolysis of 3-HMA and 4-HA glucuronides. The precision of both sample preparation procedures was evaluated by means of HPLC with UV detection. The relative standard deviation (RSD) for the metabolites were considerably greater than 10% with method I. Application of method II, however, led to intra-assay and inter-assay RSD of less than 10%.

Antipyrine↗
PubMed2000

New preconditioning strategy for the determination of inorganic anions with capillary zone electrophoresis using indirect UV detection.

It is widely accepted that preconditioning procedures are indispensable in capillary electrophoresis in order to achieve reproducibility of migration times and peak areas. Several preconditioning strategies have been employed for electrophoretic determinations of inorganic anions using indirect UV detection including simple flushing with buffer or alkaline or acid pre-rinsing followed by flushing with electrolyte. We investigated the influence of various preconditioning strategies on the reproducibility of migration times and peak areas of inorganic anions. The electrolyte systems for indirect UV detection were based on pyromellitic acid and chromic acid respectively as UV absorbing probes and hexamethonium hydroxide as electroosmatic flow modifier. Preconditioning agents under investigation were electrolyte buffer, NaOH, HCl and the free acids of the UV absorbing probes. Investigations showed that reproducibility of migration times and peak areas can be significantly improved by acid pre-rinsing using the corresponding acid of the UV absorbing probes compared to preconditioning by flushing the capillary with buffer. In contrast to acid pre-rinsing using hydrochloric acid no interfering signals within the migration time window of inorganic anions under investigation can be observed. The optimized preconditioning procedure yields relative standard deviations of migration times less than 0.25% (n = 10). Relative standard deviations of corrected peak areas were below 5% applying acid preconditioning using pyromellitic acid.

Alkalies↗
PubMed1990

Characterization of a reversed-phase high-performance liquid chromatographic system for the determination of blood amino acids.

High-performance liquid chromatography was used to separate physiological amino acids in perchloric acid supernatants of blood samples. Precolumn derivatization with phenyl isothiocyanate was carried out, starting with 20 microliters of supernatant; 2-10 microliters were injected into a 30-cm Pico Tag column, which was eluted with a gradient of two eluents in 64 min. Stock amino acid solutions prepared in water, hydrochloric acid or perchloric acid showed comparable recoveries on serial dilution (parallelism test). The recovery of crystalline amino acids added to blood in amounts ranging from normal to six times normal was generally satisfactory. The within-assay relative standard deviations were less than 5% for many amino acids. The performance of the system was less than satisfactory for cysteine and methionine. Glutamine and asparagine are interconverted into glutamate and aspartate, respectively, in a time-dependent fashion; a separate measurement of one member of the pair is therefore required in order to assay the other starting from the sum of both chromatographic peaks. The method is suitable for the relatively rapid, sensitive and accurate measurement of blood amino acids in perchloric acid supernatants (in which other relevant metabolites are customarily assayed) over a wide range of physiological concentrations, on very small amounts of sample.

Amino Acids↗
PubMed1997

Screening and identification of drugs in human hair by high-performance liquid chromatography-photodiode-array UV detection and gas chromatography-mass spectrometry after solid-phase extraction. A powerful tool in forensic medicine.

A method is described to screen for a wide range of pharmaceuticals in human hair. 75 mg of powdered hair are incubated (12 h at +56 degrees C) in 2 ml of distilled water (acidic compounds) or 0.1 M hydrochloric acid (neutral and basic compounds). A twin solid-phase extraction on C18 cartridges is used for the sample clean-up procedure. Acidic drugs are fixed at pH 2 and eluted with 1% ammoniacal methanol while neutral and basic drugs are retained on the column at pH 8.6 and eluted with methanol containing 0.5% acetic acid. The internal standard (I.S.) for the acidic extraction was bupivacaine while the I.S. for the basic extraction was prazepam. The separation of the drugs was performed using both the liquid and the gas chromatographic techniques whereas identification was achieved using photodiode array and mass spectrometric detection, respectively. The liquid chromatographic system gives an elution of the drugs following a multi step gradient from a Symmetry C8 (Waters) 5 microns column (250 x 4.6 mm I.D.) at +30 degrees C with acetonitrile-phosphate buffer (pH 3.8). Identification is achieved using the reference data (retention times and spectra) of 675 pharmaceuticals, toxicants and drugs of abuse stored in a personal library. The present method has been applied during 6 months in our laboratory. By establishing a victim's drug use history, it is a very powerful tool in forensic medicine. We illustrate the method with some real cases of police crime investigation.

Adult↗
PubMed2003

Comparison of methods for leaching heavy metals from composts.

This paper presents the determination of total iron, copper, zinc, chromium, nickel, lead, cadmium and mercury contents in the compost obtained from sorted municipal organic solid waste applying the following methods of sample mineralization: 40% hydrofluoric acid with preliminary incineration of a sample, a mixture of concentrated nitric(V) and chloric(VII) acids with preliminary incineration of organic matter and a mixture of nitric(V) and chloric(VII) acids without sample incineration. The speciation analysis of Tessier was used to estimate the bioavailability of the metals. Elution degrees of the mobile forms of the metals from the compost with 10% nitric(V) acid and 1 mol/dm(3) hydrochloric acid were compared. The contents of the elements in the eluates were determined applying atomic absorption spectrometry.

Biological Availability↗
PubMed2004

Characteristics of neutralization of acids by newly isolated fungal cells.

Soil microorganisms play an important role in maintaining soil pH at levels suitable for other soil organisms. To clarify the biological neutralization mechanism in soil, we isolated soil microorganisms showing a high ability to neutralize acids and studied their characteristics. From our taxonomic study, three isolated strains were identified as filamentous fungi, namely Mucor sp., Aspergillus fumigatus, and Aureobasidium pullulans. These strains could secrete basic materials, such as ammonia, for neutralization, grow in the medium at pH 4.0 and increase the pH of the medium to approximately 8.0. These microbial cells could neutralize not only nitric acid but also sulfuric and hydrochloric acids. The strains could also grow by utilizing nitric acid as a sole nitrogen source. In the soil containing these organisms, the pH was maintained in the neutral range by the buffering action of basic materials that they secrete. These results suggest that these fungal cells are useful for protecting the soil from acidification by acid rain.

Journal Article↗
PubMed2001

Specific distribution of sialic acids in animal tissues as examined by LC-ESI-MS after derivatization with 1,2-diamino-4,5-methylenedioxybenzene.

Simultaneous analysis of sialic acids has been a challenging target, because sialic acids having N- or O-acetyl, glycolyl, and sulfonic acid ester groups are labile during their release from carbohydrate chains and analytical procedures. In the present paper, we propose a method using high-performance liquid chromatography coupled with eletrospray ionization mass spectrometry (HPLC-ESI-MS). The method was evaluated by applying to the analysis of sialic acids in various tissues, especially digestive organs in mice and rats. The method was based on the in situ precolumn derivatization of sialic acids after releasing them by hydrolysis. The sialic acids were derivatized with 1,2-diamino-4,5-methylenedioxybenzene to form highly fluorescent quinoxaline derivatives. By using two different hydrolysis conditions (i.e., with 2 M acetic acid and with 0.1 M hydrochloric acid), both total sialic acids and sialic acid distributions were easily determined. We found that sialic acids showed characteristic distributions in the tissues of mice and rats. Further, HPLC-ESI-MS revealed that all the tissues examined in mice and rats commonly contained highly acetylated sialic acids and 8-O-sulfated N-acetylneuraminic acid.

Animals↗
PubMed2005

A variable-temperature diffuse reflectance infrared fourier transform spectroscopy study of the binding of water and pyridine to the surface of acid-activated metakaolin.

Four metakaolins were prepared by heating a Spanish kaolin at 600, 700, 800, and 900 degrees C for 10 h. Following preliminary optimization, these metakaolins were acid activated in 6 M hydrochloric acid at 90 degrees C for 6 h; the samples calcined at 600, 700, and 800 degrees C produced the highest surface area solids and were selected for further study. Variable-temperature diffuse reflectance infrared Fourier transform spectroscopy analysis of the resulting acid-activated metakaolins (AAMKs) identified a wide range of hydrogen bond strengths in adsorbed water at room temperature. Above 300 degrees C it was possible to fit the broad hydroxyl stretching band to seven contributing components at 3730, 3700, 3655, 3615, 3583, 3424, and 3325 cm(-1). As the sample temperature was increased, the 3730 cm(-1) band increased in intensity as the water hydrogen bonded to AlOHAl was thermally desorbed. The other six bands decreased in intensity. The spectra of adsorbed pyridine indicated the presence of both Brönsted and Lewis acid sites on the surface of the air-dried AAMKs. Preheating the AAMK at 200 degrees C prior to pyridine sorption reduced the number of Brönsted acid sites and increased the number of thermally stable Lewis acid sites. A reduction in the amount of adsorbed pyridine after pretreating the AAMK at 400 degrees C was tentatively attributed to a reduction in surface area. This was reflected in fewer thermally stable Lewis acid sites in the AAMK pretreated at 400 degrees C compared to the number present in the sample pretreated at 200 degrees C.

Journal Article↗
PubMed1997

Synthesis, characterization, and in vitro quantitation of N-7-guanine adducts of diepoxybutane.

Diepoxybutane (DEB) is an important metabolite of 1,3-butadiene (BD), a high-volume industrial chemical classified as a probable human carcinogen. Rodent inhalation studies show strikingly high sensitivity of mice to carcinogenic effects of butadiene compared to rats, which has been linked to differences in metabolism. Both species convert BD to 3,4-epoxy-1-butene (EB), but mice further oxidize a significantly greater part of EB to DEB. DEB is a potent bifunctional genotoxic agent which is 100-fold more mutagenic than EB and is likely to be involved in BD-induced carcinogenesis. Identification of specific BD-induced DNA adducts is critical to understanding the mechanism of its biological activity. We have previously described reactions of EB with guanine and adenine as nucleobases, nucleosides, and constituents of DNA. In this work, DEB-induced guanine adducts were isolated and structurally characterized by UV spectroscopy, mass spectrometry, and nuclear magnetic resonance. When guanosine was reacted with DEB in glacial acetic acid followed by hydrolysis in hydrochloric acid, three products were isolated: N-7-(2',3',4'-trihydroxybut-1'-yl)guanine (DEB-Gua I, major adduct), N-7-(2',4'-dihydroxy-3'-chlorobut-1'-yl)guanine (DEB-Gua II), and N-7-(2',3'-dihydroxy-4'-acetoxybut-1'-yl)guanine (DEB-Gua III). We suggest initial formation of the N-7-(2'-hydroxy-3',4'-epoxybut-1'-yl)guanine intermediate followed by nucleophilic substitution at the 3',4'-epoxy ring with hydroxide, chloride, or acetate anions to give DEB-Gua I, II, or III, respectively. DEB-Gua I and the epoxy intermediate were also isolated from hydrolysates of DEB-exposed calf thymus DNA (CT DNA). N-7-Guanine adducts are known to undergo spontaneous and enzymatic depurination producing apurinic sites. If not repaired before DNA replication, apurinic sites can give rise to mutations and ultimately cancer. The extent of alkylation at the N-7 of guanine in DEB-exposed DNA (58.7 +/- 1.1 adducts/10(3) normal guanines) was similar to that previously reported for CT DNA exposed to EB at the same molar ratio. Since EB and DEB appear to induce comparable levels of overall DNA alkylation at the conditions applied in this work, other factors, such as formation of DNA cross-links by DEB but not EB or differences in repair of EB and DEB adducts, may be responsible for the differences in mutagenicity.

Carcinogens↗
PubMed2002

Evolution of water chemistry in natural acidic environments in Yangmingshan, Taiwan.

In Yangmingshan National Park, located in the northern part of the Taiwan Island, there is a very rare area where fish (Channa asiatica) live in spite of acid environments. The origin of the acid in local acid ponds and rivers and the evolution of the water chemistry are discussed on the basis of sulfur stable isotope ratios and chemical equilibria. One of the sources of the acid is sulfuric acid, which is derived from the oxidation of hydrogen sulfide in volcanic gas gushing out from fumaroles around the area and from acid deposition supplied from Taipei City. It is also derived from the oxidation of pyrite: the sulfur stable isotope ratios of delta 34S of +1@1000 to +4@1000 (relative to CDT) of sulfate in acid pond waters (pH 3-4) could be related to those of hydrogen sulfide in volcanic gas, pyrite in local pond sediments and soils, and sulfate in rain water. One acid source is sulfuric and hydrochloric acids arising in springs from geothermal activity: the delta 34S values were characterised by +13@1000 to +17@1000 sulfate-S, which was provided by a disproportionation reaction of sulfur dioxide in the depths. Another acid source could be the oxidation of iron(II). Under acidic conditions, the water-rock reaction gives rise to high concentrations of aluminium and iron. While flowing down surface streams, iron(II) is oxidised to iron(III) and then hydrolysed to cause further acidification under oxic conditions. The concentrations of iron and aluminium are controlled by redox and dissolution equilibria.

Air Pollutants↗
PubMed1965

A STUDY ON THE GLUCOSAMINE-CONTAINING CONSTITUENTS OF THE SEEDS OF KIDNEY BEANS (PHASEOLUS VULGARIS).

1. The constituents of the seeds of kidney beans containing glucosamine that could be released by acid hydrolysis (0.5 n-hydrochloric acid at 100 degrees ) were extracted into the phenol-rich phase on partitioning between phenol and water at 70 degrees . 2. These materials were also brought into solution on extracting the seeds with water (incomplete), or preferably with a slightly alkaline buffer in the absence of phenol. When these solutions were heated at 100 degrees or treated with trichloroacetic acid, all the materials containing acid labile glucosamine were carried down with the precipitate. Treatment with pepsin rendered the materials containing glucosamine soluble again. 3. All proteins in these extracts of kidney bean were found to be associated with various amounts of neutral and amino sugars by high-voltage electrophoresis and chromatography on Sephadex G-200 columns. 4. The isolation and crystallization of the main sugar components, d-glucosamine and d-mannose, are described and their significance in plant glycoproteins is discussed.

Biochemical Phenomena↗
PubMed1968

A method for the separation of peptides and alpha-amino acids.

1. Peptides and alpha-amino acids, occurring in mixtures from various sources, can be separated into one fraction containing the amino acids and several peptide fractions. This is achieved by chelation of the mixture with Cu(2+) ions and subsequent chromatography of these chelates over the acetate form of diethylaminoethylcellulose or triethylaminoethylcellulose. 2. The amino acid fraction is obtained by elution with 0.01m-collidine-acetate buffer, pH8.0. 3. Peptide fractions are eluted with 0.01m-collidine-acetate buffer, pH4.5, 0.17n-acetic acid and 0.1n-hydrochloric acid respectively. 4. With the exception of aspartic acid and glutamic acid, which are partly found in the acidic peptide fraction, the amino acids are completely separated from the peptides. 5. Contamination of the acidic peptide fraction with glutamic acid and aspartic acid can be largely avoided by previous addition of an excess of arginine. 6. Copper is removed from the eluates by extraction with 8-hydroxyquinoline in chloroform.

Amino Acids↗
PubMed1999

Cola drinks consumption and oesophagitis.

For oesophageal epithelial changes to develop from gastro-oesophageal reflux disease (GORD), the character of the refluxate must be acid enough to cause injury. Experimentally, copious perfusion of the oesophagus with weak acid is quite harmless. However, hydrochloric acid alone with a pH below 3.0 may cause oesophageal injury. Cola drinks are strongly acidic (pH 2.5). This study analyses the influence of and possible interaction between cola consumption and oesophagitis. Twenty rats were divided into two groups of 10. The animals received saline (pH 7.0) or cola (pH 2.6) per OS with 24 h free access to these solutions. After the experiment the oesophagus was dissected. The mucosa was macroscopically and histopathologically examined, and flow cytometric analysis was used to look for proliferative activity. The histopathological analysis showed that there is no difference between saline and cola. But the findings of cell cycle analysis showed that the effects of cola and saline in inducing oesophageal mucosal damage are different. In the cola group the values were G0/G1, 7.33 +/- 2.88; S, 29.88 +/- 2.88; G2/M, 0.10 +/- 0.01; PI (proliferative-regenerative index), 29.76 +/- 2.88. The rat cell population g0/g1 phases were found to be low (p < 0.01), and the cell population S and PI phases were found to be significantly elevated compared with the control group (p < 0.01). (G0/G1, 79.30 +/- 5.97; S, 16.06 +/- 8.27; G2/M, 4.66 +/- 4.03; PI, 20.03 +/- 6.01). These results were reflected in the proliferative index, which is used as a measure of the regeneration index. The data show that cola has proliferative and regenerative effects on the oesophageal mucosa, and it is possible that its regenerative effect is caused as a result of an irritant effect.

Animals↗
PubMed1998

Not everything acid fast is Mycobacterium tuberculosis--a case report.

The Ziehl-Neelsen (ZN) stain is important in identifying organisms that are acid fast, principally Mycobacterium tuberculosis. However, decolorisation with a weaker acid concentration (for example 1% hydrochloric acid), often used in ZN staining in histology, can result in a wider variety of organisms appearing acid fast and can be a cause of misidentification. To illustrate this point, a patient is described with pulmonary nocardiosis who was misdiagnosed as having tuberculous empyema on pleural biopsy.

Aged↗
PubMed1986

Suppression of gastric H2-receptor mediated function in patients with bronchial asthma and ragweed allergy.

We have previously demonstrated a depression of airway, vascular, and cutaneous H2-histamine receptor function in sheep with experimental allergic asthma. In the present investigation, we wished to determine if there is a depression of gastric H2-receptor function in subjects with allergic bronchial asthma. In eight normal subjects and seven subjects with allergic bronchial asthma and bronchial reactivity to ragweed antigen, gastric H2-receptor function was assessed by measuring basal and maximal stimulated acid output following pretreatment with a placebo or the H2-antagonist, cimetidine. Maximal stimulated acid output was defined as the peak acid output (PAW mEq/hr) of hydrochloric acid following a subcutaneous injection of histalog (1.5 mg/kg), and selective H2-stimulation as delta PAO = PAOplacebo-PAOcimetidine. While basal acid output was not different between the two groups, mean (+/- SD) PAO was significantly lower in the asthmatic group (14.0 +/- 8.2 mEq/hr) than the normal group (27.9 +/- 9.4 mEq/hr) (p less than 0.01). Mean PAO expressed as percent of predicted maximum was 112 +/- 36 percent in the normal group and 61 +/- 34 percent in the asthmatic group (p less than 0.01). Mean delta PAO was significantly higher in the normal group (17.1 +/- 4.8 mEq/hr) than in the asthmatic group (7.0 +/- 5.3 mEq/hr) (p less than 0.005) indicating suppressed selective H2-receptor stimulation in the latter. We conclude that in subjects with bronchial asthma and marked bronchial hyperreactivity to ragweed antigen, there is a depression of gastric H2-histamine receptor function.

Adult↗
PubMed2003

Determination of carbon in aqueous solutions by atmospheric-pressure helium microwave induced plasma atomic emission spectrometry with gas-phase sample introduction technique.

A trace amount of carbon was determined by atmospheric-pressure helium microwave induced plasma atomic emission spectrometry (He-MIP-AES) with gas-phase sample introduction technique. This method was applied for the generation of a continuous flow of carbon dioxide by the acidification of carbonate ion and hydrogen carbonate ion for the determination of carbon. The generated carbon dioxide was separated from the solution by a simple gas-liquid separator, dried with a desiccant and swept into the MIP with helium carrier gas for analysis. Of the acids and drying agents investigated, hydrochloric acid for acidification and anhydrous calcium chloride as a desiccant were found to be the most appropriate for the generation of carbon dioxide. Under the optimized experimental conditions, the best attainable detection limits at C (I) 193.09 and C (I) 247.86 nm lines were 7.89 and 8.10 microg/l with linear dynamic ranges of 100 to 10,000 and 100 to 20,000 microg/l for carbon, respectively. The presence of many diverse elements and ions was found to cause a more or less depressing interference by the proposed technique. However, no interference was observed from the following elements and ions: Ca, K, Rb, Br-, Cl-, F- and I-. Finally, the present method has been applied to the determination of carbon in several water samples.

Journal Article↗
PubMedDate not supplied

Soil decontamination at the Montevecchio-Levante mine site with experimental washing and leaching techniques.

The soils in the neighbourhood of the Rio Montevecchio-Sitzerri, a stream that flows in the valley below the tailings pond of the Montevecchio-Levante mineral processing plant (SW Sardinia, Italy) are severely contaminated by heavy metals, to the extent that traditional land uses are compromised. Consequently urgent measures are needed both to abate the pollution at source and rehabilitate the contaminated land. This paper is concerned with the problem of soil decontamination using washing and leaching techniques. Laboratory experiments have been conducted in mechanically agitated reactors, using citric acid and acetic acid solutions and brine of hydrochloric acid and calcium chloride. The influence of both reagent concentration and solid-to-liquid ratio has been assessed, and in the most significant cases, the attack kinetics has been determined. The tests showed the brine to be the most effective for removing metals from the soils. Based on the findings of the investigations, the possibility of decontamination by heap leaching has been simulated in the laboratory using the column technique.

Acids↗