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PubMed2003

Rapid and simple determination of selenium in blood serum by inductively coupled plasma-mass spectrometry (ICP-MS).

An inductively coupled plasma mass spectrometer (ICP-MS) with a rapid sample-preparative procedure was used for the determination of selenium in blood serum. Blood serum was prepared by dilution in an acidic solution consisting of nitric acid (1%), X-triton (0.1%) and 1-butanol (0.8%). A calibration curve was established for 1-40 microg mL(-1) (r(2)>0.99). The limit of detection was 0.5 microg mL(-1). Repeatability and intermediate precision were satisfactory with relative standard deviations (RSD) of 2.0% and 3.2%, respectively. This method was easily applied to reference materials with satisfactory accuracy. Good correlation (r(2)=0.96) was observed between ICP-MS and atomic absorption spectrometry (AAS) for the determination of (82)Se in blood serum from 23 patients. These results suggest that the sample preparative procedure coupled with ICP-MS can be used for the routine determination of (82)Se in human blood serum.

Blood Chemical Analysis↗
PubMed2000

Rapid determination of lead and cadmium in sewage sludge samples using electrothermal atomic absorption spectrometry with slurry sample introduction.

Lead and cadmium concentrations in sewage sludge samples are determined by suspending the ground samples in a solution containing 10% (v/v) concentrated hydrofluoric acid, 1% (v/v) concentrated nitric acid, 0.5% (m/v) dihydrogen ammonium phosphate and 0.1% (m/v) sodium hexametaphosphate. Aliquots of 20 microL of these suspensions (4 mg/mL) are diluted to 1000 microL with the same solution and then injected into the electrothermal atomizer. The drying stage is performed by programming a 400 degrees C temperature, a ramp time of 20 s and a hold time of 15 s on the power supply of the atomizer. No ashing step is used. Platform atomization is carried out at 1600 and 1800 degrees C for Pb and Cd, respectively. Calibration is performed using aqueous standards in the 5-75 and 0.2-5 microg/L Pb and Cd ranges, respectively. Results obtained for three certified reference materials and four samples demonstrate the reliability of the procedures described.

Cadmium↗
PubMed1989

Determination of lead in blood by graphite furnace atomic absorption spectrometry--a critique.

Graphite furnace atomic absorption spectrometry (GFAAS) is increasingly becoming the method of choice for the determination of Pb in blood. The major GFAAS methods that have been published to date include: (i) direct introduction of the sample into the furnace; (ii) dilution with water, Triton X-100 or acid; (iii) deproteinization with nitric acid; (iv) matrix modification; and (v) solvent extraction. This review focuses on the difficulties associated with each of these methods, and highlights recent attempts to overcome matrix interferences and improve the accuracy and precision of Pb determination in blood using modern furnace technology, especially the stabilized temperature platform furnace.

Humans↗
PubMed2000

Effects of various decalcification protocols on detection of DNA strand breaks by terminal dUTP nick end labelling.

To analyse DNA strand breaks by terminal deoxy(d)-UTP nick-end labelling (TUNEL) in calcified tissues including bones and teeth, it is important to decalcify the tissues first. However, the effects of decalcifying reagents on the integrity of DNA are largely unknown. In the present study, we evaluated the usefulness of various decalcifying reagents including 10% EDTA (pH 7.4), 5% trichloroacetic acid (TCA), 5% formic acid, 5% HCl, 10% nitric acid, Plank-Rychlo's solution, Morse's solution and K-CX solution in TUNEL staining. Mouse maxilla was selected as the experimental system. Apoptotic cells naturally occurring in the epithelium were analysed. Tissues were assessed by soft X-ray imaging to confirm complete decalcification. The time required for decalcification of the tissue was 7 days with 10% EDTA and 2 days with other decalcifiers. Decalcified tissues were stained with Methyl/Green-Pyronine Y or 4',6-diamidino-2-phenylindole for assessment of DNA integrity. Nuclei of epithelial cells were strongly positive for both dyes after decalcification with 10% EDTA, 5% TCA, Morse's solution and 5% formic acid. The other reagents failed to retain DNA. Our results demonstrated good TUNEL staining of the maxilla treated with 10% EDTA or 5% TCA. Based on the required time for processing and the signal-noise ratio, we recommend 5% TCA as the decalcifying reagent to analyse for DNA strand breaks.

Animals↗
PubMed2005

Loss of PM2.5 nitrate from filter samples in central California.

Evaporative loss of particulate matter (with aerodynamic diameter < 2.5 microm, [PM2.5]) ammonium nitrate from quartz-fiber filters during aerosol sampling was evaluated from December 3, 1999, through February 3, 2001, at two urban (Fresno and Bakersfield) and three nonurban (Bethel Island, Sierra Nevada Foothills, and Angiola) sites in central California. Compared with total particulate nitrate, evaporative nitrate losses ranged from < 10% during cold months to > 80% during warm months. In agreement with theory, evaporative loss from quartz-fiber filters in nitric acid denuded samplers is controlled by the ambient nitric acid-to-particulate nitrate ratio, which is determined mainly by ambient temperature. Accurate estimation of nitrate volatilization requires a detailed thermodynamic model and comprehensive chemical measurements. For the 14-month average of PM2.5 acquired on Teflon-membrane filters, measured PM2.5 mass was 8-16% lower than actual PM2.5 mass owing to nitrate volatilization. For 24-hr samples, measured PM2.5 was as much as 32-44% lower than actual PM2.5 at three California Central Valley locations.

Aerosols↗
PubMed2006

Extraction of uranium from simulated ore by the supercritical carbon dioxide fluid extraction method with nitric acid-TBP complex.

The supercritical fluid extraction (SFE) method using CO(2) as a medium with an extractant of HNO(3)-tri-n-butyl phosphate (TBP) complex was applied to extract uranium from several uranyl phosphate compounds and simulated uranium ores. An extraction method consisting of a static extraction process and a dynamic one was established, and the effects of the experimental conditions, such as pressure, temperature, and extraction time, on the extraction of uranium were ascertained. It was found that uranium could be efficiently extracted from both the uranyl phosphates and simulated ores by the SFE method using CO(2). It was thus demonstrated that the SFE method using CO(2) is useful as a pretreatment method for the analysis of uranium in ores.

Journal Article↗
PubMed2005

[Simultaneous determination of germanium and some major ash forming elements in lignites using a dual-view ICP-OES].

In this article, an ICP-OES method of simultaneous determination germanium and some major ash forming elements especially for Fe, Al, Ca, Mg, K, Na, Ti in lignites is described. An ICP-OES instrument equipped with a dual-view plasma torch and a simultaneous detector was used. This technology allows the simultaneous determination of trace elements and major components in the axial view along with in the radial view. The moderate operation condition of the instrument and analytical wavelength lack of interference from elements in the sample matrix was selected, the spectral background was automaticly eliminated. The obtained coal ashes were dissolved in mixtures of nitric acid, hydrofluoric acid and perchloric acid after coal samples were cinerated. The analytical results were in good agreement with those provided by national standard methods. The detection limit of the instrument is ranged between 0.00039-0.10 microg. x mL(-1), the precision of the method is in the range of 0.79%-2.84%, the average recovery of samples is 92.38%, the proposed method is well suitable for the determination germanium and some major ash forming elements in lignites.

Aluminum↗
PubMed1991

Graphite furnace atomic absorption spectrometric determination of blood lead with palladium modification.

In this work we present a graphite furnace atomic absorption spectrometric method for blood lead using palladium as a chemical modifier. Whole blood was diluted 10- fold with a 0.1% v/v triton X-100 solution; 10 microL of this solution and 10 microL of the palladium-based modifier (2 mg Pd/L, 2% w/v citric acid and 0.01 M nitric acid) were injected onto the L'vov platform by using the alternate volume mode. The following furnace operating parameters were used: (a) drying steps, 120 degrees C for 10s and 250 degrees C for 30s; (b) pyrolysis steps, 800 degrees C for 45s (with oxygen) and 1100 degrees C for 25s; (c) atomization, 1600 degrees C for 3s; (d) clean out, 2700 degrees C for 4s. Accuracy was tested by using (i) a NIST standard (SRM-909) and the Behring Control Blood for Metal 1 (OSSD 21) with lead concentrations of 23.7 +/- 2.1 micrograms/L (found: 21.2 +/- 0.7 micrograms/L) and 413 +/- 51 micrograms/L (found: 407 +/- 6 micrograms/L), respectively; (ii) recovery studies (ca. 100 +/- 1%), and (iii) a reported method (mean relative error: 5.1%). Approximate standard deviations of 0.3 (within-run) and 0.7 (between-runs) micrograms Pb/L were found in the precision study. The detection limit (3 sigma) and the characteristic mass (for a 10- microL injection volume) were 0.1 micrograms Pb/L and 15 pg/0.0044 A.s, respectively. The proposed method was used to establish the lead levels of patients with renal insufficiency; a mean concentration (+/- SD) of 59 +/- 39 micrograms Pb/L (range: 12- 160 micrograms Pb/L) was found. The method was interference-free, reliable and reproducible.

Graphite↗
PubMed2003

Infrared spectra of proton transfer complexes of the cycleanine alkaloid in solid state.

Proton transfer complexes obtained between the cycleanine alkaloid and hydrogen chloride, hydrogen bromide and nitric acids have been investigated by infrared spectroscopic technique between 4000 and 400 cm(-1) in KBr. The vibrational perturbations brought about by proton transfer complex formation, discussed in terms of preferred site of interaction, show that the proton of the inorganic acids is transferred to cycleanine through one of its N sites.

Alkaloids↗
PubMed1995

Some similarities in vascular effects of oleic acid and oxidized low-density lipoproteins on rabbit aorta.

In the present study oxidized low-density lipoproteins (ox-LDL) was prepared by a new simple method: oxidizing LDL by electrolysis-generated free radicals. In endothelium-intact norepinephrine(NE)-precontracted rabbit aortic rings, ox-LDL (2 mg protein/ml)-incubation for 30 min or 3 mM oleic acid for 10 min, significantly attenuated the acetylcholine (ACh)-induced endothelium-dependent relaxation (EDR) (both P < 0.01 v control). Such attenuated EDR were sustained after washout. The oleic acid-induced endothelial dysfunction was associated with concomitant reduction of cGMP level in aortic rings. Preincubation of aortic rings with 500 microM L-arginine or 100 u/ml superoxide dismutase for 10 min partly prevented the oleic acid-induced attenuation of EDR and reduction of cGMP, indicating that oleic acid may impair the L-arginine-nitric acid pathway and/or inactivate the nitric oxide. Both ox-LDL and oleic acid potentiated NE-induced aortic ring contraction (both P < 0.01 v control). Such potentiating effects were abolished by preincubation with 1 microM verapamil, indicating the possible involvement of calcium influx in vascular smooth muscle cells during the enhanced contraction. Gas-chromatographic analysis showed that oleic acid content is the highest among all free fatty acids in ox-LDL. In conclusion, we found that oleic acid possesses certain similar vascular effects as ox-LDL in inducing endothelial dysfunction and in enhancing NE-induced vasocontraction in rabbit aortic ring. We proposed that the vasoactive effects of ox-LDL may be resulted partly from the activation or release of active oleic acid molecule during oxidative modification of LDL.

Acetylcholine↗
PubMed1981

Sampling procedure and determination of lead in canned foods.

A method is presented for improving within-can homogeneity and simplifying the determination of lead in canned foods. The entire content of a canned food product is blended with 2N HNO3 and allowed to stand 16 h; then the sample is again blended and a subsample is taken. The subsample is digested by wet ashing using nitric acid-perchloric acid or nitric acid-sulfuric acid-hydrogen peroxide. The pH of the sample is adjusted with ammonium hydroxide, and the lead is extracted into butyl acetate as the pyrrolidinecarbodithioate complex. Lead concentration is determined by flame atomic absorption spectrometry. Recoveries of lead ranged from 92 to 104% for added 100-mesh lead particulate. Within-sample variability for green beans was reduced from 37% obtained with blending alone to 3.7% using the proposed procedure at the 3.1 micrograms/g added lead level. Variability was 7.6% at the 0.68 microgram/g level and 16.4% at the 0.20 microgram/g level of added lead. The use of nitric acid-sulfuric acid-hydrogen peroxide for digestion has the advantage of not forming a precipitate during the neutralization step, as occurs when nitric acid-perchloric acid is used for dissolution.

Food Contamination↗
PubMed1997

Determination of silicon in breast and capsular tissue from patients with breast implants performed by inductively coupled plasma emission spectroscopy. Comparison with tissue histology.

A method for analysis of silicon in tissue was developed to determine silicon content in breast parenchymal and periprosthetic capsular tissues of patients with silicone or saline implants and to compare levels in tissues from normal (nonaugmented) breasts. It is of interest to determine whether increased silicon content in tissues can be associated with morbidity in patients who have received silicone implants. This manuscript addresses the issues involved in analysis of breast tissue samples for silicon and compares silicon levels with tissue histologic findings and patient morbidity. One hundred sixty tissue samples were obtained for silicon analysis from 72 patients during augmentation, capsulectomy with or without replacement mammoplasty, mastectomy, or biopsy procedures and were frozen in acid-washed polystyrene tubes at 220 degrees C until analysis. Samples were thawed, sectioned to approximately 0.1 g (dry weight), and digested in nitric acid before analysis by inductively coupled plasma emission spectroscopy, monitoring emission intensity at 251.6 nm. Tissue silicon levels (breast parenchymal and periprosthetic capsular tissue) in patients with silicone gel implants were much higher (mean, 9,287 micrograms/g, n = 106) than in patients with saline implants (mean, 196 micrograms/g, n = 37) or nonaugmented breasts (mean, 64 micrograms/g, n = 17). Histologic examination was performed on 54 tissue samples stained with hematoxylin-eosin. Tissue samples were rated as to degree of inflammation and calcification, and amount of giant cells, foamy histiocytes, and vacuoles containing a colorless refractory material. Vacuolization and foamy histiocyte ratings correlated significantly with tissue silicon concentration. No correlations were found between tissue silicon concentration and inflammation, calcification, or giant cell rating. Implant age (number of years an implant was in place before sampling) correlated with capsular tissue silicon concentration in patients with intact implants but not in those with ruptured implants. No difference in tissue silicon concentration was found between patients with or without signs or symptoms of morbidity. Using 0.1 g of tissue, the method was linear to 1,000 micrograms/g, and sensitivity was 3.7 micrograms/g. Precision between runs (mean, 5.1 micrograms/g; coefficient of variance, 13.7%; n = 13) was calculated from multiple analyses of a bovine liver standard (National Bureau of Standards, reference material 1577a). Significant biologic variability (21.4% to 52.5%) was seen in tissues with high silicon levels. Paraffin-embedded, formalin-fixed tissues are not amenable to silicon analysis by this method, because of leaching of silicone from the tissues during preparation. Thus only fresh frozen tissue samples were used.

Age Factors↗
PubMed1989

Photochemical oxidant pollution and vegetation: effects of mixtures of gases, fog and particles.

Photochemical 'smog' contains mixtures of gases (e.g. ozone, nitrogen dioxide), and dry particles (e.g. nitrates). Intermittent fog in the same geographical area can be acidic with high concentrations of nitric acid. Results from recent field studies in the Los Angeles Basin have emphasized the relative toxicity of these components of photochemical air pollution. Studies have focused on gaseous+fog or gaseous+dry particulate effects on conifers, gaseous+fog effects on crops, and the effects of trace pollutants produced during generation of ozone on crops. Data from these studies indicate that direct alterations in growth and physiological responses were observed only with gaseous pollutants (primarily ozone), or repeated applications of highly acidic fogs (pH < 2.7). Direct particle dry deposition effects are unclear. Few interactions have been found between gaseous pollutants and acidic fog. Charcoal-filtered open-top chambers are highly effective in removing pollutants in the following order: fog (100%) > peroxyacetyl nitrate > ozone > nitrogen dioxide > sulfur dioxide > nitrate ion > ammonium ion > sulfate ion. However, nitric oxide concentrations are higher in charcoal-filtered chambers than in ambient air. The studies point out the importance of considering other components of photochemical pollution in addition to ozone, especially when investigating subtle, long-term effects on vegetation.

Journal Article↗
PubMed1988

Rapid sample preparation for determination of iron in tissue by closed-vessel digestion and microwave energy.

We developed a rapid acid-digestion method for preparing tissue samples for iron determination. Specimens were digested in nitric acid and hydrogen peroxide under high temperature and pressure in closed Teflon vessels, with microwave energy. Analysis for iron in 25- to 250-mg portions of digested bovine liver powder (National Bureau of Standards Certified Reference Material no. 1577a) showed excellent linearity ([predicted] = 1.007[actual] - 0.166 micrograms per sample) and analytical recovery (98%). Precision (CV) was 5.4% when iron content was 10 micrograms per sample. Assaying split samples of mouse tissues, we found a close correlation between iron concentrations obtained with closed vs open vessels ([closed] = 0.878[open] + 68 micrograms/g, r = 0.994, range 400-4600 micrograms/g dry weight). In contrast to time-consuming conventional procedures for tissue dissolution, closed-vessel digestion with microwave energy dramatically shortens time for tissue preparation, minimizes use of caustic acid, reduces risk of sample loss or contamination, and yields accurate and reproducible results.

Animals↗