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PubMed2004

The effects of hydrofluoric acid addition on the hydrothermal synthesis of templated uranium sulfates.

The effect of employing hydrofluoric acid as a mineraliser in the formation of organically templated uranium sulfate materials has been studied. Variable amounts of HF((aq)) were added to a series of reaction gels in which all other reactant concentrations were invariant, resulting in the formation of three different phases, depending upon the fluoride concentration. Two of these phases are novel; [N(2)C(4)H(14)][UO(2)(H(2)O)(SO(4))(2)] is a new templated uranium sulfate, containing anionic [UO(2)(H(2)O)(SO(4))(2)](2-) chains that hydrogen bond to one-another forming pseudo-layers, and [N(2)C(4)H(14)][UO(2)F(SO(4))](2) is the first example of a templated uranium sulfate fluoride, which consists of uranium fluoride chains linked by sulfate groups to form [UO(2)F(SO(4))](-) layers. The role of F(-) in these reactions is two-fold; it acts as a mineraliser when present in small concentrations, while it is incorporated into the reaction product when present in larger mole fractions. Both of the new materials have been characterised using a range of physical techniques including single crystal X-ray structure analysis.

Journal Article↗
PubMedDate not supplied

Hydrofluoric acid burns of the lower extremity.

Chemical burns to the lower extremity can be disabling and of serious consequence if not managed properly. The severity and rapid onset of the burns caused by hydrofluoric acid after initial contact make this a highly dangerous substance. The potential severity of injury and the following complications make it a chemical of which all physicians should have a basic understanding.

Accidents, Occupational↗
PubMed1990

Elemental analysis of hair among hydrofluoric acid exposed workers.

The concentrations of fluorine (F), sodium (Na), magnesium (Mg), aluminum (Al), potassium (K), phosphorus (P), calcium (Ca), iron (Fe), nickel (Ni), zinc (Zn) and iodine (I) in the hair of 142 hydrofluoric acid (HF) exposed workers and 273 control subjects were analyzed by wavelength dispersive X-ray fluorescence spectrometry. Postshift urine and serum specimens were also collected for the determination of fluoride. To determine whether external contamination influences hair analysis, the control hair samples were kept in the work environment for one week. With the exception of lower K and Fe values, the levels of F and other elements in the hair of HF workers were higher than in the control subjects. The concentrations of F in hair and in postshift urine were in good correlation (r = 0.65). In the hair of HF workers F and Ca, F and Mg, F and P, F and Al were well correlated with each other (r greater than 0.6). F concentration in the hair increased after the sample was retained, however, it decreased to the reference value after washing. The levels of Ca, Mg and other elements did not change during the experiment.

Adult↗
PubMed1997

Chemical pneumonitis following household exposure to hydrofluoric acid.

A previously healthy 26-year-old woman developed hemorrhagic alveolitis and adult respiratory distress syndrome (ARDS) following use of a hydrofluoric acid-containing household cleaning agent. Exposure was inhalational in nature. The circumstances and possible mechanism of chemical pneumonitis from low-dose inhalational exposure to hydrofluoric acid are discussed.

Adult↗
PubMed2005

Characterization and adsorption properties of diatomaceous earth modified by hydrofluoric acid etching.

This work was a study of the chemical modification of diatomaceous earth (DE) using hydrofluoric acid (HF) solution. Under the experimental conditions investigated, it was found that HF under controlled conditions significantly etched inward into the interior of the existing pore structure in the clay mineral due to its high content of silica, leaving a framework possessing a larger BET surface area (ca. 10 m2 g(-1)) in comparison with that (ca. 4 m2 g(-1)) of its precursor (i.e., DE). Further, the results indicated that the HF concentration is a more determining factor in creating more open pores than other process parameters (temperature, holding time, and solid/liquid ratio). This observation was also in close agreement with the examinations by the silicon analysis, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The adsorption kinetics and the adsorption isotherm of methylene blue onto the resulting clay adsorbent can be well described by a pseudo-second-order reaction model and the Freundlich model, respectively.

Journal Article↗
PubMed1988

Surgery: a radical approach to severe hydrofluoric acid burns. A case report.

Generally, chemical burns of the skin, both acid and caustic, are best treated initially by irrigating with copious amounts of water. Subsequently the burn is managed as one would treat a thermal burn. An exception may exist when skin burn is caused by hydrofluoric acid (HF), especially in its anhydrous form. HF is a commonly used catalyst in the petrochemical industry. The following report concerns a life-threatening burn from anhydrous HF.

Accidents, Occupational↗
PubMed2001

Pediatric poisonings from household products: hydrofluoric acid and methacrylic acid.

Household products continue to be a cause of poisoning morbibidity and mortality. Young children frequently are exposed to cleaning products and cosmetics in the course of exploring their environment. Most of these exposures are insignificant, but some result in death or permanent disability. This review discusses two products that have been responsible for serious injury and death in children: hydrofluoric acid and methacrylic acid. It also discusses federal initiatives designed to protect children from these and other household hazards.

Child, Preschool↗
PubMed2005

Trace anion determination in concentrated hydrofluoric acid solutions by two-dimensional ion chromatography II. Method performance study with a hydroxide eluent and a low noise suppressor.

The two-dimensional ion exclusion chromatography/ion chromatography (ICE-IC) approach is considered to be the method of choice for the determination of trace anions in concentrated hydrofluoric acid (48-50%, w/w). In order to achieve lower detection limits, this method was for the first time used with electrolytically generated and purified hydroxide eluents in combination with a low noise electrochemical suppressor. Compared to carbonate based eluents, the achieved gain in peak height sensitivity for chloride, sulfate, nitrate and phosphate is a factor of 6, 7, 16 and 13, respectively. The instrumental detection limits, based on the background noise, are 2, 0.2, 0.4 and 1.4 microg/kg HF 50% (w/w) for the same anions. Their method detection limits, calculated according to SEMI, are all within the 6-10microg/kg HF 50% (w/w) range and thus at least 10 times lower than the current Tier C grade requirements. The chromatographic run time could be shortened with some 10 min by the use of a relatively fast high-capacity hydroxide selective anion exchange column.

Anions↗
PubMed2004

Bonding to enamel/dentin etched with phosphoric and hydrofluoric acids.

Repairing porcelain intraorally allows clinicians to provide their patients with a conservative means of treating fractured or debonded restorations. This requires, however, the etching of both porcelain and tooth structure with etching solutions. It is thus relevant to understand the effect that different etching procedures have on shear bond strengths of composite resins to both dentin and enamel structures. Based on the results of this investigation, the authors recommend isolation of tooth structures and the etching of porcelain with hydrofluoric acid.

Dental Bonding↗
PubMedDate not supplied

Hydrofluoric acid burn resulting from ignition of gas from a compressed air duster.

A young female suffered burns to her hand after the ignition of gas from a compressed air duster. After debridement and dressing, the patient continued to have pain out of proportion to injury that was refractory to intravenous morphine. The material safety data sheet revealed that the chemical used was 1,1-difluoroethane. High temperatures can cause decompensation to form hydrofluoric acid. Calcium gluconate gel was applied topically to the patient's burns, which caused prompt and complete relief of her pain. A review of different compressed air duster products revealed that the main ingredient in each was a halogenated hydrocarbon. Although not considered flammable, all products have warnings regarding the possibility of ignition under various circumstances. Ignition of the gas in compressed air cleaners not only can cause flame burns, it can also cause chemical damage from exposure to hydrogen and fluoride ions. Prompt recognition and treatment is necessary to prevent severe injury.

Adult↗
PubMed2000

An improved method for the immunological detection of mineral bound protein using hydrofluoric acid and direct capture.

Immunological detection of proteins adsorbed to mineral and ceramic surfaces has proved not only difficult but controversial. Unlike the immunological detection of proteins associated with carbonate or phosphate minerals (e.g. shells and bones) proteins adsorbed to siliceous minerals cannot readily be removed by dissolution of the mineral phase. We have previously examined alternative extraction methodologies which claim to bring the protein into solution, but found none of these to be effective. Here we report a novel strategy for immuno-detection of proteins adsorbed to siliceous minerals, the Digestion and Capture Immunoassay (DACIA). The method involves the use of cold, concentrated (4M) hydrofluoric acid (HF) with the simultaneous capture of liberated protein onto a solid phase. The combination of low temperatures and surface stabilisation enables us to detect epitopes from even partially degraded proteins. The method may have a wide application in forensic, archaeological, soil and earth sciences.

Adsorption↗
PubMed2001

Monitoring metal ion contamination onset in hydrofluoric acid using silicon-diamond and dual silicon sensing electrode assembly.

Potentiometric detection of trace levels of metallic contamination onset in hydrofluoric acid using a silicon-based sensor in conjunction with two non-contaminating reference electrode systems is presented in this paper. In the first case, conductive diamond was used as a non-contaminating reference electrode. Cyclic voltammetry and open-circuit potential experiments demonstrated the feasibility of using a conductive diamond film electrode as a quasi-reference electrode in the HF solution. In the second case, a dual silicon electrode system was used with one of the silicon-based electrodes protected with an anion permeable membrane behaving as the quasi-reference electrode. The dual silicon sensing electrode system possessed an additional operational advantage of being unaffected by the solution acidity. Though both sensing configurations were able to detect the metal ion contamination onsets at the parts-per-trillion to parts-per-billion levels, the dual silicon electrode design showed a greater compatibility for the on-line detection of metallic impurities in HF etching baths commonly used in semiconductor processing.

Journal Article↗
PubMed1992

A community-based epidemiologic study of health sequelae of exposure to hydrofluoric acid.

An accident at an oil refinery in Texas City, Texas, released around 40,000 lb of hydrogen fluoride, exposing the community to the highly toxic and corrosive substance. A population-based epidemiologic study was conducted to evaluate the impact of the accident on the health of the community. Exposure assessment was done using a multipronged approach through a door-to-door survey of 10,811 individuals. A symptom survey resulting in 1994 completed interviews was conducted with a stratified random sample selected from the exposure study database. The sampling was balanced with respect to age, gender, and predisposition across the three ordinal exposure categories. The results show a strong dose relationship (P < 10(-4)) between the exposure and symptoms reported following the accident and 2 years later, most notably breathing and eye symptoms. However, substantial improvement in health was reported over the 2-year period regardless of the level of exposure. Problems of recall bias and behavioral sensitization are considered and it is recognized that the study may have overestimated the effect. It is also recognized that the study may not have completely unraveled the relative importance of exposure and host response in health outcome, since the two were probably conflated in the exposure measure. Nevertheless, the independence of predisposition and reported level of exposure, the magnitude of effect and its consistency, the unmistakable dose response, the large sample size, and the mutual corroboration of various findings make it difficult to dismiss the interpretation that the hydrofluoric acid exposure indeed caused health problems in the community that continued for at least 2 years after the accident.

Accidents, Occupational↗
PubMed2006

The impact of hydrofluoric acid surface treatments on the performance of a porcelain laminate restorative material.

OBJECTIVES: Hydrofluoric (HF) acid etching increases the bond strength between composite resin and porcelain surfaces and has been advocated as a pre-cementation technique for ceramic restorations. The internal surface flaw distribution which is implicated in the premature failure of ceramic restorations is modified by the etching process and little agreement exists amongst researchers as to the appropriate etching regime. The purpose of the current study was to examine the impact of HF acid concentration and etching time on the performance of a low fusing feldspathic porcelain. METHODS: Sets of 30 Vitadur-Alpha dentin porcelain discs (15 mm diameter, 0.9 mm thickness) were etched with HF acid of three different concentrations (5, 10 and 20%) and for three different etching periods (45, 90 and 180s). Mean flexure strengths, standard deviations and the associated Weibull moduli (m) and characteristic stress (sigma(0)) were determined using bi-axial flexure (ball on ring). Contact profilometry was utilised to characterise the roughness of the etched porcelain surfaces. RESULTS: A univariate general linear analysis of means revealed a significant reduction in the mean strength values of the as-fired control compared with groups subjected to HF acid etching. Further significance (P<0.05) was discovered with the impact of acid concentration. Altering etching time also resulted in changes in the reliability of the fracture strength data. Contact profilometry demonstrated an increase in surface roughness following HF acid etching and an increase in roughness associated with increasing HF concentration. CONCLUSIONS: Etching of feldspathic porcelain is a dynamic process and the impact is dependent on substrate constitution, surface topography, acid concentration and etching time. A significant reduction of the flexural strength of a low fusing feldspathic porcelain has been demonstrated to result from etching and clear evidence exists that the nature of surface flaw modification is a function of etching time and HF acid concentration. Favourable combinations of HF acid concentration and etching time have been identified which enhance the reliability of the porcelain utilised although variability in clinical technique will result in the reduced reliability of porcelain laminate restorations in function.

Acid Etching, Dental↗
PubMed2004

Hydrofluoric acid releases in 17 states and the acute health effects associated, 1993-2001.

Hydrofluoric (HF) acid is 1 of the strongest and most corrosive acids known. Human exposure commonly occurs from occupational releases and can result in severe injuries and death. Data from the Agency for Toxic Substances and Disease Registry's Hazardous Substances Emergency Events Surveillance (HSEES) system were used to conduct a descriptive analysis on the acute health effects of HF acid exposure. Of the total HSEES events (n = 49,106), HF acid releases occurred in 0.3% of events (n = 134). HF acid events were 2 times more likely to involve injuries when compared with other acid events and 3 times more likely when compared with nonacid events. Employees such as those in trucking services, petroleum refining, and chemical manufacturing need to understand the dangers of HF acid and should have the appropriate personal protective equipment available to prevent exposure.

Adolescent↗
PubMed1974

The reaction of phosphoglycolipids and other lipids with hydrofluoric acid.

1. The use of HF as a dephosphorylating reagent for phospholipids was examined. 2. Hydrolysis of phosphatidylethanolamine at 0 degrees C for 24h with 60% HF gives a good yield of diglyceride. Under similar conditions phosphatidyldiglucosyl diglyceride gives diglyceride and diglucosyl diglyceride. 3. The glycolipid is also obtained from hydrolysis of glycerylphosphoryldiglucosyl diglyceride. No lyso derivative of the glycolipid could be detected and the glycosidic linkage was also stable. 4. Triglycerides, unsaturated and cyclopropane fatty acids were unaffected by the reagent. 5. 1,2-Diglycerides and 1,3-diglycerides were partially isomerized and also gave small amounts of free fatty acid and monoglyceride. 6. Monoglycerides underwent extensive rearrangement to form 1,2- and 1,3-diglycerides. 7. Lysophosphatidylethanolamine also gave 1,2- and 1,3-diglycerides as well as monoglycerides. 8. The application of this procedure to the structure determination of various phosphoglycolipids is discussed.

Acids↗
PubMed1977

Fabrication of well defined micropipette tips by hydrofluoric acid etching.

Glass tubes were drawn on a two stage pipette puller such that tips with 0.5-2.0 micron inner diameters were obtained as confirmed by scanning electron imaging. The pipettes were attached to an air reservoir with a pressure set at 0.5 bar to prevent fluid from entering the tip. They were lowered into 2% hydrofluoric acid by means of a micromanipulator. When air bubbles began to escape from the tips, they were withdrawn and immersed into 0.5 molar phosphate buffer, pH 7.4, and then rinsed with tap water and ethanol. Etching during 100 s (mean) yielded inner tip diameters of 5 micron (+/- 5% S.D.). The tips were beveled at the same angle at which they had been dipped into the etching fluid. No continuation of the etching process was noticed even after several days.

Glass↗