Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HYDROCHLORIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources
PubMed2002

Lattice Boltzmann simulation of chemical dissolution in porous media.

In this paper, we develop a lattice Boltzmann model for simulating the transport and reaction of fluids in porous media. To simulate such a system, we account for the interaction of forced convection, molecular diffusion, and surface reaction. The problem is complicated by the evolution of the porous media geometry due to chemical reactions, which may significantly and continuously modify the hydrologic properties of the media. The particular application that motivates the present study is acid stimulation, a common technique used to increase production from petroleum reservoirs. This technique involves the injection of acid (e.g., hydrochloric acid, HCl, acetic acid, HAc) into the formation to dissolve minerals comprising the rock. As acid is injected, highly conductive channels or "wormholes" may be formed. The dissolution of carbonate rocks in 0.5M HCl and 0.5M HAc is simulated with the lattice Boltzmann model developed in this study. The dependence of dissolution process and the geometry of the final wormhole pattern on the acid type and the injection rate is studied. The results agree qualitatively with the experimental and theoretical analyses of others and substantiate the previous finding that there exists an optimal injection rate at which the wormhole is formed as well as the number of pore volumes of the injected fluid to break through is minimized. This study also confirms the experimentally observed phenomenon that the optimal injection rate decreases and the corresponding minimized number of pore volumes to break through increases as the acid is changed from HCl to HAc. Simulations suggest that the proposed lattice Boltzmann model may serve as an alternative reliable quantitative approach to study chemical dissolution in porous media.

Journal Article↗
PubMed2006

Phase modifiers promote efficient production of hydroxymethylfurfural from fructose.

Furan derivatives obtained from renewable biomass resources have the potential to serve as substitutes for the petroleum-based building blocks that are currently used in the production of plastics and fine chemicals. We developed a process for the selective dehydration of fructose to 5-hydroxymethylfurfural (HMF) that operates at high fructose concentrations (10 to 50 weight %), achieves high yields (80% HMF selectivity at 90% fructose conversion), and delivers HMF in a separation-friendly solvent. In a two-phase reactor system, fructose is dehydrated in the aqueous phase with the use of an acid catalyst (hydrochloric acid or an acidic ion-exchange resin) with dimethylsulfoxide and/or poly(1-vinyl-2-pyrrolidinone) added to suppress undesired side reactions. The HMF product is continuously extracted into an organic phase (methylisobutylketone) modified with 2-butanol to enhance partitioning from the reactive aqueous solution.

Journal Article↗
PubMedDate not supplied

Method to detect minimal amounts of calcium dissolved in acidic solutions.

The study describes the application of the Arsenazo III method for detection of minimal amounts of calcium 12.4-49.4 micromol/l in different acidic solutions (hydrochloric acid, oxalic acid, maleic acid, phosphoric acid, tartaric acid, citric acid, lactic acid and acetic acid) adjusted to pH 2.0, 2.3 and 3.0. A mixture of the respective calcium concentrations with distilled water served as control. The experiments were run with ten repeats in series. Assessment of intra- and interassay coefficient of variation, and lower limit of quantification revealed that depending on the acid used, the Arsenazo III method is a reliable tool to quantify minimal calcium contents in acidic solutions.

Arsenazo III↗
PubMed1977

Flameless atomic absorption (FAA) and gas-liquid chromatographic studies in arsenic bioanalysis.

Procedures for assessment of arsenic in soft tissue by use of flameless atomic absorption (FAA) and gas-liquid chromatography (GLC), have been evolved, with special emphasis on the analytical distinction among inorganic, monomethyl-, and dimethylarsenic in several oxidation states. The chemical bases for such speciation reside in several properties of the arsenicals under consideration: (1) pentavalent inorganic arsenic, methylarsonic, and cacodylic acid are not extracted from tissue matter made strongly acid with hydrochloric acid, while the corresponding trivalent forms (as halides) are extracted; (2) chloroform extracts of samples treated under reducing conditions (HCl-KI) retain organoarsenicals when these extracts are re-extracted with water, but do not when aqueous solutions of oxidants are employed; (3) reduced cacodylate (dimethylarsinous acid) is not detected in the graphite furnace of an FAA unit under conditions selected, while cacodylate can be so detected. For GLC studies, monomethyl- and dimethylarsenic are simultaneously measured as the diethyldithiocarbamate complexes with an instrument equipped for electron-capture detection and containing a glass column packed with silanized 5% OV-17 on Anakrom A.S.

Animals↗
PubMed2004

[A comparative study of cadmium, lead, mercury, arsenic, selenium, manganese, copper and zinc in brown rice and fish by inductively coupled plasma-mass spectrometry (ICP-MS) and atomic absorption spectrometry].

A study was conducted to evaluate the applicability of ICP-MS techniques for determination of metals in brown rice and fish. Cadmium, lead, mercury, arsenic, selenium, manganese, copper and zinc were determined by this method. An open digestion with nitric acid (Method A) and a rapid open digestion with nitric acid and hydrochloric acid (Method B) were used to solubilize analytes in samples, and these procedures were followed by ICP-MS analysis. Recovery of certified elements from standard reference materials by Method A and Method B ranged from 92 to 110% except for mercury (70 to 100%). Analytical results of brown rice and fish samples obtained by this ICP-MS agreed with those obtained by atomic absorption spectrometry (AAS). The results of this study demonstrate that quadrupole ICP-MS provides precise and accurate measurements of the elements tested in brown rice and fish samples.

Animals↗
PubMed1998

Salt balance and rennet clotting properties of cow's, ewe's, and goat's milks preserved with carbon dioxide.

Cow's, ewe's, and goat's milk samples were treated with carbon dioxide gas until a pH of 6.1 was reached and stored at 4 degrees C to determine the resulting modifications in the mineral balance. The amounts of calcium and phosphorus dissolved during the acidification were similar in the three species. The acidification with CO2 produced the dissolution of phosphorus and magnesium in concentrations similar to those attained by acidification with lactic acid or hydrochloric acid. Still, the contents of soluble calcium and ionic calcium were higher with the CO2 treatment. The increase of ionic calcium due to the addition of CO2 could explain why milk subjected to such treatment is better suited for coagulation. Removal of added CO2 by shaking the milk for several hours at atmospheric pressure resulted in a higher concentration of ionic-calcium than was found in control milks to which no CO2 had been added. Thus the addition of CO2 improved milk's technological suitability for cheesemaking.

Animals↗
PubMed1999

pH-dependent stationary-phase acid resistance response of enterohemorrhagic Escherichia coli in the presence of various acidulants.

The effect of acidulant identity on the pH-dependent stationary-phase acid resistance response of enterohemorrhagic Escherichia coli was studied. Nine strains of E. coli (seven O157:H7, one O111:H-, and one biotype 1 reference strain) were cultured individually for 18 h at 37 degrees C in tryptic soy broth (TSB) plus 1% dextrose and in TSB without dextrose to yield acid resistance induced and noninduced stationary-phase cells, respectively. These cultures were then inoculated into brain heart infusion broth (BHI) supplemented with 0.5% citric, malic, lactic, or acetic acid and adjusted to pH 3.0 with HCl. The BHI tubes were incubated at 37 degrees C for up to 7 h and samples were removed after 0, 2, 5, and 7 h and plated for counting CFU on BHI agar and MacConkey agar (MA). The results were compared to data previously obtained with HCl only. Acid resistance varied substantially among the isolates, being dependent on the strain, the acidulant, and the induction of pH-dependent acid resistance. Hydrochloric acid was consistently the least damaging to cells; lactic acid was the most detrimental. The relative activity of the other acids was strain dependent. Inducing pH-dependent acid resistance increased the already substantial acid tolerance of stationary-phase E. coli. The extent of injury also varied with acid and strain, with as much as a 5-log-cycle differential between BHI agar and MA CFU counts. The accurate determination of the survival of enterohemorrhagic E. coli in acidic foods must take into account the biological variability of the microorganism with respect to its acid resistance and its ability to enhance survival through the induction of physiological stress responses.

Acids, Acyclic↗
PubMed2005

Thin layer chromatographic study of bauxite and quantitative estimation of co-existing Al3+, Fe2+ and Ti4+.

Thin layer chromatography in combination with spectrophotometry and titrimetry has been used to evaluate chromatographic characteristics of bauxite constituents. The retention behaviors of four major constituents (Al3+, Fe2+, Ti4+, Si4+) in bauxite mineral have been examined on plain and modified layers of silica gel G, silica gel H and cellulose with mobile phases containing aqueous sodium chloride, formic acid and hydrochloric acid. Ternary separation of Al-Fe-Ti was achieved on chromatographic plates made of silica gel H. The pH effect and presence of impurity elements in samples, nature of stationary phases on the ternary separation and detection limits of bauxite constituents were studied. Silicon in bauxite was detected on cellulose plates. Quantitative determinations of Al3+, Fe2+ and Ti4+ on silica gel H impregnated with sodium formate layers were achieved by titrimetry and spectrophotometry.

Aluminum↗
PubMed2006

[Soil carbohydrates: their determination methods and indication functions].

Soil carbohydrates are the important component of soil organic matter, and play an important role in soil aggregation formation. Their hydrolysis methods involve sulfur acid (H2SO4), hydrochloric acid (HCl), and trifluoroacetic acid (TFA) hydrolysis, and their determination methods include colorimetry, gas-liquid chromatography (GLC) , high performance liquid chromatography (HPLC), and high performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD). This paper summarized the methods of carbohydrates' hydrolysis, purification and detection, with focus on the derived methods of GLC, and briefly introduced the indication functions of carbohydrates in soil organic matter turnover.

Carbohydrates↗
PubMed1978

[Reaction kinetic studies on the formation of n-nitrosoephedrine in vitro and in vivo (author's transl)].

N-Nitrosoephedrine was synthesized at a high yield (greater than 90%). The influence of pH on the reaction process (ephedrine sulfate + nitrous acid in hydrochloric acid) was investigated and the pH-optimum determined. Furthermore the influence of coffee, ascorbic acid, citric acid, cyclamate/saccharin (10:1), smoke condensate of cigarettes, glucose and ethanol on the reaction process was also determined. The tests with animals (rats) showed that N-nitrosoephedrine could be detected in serum after the oral application of ephedrine sulfate and sodium nitrite.

Animals↗
PubMed1982

Cytoprotection by PGE2, atropine, pirenzepine and vagotomy in rats.

Gastric cytoprotective effects of vagotomy, PGE2 and antimuscarinic compounds (pirenzepine, atropine) were studied in the rat. Both pharmacological and surgical treatment prevented the gastric damage induced by intragastric administration of acetylsalicylic acid plus hydrochloric acid. The mechanisms of action are discussed.

Animals↗
PubMed1981

Aspirin and bile acid induced gastric mucosal damage: protection by prostaglandins and antacids.

The importance of bile acids in causing gastric mucosal haemorrhage and the protective effect of prostaglandins and antacids has been studied in a series of studies using an animal model. Bile acids alone did not damage the gastric mucosa, but conjugated bile acids together with aspirin and hydrochloric acid may cause gastric mucosal haemorrhage. The prostaglandin analogue 15(R)15-methyl-E2 methyl ester protected the gastric mucosa against damage caused by conjugated bile acids together with aspirin or hydrochloric acid. Gastric mucosal protection was also achieved with antacids, but this effect appeared to be mainly on the aspirin rather than on the bile acid component of the damage. Bile acid binding, if it did occur, did not prevent the bile acid from increasing aspirin-induced gastric mucosal damage.

Animals↗
PubMedDate not supplied

[Effect of pyrolysis products of polypropylene plastic on the defence mechanisms of the respiratory system (author's transl)].

Since the use of plastic materials, a change in the pathology of fire victims has been observed. We studied the effects of a single short-term inhalation (30 min) of a sub-lethal dose of polypropylene pyrolysis products (one LD-0). Including control and test animals, 66 rats and 112 mice were used. The exposure provoked disturbances in the antixenic defense mechanisms of the respiratory system, chiefly in tracheo-bronchial defenses, since we observed a lowering of ciliary activity of 35 to 78% in test animals exposed a few hours before, compared with the controls. These changes provoked a significant increase in death-rate of test animals, following experimental airborne infection by Klebsiella pneumoniae. The combustion products of polypropylene plastic materials did not contain hydrocyanic acid nor hydrochloric acid, and neither the temperature of the inhaled air, nor the concentration of carbon monoxide could explain these effects. On the contrary, we can suspect the well known irritative properties of aldehyde compounds formed during smoldering combustion of polypropylene.

Air Microbiology↗
PubMed1993

[Synthesis of 11-aryl-7,8,9,10-tetrahydro-1,2,3-triazino-(4',5':4,5)-thienol- -(2,3-b)-quinolines with antianaphylactic action].

Title compounds of structure B with an oxo function in position 4 of the triazine ring were synthesized by reaction of the aminocarboxamides A with sodium nitrite in acetic acid. Aminocarbonitriles of structure H yielded with sodium nitrite in acetic acid and hydrochloric acid the 4-chloro derivatives I. These compounds gave with N-nucleophiles, methoxide or thiourea the substances J. Tetracyclic compounds with a hydroxyethyl or a piperidinoethyl residue in position 3 in the triazine ring (E, G) were also prepared. Some of the investigated compounds showed an antianaphylactic activity.

Anaphylaxis↗
PubMed1996

[Collagen membranes of increased absorption as carriers of antiseptics].

Collagen membranes of increased absorption were prepared by incubation in the acidic solutions and lyophilization. The organic acids and hydrochloric acid solutions were used for this purpose. The membranes incubated in 2% citric acid possessed of highest absorption. Microdressings containing povidone-iodine or chlorhexidine glycerin solution were prepared using the collagen membranes of increased absorption. The microdressings were packed into envelopes made of laminated aluminium foil; they were stabile for eight weeks concerning their antibacterial activity. After implantation beneath mouse skin the dressings did not cause inflammation. Such dressings may be useful in a treatment of ulcers, superficial burns and chronic granulated wounds.

Absorption↗
PubMedDate not supplied

Determination of fat in olestra-containing savory snack products by capillary gas chromatography.

A quantitative method to determine fat in olestra-containing savory snack products was validated within the AOAC Peer-Verified Methods Program. The method may be used to demonstrate compliance with the guidelines of the U.S. Nutrition Labeling and Education Act for labeling products as "fat free" or "low fat." The method can measure total and saturated fat in savory snacks when present at levels of 0.2-10 g total fat and 0.1-3 g saturated fat per 30 g serving. The method is standardized to measure C6-C24 fatty acids. Extraction of olestra-containing savory snack samples with chloroform-methanol (modified AOAC Official Method 983.23) yields a lipid extract containing the total fat and olestra. The extracted lipid is hydrolyzed by lipase, yielding fatty acids and unreacted olestra. The fatty acids are precipitated as calcium soaps. Olestra is extracted from insoluble soaps with hexane and then discarded. The isolated soaps are converted back into fatty acids with hydrochloric acid and extracted with hexane. The isolated fatty acids are converted to methyl esters with boron trifluoride-methanol and quantitated by capillary gas chromatography using internal standard. Test samples were prepared by blending olestra-containing and full-fat (triglyceride) snacks to obtain 6 levels of spiking (0-10 g total fat added/30 g serving) in potato chips, potato crisps, cheese puffs, and nacho cheese-flavored corn chips. Results were linear (r2 > 0.997) between 0 and 10 g fat/30 g serving for each product matrix. Mean recovery was 101 +/- 6% standard deviation (SD) for total fat and 104 +/- 6% SD for saturated fat. Mean recovery by peer laboratory was 88 +/- 5% SD for total fat and 95 +/- 4% SD for saturated fat in potato chips (0-3 g total fat added/30 g serving). Two sets of 10 replicates of potato chips (0.5 g total fat/30 g serving and 0.16 g saturated fat/30 g serving) and potato crisps (0.5 g total fat/30 g serving and 0.16 g saturated fat/30 g serving) were analyzed by submitting and peer laboratories. Repeatability relative standard deviations ranged from 3.90 to 7.33% for total fat and from 4.01 to 11.53% for saturated fat. Reproducibility relative standard deviations were 7.33% (total fat, potato chips), 7.15% (total fat, potato crisps), 11.36% (saturated fat, potato chips), and 13.50% (saturated fat, potato crisps).

Dietary Fats↗
PubMed1964

ANION REQUIREMENTS FOR GASTRIC ACID SECRETION.

The rate of hydrochloric acid production by isolated, bullfrog gastric mucosae depends critically on the supply of chloride ion to the serosal surface. Secretion of acid is negligible if chloride is completely replaced by glucuronate and gluconate ion. The experimental evidence indicates that the rate of acid secretion may be regarded as a reaction velocity, depending on chloride concentration in a manner closely resembling Michaelis-Menten kinetics. Bromide and iodide ions substitute, in varying degree, for chloride as substrate. A familiar inhibitor of gastric acid production, thiocyanate ion, appears to act by competition with chloride in a reaction leading to the formation of acid. This reaction is included in a hypothetical reaction cycle, generalized from the redox model for gastric acid production. Under certain conditions, the model predicts a dependence of secretion rate on chloride supply of the Michaelis-Menten type, as was observed.

Animals↗