Absorption Of HCl Research Articles

Development of pectinate-ispagula mucilage mucoadhesive beads of metformin HCl by central composite design

Ionotropically-gelled mucoadhesive beads of metformin HCl composed of low methoxy (LM) pectin-ispaghula husk mucilage (IHM) polymer-blend was developed and optimized using central composite design (spherical type, single center point, and α=1.414). Effects of LM pectin and IHM amounts on drug encapsulation efficiency (DEE) and cumulative drug release at 10h (R10h) were analysed using response surface methodology. The optimized beads containing metformin HCl (F-O) showed DEE of 86.98±3.26% and R10h of 47.20±1.28%. All these beads exhibited suitable controlled in vitro sustained drug release pattern with super case-II transport mechanism over 10h. These beads were also characterized by SEM and FTIR. The optimized beads also exhibited pH-dependent swelling, good mucoadhesivity with goat intestinal mucosa and significant hypoglycemic effect in alloxan-induced diabetic rats over prolonged period after oral administration, which could possibly be lucrative in terms of prolonged systemic absorption of metformin HCl maintaining tight blood glucose level and advanced patient compliance.

Laboratory testing of a continuous emissions monitor for hydrochloric acid

Continuous monitoring of exhaust flue gas has become a common practice in power plants in response to Federal Mercury and Air Toxics Standards (MATS) standards. Under the current rules, hydrochloric acid (HCl) is not continuously measured at most plants; however, MATS standards have been proposed for HCl, and tunable diode laser (TDL) absorption spectroscopy is one method that can be used to measure HCl continuously. The focus of this work is on the evaluation and verification of the operation performance of an HCL TDL over a range of real-world operating environments. The testing was conducted at the University of California at Riverside (UCR) spectroscopy evaluation laboratory. Laboratory tests were conducted at three separate temperatures, 25ºC, 100ºC, and 200ºC, and two distinct moisture levels for the enhanced temperatures, 0%, (2 tests) and 4%, over a concentration range from 0 ppmv to 25 ppmv-m at each of the elevated temperatures. The results showed good instrument accuracy as a function of changing temperature and moisture. Data analysis showed that the average percentage difference between the ammonia concentration and the calibration source was 3.33% for varying moisture from 0% to 4% and 2.69% for varying temperature from 25 to 100/200ºC. An HCl absorption line of 1.742 μm was selected for by the manufacturer for this instrument. The Hi Tran database indicated that CO2 is probably the only major interferent, although the CO2 absorption is very weak at that wavelength. Interference tests for NO, CO, SO2, NH3, and CO2 for a range of concentrations typical of flue gasses in coal-fired power plants did not show any interference with TDL HCl measurements at 1.742 μm. For these interference tests, CO2 was tested at a concentration of 11.9% concentration in N2 for these tests. Average precision over the entire range for all 10 tests is 3.12%.Implications: The focus of this study was an evaluation of the operation performance of a tunable diode laser (TDL) for the measurement of hydrochloric acid (HCl) over a range of real-world operating environments. The results showed good instrument accuracy as a function of changing temperature from 25ºC to 200ºC and moisture from 0% to 4%. Such as an instrument could be used for continuous monitoring of exhaust flue gas in power plants once the Federal Mercury and Air Toxics Standards (MATS) standards have been fully implemented.

Analysis of a novel chlorine recycling process based on anhydrous HCl oxidation

A novel process for the recycling of chlorine based on the gaseous HCl oxidation on gas diffusion electrodes has been investigated. The cathodic and anodic reactions have been analyzed separately as half-cell reactions in a cyclone flow cell and optimized regarding catalyst as well as ionomer loadings. For the anodic hydrogen chloride oxidation, an optimal value of ca. 60 wt% Nafion has been found, whereas for the cathodic oxygen reduction a value below 37 wt% has been obtained. This discrepancy was mainly attributed to the different absorption and transport properties of HCl in Nafion compared to oxygen. The main potential losses in the reactor were identified at the cathode.

Absorption of HCl by calcium-based sorbents during filtration combustion in a continuous reactor

Experimental data on hydrogen chloride absorption by calcium-containing sorbents in solid fuel gasification in a continuous filtration combustion reactor are presented. The addition of the sorbents to the stock allows up to 80% of the chlorine to be sorbed. The chlorine remains as calcium chloride in the solid combustion residue. The incompleteness of HCl sorption is due to the hydrolysis of the resulting calcium chloride in the high-temperature zone of combustion.

The Effects of Mannitol on the Transport of Ciprofloxacin across Respiratory Epithelia

Inhalation of antibiotics and mucolytics is the most important combination of inhaled drugs for chronic obstructive lung diseases and has become a standard part of treatment. However, it is yet to be determined whether the administration of a mucolytic has an effect on the transport rate of antibiotics across the airway epithelial cells. Consequently, the aim of this study was to investigate the effects of inhalation dry powder, specifically mannitol, on ciprofloxacin transport using a Calu-3 air-interface cell model. Transport studies of ciprofloxacin HCl were performed using different configurations including single spray-dried ciprofloxacin alone, co-spray-dried ciprofloxacin with mannitol, and deposition of mannitol prior to ciprofloxacin deposition. To understand the mechanism of transport and interactions between the drugs, pH measurements of apical surface liquid (ASL) and further transport studies were performed with ciprofloxacin base, with and without the presence of ion channel/transport inhibitors such as disodium cromoglycate and furosemide. Mannitol was found to delay absorption of ciprofloxacin HCl through the increase in ASL volume and subsequent reduction in pH. Conversely, ciprofloxacin base had a higher transport rate after mannitol deposition. This study clearly demonstrates that the deposition of mannitol prior to ciprofloxacin on the air-interface Calu-3 cell model has an effect on its transport rate. This was also dependent on the salt form of the drug and the timing and sequence of formulations administered.

Pharmacoscintigraphy confirms consistent tamsulosin release from a novel triple-layered tablet

Conventional modified release preparations of tamsulosin HCl have been linked to increased incidence of cardiovascular adverse events, possibly due to rapid drug peaks soon after ingestion. A 'flattened' absorption profile has been shown to reduce the occurrence of these unwanted effects while improving symptom control. The potential of a novel triple-layered tablet to effect prolonged release and continuous absorption of tamsulosin HCl in the gastrointestinal tract was investigated in this clinical study. Gastrointestinal (GI) transit behaviour was monitored by scintigraphic imaging of technetium-labelled tablets. Drug absorption levels were simultaneously determined through pharmacokinetic analysis of blood samples. A mean Cmax of 6 ± 3 ng/nL was achieved after 324 ± 184 min (mean tmax). The mean AUC0-24 was noted as 4,359 ± 1,880 ng/mL min. The mean gastric emptying and colon arrival times of the tablets were 105.2 ± 68.9 and 270.1 ± 32.0 min post-dose; giving a mean small intestine transit time of 164.9 ± 83.6 min. Variations in gastrointestinal transit did not appear to influence drug absorption. Correlation of scintigraphic and PK data indicated that tamsulosin HCl is released steadily throughout the entire GI tract, suggesting that the mechanism of drug release is independent of GI site allowing drug release even in the low moisture environment of the colon.

Vibrationally resolved dynamics of the reaction of Cl atoms with 2,3-dimethylbut-2-ene in chlorinated solvents

Broadband transient infra-red absorption measurements are reported that contrast the dynamics of reaction of Cl atoms with 2,3-dimethylbut-2-ene and n-pentane in chlorinated solvents. In both cases, H-atom transfer produces HCl and a hydrocarbon radical, but the energy release in the former reaction is greater because of the formation of a resonance-stabilized allylic radical. The reaction of Cl atoms with n-pentane in solution in CH2Cl2 forms HCl exclusively in its lowest vibrational level (v = 0), and our measured rate coefficient agrees with a prior report by Sheps et al., J. Phys. Chem. A, 2006, 110, 3087. The time-dependence of the growth of intensity in the HCl fundamental absorption band shows two domains of reaction: a prompt rise is associated with reaction of the photolytically generated Cl atoms with n-pentane molecules lying within the first solvent shell, whereas a slower further rise is attributed to reaction following diffusion through the solution. For the reaction of Cl atoms with 2,3-dimethylbut-2-ene, these two domains of reaction are also observed, and fitting to a kinetic model incorporating these components gives bimolecular rate coefficients for formation of HCl of (1.7 ± 1.4) × 1010 M−1 s−1 in CDCl3 and (3.4 ± 1.2) × 1010 M−1 s−1 in CCl4. However, an additional transient absorption is observed ∼115 cm−1 lower in wavenumber than the fundamental HCl absorption band and is assigned to the v = 2 ← v = 1 hot band of HCl. The absorption by the nascent HCl(v = 1) peaks after ∼20 ps and subsequently decays to baseline levels because of vibrational relaxation, which is shown to be enhanced by energy transfer to 2,3-dimethylbut-2-ene. In solution in CDCl3, the fraction of HCl formed initially in v = 1 is determined to be 0.24 ± 0.04 and in CCl4 it is 0.15 ± 0.02. The branching to HCl(v = 1) for these reactions in solution is significantly lower than the 0.48 ± 0.06 fraction reported for reaction of Cl atoms with propene in the gas phase [Pilgrim and Taatjes, J. Phys. Chem. A, 1997, 101, 5776]. This comparison between similar bimolecular reactions in solution and in the gas phase therefore identifies changes to the dynamics caused by interaction with the solvent. Solvent friction experienced by the separating products of the reaction is considered more likely to be responsible for the lower vibrational excitation of the nascent HCl than is solvent modification of the topology of the potential energy surface in the vicinity of the transition state. Possible consequences of addition of Cl to the unsaturated bond in 2,3-dimethylbut-2-ene are also discussed.

Method of selective HCl and HF extraction from SDW pyrolysis gases

Results are provided for a study of the possibility of selective absorption of HCl and HF from a gas stream also containing H2S and CO2. In order to implement this hydrolysis gas cleaning method, it is proposed to maintain the absorbing solution pH in the range 4–5 by neutralizing excess HCl, for example, by means of adding Ca(OH)2.

Absorption Flue Gas Cleaning – “spheric O-element” New Prototype of first Stage and HCL Reduction

Current interest in environmental issues is closely linked to issues of waste treatment. Produced waste is mostly categorized as dangerous and other types of waste. Waste which is not suitable for material utilization may be processed in several other ways; it may be landfilled, thermally processed, etc. Though landfilling may seem like the best solution, it causes piling of produced waste, polluting of surroundings and underground water, spread of infection and so on. Processes of thermal decomposition are necessary not only for detoxication, but also for reduction of negative impacts on the environment. At the same time, waste serves as secondary source of energy. However, thermal processing has its drawbacks as well. These include release of emissions into the atmosphere, residual waste and water pollution. Waste incinerators are equipped with various types of technologies for flue gas cleaning which require various physical-chemical technological procedures and devices to efficiently clean flue gas. Dry, semi-dry and wet flue gas cleaning methods are used for capture of gaseous components of acidic nature (SO2, HCl). This paper focuses on wet cleaning. This paper presents results of research at two stage equipment for flue gas cleaning and describes new prototype of first stage wet cleaning of flue gas. This “spheric Oelement” prototype replaces old type Venturi scrubber equipment for intensive contact between gas and liquid. Paper will also give results from experimental measuring of efficiency of HCl absorption in various operating conditions.

Poloxamer/Cyclodextrin/Chitosan-Based Thermoreversible Gel for Intranasal Delivery of Fexofenadine Hydrochloride

To enhance permeation and solubility of an intranasal delivery system of fexofenadine hydrochloride (FXD HCl), a new formulation using poloxamer 407 (P407)/hydroxypropyl-β-cyclodextrin (HP-β-CD)-based thermoreversible gels with chitosan, was developed. Prepared gels were characterized by gelation temperature, viscosity, viscoelasticity, and drug release profile. The in vitro permeation study was performed in primary human nasal epithelial cell monolayers cultured by air-liquid interface method. The addition of chitosan caused the slight elevation of gelation temperature and viscosity-enhancing effect. Viscosity enhancement by the incorporation of chitosan caused the retardation of drug release from P407 gels in in vitro release test. The in vitro permeation profile showed that the increase in chitosan content (0.1% and 0.3%, w/v) significantly enhanced the permeation of FXD HCl. After intranasal administration of P407/HP-β-CD-based thermoreversible gels containing 0.1% and 0.3% of chitosan in rabbits at 0.5 mg/kg dose, plasma concentrations of FXD HCl were significantly higher than those of nasal solutions (p < 0.05). In particular, the bioavailability of the optimized thermoreversible gel containing 0.3% chitosan was about 18-fold higher than that of the solution type. These results suggested the feasibility that thermosensitive gels could be used as an effective dosage form to enhance the nasal absorption of FXD HCl.

Oral absorption and pharmacokinetics of Methadone HCl and intestinal multidrug resistance gene expression in horses

This study aimed to determine the pharmacokinetics (PK) and oral bioavailability of methadone in horses to evaluate a possible influence of transport proteins on drug absorption through a relative quantitation of multidrug resistance gene/P‐glycoprotein (MDR1/P‐gp) gene expression in horse tissues.Six healthy horses received methadone by intravenous, oral, or nasogastric tube (NG) routes. Methadone serum concentration was measure and PK analysis performed. Total RNA was extracted from tissues from 10 horses and TaqMan RT‐PCR was used to quantify the gene of interest using Relative Standard Curve Method and fold‐differences in nucleic acid across tissues. Significance was determined with a P‐value &lt; 0.05.Methadone was rapidly absorbed and eliminated with no side effects observed. Concentration was higher and occurred sooner after oral compared to the NG administration. Bioavailability was approximately 90% and 28% for oral and NG routes, respectively. Compared to the oral mucosa tissue, MDR1/P‐gp mRNA expression levels were significantly higher in the esophagus, stomach, small intestine, and liver.Methadone absorption from the small intestine appears limited possibly due to high expression levels of MDR1/P‐gp gene. High bioavailability after oral administration is supported by the low gene expression levels in tissues like oral mucosa and sublingual.Funding was provided by VCS and EHSP Grants, LSU.

Characterization of the HCl Absorption & Outgassing Mechanisms by FOUPs' Polymers

The HCl absorption and release by FOUP polymers was characterized through the determination of its solubility and diffusion coefficients in PC and PEEK in clean room conditions (21{degree sign}C and 40% humidity). For the first time, HCl diffusion coefficients were determined (D = 2.9 +/- 1.7 x 10-9 cm².s-1 in PC and D = 1.4 +/- 0.8 x 10-9 cm².s-1 in PEEK). These experimental data were then applied. First, the HCl concentration profiles in a FOUP's PC wall depending on the contamination time were calculated showing that HCl migrates until 0.5 mm thickness in less than 16h, but also that the full crossing is likely unreachable in an industrial context. Second, the efficiency of usual cleanings were evaluated depending on the temperature or time. For FOUP materials saturated in HCl, relatively low HCl rate (<35%) were determined even for high process temperature.

Study of HCl Absorption by CaO at High Temperature

The reaction of CaO with HCl was investigated in a fixed-bed reactor fabricated of quartz glass at high temperatures (600−800 °C). The inlet HCl concentration was 2000 ppm. Two sorbents with mean particle sizes of 163 and 465 μm were obtained by calcination of CaCO3. The reaction rate constant was achieved by a deactivation model. The results show that sorbent S1 with small particle size has the higher reactivity and is insensitive to the reaction temperature. In this study, two sorbents have the highest capacity for binding HCl at 650 °C. The breakthrough time of sorbent S1 with a small particle size is longer than that of S2 with a large particle size. A quantity of CaCl2 is evaporated at high temperatures, and it is one of main causes that the outlet HCl concentration does not increase sharply due to the formation of the CaCl2 product layer. Possible mechanisms are proposed to explain the decrease of the chemical reaction rate with increasing temperature.

Characterization of the HCl Absorption and Outgassing Mechanisms by FOUPs' Polymers

not Available.

Pharmacokinetics of Lofexidine Hydrochloride in Healthy Volunteers

The objective of this study was to characterize the clinical pharmacokinetic profile of lofexidine after oral delivery. A single dose, cross-over study and a multidose study using healthy volunteers were conducted for that purpose. In the single dose study the average time to maximum concentration was observed at approximately 3h for the single doses tested (1.2mg dose and 2.0mg). Area under the curve from time zero to infinity (AUC0−∞) demonstrated a degree of dose proportionality with a 1.72-fold increase as the dose increased by a factor of 1.67. Elimination rates and terminal half-lives were comparable between dose levels. The average elimination rates for the 1.2mg and the 2.0mg doses were 0.063 and 0.065h−1, respectively. In the multidose study, the average maximum concentration observed after the first dose of 0.4mg was 433 ng/L and ranged from 338 to 586 ng/L. This was slightly lower in proportion to the maximum concentration observed in the single dose study where Cmax was 1755 ng/L at the 1.2mg dose (normalized to 585 ng/L for 0.4mg dose) and for the 2.0mg dose (normalized to 559 ng/L for 0.4mg dose). The average time to maximum concentration (Tmax) was 3.33h which is comparable to values observed in the single dose study. The pharmacokinetic data indicate that lofexidine has a consistent profile. Steady state seems to be reached after 2 days on lofexidine, which is consistent with the lofexidine elimination half-life of approximately 11h. Evaluation of the Tmax, elimination rate, and terminal half-life are consistent across all dose levels studied, suggesting that changing the dose does not affect the absorption or elimination rates of lofexidine HCl. Thus, although preliminary due to the limited number of subjects, these findings are the first to document lofexidine clinical pharmacokinetic parameters in healthy volunteers using a highly sensitive liquid chromatography tandem mass spectrometric analysis. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:319–326, 2009

Mercury Oxidation over a Vanadia-based Selective Catalytic Reduction Catalyst

The process of the reaction among elemental mercury (Hg0) and reactive flue gas components across the selective catalytic reduction (SCR) catalyst was studied in a laboratory-scale reactor. Prepared vanadia-based SCR catalysts were characterized and analyzed to understand the potential reaction pathways. Mercury oxidation was observed when pro-exposure of the SCR catalyst to HCl, followed by passing through Hg0/N2 in the absence of gas-phase HCl. At testing conditions, Hg0 was found to desorb from the catalyst surface by adding HCl to the gas steam, which implies that HCl adsorption onto the SCR catalyst is strong relative to the mercury. Surface analysis verified the absorption of HCl onto the SCR catalysts, and the potential reaction pathways were proposed. Indeed, the monomeric vanadyl sites on the catalyst surface were found to be responsible for the adsorption of both Hg0 and HCl, which means they are active for mercury oxidation. Furthermore, the detailed Langmuir−Hinshelwood mechanism was proposed ...

Determination of Nitrophenols in Water Using Dynamic Liquid‐Liquid‐Liquid Microextraction under Non‐Equilibrium Consideration

AbstractTo pursue optimum condition in liquid‐liquid‐liquid microextraction (LLLME), extraction parameters dominating extraction efficiency were investigated by theoretical considerations. The theoretical considerations discussed equilibrium model for equilibrium LLLME and non‐equilibrium model for dynamic LLLME. A method described here is a dynamic LLLME technique combined with high‐performance liquid‐chromatography ultraviolet absorbance detection (HPLC/UV) to determine traces of nitrophenols in water. Analytical parameters such as organic phase, acceptor phase volume, sample agitation, extraction time, acceptor phase NaOH concentration, donor phase HCl concentration, salt addition, and absorption wavelength were identified as variable settings. Relative standard deviation (RSD, 1.8‐4.4%), coefficient of estimation (R2, 0.9994‐0.9999), and detection limit (0.032‐0.065 ng mL−1) were achieved under the variable settings. The proposed method was successfully applied to the analysis of a lake water sample, and the relative recoveries of nitrophenols from spiked water sample were up to 92.5%. The variable settings of LLLME close to optimization was responsible for an acceptable extraction efficiency.

SIMULATION OF AEROSOL FORMATION IN GAS-LIQUID CONTACT DEVICES

In gas-liquid contact devices like absorbers, quench coolers, or condensers, aerosols can be formed by spontaneous phase transitions, initiated by homogeneous or heterogeneous nucleation, if a supersaturated gas phase emerges due to simultaneous heat and mass transfer processes or chemical reactions. Typical examples are the absorption of acid gases, like HCl or SO3, the condensation of solvents in the presence of inert gases, and the humidification of cold gases by hot liquids. In this article the basic principles of aerosol formation in contact devices are briefly described. A strategy for modeling and simulation of aerosol formation and particle dynamics is discussed. Simulation results generated with the process tool AerCoDe for the countercurrent absorption of HCl and the humidification of air are presented.

Rapid-onset intranasal delivery of metoclopramide hydrochloride: Part II: Safety of various absorption enhancers and pharmacokinetic evaluation

In the present study, several nasal absorption enhancers, used in metoclopramide hydrochloride (MCP HCl) nasal solutions, have been screened for their possible damaging effect in the in vitro human erythrocytes lysis experiment. Moreover, the in vivo leaching of biological markers from the rat nasal epithelium was used as a quantitative assessment for possible nasal mucosal irritation whereby the extent of release of total protein and lactate dehydrogenase (LDH) in the nasal lavage fluid was determined. Results showed that insignificant hemolysis from normal saline ( P < 0.05) occurred with the enhancer protamine sulphate while poly- l-arginine and sodium cholate demonstrated very low (<15%) hemolysis and caused insignificant protein and LDH release from the rat nasal mucosa. Conversely, sodium deoxycholate and chitosan polymers (either of low or high molecular weight) showed high (>60%) hemolysis in vitro and the release of the biological markers in vivo was significantly higher ( P < 0.05) than the control solution (no enhancer). A significant correlation ( P < 0.05) existed between the enhancement effect of MCP HCl nasal absorption and the amounts of protein ( r = 0.85) and LDH ( r = 0.88). Furthermore, the pharmacokinetics of MCP HCl was determined after intravenous (IV), per-oral and intranasal administration of 10 mg drug dose in rabbits. The application of a nasal spray (NS) solution containing 0.5% sodium cholate resulted in a significant improvement ( P < 0.05) in both the rate and extent of absorption of MCP HCl where the T max achieved was 23.3 min as compared to 50 min in case of the oral solution while the area under the serum concentration–time curve (AUC 0–∞) were 506.1, 434.9 and 278.7 μg/ml min for IV, NS and oral solutions, respectively. These values corresponded to absolute bioavailabilities of 87.21 and 55.61% for the NS and oral solutions, respectively. It could thus be concluded that NS of MCP HCl represents a viable approach to achieving rapid and high systemic drug absorption during the emergency treatment of severe emesis.

Photoionization and photodissociation of HCl(BΣ+1,J=) near 236 and 239nm using three-dimensional ion imaging

The electronically excited states HCl(*)(E,upsilon(')=0,J(')=0) and HCl(*)(V,upsilon(')=12,J(')=0) have been prepared by two-photon resonant absorption of ground state HCl via Q(0) transitions at 238.719 and at 236.000 nm, respectively. The consequent one-or two-photon excitation at the same wavelength results in the production of H(+), Cl(+), and HCl(+) ions. The speed distributions and anisotropy parameters beta for these ions have been determined by three-dimensional photo-fragment ion imaging based on a position-sensitive delay-line anode assembly. Several results are presented: first, we measured velocity (speed and angle) distributions for HCl(+) due to the electron recoil in the photoionization of HCl(*). Such distributions give information on the photoionization process and on the vibrational distribution of HCl(+) after the laser pulse. Second, the measured beta parameters for Cl(+) and H(+) distributions give information on the symmetries of the upper states in the one-photon photoexcitation of HCl(*). Third, the measured speed distributions for H(+) help to understand the mechanism of the photodissociation of HCl(+) ions.