Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ELECTROLYTES”

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 307 records · Page 17Linked to original sources
PubMed1988

Radio-frequency vs. electrolytic VMH lesions: differential effects on plasma hormones.

Electrolytic lesions of the ventromedial hypothalamus (VMH) result in marked hyperphagia and obesity, but several studies have found the excess food intake and weight gain to be greatly reduced when lesions are produced by electrocauterization with radio-frequency current. Unlike electrolytic lesions, radio-frequency lesions leave few or no deposits of metallic ions that can potentially stimulate adjacent tissue. In the present experiment, weight gain and several endocrine responses previously associated with the VMH syndrome were compared in female rats given either electrolytic, radio-frequency, or sham VMH lesions. Both groups with VMH lesions became obese, but rats with radio-frequency lesions displayed only 63.2% of the weight gain of animals with irritative lesions (120.0 vs. 189.8 g in 20 days). Only rats with electrolytic lesions displayed elevated plasma insulin levels during an initial period of food restriction, but both groups with lesions were hyperinsulinemic when allowed to overeat. Plasma growth hormone levels were decreased by electrolytic lesions but unaffected by radio-frequency lesions. Morning corticosterone levels were elevated in both VMH groups, but only the rats with electrolytic lesions were found to have elevations in plasma adrenocorticotropin. It is concluded that some of the endocrine dysfunctions resulting from electrolytic VMH lesions are due to irritative stimulation rather than to tissue ablation.

Animals↗
PubMed1993

An in vitro evaluation of cocaine hydrochloride adsorption by activated charcoal and desorption upon addition of polyethylene glycol electrolyte lavage solution.

Cocaine body-packers and body-stuffers have become a common medical problem. Significant morbidity and mortality result when cocaine is absorbed from the gastrointestinal tract due to cocaine package compromise. The clinical prevention of gastrointestinal absorption of cocaine includes oral activated charcoal and/or whole bowel irrigation with polyethylene glycol--electrolyte lavage solution. This in vitro study investigates the maximal adsorptive capacity of activated charcoal for cocaine at varying activated charcoal:cocaine ratios, at pH 1.2 and pH 7.0, and the effect of polyethylene glycol--electrolyte lavage solution upon this binding. The percent adsorption of cocaine to activated charcoal was significantly better at pH 7.0 for all ratios of activated charcoal:cocaine tested and the maximal adsorptive capacity was 29% greater at pH 7.0 (273 micrograms/mg) than at pH 1.2 (212 micrograms/mg) (p < 0.05). Addition of polyethylene glycol--electrolyte lavage solution to the cocaine-activated charcoal slurry caused significant desorption of cocaine from activated charcoal at all pHs and ratios tested (except the 1:1 ratio at pH 7.0) and was most pronounced at pH 1.2. The addition of polyethylene glycol--electrolyte lavage solution to activated charcoal prior to adding cocaine solution further decreased the adsorption of cocaine to activated charcoal. This difference was significant at both pHs and all ratios tested except the 1:1 ratio at pH 1.2. The maximal adsorptive capacity of activated charcoal for cocaine at pH 1.2 was reduced 75% by pretreatment with polyethylene glycol--electrolyte lavage solution from 212 to 54.2 micrograms/mg, while at pH 7.0 the maximal adsorptive capacity was reduced by 11%, from 273 to 243 micrograms/mg. Polyethylene glycol--electrolyte lavage solution significantly reduces the adsorption of cocaine to activated charcoal particularly if the two are combined at a low pH prior to the addition of cocaine. The in vitro effects suggest that activated charcoal mixed in water should be administered first, followed by the polyethylene glycol--electrolyte lavage solution.

Adsorption↗
PubMed1975

Effects of strong electrolyte upon the activity of Clostridium perfringens sialidase toward sialyllactose and sialoglycolipids.

Clostridium perfringens sialidase was purified by affinity chromatography. Kinetic properties of the enzyme were examined with sialyllactose and with mixed sialoglycolipids (gangliosides) as substrates. With the latter substrate in 0.01 M Tris-acete in the absence of strong electrolyte, the pH optimum for enzymatic activity was 6.8. Addition of strong electrolyte (0.01 to 0.10 M Nac1) to the reaction medium caused an acidic shift and a broadening of the pH optimum, Enzymatic activity at pH 5.8 rose approximately 2.5-fold; a concomitant loss of activity at pH 6.8 was also observed. The alteration of enzymatic activity caused by strong electrolyte were dependent upon changes in Vmax. Km remained nearly invariant. Thus, a reversible transition of the enzyme from a relatively inactive to a highly active form occurred as a function of strong electrolyte concentration. Determination of the pK values of the active functional groups of C. perfringens sialidase revealed that the effects of strong electrolyte were exerted upon the pKa group of the enzyme. Strong electrolyte appeared to shield unfavorable electrostatic interactions between polyanionic sialoglycolipid micelles and the enzyme molecule, thus protecting the pKa group from inactivation. In comparision with the effects of strong electrolyte upon enzymatic activity toward the sialoglycolipid substrate, those observed with the monovalent substrate, sialyllacthose, were minor. Collectively, these findings indicate that ionic environment may effectively control the activity and relative substrate specificity of C. perfringens sialidase at a given pH. Furthermore, they explain the low pH optima and skewed pH profiles previously reported for enzymatic activity toward high molecular weight substrates.

Clostridium perfringens↗
PubMed1998

Daily hyperhydration effect on electrolyte deficiency of endurance-trained subjects during prolonged hypokinesia.

The aim of this study was to evaluate the effect of a daily intake of fluid and salt supplementation (FSS) on the deficiency of electrolytes, which is characterized by higher rather than lower plasma concentration of electrolytes during prolonged hypokinesia (HK) (decreased number of km taken per day). Forty long distance runners aged 22-25 yr with a peak VO2 65.4 mL min(-1) kg(-1) with an average 14.2 km d running distance were selected as subjects. They were equally divided into four groups: 1) unsupplemented control subjects (UCS); 2) unsupplemented hypokinetic subjects (UHS); 3) supplemented hypokinetic subjects (SHS), and 4) supplemented control subjects (SCS). During the investigation of 364 d, groups 2 and 3 maintained an average running distance of less than 4.7 km per day, groups 1 and 4 did not experience any modification in their normal training routines and diets. During the preexperimental period of 60 d and during the experimental period of 364 d urinary excretion of electrolytes and concentrations of sodium, potassium, calcium, and magnesium in plasma were determined. Whole blood hemoglobin, hematocrit index, plasma osmolality, and plasma protein concentration were measured. In the UHS plasma concentration of electrolytes and urinary excretion thereof, fluid elimination, hematocrit, whole blood hemoglobin, plasma osmolality, and plasma protein concentration increased significantly (p < 0.05) when compared with the UCS, SCS, and SHS groups. In the SHS plasma concentration of electrolytes and urinary excretion thereof, fluid excretion, whole blood hemoglobin, hematocrit, plasma osmolality, and plasma protein concentration decreased when compared with the UHS and increased insignificantly when compared with the UCS and SCS groups. It was concluded that FSS may be used to prevent or minimize electrolyte deficiency in endurance-trained volunteers during prolonged restriction of muscular activity.

Adult↗
PubMed1994

Effect of Golytely on serum electrolytes and hydration status of infants.

Golytely (GLP) is a commonly used oral preparation for infants and children undergoing intestinal surgery. Although the composition of GLP, a nonabsorbable electrolyte lavage solution, is designed to avoid electrolyte shifts and dehydration, systematic evaluation of the effects of this preparation on the hydration status and serum electrolytes of infants has not been performed. The authors evaluated 48 children (0 to 24 months of age) who received GLP. Serum electrolytes and blood urea nitrogen measurements were obtained before and after GLP administration. During GLP administration all the patients were allowed to drink clear fluids, including Rehydralyte in unrestricted quantities. Only two received intravenous fluids during the preparation. Statistical evaluation of the shifts in electrolytes were performed by the Students paired t test. Although the shift in serum electrolytes may be statistically significant, with a decrease in potassium and chloride and an increase in CO2, these changes were not clinically significant.

Child, Preschool↗
PubMed1991

The electrolytes in hyponatremia.

It is commonly taught that retention of free water is the dominant factor reducing the serum sodium concentration in hyponatremia. To determine whether the concentrations of other electrolytes are similarly diluted, we identified 51 patients with hyponatremia (Na = 121 +/- 1 mmol/L [mEq/L]) and compared electrolyte and laboratory values at the time of hyponatremia with values at a time when serum sodium was in the normal range (138 +/- 1 mmol/L). The medium interval between these measurements was 12 days. At the time of hyponatremia, serum sodium and chloride were substantially and significantly reduced by 12% to 15%. Although many hyponatremic patients had overtly increased or decreased concentrations of the other measured electrolytes, there were no significant changes in the mean concentration for any of these at the time of hyponatremia. Unchanged mean values were found for the plasma concentration of bicarbonate (26.1 +/- 0.6 normal v 25.2 +/- 0.8 mmol/L at the time of hyponatremia), potassium (4.31 +/- 0.10 v 4.33 +/- 0.15 mmol/L), albumin, phosphate, and creatinine. The stability of these laboratory values was observed both in patients with clinically normal extracellular fluid (ECF) volume and in those with true or effective ECF depletion. The urinary sodium (UNa) concentration was found to be a reliable predictor of the ECF volume status, whereas the fractional sodium excretion (FENa) was not. Electrolyte derangements are common in patients with hyponatremia, but are usually confined to patients on diuretics or who have an abnormal ECF volume. In the absence of these complicating situations, the plasma electrolytes are typically normal and are not reduced by dilution to the same extent as Na and CI. Based on a review of both the classic and recent knowledge concerning electrolyte regulation in hyponatremia, we propose that two factors explain these observations. First, the degree of dilution is overestimated because of Na losses in urine and perhaps Na shift into cells. Second, both renal and extrarenal adaptive mechanisms are activated by hyponatremia that stabilizes the concentration of other ions. One of these mechanisms is cell swelling, which triggers a volume-regulatory response leading to the release of ions and water into the ECF. Other adaptive mechanisms are mediated by antidiuretic hormone (ADH) per se, and by atrial natriuretic peptide (ANP).

Adaptation, Physiological↗
PubMed2003

Fluid and electrolyte therapy in ruminants.

Five important questions always must be asked and answered regarding fluid and electrolyte therapy in ruminants: (1) Is therapy needed? (2) What type of therapy? (3) What route of administration? (4) How much should be administered? and (5) How fast should the solution be administered? Food animal veterinarians routinely should carry the following commercially available crystalloid solutions and have the knowledge of how to use the products appropriately: Ringer's solution, 1.3% NaHCO3, acetated Ringer's solution, HS (7.2% NaCl), 8% NaHCO3, 23% calcium gluconate, calcium-magnesium solutions, and 50% dextrose. Ruminants with a blood pH less than 7.20 should be treated intravenously with 1.3% or 8.0% NaHCO3, and those animals with a blood pH greater than 7.45 should be treated intravenously with Ringer's solution. Oral electrolyte solutions or intravenous acetated Ringer's solution should be administered to ruminants with a blood pH greater than 7.20 but less than 7.45, and acetated Ringer's solution is preferred to lactated Ringer's solution. HS solution should be administered whenever rapid resuscitation is required. Oral administration of electrolyte solutions is underused in neonatal and adult ruminants. The optimal solution for oral administration to neonatal ruminants has a sodium concentration between 90 and 130 mmol/L; a potassium concentration between 10 and 20 mmol/L; a chloride concentration between 40 and 80 mmol/L; 40 to 80 mmol/L of metabolizable (nonbicarbonate) base, such as acetate or propionate; and glucose as an energy source. The optimal formulation for adult ruminants is unknown, but such a solution should contain sodium, potassium, calcium, magnesium, phosphate, and propionate to facilitate sodium absorption and to provide an additional source of energy to the animal. Acidemia is treated best by intravenous or oral administration of NaHCO3. Alkalemia is treated best by intravenous administration of Ringer's solution and oral administration of chloride-rich electrolytes such as KCl; the latter provides a physiologically more appropriate treatment than oral administration of vinegar or acetic acid solutions. Hypocalcemia is treated best by administering intravenous calcium borogluconate solutions or oral CaCl2 gels. Hypomagnesemia is treated best by intravenous or subcutaneous administration of combined calcium and magnesium solutions. Hypophosphatemia is treated best by oral administration of feed-grade monosodium phosphate. Hypokalemia is treated best by oral administration of feed-grade KCl; hyperkalemia is treated best by intravenous administration of 8.0% NaHCO3 or HS. The major challenges in treating fluid and electrolyte disorders in ruminants are making treatment protocols more practical and less expensive and formulating an optimal electrolyte solution for oral administration to adult ruminants.

Animals↗
PubMed1999

Electrolyte and glycerol supplementation improve water intake by horses performing a simulated 60 km endurance ride.

To replace electrolytes lost in sweat during endurance competitions, riders frequently supplement horses with hypertonic oral electrolyte pastes. To determine whether this practice and concurrent administration of the so-called hyperhydrating substance glycerol are of benefit, weight loss, voluntary water intake, plasma osmolality, and plasma protein and electrolyte concentrations were measured in 6 Arabian horses supplemented with a total of 2.4 ml/kg bwt of water (W); 0.2 g/kg bwt KCl and 0.4 g/kg bwt NaCl in 2.4 ml/kg bwt of water (E); or 0.2 g/kg bwt KCl and 0.4 g/kg bwt NaCl in 2.4 ml/kg bwt (3 g/kg bwt) of glycerol (GE) before and during a treadmill exercise test simulating a 60 km endurance ride. Weight loss was greater (P < 0.01) with W (3.2%) than with E and GE (1.0% and 0.9%, respectively) and was associated (r = -0.85, P < 0.0001) with less (P < 0.01) water intake with W (12.2 l) than with E or GE (23.5 l and 25.8 l, respectively). Plasma osmolality increased to a greater extent (P < 0.01) with GE than with E and was unchanged with W. In contrast, plasma protein concentration decreased (P < 0.01) in the later stages of the simulated ride with E and GE, reflecting plasma volume expansion, but remained unchanged with W. Plasma Na+ and Cl- concentrations increased (P < 0.01) with E and GE and were greater (P < 0.01) than values for W during the second half of the 60 km simulated ride. Despite administration are large amounts of potassium with E and GE, plasma K+ concentration was decreased (P < 0.01) at the end of the rest breaks during the simulated ride and after 60 min of recovery with all supplements. Adverse effects of administration of hypertonic oral electrolyte pastes were not observed and decreases in plasma protein concentration within 30 min after drinking with all supplements suggested that intestinal absorption was well maintained during the simulated endurance ride. In conclusion, electrolyte supplementation in the form of hypertonic oral pastes improved water intake during endurance exercise but concurrent glycerol administration provided no additional benefits in comparison to supplementation with electrolytes alone.

Animals↗
PubMed1988

[Changes in electrolyte and acid-base equilibrium in children with acute urinary tract infections].

Between 1980 and 1986 313 patients with urinary tract infection have been investigated in a retrospective study for changes in their electrolyte and acid base metabolism. A correlation with malformations of the urinary tract has been performed. In 34% of our patients obstruction of the urinary system was demonstrated. 40% of all patients with urinary tract infection showed electrolyte disturbances in serum varying from severe to moderate. No difference in electrolyte and acid base disturbances were found between patients with and without obstructive uropathy. A remarkably diverse pattern of electrolyte changes was seen: hyponatremia singly or in various combination was observed most frequently (81%) but even hypernatremia was found. In some patients only an acid base disturbance without changes in electrolytes was seen. The pattern of hyponatremia with hyperkalemia--reported in the literature with obstructive uropathy--was observed in 6.8% of our patient population with electrolyte disturbances. This was however not restricted to patients with malformation of the urinary tract.

Acid-Base Equilibrium↗
PubMed1994

Water and electrolyte studies during long-term missions onboard the space stations SALYUT and MIR.

This contribution summarizes the results of investigations of water-electrolyte metabolism and its hormonal regulation conducted in cosmonauts who performed long-term space flights (from 18 to 366 days) aboard the space stations Salyut and Mir and compares them with the results obtained during various NASA flights. The role of the kidneys in ion metabolism regulation was assessed by various water-salt load tests before and after flights. In addition, the results of a year-long space flight and of medical experiments performed during the 237- and 241-day missions by the physicians and cosmonaut-researchers Atkov and Polyakov are reviewed in detail. In spite of interindividual variations, metabolic, and endocrine studies during prolonged space flights showed a reduction in body mass, usually with a reduction in body water and electrolytes and considerable changes in blood hormone concentrations and urinary hormone excretion. These changes reflect the processes of extended adaptation to a new environment. It is likely that shifts in electrolyte metabolism in weightlessness are primarily due to metabolic changes that diminish the tissue ability for ion retention and to concomitant changes in the endocrine status. The postflight examinations revealed changes in fluid-electrolyte metabolism and in the function of the kidneys which indicated a hypohydration status and a stimulation of hormonal systems responsible for fluid-electrolyte homeostasis in order to readapt to the normal gravitation. Postflight decline in osmotic concentration of urine in cosmonauts was accompanied by an altered response to antidiuretic hormone and was probably caused by changes in the functional state of the kidneys. We conclude that detailed knowledge of the alterations in water-electrolyte metabolism and its hormonal regulation on different stages of space flight are important prerequisites for the development of countermeasures to space deconditioning and thus for increased human efficiency in space. In addition, these data contribute to an increase in our general knowledge on the regulation of kidney function.

Aerospace Medicine↗
PubMed1990

Dependence on exercise intensity of changes in electrolyte secretion from the skin sampled by a simple method.

Secreta from the palm and forearm was sampled for 1-min periods by a new technique, using a glass cylinder. Subjects exercised for 10-min periods at successive intensities of 40%, 50% and 65% VO2max with a leg ergometer operated in the supine position. Changes in the concentrations (values) of Na+, K+ and Cl- in their secreta during exercise were investigated. Significant positive correlations were found between the values of any two electrolytes in samples from the palm or the forearm, but the correlations between values for any one of the three electrolytes from the two sites were not significant. Values for concentrations of the electrolytes were significantly higher in samples from the palm than in those from the forearm at rest, 10 min after the beginning of exercise and at the end of exercise. No significant correlation was found between values for electrolytes in samples from the palm and the exercise intensity, but values for Na+ in samples from the forearm increased stepwise with increase in exercise intensity, and similar tendencies were observed for values of K+ and Cl-. The values for the three electrolytes in samples from the forearm, but not the palm, were significantly correlated with values for blood lactate, the percentage of VO2max and the heart rate. These results suggest that the present technique is suitable for successive samplings of secreta from the forearm, and that values for the electrolytes in samples are useful indices of exercise intensity.

Chlorides↗
PubMed1988

Fluid-electrolyte metabolism and renal function in men under hypokinesia and physical exercise.

It has been suggested that hypokinesia (diminished muscular activity)* induces significant changes in fluid-electrolyte metabolism and renal function in physically conditioned men. Thus, the aim of this study was to investigate fluid-electrolyte metabolism and ionoregulatory renal function during 16 days of hypokinesia (HK) and 15 days of readaptation period (RP) in 12 physically conditioned male volunteers aged 19-23 years. They were divided into two equal groups. Group 1 was subjected to HK and intensive physical exercise (PE) and group 2 was submitted to pure HK, that is, without the use of any preventive measures. For the simulation of the hypokinetic effect all of the men were kept under a rigorous bed rest regime. Sodium, potassium, calcium and magnesium, creatinine, urea and osmotic concentration were calculated in blood serum and urine samples. Renal excretion of fluid, osmotically active substances and electrolytes was insignificantly different in the two groups. The level and period of water and electrolyte retention were different with respect to the duration of HK. The basic physiological mechanisms of changes in fluid-electrolyte metabolism were consistent with a reduction of the glomerular filtration rate and a change in water and ion transport of renal tubules. It was concluded that HK induced marked changes in fluid-electrolyte metabolism and renal function in physically conditioned men regardless of their involvement in intensive physical exercise.

Adult↗
PubMed1994

Changes in myocardial metabolism and transcardiac electrolytes during simulated ventricular tachycardia: effects of beta-adrenergic blockade.

Myocardial ischemia, electrolyte changes, and fluctuations in autonomic tone may play an important role in the presentation of malignant ventricular arrhythmias. beta-Adrenoceptor blocking agents have been shown to decrease the incidence of ventricular fibrillation and sudden cardiac death in patients with coronary artery disease. Therefore we investigated the changes in myocardial metabolism and transcardiac electrolytes during simulated ventricular tachycardia before and after beta-adrenergic blockade. Six patients with normal coronary arteries (group 1) and 12 patients with documented coronary artery disease (group 2) were included in the study. The right ventricle was paced with electrode catheters to a constant cycle length of 400 msec for 3 minutes. Blood samples were withdrawn simultaneously from the coronary sinus and femoral artery to determine the transcardiac differences in metabolic variables and electrolytes before the pacing, at the end of the pacing, and 2 minutes thereafter. After pacing, the patients were given intravenous propranolol (0.15 mg/kg), and the protocol was repeated. Intraarterial blood pressure and electrocardiogram were monitored continuously. There was a rapid decline of the mean arterial blood pressures after initiation of the pacing in both study groups, whereafter the pressures began to rise. Propranolol somewhat blunted the blood pressure recovery, especially in group 2. Norepinephrine levels increased during the pacing in both patient groups, and the increase was accentuated by beta-adrenergic blockade. The femoroarterial coronary sinus difference in lactate turned negative, and pH, PCO2 and potassium differences increased in group 2 during pacing. However, the myocardial energy state remained relatively good as estimated from the nonsignificant change in the transcardiac differences of the plasma adenosine catabolites. There were no changes in the metabolic variables or transcardiac electrolytes in group 1 patients during pacing. Propranolol did not prevent the metabolic ischemia, but it did prevent the pacing-induced decrease in coronary sinus potassium and increase in transcardiac potassium difference. Propranolol also decreased arterial levels of free fatty acids and their extraction in group 2 patients during pacing. In conclusion, blood pressure decay during simulated ventricular tachycardia is followed by instantaneous sympathoadrenergic activation. In patients with coronary artery disease, this process is accompanied by metabolic ischemia and net transfer of extracellular potassium into the intracellular space. The metabolic and electrolyte changes may result in alterations of electrophysiologic millieau, thereby also modifying the clinical characteristics of ventricular tachycardia. Propranolol decreases arterial levels of free fatty acids and prevents changes in transcardiac electrolytes observed in coronary artery disease patients during simulated ventricular tachycardia. These effects of propranolol may be of clinical significance.

Adenine Nucleotides↗
PubMedDate not supplied

Chronic alcohol dependence and water-electrolyte status.

Altered water-electrolyte status resulting from chronic alcohol dependence has been reported, although the nature of any such derangement is controversial. To illuminate this problem, four groups of rats were exposed chronically to schedule-induced polydipsia conditions with a single fluid available: 5% ethanol, 0.9% NaCl solution of 5% ethanol, 0.9% NaCl solution, or distilled water. An ad lib control group was also used. The water-electrolyte status of these groups was evaluated in two ways. First, the diuretic response to hydrochlorothiazide doses (8-12 mg/kg) was measured after 3.5 months of chronic polydipsia. Second, after approximately two additional months of polydipsia, extracellular fluid volume, as well as plasma volume and electrolytes were measured. Both alcohol-intake groups drank approximately 11.5 g ethanol/kg/day over the course of the experiment. Urinary volume response to the diuretic agent did not reveal that chronic ethanol led to either water retention or dehydration, even when extra NaCl intake was imposed chronically (NaCl-EtoH group). Animals that were overdrinking either water or the 0.9% NaCl solution had extracellular fluid volumes that were greater than the NaCl-EtOH-polydipsic group, but they were not significantly larger than ad lib controls. There were no significant differences with respect to serum electrolyte concentration measures among the groups. In conclusion, animals that drank ethanol chronically in a pattern known to produce physical dependence revealed no altered water-electrolyte status when evaluated by acute responses to a diuretic agent, a chronically-imposed extra NaCl load, or body fluid compartment and electrolyte concentration measures.

Alcohol Drinking↗
PubMed2005

Assessment of supporting electrolyte contributions in electrochemically modulated liquid chromatography.

This paper reports the results of an investigation on the role of the supporting electrolyte in separations using electrochemically modulated liquid chromatography (EMLC) with a porous graphitic carbon stationary phase. With respect to the identity of the supporting electrolyte, the elution strength of the electrolyte anion increased as F- < OH- < BF4- < ClO4- < PF6- for injections of negatively charged aromatic molecules, whereas a 10-fold increase in electrolyte concentration induced a 60% change in retention for the same solutes. Furthermore, both the concentration and composition of the supporting electrolyte affected retention in a manner that varied with the charge of the analyte and applied potential. This behavior is explained using Gouy-Chapman diffuse double layer theory, coupled with comparisons of this theory with closely related models for ion-pair chromatography. Insights into the retention mechanism reveal that an ion-exchange mechanism controls the retention of negatively charged solutes at applied potentials removed from the potential of zero charge (PZC). At potentials close to the PZC, the electrostatic model is less effective with the predominant retention mechanism likely involving hydrophobic interactions with the carbonaceous stationary phase. The combined effects of these findings are demonstrated by using a temporal gradient in supporting electrolyte concentration to optimize an EMLC separation.

Chromatography, Liquid↗
PubMed2005

Treatment of olive mill effluents Part II. Complete removal of solids by direct flocculation with poly-electrolytes.

The pre-treatment of three different olive oil processing effluents by means of direct flocculation (i.e. without prior coagulation) was investigated. Four cationic and two anionic poly-electrolytes were tested and most of them were found capable of removing nearly completely total suspended solids (TSS) as well as reducing considerably the concentration of chemical (COD) and biochemical oxygen demand (BOD(5)) without altering solution pH. Flocculant dosage was crucial to achieve effective separation. For three cationic and one anionic poly-electrolytes, the minimum dosage required to initiate separation was about 2.5-3 g/L. The remaining two poly-electrolytes failed to cause separation even at dosages as high as 7 g/L. Lime and ferric chloride were also tested as reference coagulants and found quite effective in terms of TSS removal although the degree of COD reduction was generally lower than that with poly-electrolytes. However, lime treatment would require greater dosages and longer treatment times than that with poly-electrolytes and would also increase considerably solution pH. A preliminary cost analysis showed that lime treatment for complete solids removal was generally less costly than that with poly-electrolytes presumably due to its low market price. Nonetheless, cost-benefits may be defied by several drawbacks associated with the use of lime.

Costs and Cost Analysis↗
PubMed1969

Concentration dependence of permeability coefficient to an electrolyte component across bovine lens capsule in vitro.

Theoretical and experimental studies have been made on permeability coefficients to various kinds of electrolyte across lens capsules that are dissected from bovine eyes and that are found to be positively fixed charged membranes from our experiments of membrane potentials. The differential permeability coefficient, P(m), is defined as J(s) = P(m)(C(2) - C(1)), where J(s) is the flux of an electrolyte component in moles per sec across unit area of the lens capsule that separates two aqueous solutions of the same electrolyte at different concentrations, C(2) and C(1). Various types of strong electrolytes were studied; KCl, NaCl, Cacl(2), MgSO(4), MgCl(2) and LaCl(3). It was found that at C(2)/C(1) = constant, P(m) decreases to zero as C(2) decreases and P(m) increases to a limiting value, (P(m))(infinity), that is characteristic for the system of the salt used and the membrane as C(2) increases, despite of electrolytes. We assumed in theory that single ion activity coefficients of co-ion and gegen-ion are ideal, that the systems studied are in electric neutrality, that the fixed charge density of the membrane is independent of concentrations C(2), and that Donnan equilibrium holds between the bulk solution and membrane surface. Although the concentration-dependent changes of P(m) were quantitatively different depending on the type of electrolyte used, general agreement between theory and experiment was obtained over a wide range of concentrations except for the case of very dilute solutions.

Animals↗
PubMed2001

Optimization of background electrolytes for capillary electrophoresis I. Mathematical and computational model.

A mathematical and computational model is introduced for optimization of background electrolyte systems for capillary zone electrophoresis of anions. The model takes into account mono- or di- or trivalent ions and allows also for modeling of highly acidic or alkaline electrolytes, where a presence of hydrogen and hydroxide ions is significant. At maximum, the electrolyte can contain two co-anions and two counter-cations. The mathematical relations of the model are formulated to enable an easy algorithmization and programming in a computer language. The model assesses the composition of the background electrolyte in the analyte zone, which enables prediction of the parameters of the system that are experimentally available, like the transfer ratio, which is a measure of the sensitivity in the indirect photometric detection or the molar conductivity detection response, which expresses the sensitivity of the conductivity detection. Furthermore, the model also enables the evaluation of a tendency of the analyte to undergo electromigration dispersion and allows the optimization of the composition of the background electrolyte to reach a good sensitivity of detection while still having the dispersion properties in the acceptable range. Although the model presented is aimed towards the separation of anions, it can be straightforwardly rearranged to serve for simulation of electromigration of cationic analytes. The suitability of the model is checked by inspecting the behavior of a phosphate buffer for analysis of anions. It is shown that parameters of the phosphate buffer when used at neutral and alkaline pH values possess singularities that indicate a possible occurrence of system peaks. Moreover, if the mobility of any analyte of the sample is close to the mobilities of the system peaks, the indirect detector signals following the background electrolyte properties will be heavily amplified and distorted. When a specific detector sensitive on presence of the analyte were used, the signal would be almost lost due to the excessive dispersion of the peak.

Electrolytes↗