Sodium Polystyrene Sulphonate Research Articles

Interaction between methyl red and cetyltrimethylammonium bromide under the influence of sodium polystyrene sulphonate in ethanol-water binary solvent systems: A spectrophotometric investigation

This research aims to comprehensively investigate and analyze the UV–visible spectroscopic behavior of the methyl red (MR)-cetyltrimethylammonium bromide (CTAB) system under the influence of sodium polystyrene sulfonate (NaPSS) in aqueous and different volume fractions (v.f.) of ethanol (EtOH)–H2O (0.1, 0.2, and 0.3) at 298.15 ± 0.2 K. In EtOH–H2O solvent systems, the triple interactions of dyes-surfactants-polyelectrolyte (DSP) complex systems are entirely novel. MR interacts with CTAB in NaPSS in the binary solvent media (0.1, 0.2, and 0.3 v.f. of EtOH–H2O) resulting in the formation of ion-pairs at very low CTAB concentrations, far below their apparent critical micelle concentration (CMC*) reducing the absorbance, and the new complexes above the CMC* due to solubilization of the MR into CTAB micelles observed by distinct spectral shifts. The CMC* values obtained from spectroscopic data increase in the order: (CMC*)water< (CMC*)0.1< (CMC*)0.2< (CMC*)0.3. This is because of the reduced polarity or dielectric constant and increased degree of water structure disruption around the hydrophobic chains of CTAB, where micelle formation occurs at somewhat higher concentrations. The Gibbs energy of micellization (ΔGmo) increases in the order: (ΔGmo=−16.89)water <(ΔGmo=−16.17)0.1<(ΔGmo=−15.62)0.2<(ΔGmo=−15.38)0.3, which further supports the inhibitory effect of increasing ethanol content towards micellization. In the post-micellar region, the decrease in hydrophobic interactions and an increase in electrostatic interactions lead to a rise in the overall binding constant value. This means that, when NaPSS is present, the stronger electrostatic interactions in the post-micellar region contribute significantly to the increased binding of CTAB micelles with MR. The tautomeric activity of MR and the solvent composition played a prime role in affecting the interaction mechanism, as evidenced by the blue and red spectral shifts.

Hyperkalaemia in Cardiological Patients: New Solutions for an Old Problem.

Hyperkalaemia is one of the most common electrolyte disorders in patients with cardiovascular disease (CVD). The true burden of hyperkalaemia in the real-world setting can be difficult to assess, but in population-based cohort studies up to 4 in 10 patients developed hyperkalaemia. In addition to drugs interfering with potassium metabolism and food intake, several conditions can cause or worsen hyperkalaemia, such as advanced age, diabetes, and chronic kidney disease. Mortality, cardiovascular morbidity, and hospitalisation are higher in patients with hyperkalaemia. Hyperkalaemia represents a major contraindication or a withholding cause for disease-modifying therapies like renin-angiotensin-aldosterone inhibitors (RAASi), mainly mineralocorticoid receptor antagonists. Hyperkalaemia can be also classified as acute and chronic, according to the onset. Acute hyperkalaemia is often a life-threatening emergency requiring immediate treatment to avoid lethal arrhythmias. Therapy goal is cell membrane stabilisation by calcium administration, cellular intake, shift of extracellular potassium to the intracellular space (insulin, beta-adrenergic agents, sodium bicarbonate), and increased elimination with diuretics or dialysis. Chronic hyperkalaemia was often managed with dietary counselling to prevent potassium-rich food intake and tapering of potassium-increasing drugs, mostly RAASi. Sodium polystyrene sulphonate, a potassium binder, was the only therapeutic option. Recently, new drugs such as patiromer and sodium zirconium cyclosilicate give new opportunities for the treatment of hyperkalaemia, as they proved to be safe, well tolerated, and effective. Aim of this review is to describe the burden of hyperkalaemia in cardiovascular patients, its direct and indirect effects, and the therapeutic options now available in the acute and chronic setting.

Pharmacological strategies to manage hyperkalaemia: out with the old, in with the new? Not so fast….

Since the 1950s, sodium polystyrene sulphonate (SPS) has been the dominant cation exchange agent prescribed for hyperkalaemia. Clinicians have had plenty of time to learn of SPS's advantages and limitations. The demands of drug regulatory agencies regarding the incorporation of medications into the market were not so stringent then as they are today, and the efficacy and safety of SPS have been questioned. In recent years, two novel cation exchangers, patiromer and sodium zirconium cyclosilicate, have received (or are in the process of receiving) regulatory approval in multiple jurisdictions globally, after scrutiny of carefully conducted trials regarding their short-term and mid-term efficacy. In this debate, we defend the view that all three agents are likely to have similar efficacy. Harms are much better understood for SPS than for newer agents, but currently there are no data to suggest that novel agents are safer than SPS. Drug choices need to consider costs, access and numbers-needed-to-treat to prevent clinically important events; for potassium exchangers, we need trials directly examining clinically important events.

Prevalence and factors associated with hyperkalaemia in stable kidney transplant recipients.

ABSTRACTBackgroundHyperkalaemia is a frequent and potentially life-threatening condition in patients with chronic kidney disease (CKD). Even after successful kidney transplantation (KTx), KTx recipients have mild to severe CKD. Moreover, they share comorbid conditions and frequently use medications that predispose to hyperkalaemia. This study aimed to examine the prevalence and factors associated with hyperkalaemia in this population.MethodsOver a pre-specified period of 6 months (1 September 2019 to 31 March 2020), we recorded in cross-sectional fashion information on serum potassium (K+) and relevant demographics, comorbidities, medications, laboratory and transplant-associated variables in clinically stable KTx recipients attending the Transplant Outpatient Clinic of our Department. Ηyperkalaemia was classified as follows: serum K+ level >5.0 mEq/L; and further as >5.0 mEq/L with concomitant use of sodium (Na+) polystyrene sulphonate; serum K+ ≥5.2 mEq/L; serum K+ ≥5.5 mEq/L. Univariate and multiple logistic regression analyses were used to identify factors associated with serum K+ >5.0 mEq/L.ResultsThe study population consisted of 582 stable KTx recipients, 369 (63.4%) males, aged 52.4 ± 13.5 years, with estimated glomerular filtration rate (eGFR) of 55.8 ± 20.1 mL/min/1.73 m2 transplanted for >1 year. The prevalence of hyperkalaemia defined as K+ >5.0 mEq/L; >5.0 mEq/L and use of Na+ polystyrene sulphonate; K+ ≥5.2; or K+ ≥5.5 mEq/L, was: 22.7, 22.7, 14.4 and 4.1% (132, 132, 84 and 24 patients), respectively. In multivariate analysis, male gender [odds ratio (OR) = 2.020, 95% confidence interval (CI) 1.264–3.227] and use of renin–angiotensin–aldosterone system (RAAS) blockers (OR = 1.628, 95% CI 1.045–2.536) were independently associated with hyperkalaemia, while higher eGFR (OR = 0.967, 95% CI 0.955–0.979) and use of non-K+-sparing diuretics (OR = 0.140, 95% CI 0.046–0.430) were associated with lower odds of the disorder.ConclusionsThe prevalence of mild hyperkalaemia in stable KTx recipients is relatively high but that of moderate or severe hyperkalaemia is low. Among a wide range of factors studied, only male gender and RAAS blockade were associated with increased odds of hyperkalaemia, while higher eGFR and diuretics were associated with decreased odds of hyperkalaemia.

Adverse gastrointestinal events with sodium polystyrene sulphonate and calcium polystyrene sulphonate use in dialysis patients: a nationwide registry study.

Sodium polystyrene sulphonate (SPS) and calcium polystyrene sulphonate (CPS) are commonly used cation-exchange resins for the treatment and control of hyperkalaemia. However, their use (particularly SPS) has been limited by reports of adverse gastrointestinal (GI) events. The safety of these compounds in patients undergoing dialysis requires larger investigation. To study the occurrence of adverse GI events (occlusion, perforation, thrombosis/ischaemia) in the periods of SPS or CPS exposition versus the periods without exposition in dialysis patients. Dialysis patients were extracted from the French National Registry and merged with the French hospital discharge database (between 2006 and 2017). For our primary analysis, we used patients who had any claim of SPS use (n = 43 771). Time-varying Cox models, negative binomial regression and pre- versus post-treatment average treatment effects. The mean age was 66 ± 15 years, 37% were female and 92% were undergoing haemodialysis. Over a 1-year follow-up, patients on periods with SPS (on-SPS) did not present an increased risk of adverse GI events versus the periods without SPS (off-SPS): incidence rate (IR)(per 1000person years) = 7.4 (6.4-8.7) versus 9.5 (8.1-11.0); adjusted hazard ratio (HR) (95% CI) = 0.81 (0.60-1.09), P = 0.17. Patients exposed to SPS did not experience a higher rate of adverse GI events in the year after SPS initiation versus the year before SPS initiation; P-value for parallel trend = 0.87. Patients on-CPS also did not show an increased risk of adverse GI events versus off-CPS: IR (per 1000py) = 8.6 (5.1-11.9) versus 7.8 (5.1-11.9); adjusted HR (95% CI) = 0.76 (0.31-1.80), P = 0.52. The rates of adverse GI events in the periods on and off exposure were also similar over a follow-up of 5 years. Our large, nationwide study shows that the incidence of adverse GI events in patients undergoing dialysis was low and that neither the use of SPS nor CPS was associated with increased GI events risk.

Optimisation of size-exclusion chromatography with diode array detector for aquatic organic matter profiling using design of experiments: application to tropical reservoirs

ABSTRACT In this article, a size-exclusion chromatography with diode array detector (HPSEC-DAD) method was developed to determine the molecular weight distribution of natural aquatic organic matter. First, a variable screening was performed using sodium polystyrene sulphonate (PSS) standards, verifying the significant effects of ionic strength and flow rate of the mobile phase and the injection volume on resolution and final retention time. The method was then optimised using a Box – Behnken design (BBD), obtaining optimal values of 60 mM (ionic strength), 70 μL (injection volume) and 1.2 mL/min (flow rate). The process was repeated with the same design, using natural water as analyte and introducing peak area as a response, achieving optimum values of 30 mM (ionic strength), 60 μL (injection volume) and 1.17 mL/min (flow rate). In view of this discrepancy, the results of both optimal methods, using standard humic acid, were compared with the results reported in the literature, resulting in lower relative errors with the PSS method than with the natural water method. Under PSS method conditions, different samples of natural water were analysed, and it was possible to distinguish between the molecular weight profiles of organic matter coming from different environments.

Pivotal clinical trials, meta-analyses and current guidelines in the treatment of hyperkalemia.

Hyperkalemia (HK) is the most common electrolyte disturbance observed in patients with advanced stages of chronic kidney disease (CKD), is a potentially life-threatening clinical condition due to an increased risk of fatal arrhythmias, and strongly impacts the quality of life and prognosis of CKD patients. Moreover, while renin-angiotensin-aldosterone system inhibitors (RAASIs) represent the most cardio-nephro-protective drugs used in clinical practice, the treatment with these drugs per se increases serum potassium (sK) values, particularly when heart failure and diabetes mellitus coexist. In fact, the onset or recurrence of HK is frequently associated with not starting, down-titrating or withdrawing RAASIs, and is an indication to begin renal replacement treatment in end-stage renal disease. Current strategies aimed at preventing and treating chronic HK are still unsatisfactory, as evidenced by the relatively high prevalence of HK also in patients under stable nephrology care, and even in the ideal setting of randomized clinical trials. Indeed, dietary potassium restriction, the use of sodium bicarbonate or diuretics, the withdrawal or down-titration of RAASIs, or the administration of old potassium binders, namely sodium polystyrene sulphonate and calcium polystyrene sulphonate, have limited efficacy and are poorly tolerated; therefore, these strategies are not suitable for long-term control of sK. As such, there is an important unmet need for novel therapeutic options for the chronic management of patients at risk for HK. The development of new potassium binders may change the treatment landscape in the near future. This review summarizes the current evidence on the treatment of chronic HK in cardio-renal patients.

Aqueous phase and amorphous state room temperature phosphorescence from a small aromatic carbonyl derivative

Harvesting triplet excitons via room temperature phosphorescence (RTP) in solution or amorphous state from purely organic chromophores is a formidable challenge. Supramolecular hybrid co-assembly between a brominated aromatic carbonyl derivative (BrPhS) and laponite clay (LP) particles is shown to result in remarkable triplet stabilization to result room temperature phosphorescence (RTP) in aqueous solution as well as in amorphous thin films. This remarkable feature is realized by means of highly organized, rigid molecular network of the dye molecules on the inorganic scaffold which reduces the vibrational dissipations as well as limits the oxygen diffusion to facilitate the triplet harvesting under ambient conditions. The water soluble phosphor, BrPhS is also shown to be an excellent triplet emitter in other amorphous polymer matrices like polyvinyl alcohol (PVA) and sodium polystyrene sulphonate (PSS) with phosphorescence quantum yield over 30% in air.

Could drug burden be associated with severe periodontitis in patients receiving haemodialysis?

Periodontitis increases the risk of cardiovascular disease in the general population by triggering systemic inflammation. To investigate the relationship between systemic inflammation and periodontitis, and clarify any association between severe periodontitis and the medications used by patients receiving haemodialysis. A cross-sectional study. The study was undertaken with 56 patients receiving haemodialysis. Demographic and laboratory data and prescribed drugs regularly used by patients were recorded from hospital records. During the dialysis session, a validated Xerostomia Inventory score was completed. A complete dental/periodontal examination was also undertaken on all patients by the same periodontist. In the study population, stage I periodontitis was determined in 41%, stage II periodontitis in 17%, stage III periodontitis in 21%, and stage IV periodontitis in 21%. Male gender, hypertension, coronary artery disease, β antagonists, calcium channel blockers, sodium polystyrene sulphonate, teeth brushing less than twice a day and high sensitive C-reactive protein > 8 mg/l were significantly associated with severe periodontitis. Drugs, including β antagonists, calcium channel blockers, polystyrene sulphonate, co-morbid conditions and poor or insufficient oral care could facilitate an increase in the severity of periodontitis in patients receiving haemodialysis. Severe periodontitis also seems to be associated with cardiovascular disease and inflammation in patients with chronic renal disease.

Initiation of sodium polystyrene sulphonate and the risk of gastrointestinal adverse events in advanced chronic kidney disease: a nationwide study.

BackgroundDespite long-standing clinical use of sodium polystyrene sulphonate (SPS) for hyperkalaemia management in chronic kidney disease (CKD), its safety profile remains poorly investigated.MethodsWe undertook an observational analysis of nephrology-referred adults with incident CKD Stage 4+ in Sweden during 2006–16 and with no previous SPS use. We studied patterns of use and adverse events associated to SPS initiation during follow-up. Patterns of SPS use were defined by chronicity of treatment and by prescribed dose. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) associated with SPS initiation (time-varying exposure) for the risk of severe (intestinal ischaemia, thrombosis or ulceration/perforation) and minor (de novo dispensation of laxatives or anti-diarrheal drugs) gastrointestinal (GI) events.ResultsOf 19 530 SPS-naïve patients with CKD, 3690 initiated SPS during follow-up. A total of 59% took SPS chronically, with an average of three dispensations/year. The majority (85%) were prescribed lower dosages than specified on the product label. During follow-up, 202 severe and 1149 minor GI events were recorded. SPS initiation was associated with a higher incidence of severe adverse events [adjusted HR 1.25 95% CI 1.05–1.49)], particularly in those receiving per label doses [1.54 (1.09–2.17)] and mainly attributed to ulcers and perforations. SPS initiation was also associated with higher incidence of minor GI events [adjusted HR 1.11 (95% CI 1.03–1.19)], regardless of dose, and mainly accounted for by de novo dispensation of laxatives.ConclusionsInitiation of SPS in patients with advanced CKD is associated with a higher risk of severe GI complications as well as the initiation of GI-related medications, particularly when prescribed at per label doses.

Sodium polystyrene sulphonate: risk of severe GI events

Sodium polystyrene sulphonate: risk of severe GI events

The Colon as the Potassium Target: Entering the Colonic Age of Hyperkalemia Treatment?

The Colon as the Potassium Target: Entering the Colonic Age of Hyperkalemia Treatment?

An electro-conductive fluid as a responsive implant for the controlled stimuli-release of diclofenac sodium

The purpose of this study was to develop an electro-responsive co-polymeric (ERP) implantable gel from polyethylene glycol (PEG), sodium polystyrene sulphonate (NaPss), polyvinyl alcohol (PVA), and diethyl acetomidomalonate (DAA) for electro-liberation of the model drug diclofenac sodium. Various physicochemical and physicomechanical characterization tests were undertaken on the synthesized drug-free gel (ERP G1) and drug-loaded gel (ERP G2). The ability of the gel to release diclofenac sodium following electrical stimulation was evaluated using a galvanostat while Molecular Mechanics (MM) simulations were performed to elucidate the experimental mechanisms. A stable electro-active gel exhibiting superior cycling stability was produced with desirable rheological properties, rigidity (BHN = 35.4 N ± 0.33 N/mm2; resilience = 10.91 ± 0.11%), thermal properties (Tg ≈ 70 °C; Tc ≈ 200 °C) and homogeneous morphology. “ON–OFF” pursatile gradual drug release (37–94% from t30 min−t180 min) kinetics was observed upon applying electric stimulation intermittently, indicating that drug release from the gel was electrically controlled. Overall, the galvanometric and MM evaluation ascertained the suitability of the PEG/NaPss/PVA ERP-Gel for application as a subcutaneously injectable drug delivery implant.

Characterization of coal water slurry prepared for PRB coal

Powder River Basin (PRB) coal, which accounts for over 40% of the coal consumed for power generation in the United States, was investigated for preparation of coal water slurry (CWS). The static stability and rheology of the CWS were characterized as a function of loading. The coal loading was varied from 30% to 50% and both ionic (sodium polystyrene sulphonate (PSS)) and nonionic (Triton X-100) surfactants were employed as additives. The addition of PSS to PRB slurries was found to yield poor static stability. On the other hand, Triton X-100 was found to be an effective surfactant, reducing the sedimentation by more than 50% compared to the one without surfactant in 45% CWS. Adding Triton X-100 reduces the viscosity of the CWS for coal loadings of 30% and 40%. Although the viscosities for coal loading of 42.5% and 45% are higher when Triton X-100 is added, the static stability is significantly better than for samples without surfactant. The highest coal loading for PRB slurry with acceptable viscosity for pumping is 42.5%.

Electrosynthesized Polystyrene Sulphonate-Capped Zinc Oxide Nanoparticles as Electrode Modifiers for Sensing Devices

ABSTRACTZnO nanoparticles were prepared by a green electrochemical synthesis method applying low current densities followed by a thermal treatment. Sodium polystyrene sulphonate (PSS) was used as stabilizer in the electrolytic aqueous medium due to its biocompatibility and stability. The as-prepared nanocolloids were then annealed to improve their stability, and then converted via hydroxide species into stoichiometric oxide. Different calcination temperatures were studied. ZnO@PSS nanomaterials were deposited onto SiO2/Si substrates, in part in combination with an organic semiconductor layer to evaluate their influence on organic field effect transistors (OFETs). All nanomaterials and composite layers were characterized by morphological and spectroscopic techniques. Promising results regarding the use of ZnO@PSS in OFETs could be demonstrated.

The chronic kalaemia conundrum.

In this issue, Ritz and Pitt discuss mineralocorticoid-receptor blockade in patients with chronic kidney disease (CKD), the propensity to develop hyperkalaemia, and present a novel suggestion of what to do about it. Actually, the risk of hyperkalaemia in CKD patients may be less of a lethal problem than hypokalaemia; however, hyperkalaemia seems to pack the imagination of clinicians more than hypokalaemia [1]. Nonetheless, hyperkalaemic CKD patients indeed have a risk of death, and the ingestion of antihypertensive drugs blocking the renin–angiotensin–aldosterone system certainly appears to contribute [2]. Ritz and Pitt introduce us to a novel polymeric potassium binder, RLY5016, which packs its potassium-binding punch in the form of 100-µm beads. Clinical experience with RLY5016 is reported in a study assessing RLY5016 in patients with chronic heart failure. In that study, patients receiving renin–angiotensin–aldosterone-blocking drugs were randomized to RLY5016 or placebo [3]. The study group had a lower potassium level, by −0.52 mmol/L, while fewer patients developed hyperkalaemia, 7 compared with 25% with placebo. On the downside, 6% of patients developed hypokalaemia, compared with none with placebo. RLY5016 is not administered with a laxative (no sorbitol) and has not been associated with the occurrence of bowel necrosis. Interference with therapeutic drug absorption thus far seems to involve only a 30% reduction in the bioavailability of valsartan and rosiglitazone. However, the pharmacological testing of this issue may not yet be complete. Relypsa is a clinical-stage biopharmaceutical company that is developing RLY5016. I did my best to learn more about the basic pharmacology of RLY5016, but failed miserably. There are four PubMed citations to date (24 July 2013) and three of those are reviews with hymns-of-praise but little hard information. No structural information on RLY5016 was given. Of course, I would have liked to see some data from normal volunteers receiving a known and fixed dietary potassium intake, along with stool collections, and a comparison with sodium polystyrene sulphonate. For this cation exchange resin, which is also a polymer derived from polystyrene but containing sulfonic acid or sulphonate functional groups, the mode of action is well known. The ion exchange functions effectively as shown (Figure 1) in this case applied to water softening and not to potassium removal. Fig. 1. An idealized image of water softening process involving replacement of calcium ions in water with sodium ions donated by a cation exchange resin is shown. The process for potassium is similar (obtained from https://en.wikipedia.org/wiki/Polystyrene_sulfonate ... Those of us predating the ‘evidence-based era’ generally did as we were told by our chiefs-of-service, back in the ‘eminence-based era’. Way back then, dialysis was the last-resort option shortly before death, so I administered a lot of sodium polystyrene sulphonate. Anecdotally, sodium polystyrene sulphonate led to laparotomy for bowel obstruction in some patients not receiving sufficient quantities of sorbitol. Potassium removal appeared to be a function of how much sorbitol was given. Perhaps the diarrhea was more important than the sodium polystyrene sulphonate. An alternative was the sodium polystyrene sulphonate enema. This therapeutic option tortured not only the patients but also the nurses. I suppose that sodium polystyrene sulphonate must go. A decade ago I was very much interested in an N Engl J Med report on a very ill patient with bowel necrosis of unknown aetiology [4]. Ten years later, everyone knows about the association between oral sodium polystyrene sulphonate given with sorbitol and colonic necrosis, so I will not dwell on the subject here [5, 6]. Are there still other options for managing patients with, or at risk of, developing hyperkalaemia? Again, PubMed was not helpful, but an Internet website was informative (http://clinicaltrials.gov/ct2/show/NCT01737697?term=hyperkalemia&rank=4). I learned that a safety and efficacy study is currently recruiting subjects to test the efficacy of zirconium silicate in patients with mild-to-moderate hyperkalaemia. Thus, RLY5016 could be faced with competition. Spironolactone was first introduced over 50 years ago [7]. We will be faced with the prospects of paying much more for a compound to protect from the side effects than we will for the compound that prolongs the lives of heart failure patients.

Lithium poisoning: the value of early digestive tract decontamination

Objective. The objective of this study was to evaluate the effects of early digestive tract decontamination on the severity of acute-on-chronic lithium poisoning (acute poisoning in patients under long-term therapy). Materials and methods. This was an observational and retrospective study of acute-on-chronic lithium overdoses recorded by the Angers Poisons and Toxicovigilance Centre between February 2006 and September 2010. The cases of overdose were divided into two groups: those undergoing early decontamination (by sodium polystyrene sulphonate and/or whole bowel irrigation) and those in whom decontamination was delayed (> 12 h) or not performed. Severity was assessed using the Poisoning Severity Score (PSS). Results. Fifty-nine patients met the inclusion requirements, 15 of whom were decontaminated at an early stage. The mean age of the patients did not differ statistically between the two groups (49 vs. 44 years, p = 0.25). The estimated ingested doses in the early decontaminated and comparison groups were 12.75 and 12.73 g, respectively (p = 0.9), and the PSSs during the first 12 h were 0.8 and 0.69 (p = 0.32). Those patients who were early decontaminated had an overall lower PSS (1.07 vs. 1.79; p = 0.001), maintained a higher GCS (14.93 vs. 13.3; p = 0.038), and their highest measured serum lithium levels were much lower (2.39 vs. 4.08 meq/L; p = 0.001) than those in the comparison group. All patients who received early digestive tract decontamination subsequently recovered. Under multivariate analysis, undergoing early digestive tract decontamination was significantly associated with a lower risk of severe poisoning (OR, 0.21; 95% CI, 0.04–0.99; p = 0.049), regardless of the lithium dose ingested or the serum lithium level. Conclusion. Our results thus highlight the usefulness of early digestive tract decontamination. This technique was statistically associated with a reduction in the severity of acute-on-chronic lithium poisoning at a given ingested dose and serum lithium level.

Studies of Electrolytic Conductivity of Some Polyelectrolyte Solutions: Importance of the Dielectric Friction Effect at High Dilution

We present a general description of conductivity behavior of highly charged strong polyelectrolytes in dilute aqueous solutions taking into account the translational dielectric friction on the moving polyions modeled as chains of charged spheres successively bounded and surrounded by solvent molecules. A general formal limiting expression of the equivalent conductivity of these polyelectrolytes is presented in order to distinguish between two concentration regimes and to evaluate the relative interdependence between the ionic condensation effect and the dielectric friction effect, in the range of very dilute solutions for which the stretched conformation is favored. This approach is illustrated by the limiting behaviors of three polyelectrolytes (sodium heparinate, sodium chondroitin sulfate, and sodium polystyrene sulphonate) characterized by different chain lengths and by different discontinuous charge distributions.

Determination of the average molecular weight of sodium polystyrenesulphonate from viscosity measurement

Precise measurements on the viscosity of aqueous solutions of sodium polystyrenesulphonate and in presence 0.1 N sodium chloride at 308.15 K were reported. The degree of substitution of sodium polystyrenesulphonate used was one. The sodium polystyrenesulphonate (NaPSS) used in these investigations was purchased from Aldrich Chemical Company, Inc. whose viscosity average molecular weight was 70,000. The experimental viscosity average molecular weight of polystyrenesulphonate was found 70,186.15. Scientific World, Vol. 10, No. 10, July 2012 p17-19 DOI: http://dx.doi.org/10.3126/sw.v10i10.6855

Effect of Solute‐Polymer Interactions on Sorption and Diffusion in Polyacrylamide Gels

Solute‐polymer interactions can exert a large effect on selective sorption and permeation in polyacrylamide (PAAm) gels. In order to investigate this effect, three probe polyelectrolytes, sodium polystyrene sulphonate (PSS), polyvinylpyrrolidone (PVP), and sulfonated polyaniline (SPANI), were chosen as probe species in sorption, release, and permeation experiments in PAAm gels. For PAAm gels with trapped SPANI, FTIR spectroscopy has confirmed that there exists hydrogen‐bonding between SPANI and PAAm. In addition, rigid‐chain SPANI has an intense tendency to aggregate; it is likely that the effective chains of the PAAm matrices are enwrapped in these aggregates. Hydrogen‐bonding and aggregation resulted in that the release kinetics of SPANI from PAAm gels exhibited a remarkable “lag time”, as long as 100 h (lag period means that in the initial period there is no detectable SPANI released from PAAm gels.), the releasing rate of SPANI was very slow, and the selective sorption of SPANI in PAAm gels was extremely high. On the other hand, the release and permeation of PVP and PSS through PAAm gels were much faster than SPANI, and the selective sorption were close to unity. From these facts it could be deduced that there is no or only weak interaction between PAAm and PSS (or PVP). Adding of concentrated support electrolyte resulted in decrease of the release rate and a two‐magnitude decrease of the calculated diffusion coefficients of PSS; the effect of support electrolyte on release and permeation of PSS was partly attributed to the electrostatic interaction.