Plasticized Poly Vinyl Chloride Membrane Research Articles

Release behavior of diethylhexyl phthalate from the polyvinyl-chloride tubing used for intravenous administration and the plasticized PVC membrane

The release behavior of diethylhexyl phthalate (DEHP) from polyvinyl-chloride (PVC) tubing, which composes materials in an intravenous administration set, was investigated using polysorbate 80 (Tween 80) aqueous solutions. When Tween 80 solution was circulated in PVC tubing, the amount of DEHP released increased with increasing circulation velocity and temperature. In order to clarify the effect of temperature on the release behavior of DEHP, PVC films containing varying amounts of DEHP were mounted on a cylindrical shaft and rotated at 5 and 40 °C. The cumulative amount of DEHP released increased with an increase in temperature, the diffusion coefficients [ D × 10 −10 cm 2 min −1] at 5 and 40 °C were 9.1 and 156.0, respectively. The glass transition temperature ( T g) of PVC films decreased with an increase in DEHP in the PVC film, as measured by differential scanning calorimeter (DSC) and release of DEHP occurred at temperatures above T g. These results indicate that the release of DEHP from PVC tubing is closely associated with the state of the PVC and is related to diffusion of DEHP throughout the PVC.

PH Sensitivity of a Porphyrin Film Electrode

The response of plasticized polyvinyl chloride membranes containing tetraphenylporphyrin on the pH of the aqueous solution was systematically studied. The concentration of teraphenylporphyrin in the membrane, the polarity of the membrane solvent, and the background electrolyte of the aqueous solution (NaCl, NaNO3, and NaClO4) were varied. A model was proposed, that allow computer simulation of experimental E-pH curves for porphyrin membranes. The model calculations were shown to fairly fit experimental data. Parameters responsible for the shape of the E-pH curves were estimated.

Internal solid contact sensor for the determination of doxycycline hydrochloride in pharmaceutical formulation

The internal solid contact sensor for the determination of doxycycline hydrochloride (DC) was developed based on a conducting polypyrrole (PPy) film immobilized on a glassy carbon electrode surface casted by a plasticized polyvinyl chloride (PVC) membrane containing an ion-pair compound of DC with tetraphenylborate (TPB) and dibutylphthalate (DBP) as plasticizer. Effects of various factors for the electropolymerization of pyrrole or aniline, including monomer concentration, acidity or inorganic salt and thickness of polymer film were investigated experimentally. It was found that the slope and the linear range of SCSs changed with both the different concentration of monomer and of KCl in electrolyte solution and with the different substrate material and a marked influence of the change of solution pH on the potential response of sensor occurred when sample solution pH>3.5. Under the condition of pH 2.8, the sensor showed a near-Nernstian response over the range of DC concentration of 1.0×10 −2–1.0×10 −5 mol l −1 with the slope (at 25 °C) of 54.4 mV per decade. The detection limit obtained was 4.0×10 −6 mol l −1.The sensor was successfully applied to determination of DC in pharmaceutical formulation.

Cetyldimethylethylammonium-Selective PVC Electrode Basedon its Ion-Associate with Phosphotungstic Acid

A PVC membrane electrode selective for cetyldimethylethylammonium (CDEA) ion was prepared. The active element is a plasticized poly vinyl chloride membrane containing a dissolved ion associate complex of CDEA with phosphotungstic acid (PTA). The electrode showed a near-Nernstian response within the CDEA+ concentration range 2.34 × 10−6 to 1.96 × 10−4 M at 25 ± 1^C, good selectivity, and is usable within the pH range 3.5–9.0. The isothermal temperature coefficient of the electrode amounted to −0.00012 V/°C. The electrode has been used for the direct determination of cetyldimethylethylammonium bromide either by the standard addition method or by potentiometric titration against PTA.

Cetyltrimethylammonium-Selective PVC Electrode Based On Its Trinitrobenzene Sulfonate Ion-Pair

A PVC membrane electrode selective for cetyltrimethylammonium ion was prepared. The active element is a plasticized polyvinyl chloride membrane containing a dissolved ion pair complex of CTAB with trinitrobenzene sulfonic acid (TNBS). The electrode showed a near-Nernstian response within the CTA+ concentration range from 1.08×10–6 to 8×10–4 M at 25±1 °C, good selectivity, precision (RSD=1.04 %), and usable within the pH range 2.5–10.2. The isothermal temperature coefficient of the electrode amounted to –0.00007 V/°C. The electrode has been used for the direct determination of cetyltrimethylammonium bromide either by the standard addition method or by potentiometric titration against TNBS at pH 7.

Micro-optorde for urea using an ammonium ion-sensitive membrane covered with a urease-immobilized membrane

A urea optrode was constructed using a polymer membrane optically sensitive to ammonium ions and a urease-immobilized membrane. A plasticized poly(vinyl chloride (PVC) membrane containing polynactin was prepared on the distal end of an optical fibre. The PVC membrane was covered with a polyacrylamide membrane, and a positively charged fluorescent dye of hexadecyl-acridine orange was immobilized on the PVC membrane through the polyacrylamide membrane to form an ammonium ion-sensitive membrane. The composite membrane was covered with another polyacrylamide membrane in which urease was immobilized. Urea in a sample solution was hydrolysed to ammonium ion by the immobilized urease and detected optically by the ammonium ion-sensitive membrane. The response of the optrode was reversible to urea concentration in the range 10 −4 −0.1 M, the response time being 40 s. The selectivity coefficients for potassium and sodium ions were 0.3 and 5 × 10 −4, respectively. The optrode was applied to the determination of urea in blood serum. The observed concentration was corrected for the interference of potassium ion, and it agreed well with the specified urea concentration. The diameter of the optical fibre was 140 μm, so that the optrode could be easily applied to in vivo measurements.

An optical biosensor for lysine based on the use of lysine decarboxylase and a cadaverine-sensitive membrane

We describe an optical biosensor for lysine based on the use of lysine decarboxylase and an optical transducer for detection of cadaverine which is formed as a result of enzymatic action. A plasticized PVC (polyvinyl chloride) membrane containing a lipophilic tartrate as the amine carrier acts as the optical cadaverine sensor. The transport of the cadaverine cation into the membrane is coupled to a transport of a proton (of the indicator dye) out of the membrane. This causes a spectral change of the indicator dye which can be related to the cadaverine concentration, provided the pH is kept constant. The enzymatic reaction is performed in an enzyme reactor which is part of a flow-through system. The dynamic range is from 0·1 to 100 mM for both cadaverine and lysine. While the cadaverine sensor is moderately selective (ethylamines, for example, interfere), the whole sensor system is highly specific for lysine, nicotine being the only major interferent. Unlike other enzyme-based detection schemes where the production of CO 2 (in case of decarboxylates) or consumption of oxygen (in case of oxidases) is measured, this scheme is based on the measurement of the organic ammonium ion (cadaverin cation) formed in the enzymatic reaction. The major advantage of this approach is that in many real samples there is a rather low and fairly constant background of organic amines. This is in contrast to sensors based on the measurements of oxygen consumption (in the case of amino acid oxidases) or carbon dioxide production (using decarboxylases), where the background levels of the respective gases (which are ubiquitous) have to be kept constant in order to specifically measure only the concentration changes caused by the enzymatic reaction, or need to be measured in an independent assay.

Assessment of sodium‐selective ion‐selective electrodes based on methyl ketone derivative of p‐tert‐butylcalix[4]arene

AbstractThe performance of a newly synthesized tetramethyl ketone calyx [4]arene ionophore in ion‐selective electrodes has been investigated. Optimization of the plasticized polyvinyl chloride membrane composition has produced electrodes that exhibit a Nernstian response for sodium ions. The best general characteristics exhibited by the electrodes were found when the ionophore mixed with 2‐nitrophenyl octyl ether as plasticizing agent, and potassium tetrakis (p‐chlorophenyl) rate as ion exchanger. Selectivity studies carried out with the electrode have shown excellent discrimination for sodium against potassium and lithium ions. In addition, the electrode displays a rapid response time, a detection limit be low 10−6 M for sodium, and a working life of at least 4 months. Determinations of sodium in plasma patient samples have been performed and the results obtained compared to those from flame photometry and two commercial clinical analyzers.

A cetyltrimethylammonium cation-sensitive polymeric membrane electrode based on the cetyltrimethylammonium-phosphotungstate ion association

The development and testing of a cetyltrimethylammonium (CTA) cation-sensitive electrode are described. The active element is a plasticized polyvinyl chloride membrane containing a dissolved ion association complex of CTA with phosphotungstic acid (PTA). The effect of membrane composition was studied. The electrode exhibits a rapid and near-Nernstian response to CTA + from 3.2 × 10 −6 to 8.3 × 10 −4 M at 25 ± 0.1 °C. The response is unaffected by pH in the range of 2.5–8.5. Selectivity coefficients for numerous compounds are given. The electrode has been successfully applied to the direct determination of CTA in aqueous solution either by the standard addition method or by potentiometric titration vs PTA.

Plastic membrane ion selective electrodes for the determination of some anesthetic compounds

Lignocaine (LC), procaine (PC), and benzocaine (BC) ion selective electrodes based on incorporation of ion pairs of tetraphenylborate anion (TPB) with protonated LC, PC, and BC in plasticized polyvinyl chloride membranes were prepared. The electrodes showed linear responses with Nernstian slopes over the concentration ranges 3.16 × 10 −5–1.25 × 10 −2, 1.99 × 10 −5–1.60 × 10 −2, and 6.31 × 10 −6–1.20 × 10 −2 M of LC, PC, and BC, respectively. The change in pH did not affect the electrode performance within the ranges 2.0–7.6, 2.9–8.1, and 5.5–8.5 for the three electrodes, respectively. The electrodes were very selective for the respective drugs and exhibited very small isothermal coefficients amounting to 0.00099, 0.00083, and 0.00065 V/deg for LC, PC, and BC electrodes, respectively. Potentiometric titrations were successfully applied to determine LC, PC, and BC using standard TPB solution as titrant and the respective electrodes as potentiometric sensors.

Potassium-selective electrodes based on macrocyclic polyethers: The effect of structure of the neutral carrier on selectivity

The K/Na selectivity of electrodes with a plasticized polyvinyl chloride membrane containing neutral carriers of the macrocyclic polyether type has been investigated. The results obtained for twenty different crown compounds showed that the highest selectivities are obtained for polyethers with six oxygen binding sites in an eighteen-membered ring(K K.Na up to 1.1· 10 -2) and for thirty-membered rings with ten oxygen atoms (K K.Na up to 2.2·10 -3). Possible explanations of the effect of the structure of the basic macrocyclic ring on selectivity, and the effects of some substituents, are discussed.