Determination of Biguanide Groups in Polyhexamethylene Biguanide Hydrochloride by Titrimetric Methods

Determination of Polyhexamethylene Biguanide Hydrochloride Using a Lactone-Rhodamine B-Based Fluorescence Optode

A new determination method for polyhexamethylene biguanide hydrochloride (PHMB) using a lactone-rhodamine B (L-RB) based fluorescence optode has been developed. The optode membrane consists of 2-nitrophenyl octyl ether as a plasticizer, L-RB, and poly (vinyl chloride). The optode responds to tetrakis (4-fluorophenyl) borate, sodium salt (NaTPBF) in the μM range. The fluorescence intensity of the L-RB film for PHMB solution containing 20 μM NaTPBF decreased linearly as the concentration of the PHMB solution increased in the concentration range from 0 to 8.0 μM, which shows that PHMB with a concentration range of 0 to 8.0 μM is determined by the L-RB film optode. The concentration of PHMB in the contact lens detergents by the proposed method was in accord with its nominal concentration.

Determination of Polyhexamethylene Biguanide Utilizing a Glucose Oxidase Enzymatic Reaction

Polyhexamethylene biguanide (PHMB) is a cationic disinfectant widely used for personal-care products and for sanitizers in swimming pools. This paper describes a promotion effect of PHMB on a glucose oxidase (GOx) enzymatic reaction with ferricyanide ion and its analytical application. The promotion effect arose from a polyion complex formation between polycationic PHMB and polyanionic GOx. The promoted GOx reaction was analyzed by Michaelis-Menten equation, and the Michalis constant and catalytic constant were estimated to be 240 μM and 31 s^-1, respectively. Utilizing the promotion effect, PHMB was successfully determined in the range of 0.05 to 0.40 ppm, and the detection limit was calculated to be 0.027 ppm. The visual detection and semi-determination of PHMB with the same concentration level were also possible. As an application, the method was applied to the determination of PHMB in a contact lens detergent and its model solution.

Rapid, simple and stability-indicating determination of polyhexamethylene biguanide in liquid and gel-like dosage forms by liquid chromatography with diode-array detection

A rapid and simple method for the determination of polyhexamethylene biguanide (polyhexanide, PHMB) in liquid and gel-like pharmaceutical formulations by means of high performance liquid chromatography coupled to diode-array detection (HPLC–DAD) was developed. Best separation was achieved using a cyanopropyl bonded phase (Agilent Zorbax Eclipse XDB-CN column 4.6 mm×75 mm with particle size of 3.5 μm) as well as gradient elution consisting of acetonitrile/deionized water at a flow rate of 1.0 mL/min. The optimized and applied chromatographic conditions permitted separation of polyhexanide from interacting matrix with subsequent detection at a wavelength of 235 nm with good sensitivity. The method validation was carried out with regard to the guidelines for analytical procedures demanded by the International Conference on Harmonisation (ICH). Mean recoveries of 102% and 101% for gel-like as well as liquid preparations were obtained. Suitable repeatability as well as intermediate precision could be achieved with limits of detection ≤0.004 mg/mL for both formulations, equivalent to ≤0.004% PHMB concerning sample preparation. Determination of PHMB was accomplished without tedious sample preparation. Interacting matrix could be eliminated by the chromatographic procedure with excellent performance of system suitability. All analytical requirements were fulfilled permitting a reliable and precise determination of PHMB in pharmaceuticals. Furthermore, the developed method was applied to stability testing of pharmaceutical preparations containing PHMB.

Determination of polyhexamethylene biguanide hydrochloride using photometric colloidal titration with crystal violet as a color indicator

A solution of polyhexamethylene biguanide hydrochloride (PHMB-HCl) was titrated with a standard solution of potassium poly(vinyl sulfate) (PVSK) using crystal violet (CV) as an photometric indicator cation. The end point was detected by a sharp absorbance change due to an abrupt decrease in the concentration of CV. A linear relationship between the concentration of PHMB-HCl and the end-point volume of the titrant existed in the concentration range from 2 to 10 × 10(-6) eq mol L(-1). Back-titration was based on adding an excess amount of PVSK to a sample solution containing CV, which was titrated with a standard solution of poly(diallyldimethylammonium chloride) (PDADMAC). The calibration curve of the PHMB-HCl concentration to the end point volume of the titrant was also linear in the concentration range from 2 to 8 × 10(-6) eq mol L(-1). Both photometric titrations were applied to the determination of PHMB-HCl in a few contact-lens detergents. Back-titration showed a clear end point, but direct titration showed an unclear end point. The results of the back-titration of PHMB-HCl were compared with the content registered in its labels.

Biguanide-, imine-, and guanidine- based networks as catalysts for transesterification of vegetable oil

Polycationic systems based on poly(hexamethylene biguanide) (PHMBG), branched polyethyleneimine (PEI) and poly(N-vinylguanidine) (PVG) have been evaluated as heterogeneous catalysts for the transesterification of sunflower oil by methanol. Insoluble networks are synthesized via crosslinking of PHMBG by either 4,4'-methylenebis(N,N-diglycidylaniline) or polyisocyanate prepolymer, PEI with sebacoyl chloride, and PVG with 1,4-butanediol diglycidyl ether. PHMBG and its crosslinked networks appeared to be remarkably efficient catalysts, enabling 80-100% triglyceride conversion within 0.5 h at 70 degrees C. PEI-based networks catalyzed triglyceride transesterification with rates 8- to 12-fold slower than their PHMBG-based counterparts. The PVG-based networks, which were devoid of hydrophobic moieties, appeared to be inefficient catalysts due to limited accessibility of the basic guanidine groups to reactants. The PHMBG networks were shown to be recyclable by a simple centrifugal filtration. After 15 cycles of recovery and reuse, only 10-15% decline in performance was observed.

Adsorptive Voltammetry of 2-(5-Bromo-2-pyridyl)azo-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol on a Carbon Paste Electrode in the Presence of Organic Cations and Polycation

The adsorption of ion-association complexes on a carbon paste electrode (CPE) was investigated by cyclic voltammetry using an electroactive hydrophobic anion probe. The redox reactions of 2-(5-bromo-2-pyridyl)azo-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (5-Br-PAPS), the analytical probe, were irreversible. The reduction of the azo group and the oxidation of the phenol were observed at -0.1 V and 0.9 V vs. SCE, respectively, in a 0.1 mol L(-1) H(2)SO(4) solution. The peak currents for the redox reaction increased with the concentration of the cationic surfactant and the accumulation time. The increase in the ratio of the peak current to the concentration of cationic surfactants was proportional to the hydrophobicity. The peak current for 5-Br-PAPS also increased when a polycation, polyhexamethylene biguanide hydrochloride, was added and was strongly dependent on the ionic strength and pH, in contrast to cationic surfactants.