Determination of benzalkonium chloride preservative in pharmaceutical formulation of eye and ear drops using new potentiometric sensors

Comparison of aqueous and non-aqueous capillary electrophoresis for the determination of four benzalkonium chloride homologues in compound chemical disinfectants

A new method was established for the simultaneous analysis of four homologous benzalkonium chlorides (dodecyldimethylbenzyl ammonium chloride, tetradecyldimethylbenzyl ammonium chloride, hexadecyldimethylbenzyl ammonium chloride, and octadecyldimethylbenzyl ammonium chloride) in compound chemical disinfectants using non-aqueous capillary electrophoresis (CE) based on a micellar electrokinetic chromatography mode with direct ultraviolet detection. The separation was performed on an uncoated fused quartz capillary with a total length of 60.2 cm and a diameter of 25 μm. The separation buffer consisted of a mixture of methanol/acetonitrile (60:40, v/v) containing 70 mmol/L sodium acetate, 60 mmol/L trifluoroacetic acid and 20 mmol/L sodium dodecyl sulfate. The sample buffer was a methanol solution containing only 2 mmol/L trifluoroacetic acid. The separation voltage was set at 8 kV with a working current of approximately 2.3 μA. The detection wavelength was 214 nm. Under optimal conditions, the limit of detection and limit of quantification for these four benzalkonium chlorides (BACs) were 1.0 mg/L and 5.0 mg/L, respectively. Good linearities were observed in the concentration ranges from 5.0 to 100.0 mg/L, with correlation coefficients above 0.999 for all compounds. The recoveries of these four BACs ranged from 92.5 % to 109.1 % with relative standard deviations below 4.7 %. With the new method, all four BACs could be analyzed in a single injection. In contrast, the aqueous CE method in the National Standard GB/T 26369-2020 only allowed for the simultaneous analysis of the first three homologous. The new method demonstrated the improved peak shape compared to the aqueous CE method and then was successfully applied to the analysis of 19 commercially available samples, such as object table disinfectants, hand sanitizers, and disinfectant wipes, which claimed to contain quaternary ammonium compound. The results obtained using the new method were compared with those of the aqueous CE of the National Standard Method, and no statistically significant differences were observed. The new method is simple in pre-treatment and provides accurate results, making it highly suitable for routine analysis.

Development of a sustainable procedure for smartphone-based colorimetric determination of benzalkonium chloride in pharmaceutical preparations

A sustainable procedure offering green, simple, and rapid analysis was developed to determine benzalkonium chloride (BKC) in pharmaceutical preparations. The determination using smartphones was based on the ion pair colorimetric reaction with bromothymol blue (BTB), which produces a yellow color. The intensity of the product color, which is proportional to the concentration of BKC, was detected and evaluated using a smartphone camera and an image processing application. The procedure was performed in a microliter and was rapidly detected within 1 min after incubation. This offered high throughput at 28 samples per well plate in duplicate. Linear calibration, which was a plot of BKC concentrations and relative red intensities, was in the range of 2.0-24.0 μg/mL with an R2 of 0.997. The limits of detection (LOD) and quantitation (LOQ) were 1.0 and 3.2 μg/mL, respectively. This work was successful in applying it to pharmaceutical materials, disinfectant products, and pharmaceutical products containing BKC. It was discovered that the concentrations of BKC as an active ingredient in pharmaceutical materials were 82% w/v, whereas those in disinfectant products ranged from 0.4 to 2.1% w/v. In pharmaceutical products, ophthalmic drops and nasal sprays contain BKC as preservatives in the 0.01-0.02, and the 0.02% w/v, respectively. The results obtained by the proposed procedure compared with a reference titration method showed no significant differences at a 95% confidence level with 1.2-3.4% RSDs. This promotes the efficiency of pharmaceutical preparations regarding infection prevention and control by ensuring that available disinfectants contain a sufficient concentration of BKC. Additionally, this improves the efficiency of pharmaceutical preparations for quality control of pharmaceutical products by ensuring that the available preservatives maintain a sufficient concentration throughout the lifespan of the products.

Determination of Benzalkonium Chloride in a Disinfectant by UV Spectrophotometry and Gas and High-Performance Liquid Chromatography: Validation, Comparison of Characteristics, and Economic Feasibility

Simple, fast, and validated UV-spectrophotometric, HPLC, and GC methods for the analysis of benzalkonium chloride in a disinfectant were developed. UV-spectrophotometric determination was based on measuring the amount of light absorption of aqueous solutions of benzalkonium chloride at 268 nm. HPLC determination was achieved with a 150 mm × 4.6 mm, 5.0 μm C18 column. The mobile phase consisted of a 0.01% water solution of triethylamine (with pH 2.5) and acetonitrile in the ratio of 40 : 60 v/v. The column temperature was kept at 30°C, and the injection volume was 10 μL. The flow rate was 1.0 mL/min, and the diode array detector was set at 215 nm. GC determination was performed using a flame ionization detector on a glass capillary column ZB-WAX plus 30 m × 0.25 mm with an inner coating thickness of 0.25 μm. It creates a gradient increase in the temperature of the furnace to the maximum of 200°C. The temperature of the injector was 250°C, 1 μl was injected, and the separation of the sample was 1 : 100. Helium was used as a carrier gas, and the gas flow rate was constant, equaling 1.6 ml/min. The temperature of the detector was 250°C, and a mixture of hydrogen, helium, and air in a ratio of 30 : 8.5 : 350 was used in the split of the detector. All proposed methods were validated according to ICH guidelines with respect to the accuracy, precision (interday, intraday, and reproducibility), linearity, the limit of detection, the limit of quantitation, and robustness. All three methods were linear (R2 = 0.997–0.999) over a concentration range of 400–600 μg/ml for UV and 80–120 μg/ml for HPLC and GC, accurate (recovery was 98.4–101.7% for all methods), precise (RSD <2%), and robust. The cost of the analysis of one sample of the disinfectant for the content of benzalkonium chloride by three methods was calculated. The comparison of the obtained results facilitates a more efficient allocation of laboratory resources, depending on the goal.

Polyvinyl Chloride Modified Carbon Paste Electrodes for Sensitive Determination of Levofloxacin Drug in Serum, Urine, and Pharmaceutical Formulations

Levofloxacin (LF) is a medically important antibiotic drug that is used to treat a variety of bacterial infections. In this study, three highly sensitive and selective carbon paste electrodes (CPEs) were fabricated for potentiometric determination of the LF drug: (i) CPEs filled with carbon paste (referred to as CPE); (ii) CPE coated (drop-casted) with ion-selective PVC membrane (referred to as C-CPE); (iii) CPE filled with carbon paste modified with a plasticizer (PVC/cyclohexanone) (referenced as P-CPE). The CPE was formulated from graphite (Gr, 44.0%) and reduced graphene oxide (rGO, 3.0%) as the carbon source, tricresyl phosphate (TCP, 47.0%) as the plasticizer; sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (St-TFPMB, 1.0%) as the ion exchanger; and levofloxacinium-tetraphenylborate (LF-TPB, 5.0%) as the lipophilic ion pair. It showed a sub-Nernstian slope of 49.3 mV decade⁻¹ within the LF concentration range 1.0 × 10⁻² M to 1.0 × 10⁻⁵ M, with a detection limit of 1.0 × 10⁻⁵ M. The PVC coated electrode (C-CPE) showed improved sensitivity (in terms of slope, equal to 50.2 mV decade⁻¹) compared to CPEs. After the incorporation of PVC paste on the modified CPE (P-CPE), the sensitivity increased at 53.5 mV decade⁻¹, indicating such improvement. The selectivity coefficient (log KLF2+,Fe+3pot.) against different interfering species (Na⁺, K⁺, NH⁴⁺, Ca²⁺, Al³⁺, Fe³⁺, Glycine, Glucose, Maltose, Lactose) were significantly improved by one to three orders of magnitudes in the case of C-CPE and P-CPE, compared to CPEs. The modification with the PVC membrane coating significantly improved the response time and solubility of the LF-TPB within the electrode matrix and increased the lifetime. The constructed sensors were successfully applied for LF determination in pharmaceutical preparation (Levoxin^® 500 mg), spiked urine, and serum samples with high accuracy and precision.

Two Novel Methods for the Determination of Benzalkonium Chloride in Bandages by Resonance Light Scattering Technology

In this study, two novel resonance light scattering (RLS) methods were developed for the determination of benzalkonium chloride. These methods were based on the formation of inorganic anionic-surfactant aggregates in a Clark-Lubs medium, which increases the resonance light scattering intensity of the reaction system and were also predominantly divided into sodium tungstate-benzalkonium chloride (method A) or phosphomolybdate-benzalkonium chloride (method B). The detection is performed both at 285 nm. Under the established conditions, the limits of quantification ranged from 0.10 mg L–1 to 1.00 mg L–1 with the R values of 0.9994 and from 0.20 mg · L–1 to 3.20 mg · L–1 with the R values of 0.9991, with good precision and accuracy both for method A and method B. The limits of detection were 0.029 mg · L–1 for method A and 0.013 mg · L–1 for method B. These two methods were successfully applied for the assay of benzalkonium chloride for the first time. All validation parameters were in agreement with the International Conference on Harmonization of Requirements for Registration Pharmaceuticals for Human Use (ICH) guidelines. Compared to the classical spectrophotometric method, these two methods take advantages of rapidity, high efficiency and good selectivity.

Benzalkonium chloride, benzethonium chloride, and chloroxylenol - Three replacement antimicrobials are more toxic than triclosan and triclocarban in two model organisms

With the recent ban of triclosan (TCS) and triclocarban (TCC) from some personal care products, many replacement antimicrobial compounds have been used. Yet the potential health risk and environmental impact of these replacement compounds are largely unknown. Here we investigated the toxicological effects of three commonly used replacement antimicrobials, benzalkonium chloride (BAC), benzethonium chloride (BEC), and chloroxylenol (CX) to two model organisms, the nematode C. elegans and zebrafish (Danio rerio), and compared them to the banned TCS and TCC. We found that these replacement compounds are not any safer than the banned antimicrobials. In the worm, at least one of the three, BAC, showed comparable toxicity to TCS from organismal to molecular levels, with toxic effects occurring at lower hundred μg/L to lower mg/L levels. In the fish, all three compounds at the tested concentration ranges (0.05-5 mg/L) showed toxicity effects to zebrafish embryos, indicated by hatching delay or inhibition, embryonic mortality, morphological malformations, and neurotoxicity. BAC was the most toxic among the three, with acute lethal toxicity occurring at environmentally relevant concentrations (hundreds of μg/L), which is comparable to the banned TCC. However, the toxicity effects of BAC and TCC occurred within different time windows, potentially suggesting different mechanisms of toxicity. CX was the only compound that induced a "body curvature" phenotype among the five compounds examined, suggesting a unique mode of toxic action for this compound. Furthermore, all five compounds except TCS induced neurotoxicity in fish larvae, indicated by alterations in secondary motoneuron axonal projections. Such neurotoxicity has been largely understudied for these antimicrobials in the past years and calls for further investigations in terms of its underlying mechanisms and ecological significance. These findings strongly indicate that scrutiny should be put on these replacement compounds before their introduction into massive use in personal care products.

Absence of effects of different types of detergents on the cholinesterasic activity and histological markers of mosquitofish (Gambusia holbrooki) after a sub-lethal chronic exposure

The release of anthropogenic compounds into the aquatic environment has been a particular concern, since some of these substances exhibit biologic activity of different types in non-target species. Among anthropogenic compounds present in the aquatic compartment, detergents are commonly found and may be responsible for physiological modifications in exposed organisms. The impairment of key physiological functions, such as neurotransmission, and tissue damage in some important organs, has been used to assess the effects of several classes of xenobiotics, including detergents, in aquatic organisms. The present study intended to assess the effect of three types of detersive compounds (sodium dodecylsulfate (SDS), benzalkonium chloride (BZC), and Triton X-100 (TX100)) in the acetylcholinesterase activity (AChE) and tissue damage (gills and liver) of Gambusia holbrooki after a chronic exposure to realistic levels of these compounds. SDS, BZC, and TX100 did not cause any significant alteration in AChE. Furthermore, no specific gross morphological changes were also observed in the gills and liver of the exposed individuals. It is possible to conclude that, under ecologically relevant conditions of exposure, both tissue damage and cholinesterasic impairment are not toxicological pathways affected by detergents in G. holbrooki.

Effects of chronic exposure to benzalkonium chloride in Oncorhynchus mykiss: cholinergic neurotoxicity, oxidative stress, peroxidative damage and genotoxicity

Benzalkonium chloride (BAC) is one of the most used conservatives in pharmaceutical preparations. However, its use is limited to a small set of external use formulations, due to its high toxicity. Benzalkonium chloride effects are related to the potential exertion of deleterious effects, mediated via oxidative stress and through interaction with membrane enzymes, leading to cellular damage. To address the ecotoxicity of this specific compound rainbow trouts were chronically exposed to BAC at environmental relevant concentrations (ranging from 0.100 to 1.050mg/L), and the biological response of cholinergic neurotoxicity, modulation of the antioxidant defense, phase II metabolism, lipid peroxidation and genotoxicity was studied. The obtained results showed a dual pattern of antioxidant response, with significant alterations in catalase activity (starting at 0.180mg/L), and lipid peroxidation, for intermediate (0.180 and 0.324mg/L) concentrations. No significant alterations occurred for glutathione-S-transferases activity. An unexpected increased of the acetylcholinesterase activity was also recorded for the individuals exposed to higher concentrations of BAC (starting at 0.180mg/L). Furthermore, exposure to BAC resulted in the establishment of genotoxic alterations, observable (for the specific case of the comet assay results) for all tested BAC concentrations. However, and considering that the oxidative response was not devisable, other mechanisms may be involved in the genotoxic effects reported here.