Characterization Technique for Parabenes

Characterization Technique for Parabenes

 

Introduction

            Today, cosmetics and other beauty pmroducts have a high demand among consumers, and because of this high demand, several additives and ingredients are also exhausted to be able to meet the needs of consumers. At present the use of cosmetics is essential, being crucial in adding color to the lives of many individuals, especially of women. Because of this importance, different processes are being developed for faster production of the ingredients needed in making cosmetics. Likewise, these cosmetics contain a variety of ingredients, which make them exhibit necessary properties. One of the most common active ingredients of cosmetics is parabenes, and because of its importance as cosmetics’ active ingredient, this paper discusses a specific technique in improving the characterization of parabenes in body lotions, which would be useful in enhancing its quality.

 

Technique: Capillary Electro-Chromatography

             (1997) reports that cosmetics contain preservatives to extend their shelf life, and one of these preservatives is parabenes, which are used in many cosmetics because of their ability to impede microbial growth and prolong shelf life. However, the levels of parabenes and other preservatives must be monitored in any cosmetic product. It has been reported that some cosmetics ingredients can be regarded as allergens, and cause contact allergy, which results from a specific required hypersensitivity reaction, or cell-mediated hypersensitivity, and this involves significant and usually repeated contact with the allergen (2007). In addition, numerous allergens have been identified as causes for allergic contact dermatitis, where the most common contact allergens include nickel and fragrance mix (2007). However, like nickel and fragrance mix, preserving agents, such as parabenes can also cause allergic reactions when used in excess. For this reason, monitoring the amounts and levels of such ingredients in cosmetics must be monitored and checked. In addition, preservatives are crucial ingredients in cosmetics, specifically body lotions, because they contain organic compounds that may become dysfunctional without the reaction or effect of parabenes.  

            With this problem, many techniques are being developed and applied to detect levels of preservatives such as parabenes, in cosmetics products, including body lotions, and this technique is Capillary Electro-Chromatography or CEC. This technique is a fusion of liquid chromatography and capillary electrophoresis, which preserves the best aspects of both techniques ( 1997). Moreover, this is a hybrid separation method that couples the high separation efficiency of capillary zone electrophoresis or CZE, a high-efficiency separation technique for charged analytes but incapable of separating neutral molecules, and high performance liquid chromatography or HPLC, which is capable of resolving a wide range of both neutral and charged analytes. It uses an electric field rather than hydraulic pressure to propel the mobile phase through a packed bed, and since there is no back pressure, it is possible to use small diameter packings and achieve very high efficiencies (1999). This technique is suitable in examining levels of parabenes because given the characteristics of parabenes, they are hydrosoluble, insipid, colorless, and odorless substances (2006). Given these characteristics, parabenes can easily undergo the technique and can easily be identified and evaluated by using the process.

 

Basis for Chosen Technique, Advantages and Disadvantages

            Electro-chromatography is a term used to describe narrow bore packed column separations where the liquid mobile phase is driven not by hydraulic pressure an in high performance liquid chromatography but by electro-osmosis, and using electro-osmosis to propel liquids through a packed bed are the same as for in open capillaries, leading to higher peak efficiency than is possible in using pressure driven systems such as HPLC. The driving force in electro-separation methods results from the electrical double layer that exists at the liquid-solid interface between, such as the bulk liquid and the capillary surface, the packing material and mobile phase ( 1999). In addition, under alkaline conditions, the surface silanol groups or silicon atoms to which hydroxyl substituents bond directly (2006) of the fused silica will become ionized leading to a negatively charged surface, and this surface will have a layer of positively charged ions in close proximity or the Stern layer, which are relatively immobilized. The remainder of the excess charge, which constitutes the Gouy layer, which is solvated and has the characteristics of a typical solvated ion, extends into the bulk liquid and becomes the double layer. The concentration of ions in the double layer is relatively small compared to the total ionic concentration, and falls off exponentially from the capillary surface, as does the corresponding electric potential that is proportional to the charge density. From this, it can be seen that the electro-osmotic flow depends upon the surface charge density, the field strength, the thickness of the electrical double layer, and the viscosity of the separation medium, which in turn is dependent on the temperature (1999).

            Moreover, the silica gels used in the manufacture of stationary phases possess different properties, and as a result, the use of phases can produce different charge densities depending on the surface area of the silica and the acidity of the surface silanol groups. An important consideration in CEC, is the relationship between the linear velocity and the concentration of electrolyte, and since linear velocity is directly proportional to the zeta potential z, which itself decreases with increasing electrolyte concentration, it is an important variable to consider during method development. Furthermore, the driving force in this technique is the electro-osmotic flow and is highly dependent on pH, the buffer concentration, the organic modifier, and the type of stationary phase ( 1999).     

            In using this characterization technique, several advantages can be determined. Primarily, using the capillary electro-chromatography technique results to shortened analysis times and enhanced performance, for handling small volumes of complex sample, such as parabenes, and reducing sample consumption is crucial in respect of clarification of physiological processes or identification of successful drug candidates and compounds, including cosmetics (2006). Secondly, using this technique would reduce materials consumption in every respect ( 2006), for in line with the primary goal, this technique would allow the identification of the compound using small amounts, and this in turn, lessens the costs of the production and hastens the operation. With this, body lotion manufacturers would not only be able to examine parabenes as preservatives, but other active ingredients as well. Manufacturers will be able to identify the amounts of preservatives in their product, improve their quality control, and enhance the value of their product in the market. Third advantage, the application of electro-kinetic separation techniques, such as capillary electro-chromatography enhances separation performance due to decreased theoretical plate heights caused by the superior plug-flow profile of the electro-osmotic flow field, which involves particulate packed or monolithic capillary columns (2006). Lastly, combining mass spectrometry to capillary separation techniques allows the use of micro-electrospray down to nano-electrospray ionization, enhancing the mass and concentration sensitivity by a multiple (2006). Because parabenes are polar compounds, it would easier for it to undergo the process, as its component properties would be adsorbed in the columns. With these advantages, it is evident that the use of this technique would enable drugs and cosmetics manufacturers to examine the amounts of the ingredients and components of their products before introducing them and selling them in the market. In addition, being able to identify the substantial amounts of preservatives in cosmetics would lessen the incidences of causing allergies to consumers.  

            However, despite its advantages are the said disadvantages that limit the use of the capillary electro-chromatography technique. One of its basic limitations or disadvantages is that although higher electrolyte concentrations tend to produce higher efficiencies, electrolyte concentrations can limit the percentage of organic modifier used, which can severely retard method development, brought about by the low solubility of many common inorganic buffers in organic solvents (1999). Second, high electrolyte concentrations give rise to high currents when conventional buffers are used, and leads to Joule heating followed by loss of current because of bubble formation ( 1999). Bubble formation must be suppressed to increase and maximize reliability of the data, so the Agilent CE system must be used, which is uniquely designed for operating CEC in that it can apply up to 12 bar pressure simultaneously to both vials ( 1997). Third limitation is that performing CEC on conventional CZE instruments restricts the operating conditions at certain temperatures, and because of this problem, the use of a modified CZE instrument that allowed electro-chromatography to be performed with up to 90% organic solvent at 30kV and 40C with no interference due to bubble formation (1999). However, without this instrument, performing the technique would be expensive and unreliable. Lastly and most importantly, the reliability and reproducibility of some compounds is poor, being unsuitable for routine use in CEC. With this, manufacturers must be able to produce CEC phases, allowing the highly efficient analysis of acidic, neutral and basic compounds ( 1999).

 

Other Techniques Used

            Aside from the discussed technique, another useful technique for analyzing parabenes in body lotions is normal phase high performance liquid chromatography, which separates analytes based on polarity, and used when the analyte is fairly polar in nature, as it uses a polar stationary phase and a non-polar mobile phase (2007). Adsorption strengths increase with increase in analyte polarity, and the interaction between the polar analyte and the polar stationary phase increases the elution time, such that the interaction strength not only depends on the functional groups in the analyte molecule, but also on steric factors and structural isomers is often resolved from one another. In addition, particularly polar solvents in a mixture tend to deactivate the column by occupying the stationary phase surface, and since parabenes can be regarded as polar compounds because of their function as antimicrobial and fungicidal agents, they will be easily absorbed by the polar stationary phase.

            Moreover, similar with high performance liquid chromatography, another technique can also be used, and this technique is microemulsion electro-kinetic chromatography, which is an electro-driven separation technique. Separations are achieved using microemulsions, which are nanometer-sized oil droplets suspended in an aqueous buffer ( 2003). It is application include the analysis of preservatives such as parabens, wherein in the simultaneous separation of methyl, ethyl, propyl, and butyl paraben were performed using a low-pH microemulsion. A selective separation was achieved against parahydroxybenzoic acid, which is the major degradation impurity of the preservatives, and this method was employed to assay methyl and propyl paraben. The results obtained exhibited that this method was suitable for determination of paraben concentrations, and no impurities were detected in the batches tested above the limit of detection (2003).

 

Performance of Technique Based on Micro Structure of Product

            Results of the technique show that capillary electro-chromatography can be used for the easy determination of parabenes in body lotion and in cosmetic samples. From the experiment, graphs of the results indicate that the first eluting peak is thiourea, and as a non-retained marker can be used to indicate the liner velocity of the mobile phase through the column, which is necessary since the flow is physico-chemically dependent. Reproducibility of migration time was sufficient to identify the four peaks apparent in the body lotion analysis as parabenes, and this was confirmed by spectral analysis, which also indicated that the peak for ethylparabene contained an unknown component ( 1997). From the graphs, the components of parabenes and other preservatives present in the body lotion are evident. This would be useful to evaluate the components of body lotions, and determine its effects in the skins of consumers.

In addition, using this technique would improve the quality of body lotions because manufacturers will be able to detect impurities in their product easily without the hassle of altering other components of the product. Because of the issue associated with paraben, causing cancer and other allergies, this technique and process is crucial for checking excessive amount of parabens in the final product. In this way, body lotion manufacturers will be able to lessen the incidence of contact allergies, and thus, increase the sales of their product. Moreover, because temperature is restricted, the viscosity of the final product would be sufficient for its function.

 

Conclusion

            The use of the Capillary Electro-Chromatography is one efficient technique in determining the amounts of the components in cosmetic products, such as body lotions. The use of this technique must be developed and improved further to help detect other components in a variety of products that may bring harmful or damaging effects to the health of consumers. In this way, manufacturers of cosmetics, especially of body lotions will be able to meet the demands and the standards of their consumers, which would retain and help establish the company’s brand image and brand identity in the market. Furthermore, the use of this technique enhances the effective and efficient use of science and technology.

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