Meta-Analysis and Analytical Methods in Cosmetics Formulation: Comparison
Please note this is a comparison between Version 1 by Ronald Marquez and Version 2 by Sirius Huang.

The ever-evolving cosmetic industry requires advanced analytical techniques to explore, understand, and optimize product performance at nano, micro, and macroscopic levels. Nowadays, these insights are crucial for translating microstructure behavior into macroscopic properties. This knowledge is essential to formulate products with a lower carbon footprint and a higher sustainability profile, incorporating, at the same time, natural or biobased raw materials.

  • cosmetics
  • formulation
  • chromatography
  • olfactometry
  • stability
  • rheology

1. Introduction

The Perfume, Cosmetic, and Toiletry (PCT) industry dates back to the use of cosmetics by ancient civilizations, with the Egyptians, Greeks, and Romans being one of the first societies to extensively employ cosmetics for both aesthetic and functional purposes [1][2][3][1,2,3]. Neanderthal men utilized natural pigments for face painting, while the Romans employed oil-based perfumes. The Egyptians, around 4000 BC, were known for their extensive use of cosmetics for both aesthetic and functional purposes, with examples such as the lead-based kohl which was later used by Cleopatra. Then, significant milestones were attained in France during the Renaissance period, where perfumeries began crafting intricate formulations, and evolved with the 19th century seeing a transition to chemical ingredients [4]. The 20th century marked a period of rapid growth and technological innovations with the birth of iconic companies like Estée Lauder, L’Oréal, and Shiseido, who became pioneers in cosmetics R&D and marketing. Noteworthy is the industry’s adaptability and growth, even amidst global challenges such as the COVID-19 pandemic [5].

1.1. Industry Overview

In 2023, the global beauty market was valued at ca. USD 625.7 billion, with a projected CAGR (compound annual growth rate) of 3.3% from 2023 to 2028 [6]. When referring to the cosmetic industry, the latter is often misinterpreted as solely comprising the color cosmetic or makeup segments, while, in reality, these account for just over 18% of the entire personal care market. The industry itself is diverse, with various segments including skincare, haircare, fragrances, and more. The U.S. remains a significant market, but a noticeable shift towards developing regions like South America, Eastern Europe, and Asia has been observed and is projected to reach a value of USD 126.52 billion by 2025, growing at a CAGR of 9.3% from 2020 to 2025 [6]. Moreover, sustainability trends in 2023 have emphasized the use of biobased raw materials, eco-friendly packaging, and ingredient transparency, reflecting the industry’s response to consumer demands for sustainability [7][8][7,8]. The Cosmetic, Toiletry, and Fragrance Association (CTFA) and Cosmetic Ingredient Review (CIR) are among the organizations ensuring the scientific, legal, and regulatory adherence of cosmetic firms, promoting a culture of safety and transparency. As of 2022, the top 10 cosmetic companies held a market share of 62.8% of the global cosmetics market, reflecting a high concentration level within the industry [6]. Evolving consumer preferences, growing awareness related to the sustainability megatrend, and the rise of e-commerce are among the factors driving the growth of the PCT industry [7]. These industry leaders have maintained growth by employing strategies like product innovation, core brand re-marketing, and geographical expansion, particularly in high-growth regions like Asia, Latin America, and Eastern Europe.

1.2. The Importance of Instrumental Techniques in Cosmetics R&D

The development of instrumental methods marked a transformational shift in the cosmetics domain. Techniques such as high-performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS) emerged as crucial tools for both quality control and gaining valuable insights into formulations. They enabled a thorough exploration of molecular composition, which allows for an understanding of interactions at a microscopic level, elucidating macroscopic properties such as viscosity, rheology, and solubility, which are pivotal to product performance [2][9][10][2,9,10].
Macroscopic properties constitute a spectrum of characteristics crucial for the practical application and performance of cosmetic products. These properties are significantly influenced by molecular and microscopic interactions, formulation strategies, and material choices [11]. These properties allow to gain insights into the texture, hydration potential, Sun Protection Factor (SPF), and longevity of cosmetics, to name a few [12].
The 20th century has witnessed remarkable advancements in the cosmetics industry. State-of-the-art analytical methods, the incorporation of novel active ingredients, and complex formulation strategies have all contributed to the rise of high-performance cosmetics [5][10][5,10]. Purity assessment assumed a central role with the inclusion of active molecules aimed at enhancing organoleptic properties like the fragrance and texture of cosmetics [9][13][9,13]. A significant paradigm shift observed in recent times is the transition from petrochemical-derived ingredients to biobased and naturally sourced alternatives. This transition is related to the sustainability megatrend and the demand for cleaner, safer, and better-performing formulations [11][14][11,14].
One case study highlighting the importance of analytical techniques in cosmetics is demonstrated by the detailed analysis of parabens, a common preservative in over 22,000 products, initially claimed as having low toxicity and general non-mutagenicity [15]. Advanced analytical methods enabled the understanding biological interactions of parabens, particularly their reproductive and estrogenic effects, leading to a trend in which parabens are being substituted by other less harmful compounds.

1.3. Meta-Analysis of Cosmetics

Several papers and reviews highlight the evolution and application of analytical techniques in cosmetics, correlating microstructure to macroscopic properties. The topics of these works range from the formulation development of emulsions [16] to modern techniques for sample preparation in cosmetics analysis [17], surface science in cosmetic formulations and its impact on product performance [11]. Moreover, new ingredients are being explored, and their microscopic properties and translation into macroscopic performance are being studied [18][19][18,19]. Nevertheless, there is a gap in the literature related to the application of a comprehensive analytical framework in cosmetics characterization, a so-called meta-analysis. A meta-analysis of cosmetics refers to a comprehensive and integrative approach that synthesizes findings from diverse analytical methodologies to provide a holistic understanding of cosmetic products. The meta-analysis of cosmetics involves the steps summarized in Table 1.
Table 1.
Stages in the meta-analysis of cosmetics formulation.
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