How to distinguish between good and bad cosmetic raw materials?

Distinguishing the quality of cosmetic raw materials can be done from the following aspects:
Sorting of ingredient list: The ingredients in the cosmetic ingredient list are arranged in descending order of content. The top components are usually higher content basic components, such as water, glycerol, etc; Essence and preservatives are usually listed at the end of the ingredient list because they are highly irritating to the skin.
Ingredient type:
Moisturizing ingredients: such as glycerin, hyaluronic acid (hyaluronic acid), butanediol, etc. These ingredients can absorb moisture from the dermis or surrounding environment to the stratum corneum, replenishing moisture for the skin.
Moisturizing agents: such as jojoba oil, squalane, etc., can fill the gaps between skin keratinocytes, making the skin surface smooth and soft.
Sealing agents: such as Vaseline, lanolin, etc., can form a hydrophobic film on the surface of the skin, prevent water loss, and are suitable for dry skin.
Anti inflammatory and repairing ingredients: such as allantoin, urea, and various plant extracts (such as centella asiatica, purslane, etc.), can have anti-inflammatory, moisturizing, and soothing effects on sensitivity.
Whitening ingredients: such as niacin, arbutin, vitamin C, etc., can help fade pigmentation and brighten skin tone.
Antioxidant and anti-aging ingredients: such as vitamin C, vitamin E, retinol, etc., can neutralize oxygen free radicals, promote collagen synthesis, and reduce wrinkles.
Acne removing ingredients: such as azelaic acid, salicylic acid, fruit acid, etc., can help eliminate acne and fade pigmentation.
Purity and physicochemical properties: The effective ingredient content and impurities (such as heavy metals and solvent residues) are detected by techniques such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) to ensure compliance with standards. In addition, it is necessary to determine the physicochemical properties such as pH value, moisture/ash content of the components to ensure their applicability.
Microbial indicators: By detecting the total number of colonies and Escherichia coli (such as plate counting method, PCR), ensure that the raw materials are free of contamination.
Sensory indicators: By observing color uniformity and foreign objects with the naked eye, and using smell to determine the source of odors (such as oxidation or deterioration), ensure the quality of raw materials.
Stability: Observe oxidation and decomposition through accelerated testing (high temperature/high humidity conditions), track degradation products using chromatography, and ensure the stability of raw materials.
Source and process: Review supplier qualifications and production environment (such as GMP certification) to reduce risks.
Regulatory compliance: Compare national standards and industry standards (such as pharmacopoeias and FDA/EC standards) to ensure legality and compliance.