How to detect fluorescent whitening agents in cosmetics
When it comes to the detection of fluorescent whitening agents, the first thing that comes to mind is to use a money detector to irradiate, which is the ultraviolet lamp method. Since the principle of fluorescent whitening agents is to neutralize yellow light with blue light excited by ultraviolet light, using a UV lamp to directly irradiate an object to see if it emits blue fluorescence can determine whether it contains fluorescent whitening agents. This method is very simple and can be used by ordinary consumers, but it also has certain limitations. Because this method can only tell you that the product has a "fluorescent" phenomenon, it cannot prove that a fluorescent whitening agent has been added, let alone prove what has been added or what the content is. Of course, it is still helpful for ordinary consumers to avoid buying products containing fluorescent substances.
The second method is UV spectrophotometry, which requires professional instruments and equipment. Determine the content of different fluorescent whitening agents by measuring the amount of light absorbed and comparing it with standard samples. This method can accurately determine the content of fluorescent whitening agents, provided that the type of fluorescent whitening agent used is known. The equipment used in this method is cheap and easy to operate, and can be used for product testing in enterprises. However, the cosmetic matrix is very complex and prone to interference, which poses a high risk for testing unknown products and is not suitable for promotion.
The third method is molecular fluorescence spectrophotometry, which determines the type and content of fluorescent whitening agents based on their reflected light intensity and wavelength. However, before measurement, the fluorescent whitening agent needs to be separated from the product. Therefore, like the second method, it is not suitable for cosmetics with complex matrices and is more suitable for determining the type of fluorescent whitening agent used in raw materials.
The fourth method is high-performance liquid chromatography, which separates the pre treated sample by chromatography, detects it using a suitable detector, and accurately quantifies it based on the corresponding fluorescent whitening agent standard. This method has a high detection cost and is suitable for accurate quantification of specific fluorescent whitening agents in complex matrices by professional inspection agencies. However, if conventional UV or fluorescence detectors are used, there will be certain limitations in determining unknown fluorescent whitening agents. If a mass spectrometer detector is used, it can simultaneously achieve the separation, qualitative and quantitative analysis of fluorescent whitening agents, and the instrument has high sensitivity, which is very suitable for qualitative confirmation and quantitative analysis of unknown fluorescent whitening agents in complex matrices.
In summary, the probability of containing fluorescent whitening agents in cosmetics is extremely low, and even products containing fluorescent whitening agents are not necessarily unsafe. They are safe under normal usage doses, and consumers should maintain a good attitude.
