Niacinamide belongs to the separation and analysis method of B vitamins

Niacinamide is a water-soluble vitamin, one of the members of the B vitamin group, which can be converted from niacin in the living body, and its substance has vitamin effects. Nicotinamide is widely used in whitening cosmetics because of its antioxidant effect. In order to improve the quality of its cosmetics, it has become an important task to find an efficient and low-cost method for the detection of niacinamide.

For niacinamide, its substance has medicinal value and commercial application value. However, if excessive use of niacinamide substances, human health will also have a certain impact. Nicotinamide and its derivatives are widely used in whitening cosmetics today, it is necessary to find an effective detection method to improve the detection efficiency.

At present, there are many detection methods for niacinamide. In order to improve the analysis efficiency, high performance liquid chromatography (HPLC) can be chosen to analyze the substance. Based on this, this paper mainly introduces the detection method of niacinamide by high performance liquid chromatography.

1. High performance liquid chromatography

High performance liquid chromatography (HPLC)is a new detection method based on liquid chromatography.  This detection method uses a high-pressure infusion pump and a highly sensitive detection food to separate the substance to be tested.  This method can be applied to the detection of nicotinamide in complex systems.  For example: whitening series of cosmetics, food and other nicotinamide substances separation analysis.  The nicotinamide whitening additives in some daily products can be qualitatively and quantitatively analyzed by HPLC.   For example: laundry detergent, face cream, soap, etc.  In addition, some scholars in the detection of whitening additives in whitening cosmetics series, the two optical isomers of arbutin α-, β-arbutin and nicotinamide using HPLC detection methods.  In the detection of a variety of B vitamins, HPLC can be used to ensure the accuracy of the detection results.

2. Application of HPLC method for determination of α-, β- arbutin and nicotinamide in cosmetics

2.1 Work before handling samples

Before processing the samples, four kinds of whitening cosmetics were selected as the samples to be tested in this experiment, namely, whitening moisturizing cream, whitening essence, whitening skin lotion and whitening lotion. According to the product ingredients in the cosmetic instructions, it can be seen that the cosmetics containing oil include whitening lotion and whitening moisturizing cream, while the other two are non-oily cosmetics. However, whether it contains oil or does not contain oil, it is necessary to carry out sample pretreatment for these two types of cosmetics. 0.2g of oleoresin-containing cosmetic samples were placed in a 20 mL beaker and 2.5 mL of chloroform was added.  0.05 kg/L NaCl aqueous solution was added and dissolved in ultrasonic waves for 25 min, the separatory funnel was separated, the chloroform layer was washed several times with 2 mL of ultrapure water, and the aqueous solution was centrifuged for 9 min. The solution was filtered through a 0.22 μm aqueous needle-type filter before the sample was analyzed. Then, 0.2g of non-oil cosmetics samples were dissolved in water, and the extract was filtered through a 0.22μm water-based needle filter for analysis.

2.2 Work before handling samples

First, the standard solution of nicotinamide is scanned by EUD2000 UV detector, and then arbutin is scanned by controlling the scanning wavelength range, preferably between 190~700nm. It can be clearly seen from the scanning image that there is an absorption peak at 220nm for arbutin standard solution, and an absorption peak at 215nm for nicotinamide. In the specific analysis process, it was found that the sample with the same concentration was at 225nm, and its response value was the highest. Therefore, this test uses 225nm as the detection wavelength, which can ensure the detection sensitivity.

2.3 Select the corresponding mobile phase

The mobile phase selected in this experiment was methanol-water system, and the ratio of water to methanol was compared. The volume ratio of water to methanol was 5∶ 95,10 ∶ 90,15 ∶ 85,20 ∶ 80,25 ∶ 75,30 ∶70, and the flow velocity was 0.5mL/min. Under the investigation of the two structures of nicotinamide and arbutin, Focus on their separation. The mass concentration of β-arbutin and nicotinamide and α-arbutin were used as the standard solution. It is found that the proportion of methanol in the mobile phase has a great influence on the separation degree and retention time of the allogeneic compounds. However, after the methanol ratio was gradually reduced, the component retention time was significantly extended, and the separation status of the two isomers of arbutin was significantly improved. When the mobile phase was methanol-water (10∶90, v/v), the two isomers were in a completely separated state, so methanol-water (10∶90, v/v) was used as the mobile phase in this method.

2.4 Pretreated sample

In terms of composition, cosmetics can be divided into two types: oily and non-oily. The processing process of non-oily products is very simple, and sample analysis can be carried out by selecting the appropriate solvent. For the analysis of products containing grease components, some substances should be removed before they can be studied. Considering that niacinamide and arbutin are easily dissolved in water, and not easily dissolved in chloroform, chloroform extraction method is used to remove grease substances, and niacinamide and arbutin enter the water phase. According to relevant literature reports, the demulsification effect of NaCl can play a good role in improving the extraction effect of the test substance. Therefore, this paper uses a chloroform mixed system to extract the test substance, and discusses the influence of NaCl aqueous solution in the mixed structure system on the extraction effect. In the verification of the effect of NaCl solution and chloroform ratio on the extraction rate, Dabao SOD honey without substances to be measured should be selected as the base to analyze the extraction ratio of chloroform and NaCl solution, and then weigh 5 parts, each weighing about 0.2g. Then a mixed standard solution of β-arbutin and nicotinamide with a mass concentration of 100mg/L was added, and 1mL α-arbutin was added. According to the experimental results, the extraction rate of chloroform and aqueous solution is the highest in the volume of 2:1, so this ratio should be selected to carry out extraction.

2.5 Relationship between extraction rate and ultrasonic time

In order to study the influence of ultrasonic time on extraction quality and efficiency, the extraction ratio of chloroform and NaCl aqueous solution was combined to obtain the corresponding extraction liquid ratio. In the extraction process, samples were extracted with 8m L of extraction liquid, and ultrasound was carried out for 10, 15, 20, 25 and 30min one by one. After the experiment, it was found that the extraction efficiency of the tested substance would also increase with the increase of ultrasonic time, indicating a positive proportional relationship between the two, so the ultrasonic time should be set at 20min. In order to intuitively reflect its detection effect, it can be understood through the standard working curve.  Figure 1 shows the chromatogram of mixed standard solution and whitening essence with mass concentrations of 0.5 mg /L for α-arbutin, β-arbutin and nicotinamide. In the process of testing, it is necessary to accurately measure the standard reserve liquid and make it into a mixed standard solution of 0.05, 0.1, 0.5, 1,5,10,50 mg/L, and test it through the form of injection respectively.

2.6 Relationship between extraction rate and ultrasonic time

In a good experimental environment, 4 kinds of whitening cosmetics were determined, and 3 kinds of whitening ingredients of whitening cosmetics, namely arbutin, nicotinamide and arbutin, were determined for an average of 3 times for each sample. Among them, whitening lotion, whitening lotion and whitening essence all contain α-arbutin, and nicotinamide is contained in whitening moisturizing cream, whitening whitening lotion and whitening essence. No β-arbutin was detected in the four whitening cosmetics.

In summary, niacinamide and its derivatives are being used more and more widely.

People's pursuit of whitening effects and the drive of economic interests, so that its substance has become the key raw materials of whitening cosmetics. However, due to the toxic side effects of niacinamide, its application has been questioned by many people. Therefore, in order to ensure the safety of whitening cosmetics, it is necessary to find a nicotinamide detection method with high efficiency and low detection cost in time. It can guarantee the quality of its cosmetics, with the continuous development of nicotinamide detection technology, more efficient and low-cost separation and enrichment methods should be developed for the detection of complex composition and low content of nicotinamide. It can comprehensively solve the complex matrix interference, enhance the detection sensitivity of niacinamide, and provide accurate detection data for its substance detection.