Abstract: Tea polyphenols are the general term for polyphenols in tea, including flavanols, anthocyanins, flavonoids, flavonols and phenolic acids. Among them, flavanols (catechins) are the most important. â—† Summary Analysis of catechin and caffeine in tea polyphenols using VERTEX STI 5000 isocratic and gradient high performance liquid chromatography â—† Foreword The catechins in tea are a class of functional active ingredients that are abundant in tea. The mass fraction (in terms of dry leaves) in new tea is 12% ～ 32%. Due to its wide range of health and pharmacological effects and strong antioxidant properties of food, catechins in tea have become one of the hot spots in the field of medicine and food research in recent years. This article uses Shanghai Hegong VERTEX STI 5000 to analyze tea and tea polyphenols Catechin is convenient, accurate and fast. â—† Experimental part This experiment was completed on a VERTEX STIP5000 high-pressure constant-flow pump, UV5000 ultraviolet-visible detector, Rheodyne 7725i high-pressure injection valve, and Vertex AQ-C18. â—† Chromatographic conditions Column: Vertex AQ-C18 5μm 4.6 × 200 mm Mobile phase: isocratic elution is CH3OH-H2O-TFA (volume ratio 25: 75: 0.05) The mobile phase A with gradient elution was methanol, and the mobile phase B was 0.05% TFA aqueous solution. The gradient program was 22% A (4 min) 11 min 40% A (6 min) 4 min 22% A. The volume fraction of A is constant at 22% (that is, in the initial state) and equilibrated for 5 min for the next injection. Flow rate: 1.0mL / min Column temperature: 35 ℃ Detection wavelength: 278 nm or 210 nm Sample: West Lake Longjing, Century Tea Polyphenol â… Standard products: EGC, DC, EC, EGCG and ECG, the purity is 98% Injection volume: 20μL â—† Results and discussion Figure 1 Chromatographic separation of Longjing tea samples on Vertex AQ-C18 column Fig.1 Chromatogram of Longjing Tea on Vertex AQ-C18column Mobile phase: methanol-water-trifluoro acetic acid (25: 75: 0.05, V / V); detection wavelength: 278 nm; flow rate: 1 mL / min; column temperature: 35 ℃. Peak identification: 1.EGC; 2.DC; 3.EGCG; 4.EC; 5.CAF; 6.GCG; 7.ECG. Fig.2 Chromatogram of catechins in Century Green Tea Polyphenolâ… on Vertex AQ-C18column Mobile phase: A, methanol, B, 0.05% trifluoro acetic acid solution; elution procedure: 22% A (4 min) 11 min40% A (6 min) 4 min22% A; detection wavelength: 210 nm Peak identification: 8.CG; others are same as in Fig. 1. â—† Sample preparation Tea samples accurately weigh about 1 g of dry tea samples in a 250 mL beaker, pour about 200 mL of boiled ultrapure water, and keep the beaker in a hot water bath at about 95 ° C, stirring every 30 seconds. Continue leaching for 10 min. Take out the beaker, filter it with ordinary qualitative filter paper after proper cooling, and wash the beaker and residue with a small amount of ultrapure water 2-3 times, filter the washing liquid, and transfer the filtrate into a 250mL volumetric flask. When the solution in the bottle is completely cooled to room temperature, bring the volume to the mark with water and shake well. Take 3.00 mL of this tea extract in a 10 mL volumetric flask, dilute to the mark with a mixture of CH3OH-H2O-TFA with a volume ratio of 70: 30: 0.05, filter it and pass through a Sep-pakC18 cartridge. After the pore membrane was filtered, it was analyzed by HPLC. Tea polyphenol sample accurately weigh about 50 mg of sample in a 100 mL volumetric flask, dissolve it with a volume ratio of 1: 1 CH3OH-H2O mixed solution and dilute to the mark, treat it with a Sep-pak C18 cartridge, then use 0.5μm microporous membrane is used for filtration, and the filtrate is used for HPLC analysis. â—† Conclusion The analysis of catechins in tea and tea polyphenols with VERTEX STI 5000 isocratic high performance liquid chromatograph of Hangzhou Aoshi is convenient, accurate and fast. 316 Stainless Steel Tattoo Tip
Tattoo tip is a tubes for needle go through and have different sizes based on the needle sizes. Normally,tips can be made by stainless steel and plastic.
Stainless steel tips can be sterile in autoclave and use many times,but plastic tips sterile packed and for disposable use.
Professional New Tattoo Tips manufacturer is located in China. Specialize In Manufacturing Wholesale Tattoo Machine Tips, Stainless Steel Tattoo Tip, Disposable Tattoo Tips, etc products. welcome to come to the consultation.
Stainless Steel Tattoo Tip, Tattoo Stainless Steel Tip, Steel Tattoo Tip, 316 Steel Tattoo Tip Amztatto Supply Co., Ltd. , https://www.amztatto.com
Analysis of catechins in tea and tea polyphenols by high performance liquid chromatography