Phân loại nguồn gốc địa lý và xác định đồng thời của methylxanthines trong trà Việt Nam bằng cách sử dụng hóa học dựa trên trên quang phổ phản xạ hồng ngoại gần

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Tác giả: Duc Tho Bui, Van Ri Nguyen, Thi Thao Ta, Thi Hue Tran

Ngôn ngữ: vie

Ký hiệu phân loại: 663.94 Tea

Thông tin xuất bản: Tạp chí khoa học và công nghệ - Đại học Nguyễn Tất Thành, 2019

Mô tả vật lý: 33-39

Bộ sưu tập: Metadata

ID: 492279

Thêm vào giỏ

Bài báo này báo cáo kết quả phân loại nguồn gốc địa lý và phân tích đồng thời ba metylxanthin (cafein, theobromine, theophylline) trong các mẫu chè Việt Nam bằng phương pháp đo quang phổ phản xạ hồng ngoại kết hợp với hóa học. Phạm vi quang phổ là 10.000-4.000cm-1 và mỗi quang phổ được đo ở khoảng cách 2 cm-1. Với mục đích phân loại nguồn gốc địa lý, nghiên cứu này sử dụng quang phổ FT-NIR kết hợp với Phân tích phân biệt bình phương tối thiểu (PLS-DA) và Phân tích thành phần chính - Phân tích phân biệt (PCA-DA). Khả năng xác định được nguồn gốc của các mẫu chè trong bộ dự báo của mô hình PLS-DA là 100%. Sử dụng cùng một cơ sở dữ liệu phổ IR kết hợp với bình phương nhỏ nhất một phần (PLS), ba metylxanthin trong các mẫu chè cũng được định lượng nhanh chóng. Mô hình PLS dựa trên phổ của 24 mẫu chè trong đó hàm lượng của 3 chất phân tích được xác định bằng sắc ký lỏng hiệu năng cao - HPLC) được áp dụng để xác định đồng thời caffeine, theobromine và theophylline trong mẫu. Việc xác định methylxanthines trong 7 mẫu chè trong bộ thử nghiệm cho độ chính xác tốt của mô hình PLS. Hệ số tương quan (R2) trong tập dự đoán lần lượt là 0,9582, 0,8894 và 0,9303 đối với theobromine, theophylline và caffeine. Công trình này đã chứng minh rằng phép đo quang phổ phản xạ tia hồng ngoại kết hợp với phép đo hóa học có thể được áp dụng để phân loại nhanh chóng nguồn gốc địa lý và xác định đồng thời các hàm lượng chính trong trà xanh.This paper reported the results of classification of geographic origin and simultaneous analysis of three methylxanthines (caffeine, theobromine, theophylline) in Vietnamese tea samples by the infrared reflectance spectrophotometry coupled with chemometrics. The spectral range was 10,000-4,000cm-1 and each spectrum was measured at 2 cm-1 intervals. For the purpose of geographic origin classification, this study used FT-NIR spectroscopy combined with Partial Least Squares Discriminant Analysis (PLS-DA), and Principal Component Analysis- Discriminant Analysis (PCA-DA). The ability to determine the origin of tea samples in the prediction set of PLS-DA model is 100%. Using the same IR spectral database combined with the partial least squares (PLS), three methylxanthines in tea samples are also quickly quantified. The PLS model based on the spectra of 24 tea samples in which the contents of 3 analytes were determined by high performance liquid chromatography- HPLC) were applied for simultaneous determination of caffeine, theobromine and theophylline in samples. The determination of methylxanthines in 7 tea samples in test set gave the good accuracy of the PLS model. The correlation coefficients (R2) in the prediction set were of 0.9582, 0.8894 and 0.9303 for theobromine, theophylline, and caffeine, respectively. This work demonstrated that infrared reflectance spectrophotometry combined with chemometrics could be applied to rapidly classify the geographic origin and simultaneous determination of main contents in green tea.

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