tailieunhanh - HPLC for Food Analysis phần 4

Điều kiện sắc ký HPLC phương pháp trình bày ở đây để phân tích dư lượng thuốc trong trứng, sữa, và thịt là dựa trên các đảo ngược pha sắc ký và phát hiện multisignal mảng diode có thể nhìn thấy tia cực tím (UV-DAD). Quang phổ tia cực tím được đánh giá như một công cụ nhận dạng bổ sung. | Chapter 3 Analytical examples of natural components Inorganic anions Anions containing halogen nitrogen and sulfur are used as additives in food industries. For example nitrites act as preservatives in smoked sausage. Nowadays dedicated instrumentation such as special columns and electroconductivity detectors are used in the analysis of inorganic anions. Because specialized equipment has a very limited application range a method was developed for analyzing anionsusing reversed-phase chromatography and indirect UV detection. Another more selective and sensitive approach for the analysis of selected anions is electrochemical detection. Sample preparation Excepting filtration sample preparation normally is unnecessary if the sample is aqueous. Other matrices can be extracted with hot water followed by filtration. Water ACN 1 Isocratic pump Autovacuum sampler degasser Column compartment Variable wavelength detector Control and data evaluation 32 Chromatographic conditions The HPLC method presented here was used for the analysis of anions in drinking water. Sample preparation Column Mobile phase Flow rate Oven temperature Injection volume Detector filtration HP-IC modifiers for the mobile phase are included water acetonitrile ACN 86 14 adjusted to pH with carbonate-free NaOH ml min 40 C 25 pl UV-VWD detection wavelength 266 nm Figure 23 Analysis of anions in drinking water with indirect UV-detection HPLC method performance Limit of detection for UV-VWD ppb with S N 2 and 25 pl injected volume Repeatability of RT over 10 runs areas over 10 runs 1 .