PubMed · 15193114
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
Torsten Vilkner, Dirk Janasek, Andreas Manz. 2004-06-15. Micro total analysis systems. Recent developments.. https://doi.org/10.1021/ac040063q
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Explore the source record for details and available documents.
Tetracycline antibiotics (TCs) such as doxycycline (DOTC), chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline (TC) react with Cu(II) in pH 3.5 BR buffer medium to form 1:1 cationic chelates, which further react with titan yellow to form 2:1 ion association complexes. These result in great enhancement of resonance Rayleigh scattering (RRS) and the appearance of new RRS spectra. The ion association complexes of DOTC, CTC, OTC, and TC have similar spectral characteristics and their maximum RRS wavelengths are all located at 464 nm. The quantitative determination ranges and the detection limits (3sigma) of the four TCs are 0.037-4.8 microg mL(-1) and 11.2 ng mL(-1) for DOTC, 0.041-5.2 microg mL(-1) and 12.4 ng mL(-1) for CTC, 0.050-4.8 microg mL(-1) and 15.1 ng mL(-1) for TC, and 0.088-5.0 microg mL(-1) and 26.3 ng mL(-1) for OTC, respectively. The optimum reaction conditions, the effects of foreign substances, the structure of ternary complexes, and the reaction mechanism are discussed. A sensitive, rapid, and simple RRS method for the determination of DOTC has been developed.
It is a crucial issue to determine the origins of herbal medicinal materials and identify the quality grades and fakes of their final products collected from different pharmaceutical corporations. Pattern recognition technique may assist the manufacturers to achieve this purpose and effectively control the quality of their products. In this work, a widely used method in chemometrics, orthogonal projection (OP) technique, was applied to discrimination analysis and identification of fingerprints of the herbal medicine houttuynia cordata Thunb. (HCT) and its final injection products. The advantages of the OP technique are clearly shown after comparing with the conventional methods such as principal component analysis (PCA), Mahalanobis distance (MD), and similarity comparison method (SCM). Three different sources of medicinal material HCT and its final injection products from six different manufacturers were studied under 'sixfold', 'threefold' and 'threefold-bis' cross-validation procedures. The good performance of the proposed method in determination and identification of unknown samples shows it could be a powerful tool for quality control in herbal medicine production and other related research fields.