Journal of chromatography. A
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This paper is the first in a series of consecutive publications, explaining the concept of high-temperature liquid chromatography under various important aspects. The first publication deals with the determination of the vapour pressure of binary solvent mixtures used in reversed-phase liquid chromatography. Also, the practical implications regarding the use of elevated temperatures in liquid chromatography and towards commercially available HPLC systems are explained.
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In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) method for multielemental speciation of organometallic compounds of mercury, lead and tin in water samples was upgraded by the introduction of tandem mass spectrometry (MS/MS) as detection technique. The analytical method is based on the ethylation with NaBEt(4) and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC-MS/MS analysis. The main experimental parameters influencing the extraction efficiency such as derivatisation time, extraction time and extraction temperature were optimized. ⋯ The proposed method presented good linear regression coefficients (r(2)>0.9970) and repeatability (4.8-21.0%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked river water and seawater samples was higher than 80% for all the compounds studied, except for monobutyltin in the river water sample. A study of the uncertainty associated with the analytical results was also carried out.
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The gas chromatographic profiles of exhaled air from lung cancer patients have been investigated. The breath from healthy volunteers, smokers and non-smokers, and lung cancer patients without treatment and under radio and/or chemotherapy, was collected using Tedlar bags. Different profiles for healthy people and cancer patients could be recognized by multivariate analysis and significant diagnostic compounds could be established. ⋯ The method showed good precision (RSD below 26%) and limit of detection ranged from 0.04 to 8.0ppb. These findings show a high potential for establishment of laboratorial screening methods. Validation studies in a larger number of patients are being done.
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Review
Chemical analysis and quality control of Ginkgo biloba leaves, extracts, and phytopharmaceuticals.
The chemical analysis and quality control of Ginkgo leaves, extracts, phytopharmaceuticals and some herbal supplements is comprehensively reviewed. The review is an update of a similar, earlier review in this journal [T. A. van Beek, J. ⋯ More research in this direction is clearly needed. For the analysis of Ginkgo proanthocyanidins (7%) for instance, no reliable assays are yet existing. Finally the growing literature on pharmacokinetic and fingerprinting studies of Ginkgo is briefly summarised.
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Flavonoids in plants used for the treatment of various cardiovascular, cancer diseases have been reported to possess potential protective effects against oxidative injury. Ginkgo biloba leaves, known for their antioxidant activity, were chosen for this study. In this paper, 12 flavonoids in G. biloba leaves were identified by HPLC-diode array detection (DAD)-electrospray ionization MS. ⋯ It was found that the flavonol glycosides could markedly inhibit the luminescent signal, which indicated that they are mainly responsible for the antioxidant activities of G. biloba leaves. Total antioxidant activity of these flavonoids was used to evaluate the differences of G. biloba leaves collected in 13 habitats. The combination of chemical and activity analysis can provide a valid method to quantify the bioactive components in G. biloba leaves, and this may be a more rational approach to the quality assessment of G. biloba leaves.