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Query: KEGG:D01931 (TiO2)
 11,320 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new post-column photolysis technology has been developed based on the use of a low pressure, low temperature UV lamp and TiO2 coated knitted reaction coil. As a test case the developed technique was used for the determination of 3-nitro-L-tyrosine by liquid chromatography with electrochemical detection. Different photolysis lamps and reactor tubing lengths were evaluated in terms of their effect on the separation efficiency and/or photolysis efficiency. A detection limit of 0.5 nM (10 fmol) for 3-nitro-L-tyrosine was achieved under optimized conditions, with a linear correlation coefficient of R2 = 0.9898 over a concentration range of 2-100 microM. Pre-injection photolysis of 3-nitro-L-tyrosine indicated that dihydroxyphenylalanine is the main photolysis product. In general, use of the photoreactor prior to liquid chromatography is an excellent method for exploring photodegradation products of an analyte in conjunction with the full range of available liquid chromatography detectors.
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PMID:Optimization of post-column photolysis and electrochemical detection for the liquid chromatographic determination of 3-nitro-L-tyrosine. 977 Mar 5

Titanium (Ti) and TiO, Ti2O3, Ti3O5 and TiO(1.98) as well as TiO2 have been evaluated as chemo-affinity sorbents for the selective enrichment of organic phosphates. A column-switching high-performance liquid chromatography (HPLC) system, constructed with a precolumn (4.6 mm i.d. x 10 mm) packed with the titanium sorbents, an anion-exchange analytical column and a UV detector (215 nm) was used. When an aqueous 0.015% trifluoroacetic acid (TFA) was used as a sample-loading solution, O-phospho-L-tyrosine (P-Tyr), phenyl phosphate and phenylphosphonic acid were adsorbed onto all of the titanium sorbents with recoveries of 60.9 - 102.9%. Some acidic compounds other than phosphates, such as benzenedicarboxylic acid (BDA) isomers, were also adsorbed onto all of the titanium sorbents. To improve the selectivity to organic phosphates, various sample-loading solutions were examined using a Ti precolumn, two phosphorylated peptides [Ile-Ser(p)-Val-Arg (PP1) and Gln-Ile-Ser(p)-Val-Arg (PP2)], P-Tyr, BDA isomers and diglutamic acid (Glu-Glu) as test compounds. Among the sample-loading solutions tested, such as TFA, HClO4, organic acids, boric acid and NaCl, the use of 100 mM NaCl in 10 mM boric acid was found to be effective. The recoveries of PP1, PP2 and P-Tyr were 73.0, 88.3 and 71.5%, respectively, whereas those of Glu-Glu and BDAs were suppressed to only below 10%.
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PMID:Evaluation of titanium and titanium oxides as chemo-affinity sorbents for the selective enrichment of organic phosphates. 1799 46