HPLC of Amino Acids and Oligopeptides by Pre-Column Fluorescence Derivatization with 9-Acridine Formyl Chloride

A highly sensitive HPLC method for the detection of amino acids and oligopeptides with 9-acridine formyl chloride by pre-column fluorescence derivatization has been developed. Glycine, glycylglycine, histidine, triglycine and glutathione were separated on a reversed-phase C-18 column with methanol-water-triethylamine eluent, derivatization and chromatographic conditions were optimized. The five derivatives were eluted in 28 min with a good reproducibility. Linear range of the calibration graph was 0.08-260 nmol/ml(-1). The relative standard deviations(n=6) are < 5%. Detection limits (signal-to-noise ratio=3) for the five derivatives are 20-40 fmol.

HPLC Determination of Amino Acids by Pre-Column Fluorescence Derivatization with Carbazole-9-yl-Acetyl Chloride

A sensitive HPLC method for the detection of amino acids with pre-column fluorescence derivatization with carbazole-9-yl-acetyl chloride has been developed. This method, in conjunction with a multi-gradient program, offers baseline resolution of the common CRAC-amino acids from a linear acetonitrile gradient. Separation of amino acid derivatives was obtained on a reversed-phase C-18 column. Derivatization and chromatographic conditions were optimized. Amino acid derivatives were eluted in 40 min with good reproducibility. The relative standard deviations (n=6) at an analytical concentration of 100 pmol are < 4%. The methods described are also suitable for the analysis of amino acids in different biological samples.

Determination of Selenium in Water by Vortex-Assisted Cloud-Point Extraction Combination with Fluorescence Detection

A simple vortex-assisted cloud-point extraction(VA-CPE)method combined with the fluorescence(FL)strategy was developed to extract and determine inorganic Se(IV)in environmental water.Toluene was used as an extraction reagent,and Se(VI)was reduced to Se(IV)by subjecting its solution in 4 mol/L HCl to microwave heating for generating a yellow piazselenol complex using 3,3'-diaminobenzidine(DAB)and Se(IV).The concentration of the complex exhibited an excellent linear relation with the FL at 560 nm with an excitation wavelength of 420 nm.In addition,the effects of the toluene volume,pH,and VA-CPE parameters were investigated and the interference from coexisting ions was also studied.This method was successfully applied to determine the concentration selenium in environmental water samples with a detection limit of 0.05μg/L in the line range from 0.50μg/L to 50.00μg/L.

Synthesis and optical behaviors of 6-seleno-deoxyguanosine

We have developed a simple method to synthesize 6-seleno-2′-deoxyguanosine(SedG)by selectively replacing the 6-oxygen atom with selenium.This selenium-atom-specific modification(SAM)alters the optical properties of the naturally occurring2′-deoxyguanosine(dG).Unlike the native dG,the UVabsorption ofSedG is significantly influenced by the pH of the aqueous solution.Moreover,SedG is fluorescent at the physiological pH and exhibits pH-dependent fluorescence in aqueous solutions.Furthermore,SedG has noticeable fluorescence in non-aqueous solutions,indicating its sensitivity to environmental changes.This is the first time a fluorescent nucleoside by single-atom alteration has been observed.Fluorescent nucleosides modified by a single atom have great potential as molecular probes with minimal perturbations to investigate nucleoside interactions with proteins,such as membrane-transporter proteins.