| Green chemistry is a frontier area of chemistry, which has attracted abroad attention. Green analytical chemistry plays an important role in green chemistry. The goal of green analytical chemistry is to use analytical procedures that are safe to environmental. This may be achieved by developing new analytical methodologies that are more environmental friendly. The present study was therefore designed to research on the green analytical chemistry methods of ferrate(VI) and DNA biosensor. The detailed contents are described as follows.(1) Based on the homogeneous chemiluminescence (CL) reaction of luminol oxidized by ferrate(VI), a novel, convenient, environmental friendly, on-line monitoring method was developed to investigate the stability of ferrate(VI) solution. The effects of temperature, pH, additives on the stability of ferrate(VI) solution were traced by flow injection–chemiluminescence (FI–CL) method. It was found that the lowe storage temperature and high pH were the key factors for the stability of ferrate(VI) solution. Na2SiO3 and KI could enhance the synthesis efficiency and the stability of ferrate(VI) solution; NaCl could catalyze the decomposition of ferrate(VI) solution.(2) A convenient anodic pretreatment was established based on the possibility of dissolution of passivation using oxalic acid. Then, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) examinations were used to examine the structure and composition of anode surface, respectively. The high removal efficiency of passivation and the formation of porous structure on anode surface could be observed. These led to significant enhancement of the ferrate(VI) synthesis efficiency. The characteristics of ferrate(VI) solution such as stability and reproducibility were studied by FI–CL method based on the CL reaction of ferrate(VI)–luminol. The CL signal was stable for a week. The relative standard deviation (RSD) was 2.41% for six runs of electrolysis.(3) It was found ferrate(VI) could be successfully electrogenerated in low-concentration NaOH solution for direct analytical application. The characteristic of ferrate(VI) solution is relatively stable at 0±1oC. Luminol chosen as samples was detected by FI–CL method. The detailed analysis and testing revealed that luminol showed a linear CL response in the concentration range of 5.0×10-9 1.0×10-6 mol/L (R2 = 0.9964), with a detection limit (S/N = 3) of 2.5×10-9 mol/L. The RSD for 6 repeated measurements of 3.0×10-7 mol/L luminol was 2.57%.(4) The possibility of direct analytical applications of ferrate(VI) solution, which was freshly electrogenerated in low-concentration NaOH electrolyte, was studied by a FI–CL system. It was found that some inorganic ions, organic molecule and biomolecule could enhance the chemiluminescence emission caused by ferrate(VI)–luminol reaction. V(V), Ca(II), Mg(II), phloroglucinol, and bovine hemoglobin (Hb) chosen as samples were successfully detected by this developed method. The analytical characteristics of the system for the analytes determination including linear ranges, correlation coefficients, limits of detection combined with FI analysis were studied. The limits of detection for V(V), Ca(II), Mg(II), phloroglucinol and Hb were 1.96×10-10, 1.25×10-9, 1.67×10-7, 1.00×10-8, and 1.24×10-12 mol/L, respectively. The RSD for six repeated measurements of 3.92×10-9, 1.25×10-7, 4.17×10-5, 2.00×10-7 and 3.10×10-9 mol/L of V(V), Ca(II), Mg(II), phloroglucinol and Hb were 2.63, 2.38, 1.32, 0.72 and 2.74% , respectively.(5) A novel, eco-friendly, and stable homogeneous luminescent system for capillary zone electrophoresis (CE) detection was established, based on the CL flash caused by mixing ferrate(VI) with luminol solution. To test this CL system, 8-hydroxyquinoline (HQ) was chosen as a modal sample by CE detection. The detailed analysis and testing revealed that HQ showed a linear CL response in the concentration range of 5.0×10-10 5.0×10-8 mol/L (R2 = 0.997), with a detection limit (S/N = 3) of 5.0×10-10 mol/L. For 2.5×10-9 mol/L HQ, when the repeated injections were performed with the same run of electrolyzed ferrate(VI), the RSD of peak height was 1.43% (n = 5).(6) A simple method was proposed to prepare magnetic gold electrodes for DNA hybridization detection. The magnetic gold electrodes displayed several excellent performances such as good electrical conductivity, moderate magnetic field intensity, easy to capture and enrich probe-magnetic beads onto the electrode surface, robust and simple to operate. A thiolated capture probe DNA was self-assembled on gold magnetic nanobeads (GMNBs) by gold-sufur affinity. The probe DNA-GMNBs selectively hybridized with the target DNA. Methylene blue (Mb) was then used as the electrochemical intercalator to indicate DNA hybridization. The target DNA/probe DNA/GMNBs were enriched onto the electrode surface for detection. The peak current of Mb linearly decreased with the concentration of the complementary target DNA over a range from 0.3 to 300 nM with a detection limit of 0.1 nM. Furthermore, the selectivity of this biosensor for DNA hybridization was successfully examined.
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