| Environmental science, life science and information science are dominating the 21st century. All the basic studies and high-tech development in these scientific area need the support of the analytical science, which brought forward new challenges to it. Analytical science has experienced rapid progress in recent years, in particular, in the field of chemically modified electrode, piezoelectric impedance analysis techniques, chromatographic analysis, back-end data processing and modeling algorithms where tremendous theoretical and applicapable achievements were obtained, which had greatly promoted the development in relevant subjects. In this work, the following research works were carried out on the basis of extensive literature investigation.1. An electrochemical sensor for hydroquinone (HQ) usingβ-cyclodextrin/poly (N-acetylaniline)/carbon nanotube composite (P-CD/PAA/MWNTs) modified glassy carbon electrode has been successfully developed. Based on the synergistic effect of MWNTs and conducting PAA polymer and the accumulation effect ofβ-CD, the analytical response of theβ-CD/PAA/MWNTs film to the electrochemical behavior of HQ was better than that of aβ-CD/PAA film, a PAA/MWNTs film, a PAA film, or a bare glassy carbon (GC) electrode. Under the conditions chosen, the anodic currents increased linearly with HQ concentration from 1×10-6 to 5×10-3 mol L-1 and the detection limit was 8×10-7 mol L-1. This electrochemical sensor showed excellent reproducibility, stability and recovery for the determination of HQ.2. Mulilayer films of multiwalled carbon nanotubes (MWCNTs) with molecule recognition function were assembled on glassy carbon (GC) electrode with lower capacitive background current by two steps:first, MWCNTs interacted withβ-cyclodextrin (β-CD) with the aid of sonication to formβ-CD-MWCNTs nanocomposite, then theβ-CD-MWCNTs nanocomposite was assembled on GC electrode using layer-by-layer (LBL) method based on electrostatic interaction of positively charged biopolymer chitosan and negatively charged MWCNTs. The assembledβ-CD-MWCNTs mulitilayer films were characterized by scanning electron microscopy (SEM) and cyclic voltammetry. The SEM indicated that the MWCNTs mulitilayer films withβ-CD were somewhat more compact than the MWCNTs multilayer films withoutβ-CD. The cyclic voltammetric results indicated that the assembled MWCNTs withβ-CD on GC electrode exhibited lower capacitive background current than the assembled MWCNTs withoutβ-CD. The MWCNTs multilayer films withβ-CD were studied with respect to the electrocatalytic activity toward dopamine (DA). Compared with the MWCNTs multilayer films withoutβ-CD, the MWCNTs multilayer films with P-CD possessees a much lower capacitive background current and higher electrocatalytic activity in phosphate buffer, which was ascribed to the relatively compact three-dimensional structure of the MWCNTs multilayer films withβ-CD and the excellent molecule recognition function ofβ-CD.3. A novel method for the simultaneous determination of cadmium (Ⅱ) and copper (II) during the adsorption process onto Pseudomonas aeruginosa was developed. The concentration of the free metal ions was successfully detected by square wave anodic stripping voltammetry (SWASV) on the mercaptoethane sulphonate (MES) modified gold electrode, while the P. aeruginosa was efficiently avoided approaching to the electrode surface by the MES monolayer. And the anodic stripping peaks of Cd2+ and Cu2+ appear at -0.13 V and 0.34 V respectively. At the concentration range of 5-50μM, the peak currents of SWASV present linear relationships with the concentrations of cadmium and copper respectively. As the determination of Cd2+ and Cu2+ was in real time and without pretreatment, the kinetic characteristics of the adsorption process was studied and all the corresponding regression parameters were obtained by fitting the electrochemical experimental data to the pseudo-second-order kinetic model. Moreover, Langmuir and Freundlich models were well described the biosorption isotherms. And there were some differences in the amount of metal ion adsorbed at equilibrium (qe) and other kinetics parameters when the two ions coexisted compared with the unaccompanied condition, which were also discussed in this paper. The proposed electrode system provides excellent platform for the simultaneous determination of trace metals in complex biosorption process.4. The kinetics of chromium (VI) reduction by Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) was studied under both pure and mixed cultures. Initially, the study of kinetics was performed in pure culture. It was observed that the growth of the two bacteria was both inhibited in the presence of chromium (VI). The maximum specific growth rate (μm) of P. aeruginosa decreased from 2.3942 h-1 (without Cr(VI)) to 1.8551 h-1 (with Cr(VI)). Under the mixed culture, the growth of E. coli was inhibited by P. aeruginosa. The maximum specific growth rate (μm) of E. coli decreased form 0.871 h-1 (in pure culture) to 0.153 h-1 (in mixed culture). When the concentration of each bacterium was 4.5×108 cells mL-1, the half-velocity reduction rate constant (Kc) and the maximum specific reduction rate constant (vmax) of chromium (VI) were 80.05 mg chromium (VI) L-1 and 3.674 mg chromium (VI) cells-1 h-1, respectively. The results showed that the simulation appeared in good agreement with the experimental data, supporting the series of mathematical models represented the bacteria growth and chromium (VI) reduction in both pure and mixed cultures usefully.5. A rapid, simple and reliable micellar liquid chromatography (MLC) analytical procedure has been developed for the determination of polyphenols, including chlorogenic acid, rutin and scopoletin, in tobacco samples. After extraction, the polyphenols were analyzed by MLC coupled with UV detection at 340 nm without sample preparation step. The compositions of the micellar mobile phase for the separation of these polyphenols were selected adequately by a chemometric method. The optimal resolution and satisfactory peak shapes were achieved with 0.022 mol L-1 sodium dodecyl sulfate (SDS) and 0.45%(volume fraction) 1-propanol solution at pH 5.0 using Eclipse XDB-C18 (150mm×3.0mm, 5μm) column. The limits of detection (LODs) for chlorogenic acid, rutin and scopoletin were 0.15,0.29 and 0.22μg mL-1, respectively. This validated method was successfully applied to qualitatively and quantitatively analyze the polyphenols in tobacco in less than 10 min.6. In order to reveal the relationship between neutral flavor constituents in tobacco and the quality of tobacco, a quality evaluation method based on neutral flavor constituents and GA-BP neural networks was proposed. Neutral flavor constituents in tobacco was analyzed using steam distillation method:GC-MS analytical techniques, combined with GA-BP neural network chemometrics methods for processing data to establish prediction models. The results showed that the methods of sample pretreatment and instrumental analysis provided a comprehensive and accurate way to analysis neutral flavor constituents in tobacco,76 kinds of important neutral constituents were identified. Genetic Algorithm was used firstly in data-processing stage for features selection,28 kinds of neutral constituents were picked out, which were used in BP network model. Compared with the single BP network model, GA-BP neural networks not only simplified the model but also enhanced the validity of the model. Fitting error of training samples was controlled in less than 2%, and the error of prediction was controlled within 5%. So the whole method can be well applied in quality evaluation of tobacco. 7. Key chemical constituents in more than 200 kinds of tobacco leaf samples were provided by a cigarette factory using a complete set of pretreatment methods and fingerprint analysis techniques. On this basis, relevant metrology algorithms such as feature selection, cluster analysis were used to simplifying and optimizing the component indexes system, the linkage between tobacco organoleptic properties and chemical constituents was established. Tobacco classification and identification were carried out accordingly. Visual Basic programming language were used to programming correlation algorithm, and then established a set of Intelligent System which provided with the functions of tobacco classification, identification of new tobacco leaf, alternative tobacco substitution, intelligent tobacco blending and standard inventory management. This software has the advantage of full-featured, accurate and reliable, nicety and high reliability, flexible program and convenient data complementation.
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