| The determination of metal/metalloid contaminants is one of the most important analytical tasks in environmental monitoring. Currently, some of the bulky atomic/mass spectrometric instrumentations, e.g., electrothermal atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma-mass spectrometry, are among the main analytical methods for the quantification of the metal/metalloid species, and it will be so in the future. However, modern analytical sciences require not only high detection sensitivity, precision and analytical throughput, but the miniaturization and automation of analytical instruments have attracted nore and more efforts. Nowadays, field analytical tasks caused by some accidental pollution incidents have to be faced. In this respect, the bulky instruments are out of choice. Therefore, the development of miniaturized instrumentations for specific analytical purposes has been one of the most important momentum in the field of instrumental innovation.Recently, the emergence and development of sequential injection-lab-on-valve (SI-LOV) analytical system has been paid more attention, which has played an important role in the sample pretreatment and miniaturization of analytical systems. SI-LOV not only provides various flexible procedures for sample pretreatment, but also incorporates the detection unit in the module of LOV for fulfilling various analytical tasks. The incorporation/integration of atomic spectrometry into the SI-LOV system is highly promising for the development of miniature atomic spectrometric system, which might open a new avenue for field analysis of metal/metalloid contaminants.In the present dissertation, the SI-LOV system incorporating light source and detector was chose as an analytical platform for the development of miniature atomic spectrometric analytical systems. The miniature spectrometers can be applied to the determination of metal/metalloid species in real samples by employing sample pretreatment in combination with vapor generation technique.Chapter 1 gives an introduction to the updated progress of sequential injection lab-on-valve systems.Chapter 2 investigates the development of a miniature atomic fluorescence spectrometric (AFS) system by integrating a gas-liquid separator and atomic florescence detection unit in the module of LOV. The determination of trace mercury can be achieved by cold vapor generation. With a sample loading volume of 0.5 ml, the detection limit and relative standard deviation of the system for mercury were 0.1μg l-1 (3σ, n=11) and 2.7%(1.0μg l-1, n=7) respectively, within a linear range of 0.3-10.0μg l-1.Chapter 3 proposes a simple procedure for mercury cold vapor generation. Mercury vapor was generated by the reaction with a thin film of NaBH4 solution pre-coated onto the interior surface of the reaction coil, when mercury sample solution flows through the tubing. This procedure not only simplified the hydride generation process in the miniaturized system, but also provided a useful approach for the commercially available atomic fluorescence spectrometric systems.Chapter 4 investigates a new atomization approach for the miniature AFS system by incorporating a dielectric barrier discharge (DBD) atomizer. The entire system integrates a gas-liquid separator, a DBD atomizer and a fluorescence detection unit in a LOV. The analytical performance of the entire system has been investigated by the determination of arsenic. With a sample loading volume of 0.5 ml, the detection limit and relative standard deviation of the system for arsenic were 0.03μg l-1 (3a, n=11) and 2.8%(2.0μg l-1, n=9) respectively, within a linear range of 0.1-5.0μg l-1, which is at the same level as those obtained by employing the present commercial AFS instruments.In Chapter 5, atmospheric pressure dielectric barrier discharge (DBD) is used for the first time as excitation source for optical emission spectrometry, and a miniature optical emission spectrometric system in a micro-sequential injection configuration is developed. The low temperature plasma generated by DBD as a radiation source was used for the excitation of the mercury vapor generated from the sample solution, and the determination of mercury was achieved by the response of a miniature CCD spectrometer. With a sample loading volume of 0.5 ml, the detection limit and relative standard deviation of the system for mercury were 0.2μg l-1 (3σ, n=11) and 2.1%(10.0μg l-1, n=9) respectively, within a linear range of 0.6-50.0μg l-1... |
