Sensitive flow-injection technique for the determination of dissolved organic carbon in natural and waste waters

Flow Chemistry in Contemporary Chemical Sciences: A Real Variety of Its Applications

Flow chemistry is an area of contemporary chemistry exploiting the hydrodynamic conditions of flowing liquids to provide particular environments for chemical reactions. These particular conditions of enhanced and strictly regulated transport of reagents, improved interface contacts, intensification of heat transfer, and safe operation with hazardous chemicals can be utilized in chemical synthesis, both for mechanization and automation of analytical procedures, and for the investigation of the kinetics of ultrafast reactions. Such methods are developed for more than half a century. In the field of chemical synthesis, they are used mostly in pharmaceutical chemistry for efficient syntheses of small amounts of active substances. In analytical chemistry, flow measuring systems are designed for environmental applications and industrial monitoring, as well as medical and pharmaceutical analysis, providing essential enhancement of the yield of analyses and precision of analytical determinations. The main concept of this review is to show the overlapping of development trends in the design of instrumentation and various ways of the utilization of specificity of chemical operations under flow conditions, especially for synthetic and analytical purposes, with a simultaneous presentation of the still rather limited correspondence between these two main areas of flow chemistry.

A system for the direct determination of the nonvolatile organic carbon, dissolved organic carbon, and inorganic carbon in water samples through inductively coupled plasma atomic emission spectrometry

A new system has been developed for the determination of total organic carbon (TOC) and inorganic carbon (IC) or total inorganic carbon (TIC) in waters. Only nonvolatile organic compounds can be detected through the present method. The system presented in this work is based on the measurement of the carbon atomic emission intensity in inductively coupled plasma atomic emission spectrometry (ICP-AES). This way, the organic matter does not undergo any preoxidation step. A semiautomatic accessory connected to the spectrometer separates the different carbon fractions (i.e., organic and inorganic). Because most of the solutions used in the present work did not contain suspended solid particles, the actual parameter that was determined was the dissolved organic carbon (DOC). The present system exhibits good sensitivities compared to those provided by conventional TOC and IC determination methods. The limits of detection obtained in the present work have been 0.07 and 0.0007 mg/L C in terms of TOC and IC, respectively. Furthermore, the system is able to handle high-salt-content solutions. This fact suggests that it would be possible to analyze seawater samples, avoiding some of the problems encountered with conventional methods, such as system blocking or interferences. The TOC and IC values found for natural samples are very close to those measured using conventional methods. The ICP-AES method has been successfully used in two interesting applications: (i) monitoring the efficiency of a water treatment plant and (ii) determining the contents of dissolved carbon dioxide, on one hand, and that of carbonate and bicarbonate, on the other, in the same sample.