Recent years have seen a growing interest in “green chemistry”. Unfortunately, analytical chemistry was, until recently, an exception [1].Armenta et al. state that the main principles of green analytical chemistry “are to replace toxic reagents, to miniaturize and to automate methods, making it possible to reduce dramatically the amounts of reagents consumed and wastes generated, so reducing or avoiding side effects of analytical methods” [1].We have previously published articles devoted to automation and miniaturisation of analytical procedures which describe a novel dual-valve sequential injection manifold (DV-SIA) for automated liquid–liquid extraction (LLE) [2] and [3], the application of ultrasound as a replacement for heating [4] and the development of novel dispersive liquid–liquid microextraction (DLLME) procedures for the determination of various analytes [5] and [6].lthough elemental boron has only limited industrial uses, many of its compounds, boric acid and sodium salts of boron in particular, are commonly used in a variety of industries, including the production of herbicides, insecticides and fertilizers and the manufacture of glass, porcelain enamel, ceramic glazes and metal alloys [7], [8] and [9]. Argust [7] and Howe [10] reviewed the distribution [7] and effects of boron in the environment [10]. According to Kot [11], data on the physiological functions of boron are incomplete and frequently contradictory, and published data are both scarce and vague. He therefore reviewed the most current references on the sources, turnover and speciation of boron in the environment and boron's possible effects on human health. Based on evidence from various laboratories, Nielsen states that boron is a bioactive and beneficial element and that some higher animals require it to complete the life cycle [12].Parks and Edwards summarized the chemistry, occurrence and health effects of boron, along with the existing regulations and guidelines for boron and different methods for removing it from drinking water [13]. Minoia and co-workers focused on boron's toxicology and health impacts [14] and [15]. Boron is an essential nutrient for the normal growth of higher plants, and the availability of boron in soil and irrigation water is an important determinant of agricultural production, though if present in excess it becomes toxic for plants [16], [17], [18] and [19].Boron exists in natural waters primarily as undissociated boric acid along with some borate ions. Soils and sediments can adsorb waterborne boron, though this process depends on boron concentration and the pH of the water [9]. The natural content of borate in groundwater and surface water is usually quite small, while boron concentration in fresh water depends primarily on the leaching of boron from the surrounding land as well as from industrial and municipal outflows. Boron concentrations in groundwater have a broad range, from less than 0.3 to over 100 mg L−1. Average concentration in the oceans is 4.5 mg L−1 and ranges in fresh surface waters from <0.001 to 2 mg L−1[9]. Conventional drinking water treatment methods do not typically remove boron from water [9]. According to Council Directive 98/83/EC from 3 November 1998 on the quality of water intended for human consumption, the boron content in drinking water must be no more than 1.0 mg L−1[20].Boron is a difficult element for analysis [11]. Its analytical chemistry has been discussed in a number of books and reviews [21], [22] and [23], while variety of methods have been described for boron determination in water samples [22] and [23], a spectrophotometric method using azomethine-H being the most common utilised. In addition, other methods based on the reaction of boron with a variety of organic reagents have also been suggested. The primary drawbacks of these methods are considered the necessity for separating boric acid through distillation as methyl borate or the need for concentrated sulphuric acid as a reaction medium. As a result, with boron determination special attention must be paid on preventing the escape of volatile boron compounds and contamination of the sample by boron from the glass used in the laboratory. One potential way of developing novel procedures for boron determination could be a method based on the conversion of boric acid to tetrafluoroborate anion followed by ion pair formation with dye reagents and the extraction of the ion pair formed into organic solvent with subsequent spectrophotometric detection [4], [21], [22] and [24].
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