**1. Introduction**

420 Macro to Nano Spectroscopy

WHO (World Health Organization) (1999). WHO monographs on selected medicinal plants.

WHO (World Health Organization) (2001). Legal status of traditional medicine and

WHO (World Health Organization) (2002). WHO monographs on selected medicinal plants.

complementary alternative medicine: A world wide review.

Vol 1, Ginebra.

Vol 2, Ginebra.

WHO/EDM/TRM/2001.2, Geneva.

Determination of iron in analytical chemistry has become a routine procedure because of its importance in our life. Various chemical forms of iron can be found in natural waters depending on geological area and chemical components present in the environment. The main source of iron in natural waters is from the weathering and leaching of rocks and soils (Dojlido & Best, 1993). Also, metallic iron and its compounds are used in various industrial processes and may enter natural waters through the discharge of wastes. Iron(II) is normally less present in river water (Sangi et al., 2004) and iron (III) can precipitate rapidly by the formation of hydrous iron oxide and hydroxides, which they can absorb other trace metals. Thus, iron ion controls the mobility, bioavailability and toxicity of other trace metals in the natural water system (Wirat, 2008; Lunvongsa et al., 2006). Amounts of iron are widely present in tap, pond, well and underground water, and this metallic ion is essential for biological systems (Ohno et al., 2004; Kawakubo et al., 2004).

As iron is one of the most frequently determined analyte in environmental (water, soil and sediment) samples, many spectrophotometric and/or flow-injection spectrophotometric methods have been developed for iron determination. When trace levels of the iron are concerned, the detection methods applicable are reduced (Tarafder et al., 2005; Weeks & Bruland, 2002; Giokas et al., 2002; Themelis et al., 2001; Bagheri et al., 2000; Pascual-Reguera et al., 1997; Teshima et al., 1996; Tesfaldet et al., 2004; Udnan et al., 2004; Pojanagaroon et al., 2002; van Staden & Kluever, 1998; Asan et al., 2003, 2008; Andac at al., 2009). Flow-injection analysis, as a rapid and precise technique, has found wide application in the determination of iron in several sample matrices (Bowie A.R., et al. 1998; Hirata S., et al. 1999; Qin W., et al. 1998; Kass M., et al. 2002; Saitoh K., et al. 1998; Weeks D.A., et al. 2002; Giokas D.L., et al. 2002; Themelis D.G., et al. 2001; Bagheri H., et al. 2000; Molina-Diaz A., et al. 1998; Teshima N., et al. 1996).

Highly sensitive, selective and rapid flow-injection spectrophotometric analysis (FIA) methods for the determination of iron (II), iron (III) and total iron will be defined under proposed chapter of the book. The methods were based on the reactions of iron (II) and iron (III) with different complexing agents in different carrier solutions in FIA (Asan A. et al., 2010; Andac M. et al., 2009; Asan A. et al., 2008). Several parameters acting on the

Flow-Injection Spectrophotometric Analysis of Iron (II), Iron (III) and Total Iron 423

soaking in acidified solutions of KMnO4 or K2Cr2O7 followed by washing with concentrated HNO3, and were rinsed several times with high-purity deionized water. Stock solutions and environmental water samples (1000 mL each) were kept in polypropylene bottles containing 1 mL of concentrated hydrochloric acid. Standard iron (II) and iron (III) stock solutions were prepared by solving 278.02 mg of iron (II) and 489.96 mg of iron (III) sulphate (Merck) in 0.01 M 100 mL hydrochloric acid to give 0.01 M stock solution of iron (II) and iron (III). Iron (II) and iron (III) working standard solutions were prepared daily by suitable dilution of stock solutions with double deionized water. Standard reference material consisting of 0.085 % Fe (Zn/Al/Cu 43XZ3F) was provided from MBH Analytical Ltd. (UK). Hydrogen

A stock solution of Morin (5x10-3M) was prepared by dissolving requisite amount of Morin (BDH Chemicals) in 100 mL of ethanol:water (4:96 v/v) because of it's low solubility in water only. For spectrophotometric study, morin complex solutions of various metals were prepared by mixing 1 mL of 1x10-4 M standard solution of each metal in double deionised water with a suitable volume of 1x10-4 M Morin solution. All stock solutions were stored in polyethylene containers. All polyethylene containers and glassware used for aqueous solutions containing metallic cations were cleaned with (1+1) nitric acid while the rest were cleaned with 3 % Decon 90, all were rinsed with deionized water before use. The working standard solutions were prepared by appropriate dilution immediately before use. All solutions were degassed before use using a sonicator (LC 30). Reagent carrier solution was

UV-Visible spectra of metal-AcSHA complexes were taken with a Unicam spectrophotometer (GBC Cintra 20, Australia). A Jenway 3040 Model digital pH-meter was

In the FIA system, peristaltic pump (ISMATEC; IPC, Switzerland) 0.50 mm i.d. PFTE tubing was used to propel the samples and reagent solutions. Samples were injected into the carrier stream by a 7125 model stainless steel high pressure Rheodyne injection valve provided with a 20 L loop. The absorbance of the coloured complex formed (λmax 415 nm) was measured with a UV-Visible spectrophotometer equipped with a flow-through micro cell (Spectra SYSTEM UV 3000 HR, Thermo Separation Products, USA), and connected to a

A UNICAM 929 model (Shimadzu AA-68006) flame atomic absorption spectrophotometer with deuterium-lamp background correction was used for the determination of iron in reference to the FIA method. The measuring conditions were as follows: UNICAM hollow cathode lamp, 10 cm 1-slot burner, air-acetylene flame (fuel gas flow-rate 1.50 L/min), 0.2 nm spectral bandwidth, and 7 mm burner height. The wavelength and the lamp current of

The FIA system used was simple as shown schematically in Fig.2. The sample solution was introduced into the reagent carrier solution by the Rhodyne injection valve. The complex (max=415 nm) was formed on passage of the reagent and iron (II) ion solution through the

buffer (pH:4.50) solution consisting of metanol 4 %.

peroxide solution 30 % (v/v) used was from Merck.

computer incorporated with a PC1000 software programme.

composed of Morin in 0.1 M HAc/Ac-

Fe was respectively 248 nm and 5 mA.

**2.1.3 General procedure** 

used for the pH measurements.

**2.1.2 Apparatus** 

determination of iron (II) and iron (III) were examined. The developed methods have been successfully applied to the determination of iron (II), iron (III) and total iron in water and ore samples. The methods were also verified by applying certified reference materials.
