Summary
The dissertation includes six main chapters:
Chapter One: Is an introduction about amplification reactions. It deals with the principles of some developed amplification reactions for determination of different species with classifications.
Chapter Two: Is a general review of amplification reactions, some analytical methods that are used in this work and aim of the study.
Chapter Three: Describes a simple and sensitive online monitoring amplification method coupled with the flow injection spectrophotometric approach (OMAFIA) for determination of bromate in ozonated bottled water samples. The method is based on the use of two mini-anion exchange columns to amplify bromate anion. It involves a passage of a sample solution containing BrO3– through an OH–– form column to release an equivalent amount of OH–, which is then passed again through a BrO3– form column, and then the released BrO3– is passed back through the first column and so on. After a definite amplification period, a suitable eluent is used to elute the collected amount of bromate anions, and the reaction between the eluted BrO3– and chlorpromazine hydrochloride in an acidic medium produces an intense pink color detected spectrophotometrically at 528 nm. In this method, all conditions were optimized such as the effects of reagent concentration, length of columns, and flow rate …etc. Prior to injection, real samples underwent significant sample pretreatment by using OnGuard Ba/Ag/H cartridge. The concentration range, obeying Beer’s law, was 0.9–200 µg/L with a method limit of detection 0.56 µg/L of BrO3– and a limit of quantification of 1.72 µg/L. The repeatability was satisfactory, with intraday relative standard deviations of 3.66% and 1.23% for 10 and 100 µg/L, respectively, through 10 injections. The amplification method is exceptionally effective for ozonated bottled mineral waters containing bromate compared with ion chromatography as the reference method, which is below the standard level of 10µg/L.
Chapter Four: Includes a rapid and sensitive online monitoring amplification approach combined with a flow injection Chemiluminescence method (OMAFIA-CL) to evaluate bromate in ozonated bottled water samples. The process is composed of two switching valves 6-way to control the flow of sample solution containing BrO3– passing through a Cl– -form column to release an equivalent amount of Cl–, which is then passed through a (BrO3– form) column, and the released BrO3– is passed back through the first column. The amplified amount of bromate anion is eluted by a suitable eluent after a definite amplification period. The eluted BrO3– solution is mixed with NaBr to form bromine solution which gives a blue light CL with an aqueous solution of Luminol/H2O2 in basic medium. Effects of anion interferences and metals were removed before injection by using the Dionex OnGuard (II Ba/Ag/H) cartridges and standing in a strong cation exchange (H+) form resin respectively. The calibration curve with a concentration range of (5-100 μg /L) was linear and techniques limits of detection was (3.9μg/ L) and 12 μg/L of limit of quantification. The RSD for (10 and 80 μg /L, 7 injections) was 1.63% and 0.62 % respectively. The ion chromatography as a reference method was applied. The amplification approach was successful for direct determination of bromate in ozonated bottled waters.
Chapter Five: Includes indirect determination of bromate by an online monitoring amplification by exchange with thiocyanate. The online monitoring amplification reaction coupled with a flow injection spectrophotometric approach (OMA-FIA), the method employs two anion exchange mini-columns. A sample solution containing BrO3– is passed through a Cl– form column to release an equivalent amount of Cl–, which is subsequently passed through a SCN–-form column, and the released thiocyanate is passed back through the first column. After a particular amplification period, the appropriate eluent is used to elute the collected amount of thiocyanate anions. The interaction between thiocyanate swiftly creates a red complex with Fe3+, which can be detected spectrophotometrically at 461.5 nm. The optimizations including effects of reagent concentration, column length, and flow rate during the elution and amplification process, number of cycles and injection volume were carried out. Before injection, real samples are subjected to extensive on-line sample pretreatment with (OnGuard Ba/Ag/H cartridge). Beer’s law was followed for a concentration range of (1-75 µg/L) BrO3–, with detection limit of (0.20µg/L) and quantification limit of (1.52µg/L). For (10, and 50 µg/L, 8 injections), the RSD was 2.08 and1.13 % respectively. When compared with the reference method of ion chromatography, which is below the standard level of 10µg/L, the amplification approach is highly successful for ozonated bottled mineral waters containing bromate.
Chapter Six: contains the recommendation and future works.