Novel nanocomposite polymeric membranes for solid phase microextraction of some insecticides and drugs of abuse

Abstract

Forensic science is a discipline that applies scientific analysis to the justice system, often to help prove the events of a crime. Forensic scientists analyze and interpret evidence found at the crime scene. One of the most crucial steps in testing of toxins in biological samples is sample preparation. Traditionally, a pre-analytical isolation procedure to separate drugs from interfering substances in biological matrices is required in HPLC and LC-MS/MS. These instruments need sample preparation, analytes clean up and concentration. Combining unique functionalities afforded by nanoparticles with other functions in one hybrid process can enhance the overall treatment efficiency and remove excessive redundancy. This study is performed to develop a new environmental friendly extraction technique in which analytes of interest are contained in a volume suitable for direct analysis. The present study is divided into three chapters as follows: 1. Chapter I This chapter includes two sections. The first section comprises an introduction about the importance of the extraction process on analyzing the biological samples in forensic analytical chemistry. Furthermore, a brief account about the history of developing the extraction methods up till the usage of membrane science in the extraction procedures. In addition, a short note about the role of nanoparticles in enhancing the physical properties of composite membranes and elevating its adsorption capacity toward some drugs of abuse. As well, brief account on abused drugs problem especially cannabis, tramadol and benzhexol. Also a short note about malathion and chlorpyrifos as a toxic pesticides. The second section includes the literature survey on development of the methods used for extracting drugs from biological samples, including the usage of polymeric membranes as a solid phase extraction technique. Furthermore, the behavior and usage of chitosan, polyvinylchloride (PVC), carboxylated polyvinylchloride (PVC-COOH) and some polymers as adsorbent agent were also tacked in account. The survey also includes preparation methods of silver and palladium nanoparticles and the antimicrobial activity of palladium nano particles. As well it includes preparation and application of nanocomposite polymers and the behaviors of 11-nor-D-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) toward some polymers. The survey threw light also on the determination methods of malathion and chlorpyrifos, the usage of tramadol and benzhexol as abused drugs and method validation. 2. Chapter II This chapter includes the experimental methods, materials and instruments which used in this work. Furthermore, it includes the preparation methods of polymeric membranes, nanoparticles and nanocomposite membranes. In addition, the methods and techniques used for characterization of nanoparticles were discussed in this chapter. As well, the method used to study the antimicrobial activity of the nanopalladium membranes was also mentioned. The extraction and determination methods of tramadol and benzhexol in human blood, the extraction and determination methods of 11-nor- d9-Tetrahydro-cannabinol-9-Carboxylic acid (THC-COOH) in human urine and the extraction and determination methods of malathion in human blood were discussed in detail. Stipulations used to validate the used methods were also dscussed. 3. Chapter III This chapter includes the results and discussions and is divided into three sections: 3.1. Characterization of nanoparticles. The nanoparticles are characterized using two different techniques. The first was UV–visible spectrometry. From this technique a strong, broad peak, observed at around 430 nm for the prepared silver nanoparticles; indicates the formation of metal nanoparticles with size ranging from 2 to 100 nm. The prepared Pd nanoparticles were confirmed by a sharp and strong peak observed at 265 nm indicating nanoparticles with size in the range of 2–30 nm. The second technique was transmission electron microscope (TEM). TEM indicated that silver nanoparticles were in size distribution ranging from 10 to 80 nm with an average particle size of 50 nm. While, Pd nanoparticles were spherical and irregular shapes ranging from 2 to 20 nm with average size of 8 nm. Morphology of palladium nanocomposite membranes and distribution of the palladium nanoparticles within the prepared membranes was evaluated using scan electron microscope (SEM). SEM indicated that blank membranes displayed a smooth and nonporous surface, while the nanocomposite membranes had a rough and porous structure. This result also indicated that the nanocomposite membranes have been chemically modified. Compared to the PVC-COOH, the PVC-COOH/nanopalladium membrane showed a complete inhibition to gram-negative bacteria (E. coli).

3.2 Applications on chitosan membrane In this study, chitosan membrane was used for extracting tramadol and benzhexol from human blood. The extraction method was optimized to satisfy the higher recovery for the extraction method. The optimization parameters include; property of the membranes, effect of pH, extraction time, effect of stirring, ionic strength, membrane thickness and desorption conditions. The results indicated that chitosan/nanopalladium composite membrane establishes the highest extraction recovery. Tramadol and benzhexol reached its optimum recovery at a membrane thickness of o.5 mm, pH 8.5, ionic strength concentration of 0.5M NaCl and 40 min. extraction time.