2. SAMPLING AREA Among all the samples presented with other informations, Thankuni and Ulotkambol are collected from Jahangirnagar University campus, and Holud, Shimul and Methi were collected from Savar, and Mashroom was collected from Mashroom Development Centre, and Bohera was collected from Bangladesh Livestock Research Institute. All the three spots are situated at Savar Upozila under Dhaka district.
It is almost situated in the central region of Bangladesh and is located at 23°51′30″N latitude and 90°16′00″E longitude, and is about 24 kilometres away to the northwest of Dhaka city. The Upazila encompasses about 280.12 km2 area and most of which are used in industrial purposes. It’s soil is mainly acidic with small rocks and yellowish to reddish in colour. In summer temperature is very high and April is found the hottest month with a maximum temperature of 33.90. January is the coldest month with minimum temperature 14.10. Humidity keeps remain in between 55-78% (source: Meteorological Dept., Dhaka). There are many canals and ponds in Savar area but all are intoxicated with industrial dumping. In rainy season the pollution gets mild and acidic behaviour of soil also reduced. That’s why samples were collected in rainy season.
2.1. SAMPLE PREPARATION Six frequently used medicinal plants were collected and prepared carefully as no contamination can introduce further during the process. Thankuni, Ulotkambol and Mashroom samples were dried with temperature (50-80) 0C for 48 hours, while the other four were dried with temperature of about 90 0C for about 100 hours with an oven “Memmert Schutzart DIN 40050 – IP 20”. After ensuring about the complete dry and moisture free, the samples were grounded into powder with a mortar-pester to avoid chromium contamination from stainless steel devices. Again, in order to avoid cross contamination, after grinding each sample, the pester was cleaned with acetone (CH3- CO-CH3). Each sample powder was then pelletized into pellet of 7 mm diameter and 2 mm thickness using hydraulic press with pressure 125 kg/cm2.
2.2. METHODOLOGY Among different analytical methods available in this technological age, such as atomic absorption, neutron activation technique, atomic emission, mass spectrometry, ion beam analytical (IBA) technique and chemical and electro analytical methods, a particular technique ion beam analytical technique has been selected. IBA technique is multi elemental and sensitive. Moreover, IBA methods are nondestructive means collected samples may be archived for future work or for regulatory purposes. The technique involves the use of energetic ion beam to study the surface of a specimen to reveal details of the elemental details of its makeup. When high-energy charged particles hit a target there is a possibility of happening so many processes, such as Rutherford Back Scattering (RBS), Proton Induced X-ray Emission (PIXE), Proton Induced Gamma-ray Emission (PIGE), Nuclear Reaction Analysis (NRA) and Scattering Transmission Ion Microscopy (STIM). Among them PIXE is important and widely used analytical technique at MeV energy accelerator. The energetic proton beam from the accelerator tube hit the sample which causes X-ray emission is proportional to the mass of corresponding element in the sample being analyzed [7-8]. In our study, PIXE spectroscopy is carried out at 3 MV Van de Graff accelerator, Atomic Energy Center, Dhaka (AECD).
2.3. IRRADIATION AND DATA COLLECTION All the pelletized medicinal plant samples were irradiated with 2.5 MeV collimated Proton beams at the current intensity range of (10-20) nA using a 3 MV Van de Graff accelerator. The emitted X-rays in the irradiation were detected by using [Si(Li)] detector and the MAESTRO software was used to collect and save the signals in a specific file format(ORTEC).
2.4. DATA ANALYSIS In PIXE method the data of different elements were assessed by analyzing the peaks from the spectrum saved by MAESTRO software of different X-rays by using GUPIX database [9]. GUPIX software was used to analyze PIXE spectra because of its good status of the databases, such as cross-sections, fluorescence and Coster–Kronig probabilities, stopping powers and attenuation coefficients. The measured concentrations of the elements of the sample were calculated.