508 Journal of Basic & Applied Sciences, 2012, 8, 508-512 ISSN: 1814-8085 / E-ISSN: 1927-5129/12 © 2012 Lifescience Global Dosimetry Characterization of Unknown Dye Polyvinyl Alcohol Films Muhammad Attique Khan Shahid a,* , Noureen Kousar a , Naseem Akhtar b , Taqmeem Hussain a , Mariam Saeed Awan b , Arfa Mubashir b , Bushra Bashir b and Asif Javed b a Department of Physics,GC University, Faisalabad, Pakistan b Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan Abstract: In the present study chemical dosimeters having aqueous solutions of crystal violet commercial dye were irradiated by Co 60  source in the range (0-120)KGy. The standard aqueous solutions were scanned by UV/VIS spectrophotometer for the determination of maximum wave length (max) which was found to be 591nm at this value maximum absorbance was found to be 3.5; it was also observed that with increase in dose, absorbance decreases correspondingly. At this value, the absorbance (A) of irradiated samples was measured in UV region. The plot between concentration C and A gave approximate linear relationship and hence verified Beer’s Law which proved that these dye solutions can satisfactorily be used as the dye dosimeters in 0-120kGy gamma dose range. Keywords: Aqueous solutions, the crystal violet dye, dosimetry, gamma irradiation, Optical density (OD), decolouration. 1. INTRODUCTION Radiation (may be electromagnetic, light photons or ionizing radiations comprised of -photons,  or - particles) is emission and propagation of energy from one point to another from a source to sink. The ionizing radiations can cause biological, chemical as well as physical changes in the exposed matter. So Co 60 - radiation source caused chemical changes in the aqueous solutions of crystal violet commercial dye in the form of increase in the acidity of the sample solutions (a definite clue of gamma interaction with water). The present study dealt to find a new dye dosimeter of its type. Radiation doses are generally measurable with linear response, over absorbed dose ranges between 1 and 10 4 Gy, depending on the initial dye concentration, the pH and the presence of additives as alcohols, buffers and inorganic salts [1-14]. This dye is relatively a cheap dye. The aim of the present work was to explore that the synthetic commercial dye can be used as a dosimeter. It is known that commercial dyes contain pigmentations (colouring substances) which are used to impart colour to the fibres. However, these dyes also have other uses like as chemical dosimeters for high gamma radiation doses [15]. The overall objective of this work was to check for this commercial dye to respond to Gamma radiation like as a dosimeter. Furthermore, the other parameters studied were the effect of dye concentration on the gamma response and the *Address corresponding to this author at the Department of Physics,GC University, Faisalabad, Pakistan; Tel: 0302-6062879; E-mail: profkhan786@yahoo.com verification of Beer’s law in order to find the suitability of this commercially available dye to be used for dosimetric studies in 0-120kGy dose range. C N(CH 3 ) 2 N(CH 3 ) 2 (CH 3 ) 2 N Figure 1: The structure of crystal violet. 2. MATERIALS AND METHODS The stock solution of crystal violet (C 25 H 30 N 3 Cl) dye was prepared by preparing the dye concentrations in de-mineralized water that was collected from Steam Power Station, Faisalabad and had electrical conductivity less than 1μSiemens/cm. The pH of this solution was found to be nearly 7.0. The dye was readily dissolved in water at room temperature because of its high solubility. From the stock solution, different concentrations of the dye such as C 1 =0.019/L, C 2 =0.029g/L and C 3 =0.039g/L were prepared at different pH values. In dosimetric studies, those dye dosimeters are considered to be satisfactory which show a linear relationship between the concentrations (C) of the dye in the solutions and absorbance (A) measured at the primary absorption peak maxima that is actually verification of Beer’s Law [1-14]. For irradiation, the dye solutions were placed in 5 ml glass ampoules having internal diameter 1.03 cm and