1. INTRODUCTION:

The linear and mass attenuation coefficient is an important parameter, which is widely used in industry, agriculture, science, and technology, etc. [1]. With wide spread utilization of radiation and radioisotopes in medicine, industry and basic sciences, the problem of radiation protection has become important aspect while handling radiation sources and radiation generating equipments [2]. However the ill effects and hazards of radiation, especially the high energy gamma radiation, are well known. Hence the person using the radiation technology, the workers and the public around must be protected or shielded from these radiations [3]. The interaction of gamma radiations with the materials of common and industrial use, as well as of biological and commercial importance has become major area of interest in the field of radiation science.

A proper characterization and assessment of penetration and diffusion of gamma rays in the external medium is necessary for a scientific study of interaction of radiation with matter. The mass attenuation coefficient (usually depends upon the energy of radiations and nature of the absorbing material) plays very important role for characterization and penetration of gamma radiation in any medium. Attenuation measures gradual loss in the intensity of any kind of flux through a medium. Attenuation is a negative exponential function of the path length through the medium. Attenuation coefficient gives us the fraction of energy scattered or absorbed [4].

Teli and Chaudhari [5-8] determined their research work on gamma ray mass attenuation coefficients of salts magnesium chloride, zinc sulphate and ferrous sulphate at energies 123 keV and in the form of solutions. Hubbell [9] has compiled an extensive data on mass attenuation coefficients of gamma rays in some compound and mixtures of dosimetric interest in the energy range of 1 keV to 20 MeV. Hubbell and Seltzer [10] have compiled an updated version of attenuation coefficients for elements having atomic number from 1-92 and for 48 additional substances. Similar findings were by Carlsson, Cunningham, Jahagirdar, Singh and Bradley [11-15] has conducted systematic studies of attenuation coefficients from time to time. The mixture rule developed by them can be applied to measure the mass attenuation coefficients of substances, with a greater accuracy, in the form of the solution [16-17]. The solution method has thereafter been used for measuring mass attenuation coefficients of several salts, some amino acids, sugars, and starches [18]. For materials composed of various elements, one may assume that the contribution of each element to the total interaction of the photon is additive “Mixture Rule” [19]. In accordance with this rule, the total mass attenuation coefficient of a composite is the sum of the weight proportion of each individual atom present in it [19].

Therefore:

In which: (μ/ρ) comp is the mass attenuation coefficient for the composite, (μ/ρ)i is the mass attenuation coefficient of each individual element and wi is the fractionated weight of the elements in the composite. The weight fractions of each element present in the biomaterials samples were determined by analytical means mentioned above.

1.1 Importance of organic acids:

Organic acids are involved in the regulation of a broad range of basic cellular processes, e.g. the modification of cellular pH or the redox state. Therefore, it makes sense that these compounds also play a role in the control of various biochemical and physiological processes in vivo. As extensively analyzed in the case of sugars, a role of organic acids as signaling messengers is emerging [20], as well as a role as modulators of the transport across biological membranes [21-23].

1.1.1 Salicylic Acid:

It is an organic compound with the formula C₇H₆O₃, name derived from Salix (Latin name for the willow tree). Organic compound-chemically synthesized and biosynthesized. Functions as a hormone in plants-defense against pathogens. Vast array of benefits and uses. Applications in food chemistry, textiles, medicine, cosmetics, dermatology. Food Chemistry- preservative. Textiles- synthesis of dyes; used for its antibacterial properties. Medicine- relieve fever and pain.

Cosmetics- preservative; has exfoliating and cleansing properties. Dermatology- seborrheic dermatitis, viral warts, psoriasis, acne vulgaris, and more 4000 BC - Assyrians used the extracts of willow leaves to treat painful musculoskeletal joint pain conditions, as well as an antipyretic drug to reduce fever.

1.1.2 Citric acid:

It is an organic compound with the formula C₆H₈O₇. Knowledge of the citric acid content of beverages may be useful in nutrition therapy for calcium urolithiasis, especially among patients with hypocitraturia. Citrate is a naturally-occurring inhibitor of urinary crystallization; achieving therapeutic urinary citrate concentration is one clinical target in the medical management of calcium Urolithi as is. When provided as fluids, beverages containing citric acid add to the total volume of urine, reducing its saturation of calcium and other crystals, and may enhance urinary citrate excretion. Information on the citric acid content of fruit juices and commercially-available formulations is not widely known. We evaluated the citric acid concentration of various fruit juices.

1.1.3 Cinnamic acid:

It is an organic compound with the formula C₆H₅CHCHCO₂H. It is a white crystalline compound that is slightly Soluble in water, and freely soluble in many organic solvents. Classified as an unsaturated Carboxylic acid, it occurs naturally in a number of plants. It exists as both a cis and a transisomer, although the latter is more common.

Uses:

Cinnamic acid is used in flavors, Synthetic indigo and certain pharmaceuticals. A major use is in the maufacturing of the methyl, ethyl, and benzyl esters for the perfume industry. Cinnamic acid is a precursor to the sweetener aspartame via enzyme-catalysed amination to phenylalanine. Cinnamic acid can dimerize in non-polar solvents resulting in different linear free energy relationships Cinnamic acid is also a kind of self-inhibitor produced by fungal spores to prevent germination.

1.1.4 Oxalic acid:

It is an organic compound with the formula C₂H₂O₄. It is a colorless crystalline solid that forms a colorless solution in water. Its condensed formula is HOOCCOOH, reflecting its classification as the simplest dicarboxylic acid. Its acid strength is much greater than that of acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate (C₂O₂-₄), is a chelating agent for metal cations. Typically, oxalic acid occurs as the dihydrate with the formula C₂H₂O₄·2H₂O. Excessive ingestion of oxalic acid or prolonged skin contact can be dangerous. Oxalic acid is used as bleach for wood, removing black stains caused by water penetration.

Content in food items: About 25% of produced oxalic acid is used as a mordant in dyeing processes. It is used in bleaches, especially for pulpwood. It is also used in baking powder and used as a third reagent in silica analysis instruments.

The present work deals organic acids (C₁–C₇), they are widely distributed in nature as normal constituents of plants or animal tissues. They are also formed through microbial fermentation of carbohydrates mainly in the large intestine. They are sometimes found in their sodium, potassium or calcium salts or even stronger double salts [24]. So, we made attempt to investigate some of the organic acids with the linear and mass attenuation coefficient such as Salicylic Acid, Citric acid, Cinnamic acid and Oxalic acid after dry for beta rays of source Cs has been studied. Organic acids are used in food preservation because of their effects on bacteria [25]. With these points in consideration the experiments for measurement of mass attenuation coefficient have been taken to the unexplored frontiers of biophysical science.

2. MATERIALS AND METHODS:

Initial setup made with standard connections and arrangement between NaI (TI), detector, absorber and source. Beta source in the source tray at about 2 cm from the end window of NaI (TI) scintillation detector. Set the experiment was performed at the Radiation Application Laboratory at Central Instrumentation Centre at Mangalore University, Mangalore, Karnataka, India. The experimental setup in the present work is shown in figure-1.

The gamma rays are well collimated using collimators of cylindrical shape and a circular aperture of 6mm diameter between the source and the detector. NaI (TI). Place the absorber (organic compound) between end window detector and source holder containing eight absorbers of respective thickness. We are taken the reading for a present time of 1000 seconds without any absorber, tabulate and repeated the experiment by recording the data stored for the same present time for different thickness in the increasing order. Repeat the same steps as explained above for next absorber sets of organic acids. Plot the graph of ln (No/N) Vs thickness of absorber. The slope graphs gives as linear absorption coefficient and for mass attenuation coefficient first calculate density of absorber by taking mass and area of absorber. The ratio of linear mass coefficient to the density of absorber gives the “Mass Attenuation Coefficient” of respective absorber.

The signal is detected by NaI (Tl) scintillation detector of 3×3 inch crystal and a high bias voltage of 1000 volts. A lead shield surrounds the detector to reduce the undesired external radiation. The weak detector pulse enters the preamplifier (or preamp.), the pulse then enters the linear amplifier which has two main functions, pulse shaping and amplitude gain, for which the multi-channel analyzer has been designed. The amplified pulse is then fed to the Multi-Channel Analyzer (MCA), which converts the analog signal into a digital through an analog to digital converter (ADC). The energy and the efficiency of the system were calibrated using a certified standard source.

The sample was exposed to 662.16 KeV photons emitted by Cs¹³⁷ radioactive point sources, respectively. Io and I are the intensities before and after attenuation were measured by a high resolution NaI (Tl) detector. The sample was placed between the source and the detector, the distance between the radioactive point source with sample and the sample to detector was 12cm and 4cm, respectively. The measurements for the sample were carried out for five times for each energy value. Photon spectra were recorded in the following order firstly, source spectrum recorded with source but without sample and the incident spectrum (without attenuation) I₀ was obtained. The transmitted spectrum recorded with source and sample I (after attenuation) was obtained. In both the spectra the photo-peak had Gaussian distribution. The peak areas have been calculated from the spectrum obtained for each measurement. The each spectrum was recorded for sufficient time (30 min) to accumulate an adequate number of counts under the photo peak. In this work, Io (without attenuation) and I (after attenuation) intensity measurements and μm calculations were carried out for the photon energies (1173keV).

Further graph of absorbance versus thickness of each organic compounds, the slope of the graph gave value a straight line, which showed that the absorbance followed exponential law with respect to thickness. The slope of graph gave value of linear absorption coefficient for particular sample. The unit of linear absorption coefficient so obtained is cm^-1.Therfore the mass attenuation coefficient was calculated by dividing linear absorption coefficient with its measured density. The mass attenuation coefficient thus obtained has unit cm³.g.cm^-1 or cm²/g.

3. RESULTS AND DISCUSSION

Experimental block diagram:

Experimental study of the linear and mass attenuation coefficients values were measured for the Different organic compounds samples by using Cs¹³⁷ sources. The measured values were found to be in well, as per the agreement with mixture rule. The linear attenuation coefficient of organic acids like Citric acid is greater than Salicylic acid, Cinnamic acid and Oxalic acid. The difference between Citric acid and Oxalic acid that is contain of organic compounds. This research method is very useful for systematic study in basic sciences to know applied aspects of research area. The results valid the gamma absorption law total attenuation cross sections of the organic compounds obtained from an accurate database of photon-interaction cross section are listed in Table 1,2,3 and 4.The chemical compositions of the organic acids studied in the present work are shown in graph 1, 2, 3 and 4.

The experimental mean value of mass attenuation coefficients for medicinal plants at five photon energies are presented in all the Tables of the organic acid sample. Using the chemical analysis method the following different percentage of the Citric acid, Cinnamic acid, Oxalic acid and Salicylic acid are found in different concentration of the organic acids. These percentages are then used to calculate the theoretical values of the organic acids and are presented after each experimental values of mass attenuation coefficient in Table1, 2, 3 and 4. These values are utilized for plotting the graph. Another interesting point to discuss from Figure 1, 2, 3 and 4 is that; graph of ln (Energy) against ln(mass attenuation) yields a straight line, showing the variation of the attenuation coefficient with energy. This is linear irrespective of the elements present, provided that the sample does not contain an element whose k shell binding is not close to the incident photon energy, in which case, the graph would show a deviation from linearity. Hence the measured value of the linear and mass attenuation coefficient will give at least, in a broad sense, that the sample is uniformly prepared the values in the true values at these energies.

Table 1: Linear and Mass attenuation coefficient, mean free path and total atomic number of Citric acid

Sample No	Pellet mass (gm)	t gm/Cm²	Net area under peak	Count rate N	In (N)
01	0.20	0.15	837849	2796.37	7.93
02	0.25	0.18	799769	2651.40	7.88
03	0.30	0.22	767765	2559.90	7.84
04	0.33	0.24	743992	2478.82	7.81
05	0.38	0.28	729405	2403.39	7.78

Figure1: Ln (N ) for various thickness of Citric acid by suing source Cs

Table 2: Linear and Mass attenuation coefficient, mean free path and total atomic number of Cinnamic Acid

Sample Name	Pellet mass (gm)	t gm/Cm²	Net area under peak	Count rate N	In (N)
01	0.05	0.03	17656	58.85	4.07
02	0.10	0.07	17464	58.21	4.06
03	0.15	0.11	17100	57.00	4.04
04	0.20	0.15	17445	58.15	4.03
05	0.25	0.18	17219	57.40	4.05

Figure 2. Ln (N ) for various thickness of Cinnamic acid by suing source Cs

Table 3. Linear and Mass attenuation coefficient, mean free path and total atomic number of Oxalic acid

Sample Name	Pellet mass (gm)	t gm/Cm²	Net area under peak	Count rate N	In (N)
01	0.15	0.11	17953	59.84	4.09
02	0.20	0.15	17727	59.09	4.079
03	0.25	0.18	17679	58.62	4.071
04	0.30	0.22	17586	58.93	4.070
05	0.35	0.26	17520	58.40	4.067

Figure 3: Ln (N ) for various thickness of Oxalic acid by suing source Cs

Table 4. Linear and Mass attenuation coefficient, mean free path and total atomic number of Salicylic acid

Sample Name	Pellet mass (gm)	t gm/Cm²	Net area under peak	Count rate N	In (N)
01	0.20	0.15	17774	59.24	4.081
02	0.25	0.18	17157	57.19	4.046
03	0.30	0.22	17085	56.95	4.042
04	0.35	0.26	16926	56.42	4.032
05	0.40	0.30	16892	56.24	4.029

Figure 4: Ln (N ) for various thickness of Salicylic acid by suing source Cs

4. CONCLUSION:

The linear and mass absorption coefficients values were measured for the compounds of organic acid sample by using Cs sources. The measured values were found to be in well and agreement with the mixture rule. The linear and mass attenuation coefficient of Citric acid sample is greater than Salicylic Acid, Cinnamic acid and Oxalic acid and possess numerous biological application in Food Chemistry, Textiles, Medicine, Cosmetics, Dermatology etc. This research method is very useful for systematic study in basic sciences and also in applied research. The results valid the gamma absorption law and considered as an absorber have been measured with great accuracy in view of the determination of effective atomic number and electron density.

5. ACKNOWLEDGEMENT:

The authors wish to record their heartfelt gratitude and thanks to Radiation Application Laboratory at Central Instrumentation Centre at Mangalore University, Mangalore, Karnataka, India.

REFERENCES:

1. Terra F.S., Effect of γ radiation on some physical properties of the spinel ferrite system Ni_0.65Zn_0.35Cu_xFe_2−xO₄. Mod. Phy. Letters, B8 (28), 1781 (1997). doi.org/10.1142/S0217984994001692.

2. Tupe V.A., Pawar P.P, Shengule D.R. and Jadhav, K.M, Studies on Mass and linear attenuation coefficients of γ- rays of photons for Ag in the energy range 360-1330 keV. J. Chem. Pharm. Res., 4(9), 4185-4191(2012).

3. Chaudhuri L.M. Study of attenuation coefficients of leaves of Asoka plant by using Cs and Tl sources. Res. J. Phys. Sci., 1(2), 1-8, (2013).

4. Kumar R. and Kaur B. Gamma ray attenuation technique for measuring water content and density of selected wood samples. J. Chem. Biol. Phy. Sci., 6(1) 135-144 (2016).

5. Teli M.T., Chaudhari L.M. and Malode S.S. Attenuation coefficients of 123 keV gamma radiation by dilute solution of sodium chloride. Appl. Rad. Isotop., 45(10), 987-990 (1994). doi:10.1016/0969-8043(94)90166-X.

6. Teli M.T., Chaudhari L.M. and Malode, S.S. Study of absorption of 123 keV gamma radiation by dilute solution of zinc sulphate. Ind. J. Pure Appl. Phy., 32(5), 410-412 (1994).

7. Teli M.T. and Chaudhari L.M. Attenuation coefficient of 662 keV gamma radiation by dilute solutions of sodium chloride. Appl. Rad. Isotop., 46(5), 369-370 (1995). doi:10.1016/0969-8043(94)00148-S.

8. Teli M.T. and Chaudhari L.M. Linear attenuation (or absorption) coefficient of gamma radiation in dilute solutions of potassium chloride. App. Rad. Isotop., 47(3), 365-367 (1996). doi:10.1016/0969-8043(95)00305-3.

9. Hubbell J.H. Photon mass attenuation and energy absorption coefficients from 1 keV to 20 keV. Appl. Rad. Isotop., 33(11), 1269-1290 (1982).

10. Hubbell J.H. and Sheltzer, S.M. Tables of X-ray mass attenuation coefficient and mass energy absorption coefficients 1 keV to 230 MeV for elements z=1 to 92 and 48 additional substances of dosimetric interest. NISTIR, 5632 (1995).

11. Carlsson G.A. Absorbed dose equations, on the derivation of a general absorbed dose equation and equations valid for different kinds of radiation equilibrium. Rad. Res., 85(2), 219-237 (1981). (doi: 10.2307/3575556).

12. Cunningham J.R. and Johns H.E. Calculation of the average energy absorbed in photon interactions. Med. Phy., 7(1), 51-54 (1980). doi: 10.1118/1.594658.

13. Jahagirdar H.A., Hanumaiah B. and Thontadarya B.R. Determination of narrow beam attenuation coefficients from broad beam geometrical configuration for 320 keV photons. Appl. Rad. Isotop., 43(12), 1511-1514 (1992). doi:10.1016/0883-2889(92)90180-M.

14. Singh K., Bal H.K., Sohal I.K. and Sud S.P. Measurement of absorption coefficients at 662 keV in soil samples. Appl. Rad. Isotop., 42(12), 1239-1240 (1991). doi:10.1016/0883-2889(91)90205-F.

15. Bradley D.D., Chong C.S., Shukri A., Tajuddin A.A. and Ghose A.M. A new method for the direct measurement of the energy absorbtion coefficient of gamma rays. Nucl. Inst. Meth. Phys. Res., (Section A), 280(2-3), 392-394 (1989). doi:10.1016/0168-002(89)90939-X.

16. Gerwad L. Comments on “attenuation co-efficients of 123 KeV gamma radiation by dilute solutions of sodium chloride”. Appl. Rad. Isotop., 48(6), 871-872 (1997). doi:10.1016/S0969-8043(97)88609-5.

17. Gerward L. On the attenuation of X-rays and gamma rays in dilute solutions. Rad. Phy. Chem., 47 (6): 697 (1996). doi:10.1016/S0969-806X(96)00131-4.

18. Teli M.T. On the attenuation of X-rays and gamma rays for aqueous solutions of salts. Rad. Phys. Chem., 53(6): (1998). doi:10.1016/S0969-806X(97)00275-2.

19. Morabad R.B. and Kerur B.R. Mass attenuation coefficients of X-rays in different medicinal plants. Appl. Rad. Isotop., 68(2): 271-274 (2010). doi.org/10.1016/j.apradiso.2009.10.033

20. Finkemeier I., König A.C., Heard W., Nunes-Nesi A., Pham P.A., Leister D., et al. Transcriptomic analysis of the role of carboxylic acids in metabolite signaling in Arabidopsis leaves. Plant Physiol., 162 (1), 239–253 (2013).doi: 10.1104/pp.113.214114.

21. Hedrich, R., and Marten, I. Malate-induced feedback regulation of plasma membrane anion channels could provide a CO2 sensor to guard cells. The EMBO J., 12 (3), 897–901 (1993).

22. De Angeli A., Zhang J., Meyer S., and Martinoia E. AtALMT9 is a malate-activated vacuolar chloride channel required for stomatal opening in Arabidopsis. Nat. Communi., 4, 1804 (2013). doi: 10.1038/ncomms2815

23. Drincovich M.F. Voll L.M., and Maurino, V.G. Editorial: On the Diversity of Roles of Organic Acids. Front. Plant Sci., 7:1592 (2016). doi: 10.3389/fpls.2016.01592

24. Patanen K.H. and Mroz Z. "Organic acids for preservation". In Block, S. S. Disinfection, sterilization and preservation (5th ed.). Philadelphia: Lea Febiger, ISBN 0-683-30740-1(1999).

25. Brul S. and Coote P. Preservative agents in foods. Mode of action and microbial resistance mechanisms. Int. J. Food Microbiol., 15(50-(1–2)) 1–17 (1999).

Received on 06.02.2017 Modified on 06.03.2017

Asian J. Research Chem. 2017; 10(5): 629-634.

DOI: 10.5958/0974-4150.2017.00106.7