Marina Chim. Acta. 20 (1), pp.1-8, 2019 Marina Chim. Acta, Vol. 20 (1), 2019 MARINA CHIMICA ACTA p-ISSN : 1411-2132 e-ISSN : 2620-6145 Jurnal Tiga Bahasa Tentang Kimia Laut Open Access Journall at : http//journal.unhas.ac.id/index.php/mca DETERMINATION OF KOH EFFICIENCY AS CARBOSORB IN DETERMINING AGE OF CORAL REEF SAMPLES IN SELAYAR ISLANDS THROUGH LSC METHOD (LIQUID SCINTILLATION COUNTING) Muhammad Amri*, Alfian Noor, Maming Department of Chemistry, Faculty of Mathematics and Natural Sciences, Hasanuddin University, Jl. Perintis Kemerdekaan Km.10, Makassar, Indonesia 90245 *Corresponding author: [email protected] ABSTRACT Research using the method of LSC (Liquid Scintillation Carbon) in determining the age of coral reefs in the Selayar islands has been carried out. The samples of coral reefs were taken between the tides. Sample preparation was carried out physically and chemically using an acid-base mixture solution: NaOH, H2O2, HClO4 and HCl produced coral samples that looked whiter with weight reduction of up to 1.6%. Carbonate is separated into CO2 by reaction with 10% HCl and absorption with KOH 1 M as K2CO3. Total carbon is determined by the titration method which produces 0.0542 g of total carbon sample. Specific activity of 14C measured by enumeration with LSC is 12.0542 DPM/gC. The age of coral reef samples obtained from sample specific activity data was 1971,728 years Keywords: Carbosorb, Selayar Islands, Liquid Scintillation Counting, Coral Reef Received : 5 April 2019 Accepted :29April 2019 Published online :21 May 2019 2 1. INTRODUCTION million km . Indonesia have marine biodiversity, including the content of coral The story of the maritime reefs reaching more than 400 species [2]. empowerment of the kingdoms of Coral reefs are one of the oldest Majapahit and Gowa or the resilience of ecosystems on earth. According to [3], maritime sailors with sandeq boats that can coral reef ecosystems have experienced cross the ocean cannot be used as a tide for approximately 5000 years. In fact, backing in tracking and projecting the geological studies prove that 75% of coral condition of Indonesia in the future. species have existed since the Pleistocene Understanding the reality of the era [4]. Modern / fossil massive coral reefs development of contemporary science, are composed of deposits of calcium especially in the maritime field, has carbonate (CaCO3) which can grow from a become a starting point for how historical scale of millimeters to centimeters per knowledge is empowered. Every reality year. will clash with the conditions in their Coral reefs contain radioactive respective times, nothing is truly static, the elements which are measured by carbon cause is eternal is only a change [1]. element isotopes, namely carbon-14 (14C). Indonesia has a vast sea area with an Element 14C emits beta particles (β) and area of more than 75% reaching 5.8 will decay half in 5,730 years to become 1 Marina Chim. Acta, Vol. 20 (1), 2019 stable 14N. Carbon-14 persists in materials in the last two decades has been widely such as trees and corals that are tens of used to measure 14C in various samples thousands of years old. This phenomenon such as trees, seawater, sediments and is useful in radiocarbon dating [5]. coral reefs. The radiocarbon dating method is This research, CO2 absorption method used to determine the age of various was used because it was easier, more objects. Measurements are based on the economical and simpler than other 14 results of the calculation of C activity or methods. To absorb CO2, a solution that the ratio of the number of radioactive has the ability as an absorbent is used, isotopes 14C that exist on the object using namely KOH. Use KOH as adsorbent is the standard of a radioactive known based on the ability of CO2 adsorption number of isotopes [6]. Furthermore, [7] efficiency and enumeration efficiency on states that the radiocarbon dating method LSC instruments. was chosen based on the assumption that the proportion of cosmogenic 14C 2. MATERIAL AND METHOD radionuclides (radioactive isotopes) in the body of living things is always constant Materials The materials used in this research because continuous input, expenditure or were: HCl 6 N, NaOH 1 M, KOH 1 M, decay. After living things do not show life 14 H O 30%, BaC 10%, Methyl Orange activity, C inclusion does not occur 2 2 l2 14 (MO), HClO 1%, Phenol Thalein (PP), again. However, because radioactivity C, 4 Aqualight LLT, filter paper, aquades and the radionuclide decays so that the amount 14 coral reefs from the Selayar Islands. of C will decrease exponentially by time. 14 Preparation equipment in the form of Determination of the remaining C separating funnel, hotplate, ruler, statif, activity contained by coral reef samples mortal, gloves, oven, hammer and glass will correlate with the age calculated from tools commonly used in the laboratory as the example no show life activities. This well as β radiation counter from carbon-14 age can be calculated using the decay half- 14 samples, namely LSC Hidex 300 SL. life of the C isotope. Liquid Scintillation Counting (LSC) is Sampling popular in radiocarbon dating. According to [8], LSC has a very high detection Sampling was carried out in selayar efficiency. The geometry of the islands, South Sulawesi. Samples of coral measurement achieves enumeration reefs were taken in tides. efficiency of around 99.99%. The other advantages of this method are ease of Phisical and Chemical Cleaning sample preparation, data processing, and the ability of spectrometers to synthesize Cleaning is initial stage in sample and analyze different nuclides preparation before carbonate separation in simultaneously [9]. the sample [12]. There are two methods pre-treatment Physical cleaning, samples of coral radiocarbon analysis with LSC, benzene reefs were washed with water and brushed synthesis and CO2 absorption [10]. [11], several times until they clean. After stated that the method of CO2 absorption 2 Marina Chim. Acta, Vol. 20 (1), 2019 physical cleaning, coral reef is placed in a CO2 produced is flowed into the KOH container and dried. Then the coral reefs 1 N absorbent solution to produce K2CO3 are cut into small pieces and then weighed as in the following reaction: to determine the initial weight before chemical cleaning [12]. 2KOH + CO2 K2CO3 +H2O Chemical cleaning begins with The scheme of the series of CO immersion of coral samples into a mixture 2 absorption samples of coral reefs can be of 50/50 H O 30% and 1 N NaOH in a 2 2 seen in Figure 1. 100 mL beaker and ultrasonic for ± 10 minutes. Then solution is separated from the sample, brushed and rinsed again with distilled water to remove black stains which are in the narrowest blemish of the sample. Furthermore, the coral reef samples were soaked back in a mixture of 50/50 H2O2 30% and HClO4 1 N in a 100 mL beaker for 30 seconds- 2 minutes. The Figure 1. Design of a carbonate separation last process in chemical cleaning is a tool sample of coral reefs soaked in 10 mL of HCl 6 N solution for 15-60 seconds and Determination of Total Carbon rinsing again with distilled water repeatedly. Coral reef were dried in oven The total carbon in sample solution at 105 C to dry and weighed again to find (dissolved K2CO3) can be calculated from out percentage of lost weight during the the carbonate concentration obtained from ⁰ chemical cleaning process [12]. the titration of the sample solution with HCl. 10 mL of sample solution inserted into erlenmeyer 50 mL, added methyl Separation of Carbonate as CO2 orange indicator and titrated with HCl 5 N. Then sample solution 10 mL put into CO2 analysis in coral reef was carried Erlenmeyer 50 mL and added with BaCl out as CO2 gas by KOH. The stages in 2 10% saturated. Then the solution is filtered separating carbonates as CO2 samples were carried out by adding HCl 10% to 10 and the filtrate obtained is put into grams of sample powder of coral reefs Erlenmeyer 50 mL, added Phenol Pthalein placed in a round bottom flask until HCl indicator and titrated with HCl 5 M. 10% was used to react with calcium 14 carbonate in 10 grams of sample. The Measurement C Activity with LSC Hidex 300 SL reactions that occur between calcium carbonate and phosphoric acid are as The activity of 14C in sample is follows: expressed in unit disintegration per minute (DPM) of 14C. The results of sample CaCO3 + 2HCl CaCl2 + CO2 + H2O enumeration with Liquid Scintillation Counter Hidex 300 SL produced data in CPM units (counts per minute) and TDCR 3 Marina Chim. Acta, Vol. 20 (1), 2019 (Triple To Double Coincidence Ratio) or coral reef fossil which can be seen in known as efficiency of enumeration (E). Figure 2. E = x 100% Statistical calculation of radioactive sample using LSC is natural decay calculation on radioactive elements that emit pure beta particles at any time or random decay. Coral Reefs from Selayar 14 Figure 2 Determination of C activity in coral Islands reef can be determined through enumerating samples with LSC Hidex 300 Cleaning of Coral Reef SL. Mixture sample 8 mL and aqualight scintillator 12 mL in vial 20 mL. Then, Physical cleaning is done using analysis for 5-1440 minutes. The same running water and then rinsed with procedure is done in the background as a distilled water. This cleaning can remove comparison. mud and some stains that are attached on the surface of coral reef. Furthermore, Determined Age of Coral Reef chemical cleaning process starts from immersing the sample in a mixture (50/50) The age of a coral reef sample can be of H2O2 30% and NaOH 1 N and is calculated based on a comparison of ultrasound for ± 10 minutes to remove specific carbon activity (15.3 ± 0.1 dpm / various stains that stick.