Penentuan Komposisi Bahan Bakar Nabati Dalam Bahan Bakar Minyak Campuran Menggunakan Metode Direct Counting C-14

ABSTRAK. Telah dilakukan penentuan komposisi bahan bakar nabati (BBN) dalam bahan bakar minyak campuran (BBMC) dengan metode direct counting C-14. Penentuan komposisi BBN dalam BBMC dilakukan dengan cara memipet 10 mL BBMC ke dalam vial gelas kemudian ditambahkan 10 mL larutan sintilator Ultima Gold F (UGF) ke dalamnya. Vial tersebut dikocok agar campuran menjadi homogen kemudian dicacah menggunakan LSC (Liquid Scintillation Counter) Elmer Perkin 2900TR selama 20 menit sebanyak 30 siklus. Hasil pencacahan ditampilkan dalam bentuk tSIE (transformed external standard spectrum) dan cpm (cacahan permenit). Hasil analisis memperlihatkan nilai cpm yang meningkat seiring kenaikan persentase BBN dalam BBMC. Nilai cpm terendah dan tertinggi untuk sampel bensin, avtur, dan solar berturut-turut adalah 14,2363 dan 62,0343, 10,664 dan 44,535, serta 9,410 dan 61,789. Terdapat korelasi kuat antara nilai tSIE dan nilai cpm pada bensin dan solar tapi tidak pada avtur. Hasil analisis terhadap sampel uji menunjukkan bahwa sampel tersebut berada di luar grafik deret sampel. Metode direct counting ini diharapkan dapat menjadi referensi dalam uji mutu BBMC.ABSTRACT. The composition of biofuel (BF) in mixed oil fuel (MOF) has been determined using the C-14 direct counting method. Determination of the composition of BF in MOF was carried out by pipetting 10 mL of BBMC into a glass vial and then adding 10 mL of Ultima Gold F (UGF) scintillator solution into it. The vial was shaken so that the mixture became homogeneous and then counted using the Elmer Perkin 2900TR LSC (Liquid Scintillation Counter) for 20 minutes for 30 cycles. The results of the counting are displayed in the form of tSIE (transformed external standard spectrum) and cpm (counts per minute). The results of the analysis show that the value of cpm increases with the increase in the percentage of BF in MOF. The lowest and highest cpm values for gasoline, avtur, and diesel samples were 14.2363 and 62.0343, 10.664 and 44.535, and 9.410 and 61.789, respectively. There is a strong correlation between tSIE and cpm values for gasoline and diesel but not for avtur. The results of the analysis of the test sample indicate that the sample is outside the sample series graph. This direct counting method is expected to be a reference in the BBMC quality test.

Direct Fixation of Atmospheric CO2 towards Chemical Synthesis of Fuel Hydrocarbon

We have reported that fuel hydrocarbon was chemically synthesized from CO2 and activated water. In this report, we show the direct evidence of CO2 fixation from air. CO2 in the air is composed of about 99 % 12C, about 1% 13C, and about one trillionth radioisotope 14C. The extremely trace amount of 14C was measured with liquid scintillation counter by following beta-decay. The newly synthesized hydrocarbon revealed 14.6 dpm/gC. These facts clearly demonstrate direct fixation of atmospheric CO2 toward hydrocarbon synthesis.

TRITIUM ANALYSIS IN URINE BY THE TRIPLE-TO-DOUBLE COINCIDENCE RATIO METHOD WITH THE HIDEX 300 SL LIQUID SCINTILLATION COUNTER

The triple-to-double coincidence ratio (TDCR) method is a liquid scintillation primary method for the absolute activity measurement of pure β− and pure electron capture emitters. This method requires specific three-photomultiplier liquid scintillation counters. The aim of the present work is to assess the TDCR method performance for routine tritium analysis in urine using an HIDEX 300 SL, the only three-photomultiplier liquid scintillation counter designed for routine laboratories. The physical parameters and the semi-empirical Birks parameter (kB) of the prepared liquid scintillation source were firstly determined. TDCR model equations solving and detection efficiencies calculations for measured samples were performed by TDCR07c computing program. Accuracy, uncertainties and detection limit of TDCR method were assessed through the tritium analysis of six intercomparison urine samples. The results demonstrate that the analytical performance of the TDCR method implemented on the HIDEX 300 SL is conform to the recommendations for the monitoring of workers exposed to tritium.