High-sensitive colour indicator of absorbed dose of epithermal neutrons radiation

In our study, the high-sensitivity colour indicator of the absorbed dose of radiation of epithermal neutrons with energy 0 to 10 keV for dosimetry of low-energy neutrons was developed. We had been developed an indicator on the basis of the dye solution of arsenazo III and gadopentetic acid, allowing precisely define of absorbed dose in the range 2 to 103 Gy. The properties of arsenazo III as metallic indicator, which changes colour after binding of free ions of metals, were used. Colour of the indicator solution before irradiation and after it is stable enough in time at storage in the dark, at artificial illumination or at scattered sunlight. The developed indicator, consisting of a solution of arsenazo III and gadopentetic acid, allows estimating the absorbed dose of epithermal neutron irradiation with good accuracy and reduces the error of measurement related to changing colour of dye under the influence of other factors (light, temperature etc.) Dosimeter is tissue-equivalent and possesses a high-sensitivity neutron radiation due to the content of gadolinium in solution, which has great neutron capture cross-section. The developed dosimeter persists spectrophotometric characteristics after irradiaion within few weeks that allows to use it for measurement of the absorbed dose, both in real time mode and with the delayed measurement within few weeks.

Performance Improvement of Fruit Ripeness Smart Label Based On Ammonium Molibdat Color Indicators

Research in fruit ripeness indicator is still experiencing especially due to major difficulties of several fruits with no color changes in its skin when it is ripen. From the previous research, there was found that ammonium molybdate [(NH4) 6Mo7O24.4H2O] embedded in the polymer matrix could be used as an indicator label to detect the ripeness of climacteric fruits base on the color change from yellow to blue and then green. However, the performance label still needs to be developed further. The surface of the label was still poor due to air or bubble trapping inside the film. It was found that mixing H2O2 and molydate agent produced air or bubble thus in this research, a pre-treatment of film solution was done to chase away the air by storing and vacuuming the solution in cold temperature and time period of storage. A variety of film drying method was also carried out to find the best temperature of the oven to produce smooth surface of the film. The sensitivity of the label to ethylene gas was improved by adding more agent solution into the film. The best form of smart labels was produced using an oven at 40°C for 18 hours. The label composition was 100 mL distilled water, 3.5 g PVOH, 2 mL glycerol, and a color indicator solution (ammonium molybdate and hydrogen peroxide ratio of 1:10) at 4 mL. The molydate solution had to be stored for 3 days in temperature of 7oC before used. The label sensitivity was improved as low as 100 ppm of pure ethylene gas. Label application in a pack of avocados showed a relationship between label color changes and fruit quality degradation. The value of hue label on days 0 to 6 changed from yellow to greenish yellow, while on the 7th to the 10th day the color of the label was still in the same color as the day of 6th. Decreasing the quality of fruit during storage can be seen from the increase in the percentage of weight loss and hardness of fruit texture.

Determination of the Adsorption Activity of the Specific Surface of Artificial Graphite by the Indicator of Methylene Blue

This article investigated and determined the specific surface area of artificial graphite for adsorption through a methylene blue solution. The study showed that the specific surface area of graphite adsorption obtained from coal from the Uzgen deposit in Kyrgyzstan for methylene blue is 599.4 m2/g and this is very close to the performance of activated carbons. The specific surface area of artificial graphite obtained from coal from the Uzgen deposit for adsorption activity was determined by titration of a suspension with a methylene blue indicator solution.

Acid Base Indicator from Shoot-Leaves Ethanol Extract of Pucuk Merah (Syzygium oleana)

Experiment on natural acid-base indicators is usually done by extracting the natural sources with certain solvent, testing the extract with acid, base and neutral solutions, observing the color changes, making conclusion and discharging the remaining extract at the end of the experiment. Production of long-lasting natural acid-base indicator is needed to reduce the discharged of chemicals excessively. This research was carried out to produce natural acid-base indicator from extract of shoot leaves of <em>Syzygium oleana</em> (SLS). The extraction was done by maceration technique using ethanol 95% for 13 h. The extract of SLS (SLS indicator solution) is then used to produce SLS indicator paper by soaking the filter paper in SLS indicator solution and followed by drying under shade. Both of the solution and paper indicators were tested for their color changes in pH solutions range of 1-13. Durability and performance of the indicator was investigated for 6 d. Absorbance of the indicator solution was measured under wavelength of 200-700 nm by using UV-Vis spectrophotometer. The results showed that, both of the indicators can be used as acid-base indicator; even it can be used to determine the pH range of solution. The color changes of SLS indicator in solution pH of 1-13 were pink-fade green-moss green-brown. Both of the indicators showed a good performance in their color change for 6 d of storage. Thus, the ethanol extract of SLS can be used as raw material to produce acid-base indicator.

SELECTIVE MERCURIMETRIC TITRATION ASSAY OF CHLORIDE CONCENTRATION IN THE WATER OF GREEN COCONUTS USING NOVEL INDICATOR SYSTEM

Objective: A selective mercurimetric titration procedure is proposed for the assay of chloride concentration in the water of green coconut using mercury(II) nitrate [(Hg(NO3)2] reagent and iron(III) nitrate [Fe(NO3)3] with synthetically prepared mercury(II) thiocyanate [Hg(SCN)2] indicator system.Methods: An indicator solution was prepared by titrating Hg(NO3)2 against potassium thiocyanate (KSCN) till a red color end point using Fe(NO3)3. Then a known amount of Hg(NO3)2 was added to indicator solution and titrated against the water of green coconut till the original red color reappeared.Results: The concentration of chloride present in the volume of coconut water utilized in between these two end points was found to be reacting in the 2:1 stoichiometric ratio with the Hg(NO3)2 taken in the second step of the titration. The statistical treatment of the experimental data obtained by using standard solutions of sodium chloride (NaCl) indicates that the procedure is precise and accurate. The phosphate, sulfate, organic compounds and inorganic minerals present in the coconut water did not interfere with the measurement of chloride by this procedure. Both the cationic mineral value (was also determined by complexometric titration) and chloride concentration in the coconut water were found to be decreased with the development of the coconuts.Conclusion: The proposed procedure of determination of chloride concentration in the water of green coconut is simple, reliable and inexpensive. This procedure is excellent for determination of chloride in the acidic solution without precise adjustment of the pH for detection of the end point. Owing to the homogenous reaction condition no titration errors those are commonly encountered by co-precipitation in the argentometric assay of chloride.

Determination of Ammonium Concentration in Post-Process Waters from Underground Coal Gasification

A flow injection analysis method for spectrophotometric determination of ammonium in waters produced during underground coal gasification (UCG) of lignite and hard coal was described. The analysis of UCG water samples is very difficult because of their very complicated matrix and colour. Due to a huge content of organic and inorganic substances and intensive colour of samples (sometimes yellow, quite often dark brown or even black), most analytical methods are not suitable for practical application. Flow injection analysis (FIA) is based on diffusion of ammonia through a hydrophobic gas permeable membrane from an alkaline solution stream into an acid-base indicator solution stream. Diffused ammonia causes a colour change of indicator solution, and ammonia is subsequently quantified spectrophotometrically at 590 nm wavelength. The reliability of the results provided by applied method was evaluated by checking validation parameters like accuracy and precision. Accuracy was evaluated by recovery studies using multiple standard addition method. Precision as repeatability was expressed as a coefficient of variation (CV).