A new analytical device for mercury detection has been developed by doping dithizone on to hydrophobic PTFE (polytetrafluoroethylene) membrane to form a blue dithizone membrane which instantaneously changed to orange color of mercury(II)-dithizonate complex, when this dithizone membrane was contacted to mercury(II) solution. The higher concentration of mercury showed the greater intensity of the orange colour mercury(II)-dithizonate complex. The design and chemicals were optimized to obtain the best performance for mercury measurement. This method is prospective as mercury test kit for simple, low cost, and rapid semi-quantitative method for mercury(II) determination from 1-10 mgL-1 suits for on-site mercury detection and has been applied to cosmetics with satisfactory results.

A new spectrophotometric method for mercury determination has been developed based on the complexation of mercury(II) in ascertained excess of thiocyanate. The remaining thiocyanate is reacted with iron(III) to form a red iron(III)-thiocyanate complex which gave maximum absorbance at 460 nm. The concentration of mercury(II) is inversely proportional to the decrease absorbance of the complex. The method was optimized to the concentrations of thiocyanate and iron(III). Selectivity of the method has also studied based on percent recovery of mercury(II) in the presence of common metal ions in the tailing waters of gold mine. Under the optimum conditions, the method showed linear correlation to mercury(II) concentration from 1-30 mg L−1 with detection limit of 0.58 mg L−1. The method was not interfered in the presence of all metal ions studied up to 50 mg L−1, except of silver which was tolerated at 10 mg L−1. The developed method has been satisfactorily applied for mercury(II) determination in synthetic and tailing waters of gold mine samples.

Nitrogen is an essential nutrient required by majority of plants to enhance metabolic processes for growing. Insufficient supply of nitrogen leads to severe plant disorders in flowering and fruiting; however, there are many false fertilizers available in markets. This project is focused on developing a smart method as a means for quality detection of nitrogen fertilizer. The smart ammonia analyzer was constructed on a normal smartphone which filled with Qpython3 software functions as an information processing application to analyze the level of nitrogen-ammonium and Color Grab application to process the RGB image of coloured product reaction of nitrogen-ammonium to be measured. The image of blue indophenol as the coloured product of the nitrogen was developed on a paper containing phenate reagent by releasing nitrogen ammonia from sample. The measurement process using the constructed “Smart Ammonia Analyzer’ involving taking image by smartphone camera, measuring image intensity on position with RED readings, and analyzing process to change the RED-value to concentration of nitrogen-ammonium. The chemicals used for colour formation of blue indophenol were 0.2 M NaOCl, 0.5 M HCl, 0.003 M MnSO4 M, and 2 M phenate with 0.1 M of NaOH for releasing agent of nitrogen fertilizer as ammonia. The developed smart ammonia analyzer resulted linear relation between the absorbance of blue indophenol image to concentration of nitrogen ammonia (y = 0.0181x + 0.2834, R2 = 0.9726) and has been successfully applied to nitrogen fertilizer. Development of smart ammonia analyzer has been achieved to provide an easy, inexpensive, and fast device for detecting quality of nitrogen fertilizer with satisfactory results.

<p class="02abstracttext">The purpose of this study was to determine the effect of immersion time of NaOH at a temperature of 60-70 ℃ in wulung bamboo fibers on the tensile strength of the epoxy matrix composites. Wulung bamboo fibers (Gigantichloa Atroviolacea) have the potential to be used as reinforced in composites because they have high strength and are widely grown in Indonesia. In this study, bamboo wulung fiber reinforcement was used without treatment and with variations, soaking time 30 minutes, 60 minutes, and 90 minutes in 6% NaOH solution with a temperature of 60-70 ℃. The composite manufacturing method used was vacuum assisted resin infusion and the standard composite specimen used as a tensile test was ASTM D638-01. The results showed that the longer the immersion time resulted in a rougher topography of the fiber surface which caused the composite tensile strength to increase due to the better mechanical interlocking between the fibers and the epoxy resin matrix. The wettability results on the fibers also show that the wetness between the fibers and the epoxy resin matrix is getting better, which is shown from the droplet contact angle on the resulting fibers. The highest composite tensile strength was obtained at 90 minutes immersion time of 169.765 MPa followed by immersion time of 60 minutes of 123.2 MPa, immersion time of 5 minutes of 81.7 MPa and without treatment of 71.6 MPa. Based on the results of the macro photo shows that the treatment given will reduce the failure of the pull out and debonding defects on the composite fracture.</p>

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