Somkid Pencharee

Determination of iron in zeolite catalysts by a smartphone camera-based colorimetric analyzer

ABSTRACT A colorimetric analyzer was improved to determine iron in zeolites prepared by incipient wetness impregnation. Software was installed in an Android smartphone for measuring red, green, and blue light intensities. The blue color was suitable for creating a calibration relationship for iron. The optimum distance from the smartphone camera to the sample holder was 5 cm. The brightness was controlled by a table lamp with a 7 W light emitting diode located at 25 cm above the sample holder. Under these conditions, there was no influence from ambient light. A calibration equation was created from 0–1.2% (w/w) iron and stored in the program for analysis. The results agreed well with flame atomic absorption spectrophotometric measurements with a sample throughput exceeding 40 h−1. The relative standard deviation and the relative error were less than 1%. This method was convenient, rapid, simple, inexpensive, and easy with little chemical waste produced.

Use of a Smartphone as a Colorimetric Analyzer in Paper-based Devices for Sensitive and Selective Determination of Mercury in Water Samples

A smartphone application, called CAnal, was developed as a colorimetric analyzer in paper-based devices for sensitive and selective determination of mercury(II) in water samples. Measurement on the double layer of a microfluidic paper-based analytical device (μPAD) fabricated by alkyl ketene dimer (AKD)-inkjet printing technique with special design doped with unmodified silver nanoparticles (AgNPs) onto the detection zones was performed by monitoring the gray intensity in the blue channel of AgNPs, which disintegrated when exposed to mercury(II) on μPAD. Under the optimized conditions, the developed approach showed high sensitivity, low limit of detection (0.003 mg L-1, 3SD blank/slope of the calibration curve), small sample volume uptake (two times of 2 μL), and short analysis time. The linearity range of this technique ranged from 0.01 to 10 mg L-1 (r2 = 0.993). Furthermore, practical analysis of various water samples was also demonstrated to have acceptable performance that was in agreement with the data from cold vapor atomic absorption spectrophotometry (CV-AAS), a conventional method. The proposed technique allows for a rapid, simple (instant report of the final mercury(II) concentration in water samples via smartphone display), sensitive, selective, and on-site analysis with high sample throughput (48 samples h-1, n = 3) of trace mercury(II) in water samples, which is suitable for end users who are unskilled in analyzing mercury(II) in water samples.

Structural investigation of glasses with doped some transition metal oxides under the influence of gamma irradiation

The ultrasonic velocity of the alkali-borosilicate with different transition metal oxides (TMO) has been studied using the pulse echo technique. The elastic moduli such as elastic constant and bulk modulus have been obtained from the experimental data. Changes in the structure with different gamma irradiation doses have been investigated by using FTIR spectroscopy and ultrasonic studies. The results show that structural changes in the BO3 to BO4 due to TMO and irradiation are obtained.

Comparative studies of glow peaks and kinetic trapping parameters of LiF(Mg,Cu), LiF(Mg,Cu,P), LiF(Mg,Cu,Si) and LiF(Mg,Cu,Na,Si) single crystals

Glow curve structure and kinetic trapping parameter of the thermoluminescent (TL) phosphors based on LiF(Mg,Cu) LiF(Mg,Cu,P) LiF(Mg,Cu,Si) and LiF(Mg,Cu,Na,Si) single crystals were investigated (denoted as SMC, SMCP, SMCS and SMCNS, respectively). Wet mixing and drying before TL phosphors production in single-crystal form were achieved by the Bridgeman method. The transparent solid single crystals were cut to the size of 5.0×5.0×0.6 mm3 for use as thermoluminescence dosimeters (TLD). Four different types of TLD were irradiated with X-ray photon energy 128 keV in the dose of 3 mGy after dual step pre-irradiation annealing. From the glow curve structure, the geometrical factors (μ) were calculated. The graph created by Chen confirms the first-order kinetics. Moreover, the glow curve shape results in more fading of the TLD 100 sample than the SMCS and SMCNS samples. It is evident that the kinetic trapping parameters depend on the type of dopant. The frequency factors of all TLD single crystals are higher than TLD100 (poly-crystal). These results are useful to provide the TL trapping and recombination centers for these materials.

Mobile-phone-based colourimetric analysis for determining nitrite content in water

Environmental context A widespread pollutant in groundwater, rivers and lakes is nitrite, which is commonly determined batchwise by using colourimetry. The batchwise method, however, requires relatively large and expensive instrumentation, and hence is unsuitable for in-field measurements. This work introduces a simple and portable colourimetric analyser based on a mobile-phone camera for monitoring nitrite concentrations in environmental water samples. Abstract A cost-effective and portable colourimetric analyser installed on a mobile phone was used to measure nitrite in water samples in Chiang Mai City, Thailand. The colourimetric detection was based on the Griess reaction, in which nitrite ion reacts with sulfanilic acid under acidic conditions to produce a diazonium salt that further reacts with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a red–violet azo dye. Under controlled conditions using a light-tight box with LED flash lights, images of the red–violet solution were captured using a built-in camera and further analysed by a program, Panalysis, on the mobile phone. The calibration graph was created by measuring the red colour intensity of a series of standard nitrite solutions from 0.09–1.8 mg N L−1. The calibration equation was then automatically stored for nitrite analysis. The results demonstrated good performance of the mobile phone analyser as an analytical instrument. The accuracy (RE <4%) and precision (RSD ≤ 1%, intra- and inter-day) were also obtained with a detection limit of 0.03 mg N L−1 and a sample throughput of 40 samples per hour. Our results establish this simple, inexpensive and portable device as a reliable in-field monitor of nitrite in environmental waters.