scholarly journals Quantification of Silicon in Rice Based on an Electrochemical Sensor via an Amplified Electrocatalytic Strategy

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1048
Author(s):  
Li Fu ◽  
Yuhong Zheng ◽  
Pengchong Zhang ◽  
Guosong Lai
Keyword(s):  
Electrochemical Sensor ◽  
Spectrophotometric Method ◽  
Silicon Content ◽  
Electrochemical Techniques ◽  
Correlation Coefficients ◽  
Field Testing ◽  
Leaf Sheath ◽  
Electrochemical Analysis ◽  
Carbon Surface ◽  
Molybdenum Blue

Silicon plays a very important role in the growth of rice. The study of the relationship between rice and silicon has become a hot area in the last decade. Currently, the silica-molybdenum blue spectrophotometric method is mostly used for the determination of silicon content in rice. However, the results of this method vary greatly due to the different choices of reducing agents, measurement wavelengths and color development times. In this work, we present for the first time an electrochemical sensor for the detection of silicon content in rice. This electrochemical analysis technique not only provides an alternative detection strategy, but also, due to the rapid detection by electrochemical methods and the miniaturization of the instrument, it is suitable for field testing. Methodological construction using electrochemical techniques is a key objective. The silicon in rice was extracted by HF and becomes silica after pH adjustment. The silica was then immobilized onto the glassy carbon surface. These silica nanoparticles provided additional specific surface area for adsorption of sodium borohydride and Ag ions, which in turn formed Ag nanoparticles to fabricate an electrochemical sensor. The proposed electrochemical sensor can be used for indirect measurements of 10–400 mg/L of SiO2, and thus, the method can measure 4.67–186.8 mg/g of silicon. The electrochemical sensor can be used to be comparable with the conventional silicon-molybdenum blue spectrophotometric method. The RSD of the current value was only 3.4% for five sensors. In practical use, 200 samples of glume, leaf, leaf sheath and culm were tested. The results showed that glume had the highest silicon content and culm had the lowest silicon content. The linear correlation coefficients for glume, leaf, leaf sheath and culm were 0.9841, 0.9907, 0.9894 and 0.993, respectively.

scholarly journals Simple Spectrophotometric Method for Determination of Paroxetine in Tablets Using 1,2-Naphthoquinone-4-Sulphonate as a Chromogenic Reagent

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Ibrahim A. Darwish ◽  
Heba H. Abdine ◽  
Sawsan M. Amer ◽  
Lama I. Al-Rayes
Keyword(s):  
Spectrophotometric Method ◽  
Correlation Coefficients ◽  
Molar Absorptivity ◽  
Official Method ◽  
Calibration Data ◽  
Pharmaceutical Tablets ◽  
Relative Standard ◽  
Label Claim ◽  
Colored Product

Simple and rapid spectrophotometric method has been developed and validated for the determination of paroxetine (PRX) in tablets. The proposed method was based on nucleophilic substitution reaction of PRX with 1,2-naphthoquinone-4-sulphonate (NQS) in an alkaline medium to form an orange-colored product of maximum absorption peak () at 488 nm. The stoichiometry and kinetics of the reaction were studied, and the reaction mechanism was postulated. Under the optimized reaction conditions, Beer's law correlating the absorbance (A) with PRX concentration (C) was obeyed in the range of 1–8 g . The regression equation for the calibration data was: A = 0.0031 + 0.1609 C, with good correlation coefficients (0.9992). The molar absorptivity () was L  1 . The limits of detection and quantitation were 0.3 and 0.8 g , respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the determination of PRX in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was %. The results obtained by the proposed method were comparable with those obtained by the official method.

scholarly journals A SIMPLE SPECTROPHOTOMETRIC METHOD FOR THE QUANTITATIVE ANALYSIS OF PHOSPHATE IN THE WATER SAMPLES

2018 ◽  
Vol 7 (2) ◽  
pp. 198
Author(s):  
Nur Habibah ◽  
I Gusti Ayu Shri Dhyanaputri ◽  
I Wayan Karta ◽  
Cokorda Dewi Widhya Hana Sundari ◽  
Mochammad Choirul Hadi
Keyword(s):  
Quantitative Analysis ◽  
Spectrophotometric Method ◽  
Water Samples ◽  
Calibration Graph ◽  
Ammonium Molybdate ◽  
Official Method ◽  
Phosphate Content ◽  
Color Intensity ◽  
Molybdenum Blue ◽  
Sulfuric Acid Medium

A simple spectrophotometric method was used to determine the phosphate content in the water sampels. The method is based on the formation of molybdenum blue complex from the reaction of orthophosphate and ammonium molybdate followed by reduction with ascorbic acid in the aqueous sulfuric acid medium. The color intensity of the molybdenum blue complex is proportionally to the phosphate content in the solution. The system obeys Lamber-Beer’s Law at the 890 nm in the concentration range of 0.1-1 mg P/L and the linier calibration graph was obtained with the slope, 0.6334, intercept, 0.0074 and correlation coefficient of 0.9988. This official method was also used for the quantitative analysis of phosphate in the water samples and the satisfactory result was obtained. The range of phosphate concentration in the water samples are 0.033 – 2.943 mg P/L.

SIMULTANEOUS ESTIMATION AND VALIDATION OF RAMIPRIL AND TELMISARTAN BY UV SPECTROPHOTOMETRY

INDIAN DRUGS ◽  
2014 ◽  
Vol 51 (09) ◽  
pp. 31-35
Author(s):  
R Rambabu ◽  
◽  
S Vidyadhara ◽  
J Subbarao
Keyword(s):  
Spectrophotometric Method ◽  
Correlation Coefficients ◽  
Simultaneous Equation ◽  
Dosage Forms ◽  
Simultaneous Estimation ◽  
Uv Spectrophotometry ◽  
Intermediate Precision ◽  
Pharmaceutical Dosage Forms ◽  
Sensitive Spectrophotometric Method

A simple and sensitive spectrophotometric method for the determination of ramipril and telmisartan in pharmaceutical dosage forms has been developed. The absorption maxima were found at 220nm for ramipril and 297nm for telmisartan using 0.1N NaOH as solvent. Beer’s law was obeyed for both the drugs in the concentration range of 2-10μg/ml with correlation coefficients 0.999 for both ramipril and telmisartan. The limits of detection for ramipril and telmisartan were found to be 0.142 and 0.405μg/mL respectively and the limits of quantitation were 0.43 and 1.22μg/mL. Accuracy of the method was verified by performing recovery studies using simultaneous equation method and found to be 98.33 to 99.54%w/w for ramipril and 99.36 to 99.82 %w/w for telmisartan. %RSD of repeatability and intermediate precision studies were found to be <2 for both the drugs. Ruggedness of the method was checked by changing analyst worked and instrument used. In both the cases, the %RSD was found to be less than 2.

scholarly journals Novel Spectrophotometric Method for the Quantitation of Urinary Xanthurenic Acid and Its Application in Identifying Individuals with Hyperhomocysteinemia Associated with VitaminB6Deficiency

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Chi-Fen Chen ◽  
Tsan-Zon Liu ◽  
Wu-Hsiang Lan ◽  
Li-An Wu ◽  
Chin-Hung Tsai ◽  
...  
Keyword(s):  
Spectrophotometric Method ◽  
Solid Phase ◽  
Correlation Coefficients ◽  
Urinary Metabolites ◽  
Hplc Method ◽  
Small Scale ◽  
Extraction Column ◽  
Xanthurenic Acid ◽  
Activation Coefficient ◽  
Coefficient Method

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described. The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column. The linearity of proposed method extends from 2.5 to 100.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively. Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively. Interference from various urinary metabolites was insignificant. In a small-scale screening of elderly conducted at Penghu county in Taiwan (n=80), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15 μmole/L). Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC’s AST/B6functional test. These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B6deficiency-associated hyperhomocysteinemic condition.

scholarly journals Error correlation between CO<sub>2</sub> and CO as constraint for CO<sub>2</sub> flux inversions using satellite data

2009 ◽  
Vol 9 (19) ◽  
pp. 7313-7323 ◽  
Author(s):  
H. Wang ◽  
D. J. Jacob ◽  
M. Kopacz ◽  
D. B. A. Jones ◽  
P. Suntharalingam ◽  
...  
Keyword(s):  
Inverse Modeling ◽  
Large Scale ◽  
Transport Model ◽  
Meteorological Data ◽  
Correlation Coefficients ◽  
Surface Fluxes ◽  
Satellite Observations ◽  
Carbon Surface ◽  
Chemical Transport Model ◽  
Error Correlation

Abstract. Inverse modeling of CO2 satellite observations to better quantify carbon surface fluxes requires a chemical transport model (CTM) to relate the fluxes to the observed column concentrations. CTM transport error is a major source of uncertainty. We show that its effect can be reduced by using CO satellite observations as additional constraint in a joint CO2-CO inversion. CO is measured from space with high precision, is strongly correlated with CO2, and is more sensitive than CO2 to CTM transport errors on synoptic and smaller scales. Exploiting this constraint requires statistics for the CTM transport error correlation between CO2 and CO, which is significantly different from the correlation between the concentrations themselves. We estimate the error correlation globally and for different seasons by a paired-model method (comparing GEOS-Chem CTM simulations of CO2 and CO columns using different assimilated meteorological data sets for the same meteorological year) and a paired-forecast method (comparing 48- vs. 24-h GEOS-5 CTM forecasts of CO2 and CO columns for the same forecast time). We find strong error correlations (r2>0.5) between CO2 and CO columns over much of the extra-tropical Northern Hemisphere throughout the year, and strong consistency between different methods to estimate the error correlation. Application of the averaging kernels used in the retrieval for thermal IR CO measurements weakens the correlation coefficients by 15% on average (mostly due to variability in the averaging kernels) but preserves the large-scale correlation structure. We present a simple inverse modeling application to demonstrate that CO2-CO error correlations can indeed significantly reduce uncertainty on surface carbon fluxes in a joint CO2-CO inversion vs. a CO2-only inversion.

scholarly journals Electrochemical Analysis of the Anti-corrosion Properties of Benzonitrile Compound on Quenched 420 Martensitic Steel in Strong Aqueous Environment

2018 ◽  
Vol 34 (4) ◽  
pp. 1749-1754
Author(s):  
ROLAND TOLULOPE LOTO. ◽  
BRYAN UCHE AYOZIE
Keyword(s):  
Analytical Study ◽  
Adsorption Mechanism ◽  
Inhibition Efficiency ◽  
Martensitic Steel ◽  
Correlation Coefficients ◽  
Electrochemical Analysis ◽  
Aqueous Environment ◽  
Corrosion Properties ◽  
Adsorption Models ◽  
Inhibition Performance

Investigation of the corrosion inhibition properties of benzonitrile compound on the surface degradation of quenched 420 martensitic steel in 6 M H2SO4 was evaluated through the application of potentiodynamic polarization method, micro analytical study and ATR-FTIR spectroscopic analysis. Experimental data showed optimal inhibition performance of the compound with peak inhibition efficiency of 99.4% with mixed type inhibition but dominant anodic inhibition properties. The inhibiting compound significantly influenced the thermodynamic behaviour of the steel resulting in chemisorption adsorption mechanism onto steel surface in consonance with Langmuir and Freundlich adsorption models with correlation coefficients of 1 and 0.7570. The transmittance of identified functional groups of benzonitrile from ATR-FTIR spectroscopy decreased at extended wavelengths due to surface coverage and adsorption of the compound onto the steel.

Field Testing: Assessing the Physical Fitness of Mildly Mentally Retarded Individuals

1988 ◽  
Vol 5 (4) ◽  
pp. 318-331 ◽  
Author(s):  
Kenneth H. Pitetti ◽  
Jeffrey E. Fernandez ◽  
David C. Pizarro ◽  
Nancy B. Stubbs
Keyword(s):  
Body Fat ◽  
Aerobic Capacity ◽  
Correlation Coefficients ◽  
Bioelectrical Impedance ◽  
Field Testing ◽  
Mentally Retarded ◽  
Percent Body Fat ◽  
Assessment Protocol ◽  
Hand Grip ◽  
Fitness Assessment

This study set out to develop a simple field testing protocol for evaluating the aerobic capacity, forearm isometric strength, and percent body fat of mentally retarded individuals (MRI). A total of 33 (MR) (M IQ=68) subjects (26 males, 7 females) ranging in age from 12 to 49 years participated in this study. A submaximal exercise test using the Schwinn Air-Dyne ergometer was used to estimate aerobic capacity (V̇O2max). Forearm strength was determined by using a hand grip isometric dynamometer. Percent body fat (%BF) was determined by the skinfold method and bioelectrical impedance. All 33 MR subjects who were tested successfully completed the fitness assessment protocol. Correlation coefficients for directly measured versus estimated V̇O2 max and test-retest for forearm strength for 10 of the subjects was .91 and .95, respectively. Slight variations were seen in the methods used to determine %BF. Based on these statistics, it is recommended that the protocol used in this study be considered by those involved in the physical education or training of MRI.

Molybdenum-Blue Spectrophotometric Method for Determination of Lewisite Vapor in Air

1985 ◽  
Vol 18 (19) ◽  
pp. 2381-2394 ◽  
Author(s):  
William K. Fowler ◽  
Thomas T. Hancock ◽  
John J. Martin
Keyword(s):  
Spectrophotometric Method ◽  
Molybdenum Blue

scholarly journals Development and Validation of First-Order Derivative Spectrophotometry for Simultaneous Determination of Levocetirizine Dihydrochloride and Phenylephrine Hydrochloride in Pharmaceutical Dosage Form

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Kaminee Parmar ◽  
Sunil Baldania ◽  
Dimal Shah ◽  
Usmangani Chhalotiya ◽  
Naimin Parmar
Keyword(s):  
Spectrophotometric Method ◽  
Dosage Form ◽  
Correlation Coefficients ◽  
Order Derivative ◽  
Simultaneous Estimation ◽  
Pharmaceutical Dosage Form ◽  
Zero Crossing ◽  
Phenylephrine Hydrochloride ◽  
First Order ◽  
Crossing Point

A simple, precise, accurate, and economical spectrophotometric method has been developed for simultaneous estimation of levocetirizine dihydrochloride (LCT) and phenylephrine hydrochloride (PHE) by employing first-order derivative spectrophotometric method. The first-order derivative absorption at 240 nm (zero crossing point of PHE) was used for quantification of LCT and 283.2 nm (zero crossing point of LCT) for quantification of PHE. The linearity was established over the concentration range of 4–24 μg/mL and 8–48 μg/mL for LCT and PHE with correlation coefficients (r2) 0.9964 and 0.9972, respectively. The mean % recoveries were found to be in the range of 99.14%–100.43% for LCT and 98.73%–100.83% for PHE. The proposed method has been validated as per ICH guideline and successfully applied for the simultaneous estimation of LCT and PHE in combined tablet dosage form.

Sign in / Sign up

Export Citation Format

Share Document