scholarly journals Rapid in situ determination of ClO2 in drinking water by improved solid DPD spectrophotometry

2021 ◽  
Vol 252 ◽  
pp. 02063
Author(s):  
Qianqian Zhang ◽  
Lijun Jia ◽  
Tianli Hao ◽  
Ke Zeng
Keyword(s):  
Drinking Water ◽  
Low Cost ◽  
Direct Determination ◽  
Correlation Coefficients ◽  
Good Precision ◽  
Relative Standard ◽  
Relative Errors ◽  
Parallel Tests

This research aims to realize the rapid detection of ClO2 content in drinking water by adopting improved solid DPD. This method is fast and convenient with low cost and less waste liquid. The results show that this method has good precision and sensitivity. The linear correlation coefficients of the cubic regression equation were all greater than 0.999. The detection limit of the method was 0.002mg/L ClO2. The relative standard deviations (RSD) of seven parallel tests were between 1.37% and 8.87%, and the relative errors were small. The recovery rate was 96.67~110%. The method could be used for the direct determination of water samples with a mass concentration of 0.02mg/L~2.00mg/L in drinking water after ClO2 disinfection.

An improved method for determining HNMs in drinking water

2013 ◽  
Vol 13 (5) ◽  
pp. 1257-1264 ◽  
Author(s):  
F. Q. Huang ◽  
M. Y. Ruan ◽  
J. D. Yan ◽  
H. C. Hong ◽  
H. J. Lin ◽  
...  
Keyword(s):  
Drinking Water ◽  
Extraction Efficiency ◽  
Tap Water ◽  
Correlation Coefficients ◽  
Method Detection Limit ◽  
Good Reliability ◽  
Liquid Liquid Extraction ◽  
Relative Standard ◽  
Water Ph

Halonitromethanes (HNMs) in drinking water are increasingly becoming a public concern due to their high health risks, so development of a sensitive method for their analysis has become a priority. Liquid–liquid extraction (LLE) method is dominantly used in current studies regarding HNMs. However the sensitivity is far from ideal. The present study aims to investigate the factors that may influence the extraction efficiency during HNM analysis by LLE method, and as a result develop a more sensitive extraction method for HNM determination. Results showed that the dose of sodium sulfate exerted the most significant influence, followed by copper sulfate, while the pH and manual shaking times have little effect. Under the suitable conditions (for extracting HNMs in 45 mL water: pH = 3.5–5, CuSO4 = 1.0 g, Na2SO4 = 6 g, shaking times = 120–180), the correlation coefficients (r) of the calibration curves for nine HNMs were all more than 0.9925. The method detection limit (MDL) ranged from 0.017 to 0.217 μg L−1 with an average of 0.076 μg L−1, which was dominantly lower than the method reported. The recovery (spiked blank samples: 98–108%; spiked tap water: 81–120%) and precision (relative standard deviation: 0.46–6.72) also showed good reliability and reproducibility of the method. Finally, the developed method was applied to the determination of HNMs in real water samples.

Direct speciation of Cr in drinking water by in situ thermal separation ETAAS

2017 ◽  
Vol 9 (8) ◽  
pp. 1307-1312 ◽  
Author(s):  
Hao Cui ◽  
Wei Guo ◽  
Lanlan Jin ◽  
Qinghai Guo ◽  
Shenghong Hu
Keyword(s):  
Drinking Water ◽  
Direct Determination

Evaluation of anin situthermal separation ETAAS method for the direct determination of Cr species was carried out.

CdS-Intercalated Bentonite/Carbon Composite as Electrode for Sulfide Ion

2010 ◽  
Vol 663-665 ◽  
pp. 690-693 ◽  
Author(s):  
Kemawadee Udomphan ◽  
Atchana Wongchaisuwat ◽  
Ladda Meesuk
Keyword(s):  
Aqueous Solution ◽  
Low Cost ◽  
Carbon Composite ◽  
Good Precision ◽  
Solid Reaction ◽  
Artificial Graphite ◽  
Bright Yellow ◽  
Photochemical Properties

CdS, a bright yellow precipitate is well known for its optical, electrical, electro-optical and photochemical properties. CdS has also been prepared in the interlayer spaces of layered materials such as laponite and montmorillonite (bentonite). Several properties of intercalated CdS have been studied, but for the best of our knowledge there is no reports on its use. In this work, we applied CdS-intercalated bentonite / carbon composite as an electrode for determination of S2- ion in aqueous solution. CdS- intercalated bentonite was prepared by the in situ solid-solid reaction between Cd(II)-bentonite and Na2S. To construct a potentiometric electrode, CdS-intercalated bentonite was mixed with artificial graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. The electrode was used to determine S2- in aqueous solution, graphs of log [S2-] vs measured voltage (mv) gave linear relation up to 3 orders of ion concentrations. Apart from the reproducibility and good precision, the electrode is good for its selectivity, durability and low cost.

Development of a low cost microfluidic sensor for the direct determination of nitrate using chromotropic acid in natural waters

2015 ◽  
Vol 7 (13) ◽  
pp. 5396-5405 ◽  
Author(s):  
Deirdre Cogan ◽  
Cormac Fay ◽  
David Boyle ◽  
Conor Osborne ◽  
Nigel Kent ◽  
...  
Keyword(s):  
Natural Waters ◽  
Simple Procedure ◽  
Low Cost ◽  
Direct Determination ◽  
Chromotropic Acid ◽  
First Time

This study has demonstrated, for the first time, a microfluidic autonomous analyser for the direct determination of nitrate, incorporating a modified version of the chromotropic method resulting in a direct, quick, inexpensive and simple procedure to measure nitrate in situ.

scholarly journals Determination of 9 kinds of volatile halogenated alkane and chlorobenzene compounds in water by gas chromatography-mass spectrometry with purge and trap method

2021 ◽  
Vol 2079 (1) ◽  
pp. 012018
Author(s):  
Yanqin Liu
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Good Precision ◽  
Purge And Trap ◽  
Efficient Detection ◽  
Relative Standard ◽  
Volatile Organic

Abstract In this study, in the face of water environmental pollution, a more simple and efficient detection method was obtained for simultaneous determination of 9 kinds of volatile halogenated alkane and chlorobenzene compounds in water by PT/GCMS. By optimizing the purge and trap conditions, the optimal experimental conditions were obtained as follows: purge time was 15 min, purge temperature was 35 °C, purge velocity was 40 mL/min, desorption time was 2 min, desorption temperature was 240 °C. The linearity of the method was good, and the correlation coefficients were all greater than 0.999. The minimum detection limit(MDL) of the method was 0.1 μg/L. The average recovery rate ranged from 85.4 %~102.1 % in surface water and drinking water with relative standard deviation (RSD) ranged from 5.3 %-9.2 % in the spiked concentration levels of 5 μg/L and 10 μg/L. This method has the advantages of simple operation, good separation effect, rapid detection, high recovery and good precision, and can simultaneously meet the requirements of 9 kinds of volatile organic compounds detection in drinking water and surface water. This work provides a new method for the detection of volatile organic compounds in water and will have great significance for the detection of water quality.

scholarly journals Potentiometric Sensors for the Determination of Valdecoxib in Pharmaceutical Preparation

2015 ◽  
Vol 59 ◽  
pp. 93-105 ◽  
Author(s):  
Salwa Fares Rassi
Keyword(s):  
Pharmaceutical Preparation ◽  
Direct Determination ◽  
Correlation Coefficients ◽  
Life Time ◽  
Potential Method ◽  
Ion Pair ◽  
Linear Range ◽  
Potentiometric Sensors ◽  
Relative Standard

Valdecoxib (VALD) selective electrodes based on VALD-5,6-diamino-2-thiouracil hydrochloride (DTUH) (VALD-DTUH) ion pair in PVC matrix membrane were constructed. The plasticizers used were dibutylphthalate (DBP) (Electrode B) tri-n-butylphosphate (TBP) (electrode C), or dioctylphthalate (DOP) (electrode) A. The electrodes gave the linear range between 6.0×10−6-17.9×10−3, 2.5×10−5–8.3×10−3M, M and 2.5×10−6–2.0×10−2M respectively. The slopes for linear range ranged from 39.29 to 58.76mV/decade with correlation coefficients lying between 0.997, 0.989 and 0.999 respectively. The best detection limit was 1.50×10−6M for the electrode based on DOP. Selectivity coefficients of VALD related to a number of interfering cation and some organic compounds and excipients were studied using matched potential method (MPM(, and there were negligible interference caused by most of the investigated species. The pH and life time of the electrodes were also studied. The direct determination of VALD shows an average recovery of (100.08-100.61 and 99.75-101.00)% and a mean relative standard deviation of (2.70-0.61 and 2.39-0.56)% for sensor A and B respectively. The results obtained by determination of VALD in tablets using the proposed sensors which comparable favorably with those obtained by spectrophotometric method. Validation of the method shows the suitability of the electrodes for the determination of VALD in pharmaceutical formulation.

Determination of Epsilon Aminocaproic Acid Based on Charge Transfer Complexation with p-Nitrophenlol by Spectrophotometry

2020 ◽  
Vol 16 ◽  
Author(s):  
Sheng-Yun Li ◽  
Fang Tian
Keyword(s):  
Charge Transfer ◽  
Aminocaproic Acid ◽  
Concentration Limit ◽  
Official Method ◽  
Good Precision ◽  
Pharmaceutical Dosage Forms ◽  
Relative Standard ◽  
A Charge ◽  
Epsilon Aminocaproic Acid

: A spectrophotometry was investigated for the determination of epsilon aminocaproic acid (EACA) with p-nitrophenol (PNP). The method was based on a charge transfer (CT) complexation of this drug as n-electron donor with π-acceptor PNP. Experiment indicated that the CT complexation was carried out at room temperature for 10 minutes in dimethyl sulfoxide solvent. The spectrum obtained for EACA/PNP system showed the maximum absorption band at wavelength of 425 nm. The stoichiometry of the CT complex was found to be 1:1 ratio by Job’s method between the donor and the acceptor. Different variables affecting the complexation were carefully studied and optimized. At the optimum reaction conditions, Beer’s law was obeyed in a concentration limit of 1～6 µg mL-1. The relative standard deviation was less than 2.9%. The apparent molar absoptivity was determined to be 1.86×104 L mol-1cm-1 at 425 nm. The CT complexation was also confirmed by both FTIR and 1H NMR measurements. The thermodynamic properties and reaction mechanism of the CT complexation have been discussed. The developed method could be applied successfully for the determination of the studied compound in its pharmaceutical dosage forms with a good precision and accuracy compared to official method as revealed by t- and F-tests.

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

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.

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