scholarly journals An Environmental Friendly Procedure for Photometric Determination of Hypochlorite in Tap Water Employing a Miniaturized Multicommuted Flow Analysis Setup

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Sivanildo S. Borges ◽  
Boaventura F. Reis
Keyword(s):  
Tap Water ◽  
Accuracy Assessment ◽  
Flow Analysis ◽  
Photometric Determination ◽  
Waste Generation ◽  
Relative Standard ◽  
Significant Difference ◽  
Leucocrystal Violet ◽  
Reagent Consumption

A photometric procedure for the determination ofClO-in tap water employing a miniaturized multicommuted flow analysis setup and an LED-based photometer is described. The analytical procedure was implemented using leucocrystal violet (LCV; 4,4′,4′′-methylidynetris (N,N-dimethylaniline), C25H31N3) as a chromogenic reagent. Solenoid micropumps employed for solutions propelling were assembled together with the photometer in order to compose a compact unit of small dimensions. After control variables optimization, the system was applied for the determination ofClO-in samples of tap water, and aiming accuracy assessment samples were also analyzed using an independent method. Applying the pairedt-test between results obtained using both methods, no significant difference at the 95% confidence level was observed. Other useful features include low reagent consumption, 2.4 μg of LCV per determination, a linear response ranging from 0.02 up to 2.0 mg L−1  ClO-, a relative standard deviation of 1.0% (n=11) for samples containing 0.2 mg L−1  ClO-, a detection limit of 6.0 μg L−1  ClO-, a sampling throughput of 84 determinations per hour, and a waste generation of 432 μL per determination.

scholarly journals Automatic Flow Procedure for the Determination of Ethanol in Wine Exploiting Multicommutation and Enzymatic Reaction with Detection by Chemiluminescence

2004 ◽  
Vol 87 (4) ◽  
pp. 920-926 ◽  
Author(s):  
Elizabeth N Fernandes ◽  
Boaventura F Reis
Keyword(s):  
Sampling Rate ◽  
Enzymatic Reaction ◽  
Alcohol Oxidase ◽  
Parameters Optimization ◽  
Official Method ◽  
Relative Standard ◽  
Significant Difference ◽  
On Line ◽  
Reagent Consumption

Abstract An automatic procedure for the determination of ethanol in wines using a flow system based on multicommutation and enzymatic reaction is described. Alcohol oxidase was immobilized on aminopropyl glass beads and packed in an acrylic column. The peroxide due to enzymatic reaction with ethanol reacted with luminol and generated the chemiluminescence radiation that was monitored by using a laboratory-made detector based on photodiodes. The system manifold comprised a set of 3-way solenoid valves controlled by a microcomputer furnished with electronic interfaces, which ran on software written in Quick BASIC 4.5 to provide facilities to perform on-line sample dilution, reagent addition, and data acquisition. After system parameters optimization, ethanol samples were processed without prior pretreatment. The following suitable features were achieved: linear response ranging from 2.5 to 25% (v/v) ethanol, relative standard deviation of 1.8% (n = 10), detection limit of 0.3% (v/v) ethanol, sampling rate of 23 determinations per hour, and low reagent consumption of 0.23 mg luminol and 7 mg hexacyanoferrate (III) per determination. When the results were compared with those obtained using the AOAC Official Method, no significant difference at the 90% confidence level was observed.

scholarly journals Automatic flow system for simultaneous determination of iron and chromium in steel alloys employing photometers based on LEDs as radiation source

2003 ◽  
Vol 25 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Ridvan N. Fernandes ◽  
Boaventura F. Reis ◽  
Luís Fernando P. Campos
Keyword(s):  
Simultaneous Determination ◽  
Flow System ◽  
Atomic Emission ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry ◽  
Steel Alloys ◽  
Relative Standard ◽  
Significant Difference ◽  
Reagent Consumption

A multicommutated flow system for simultaneous determination of iron and chromium in steel alloys by photometry is described. The flow network consisted of an automatic injector and four solenoid valves assembled to form two independent analytical pathways, each one comprising reaction coils and a flow cell. The light source (LED) and detector (photodiode) were attached to the flow cells to form a compact unit. The flow system was microcomputer controlled by Quick BASIC 4.5 software, which carried out all steps of the analytical procedure. The feasibility of the system was proved by the determination of iron and chromium in steel alloys and its accuracy was accessed by comparing results with those obtained by plasma atomic emission spectrometry (ICP-AES). No significant difference at the 95% confidence level was observed. Other profitable features such as low reagent consumption (0.33 mg 1,10-phenantroline and 0.03 mg 1,5-diphenylcarbazide per determination); relative standard deviations (n=5) of 0.4% for iron and 1.2% for chromium; and an analytical throughput of 160 determinations per h were also achieved.

scholarly journals Determination of essential and non-essential element contents of drinking water and baby water for infant’s nutrition

2021 ◽  
Vol 44 (1) ◽  
pp. 194-202
Author(s):  
Funda Demir ◽  
Meral Yildirim Ozen ◽  
Emek Moroydor Derun
Keyword(s):  
Water Samples ◽  
Infant Nutrition ◽  
Tap Water ◽  
Essential Element ◽  
Essential Elements ◽  
Local Market ◽  
Drinking Waters ◽  
Significant Difference ◽  
Element Contents

Abstract In this study, essential (Ca, Cr, Cu, Fe, K, Mg, Na, P, Zn), and non-essential (Al, Ni, Pb) element contents of the drinking and baby water samples which are sold in the local market and tap water samples in Istanbul were examined. It was determined that elements of Cr, Cu, Fe, P, Zn, Al, and Ni were below detection limits in all water samples. Among the non-essential elements analyzed in water samples, Pb was the only detected element. At the same time, the percentages that meet the daily element requirements of infants were also calculated. As a result of the evaluations made, there is no significant difference in infant nutrition between baby waters and other drinking waters in terms of the element content.

scholarly journals A multicommuted flow analysis method for the photometric determination of amoxicillin in pharmaceutical formulations using a diazo coupling reaction

2011 ◽  
Vol 22 (2) ◽  
pp. 279-285 ◽  
Author(s):  
Sueny K. B Freitas ◽  
Valdinete Lins da Silva ◽  
Alberto N Araújo ◽  
Maria Conceição B. S. M Montenegro ◽  
Boaventura F Reis ◽  
...  
Keyword(s):  
Flow Analysis ◽  
Coupling Reaction ◽  
Pharmaceutical Formulations ◽  
Photometric Determination ◽  
Analysis Method ◽  
Diazo Coupling ◽  
Diazo Coupling Reaction

scholarly journals Stability indicating HPLC-Fluorescence detection method for the simultaneous determination of linagliptin and empagliflozin in their combined pharmaceutical preparation

2021 ◽  
Vol 12 (2) ◽  
pp. 168-178
Author(s):  
Mohamed Rizk ◽  
Ali Kamal Attia ◽  
Heba Yosry Mohamed ◽  
Mona Elshahed
Keyword(s):  
Fluorescence Detection ◽  
Mobile Phase ◽  
Pharmaceutical Preparation ◽  
Pharmaceutical Preparations ◽  
Forced Degradation ◽  
Stability Indicating ◽  
Accuracy And Precision ◽  
Relative Standard ◽  
Significant Difference

A sensitive, accurate, and precise liquid chromatographic method has been developed and validated for the determination of Linagliptin (LNG) and Empagliflozin (EMP) in their combined tablets. Chromatographic separation was carried out on ODS-3 Inertsil® C18 column (150×4.6 mm, 5 µm). The mobile phase A (consisting of 0.30% Triethyl amine buffer (TEA) at pH = 4.5, adjusted using ortho-phosphoric acid); the mobile phase B (consisting of acetonitrile) was pumped through the column whose temperature was maintained at 40 °C, with a flow rate 1.7 mL/min, using gradient elution from 0-3 min A:B (75:25, v:v), then from 3-6 min the ratio changed to be A:B (60:40, v:v). Fluorescence detection (FLD) was performed at 410 nm after excitation at 239 nm. Acceptable linearity, accuracy and precision values of the proposed method were found over the concentration ranges of 0.5-15 µg/mL for LNG and 1.0-30 µg/mL for EMP with correlation coefficients of 0.9997 and 0.9998 in the case of LNG and EMP, respectively. The recoveries and relative standard deviations percentages were found in the following ranges: 98.56-101.85 and 0.53-1.52% for LNG and 98.00-101.95 and 0.31-1.05% for EMP. The detection and quantification limits were 0.15 and 0.45 µg/mL for LNG and 0.22 and 0.67 µg/mL for EMP. The optimized method was validated and proved to be specific, robust, accurate and reliable for the determination of the drugs in pure form or in their combined pharmaceutical preparations. No significant difference was found regarding accuracy and precision upon statistical comparison between the obtained results of the proposed method and those of the reported method. Furthermore, the proposed method is proved to be a stability-indicating assay after exposure of the studied drugs to variable forced degradation parameters, such as acidic, alkaline and oxidative conditions, according to the recommendations of the International Conference on Harmonization guidelines. The simplicity and selectivity of the proposed method allows its use in quality control laboratories.

Sulfuric Acid/Hydrogen Peroxide Digestion and Colorimetric Determination of Phosphorus in Meat and Meat Products: Collaborative Study

1991 ◽  
Vol 74 (1) ◽  
pp. 22-26 ◽  
Author(s):  
David K Christians ◽  
Thomas G Aspelund ◽  
Scott V Brayton ◽  
Larry L Roberts
Keyword(s):  
Hydrogen Peroxide ◽  
Sulfuric Acid ◽  
Collaborative Study ◽  
Meat Products ◽  
Colorimetric Determination ◽  
Pork Sausage ◽  
Relative Standard ◽  
Significant Difference ◽  
Standard Deviations

Abstract Seven laboratories participated In a collaborative study of a method for determination of phosphorus in meat and meat products. Samples are digested In sulfuric acid and hydrogen peroxide; digestion Is complete In approximately 10 mln. Phosphorus Is determined by colorimetric analysis of a dilute aliquot of the sample digest. The collaborators analyzed 3 sets of blind duplicate samples from each of 6 classes of meat (U.S. Department of Agriculture classifications): smoked ham, water-added ham, canned ham, pork sausage, cooked sausage, and hamburger. The calibration curve was linear over the range of standard solutions prepared (phosphorus levels from 0.05 to 1.00%); levels in the collaborative study samples ranged from 0.10 to 0.30%. Standard deviations for repeatability (sr) and reproducibility (sR) ranged from 0.004 to 0.012 and 0.007 to 0.014, respectively. Corresponding relative standard deviations (RSDr and RSDR, respectively) ranged from 1.70 to 7.28% and 3.50 to 9.87%. Six laboratories analyzed samples by both the proposed method and AOAC method 24.016 (14th Ed.). One laboratory reported results by the proposed method only. Statistical evaluations Indicated no significant difference between the 2 methods. The method has been adopted official first action by AOAC.

scholarly journals Simultaneous Determination of Sitagliptin and Metformin in Pharmaceutical Preparations by Capillary Zone Electrophoresis and its Application to Human Plasma Analysis

2012 ◽  
Vol 7 ◽  
pp. ACI.S9940 ◽  
Author(s):  
Mohamed Salim ◽  
Nahed El-Enany ◽  
Fathallah Belal ◽  
Mohamed Walash ◽  
Gabor Patonay
Keyword(s):  
Simultaneous Determination ◽  
Human Plasma ◽  
Capillary Zone Electrophoresis ◽  
Pharmaceutical Preparations ◽  
Effective Length ◽  
Relative Standard ◽  
Significant Difference ◽  
Zone Electrophoresis ◽  
Capillary Zone

A novel, quick, reliable and simple capillary zone electrophoresis CZE method was developed and validated for the simultaneous determination of sitagliptin (SG) and metformin (MF) in pharmaceutical preparations. Separation was carried out in fused silica capillary (50.0 cm total length and 43.0 cm effective length, 49 μm i.d.) by applying a potential of 15 KV (positive polarity) and a running buffer containing 60 mM phosphate buffer at pH 4.0 with UV detection at 203 nm. The samples were injected hydrodynamically for 3 s at 0.5 psi and the temperature of the capillary cartridge was kept at 25 °C. Phenformin was used as internal standard (IS). The method was suitably validated with respect to specificity, linearity, limit of detection and quantitation, accuracy, precision, and robustness. The method showed good linearity in the ranges of 10-100 μg/mL and 50-500 μg/mL with limits of detection of 0.49, 2.11 μm/mL and limits of quantification of 1.48, 6.39 μg/mL for SG and MF, respectively. The proposed method was successfully applied for the analysis of the studied drugs in their synthetic mixtures and co-formulated tablets without interfering peaks due to the excipients present in the pharmaceutical tablets. The method was further extended to the in-vitro determination of the two drugs in spiked human plasma. The estimated amounts of SG/MF were almost identical with the certified values, and their percentage relative standard deviation values (% R.S.D.) were found to be ≤1.50% (n = 3). The results were compared to a reference method reported in the literature and no significant difference was found statistically.

A Compact Microcontrolled Microfluidic System for Photometric Determination of Phosphate in Natural Water Samples

2015 ◽  
Vol 68 (7) ◽  
pp. 1108 ◽  
Author(s):  
Osmundo Dantas Pessoa-Neto ◽  
Tiago Almeida Silva ◽  
Vagner Bezerra dos Santos ◽  
Orlando Fatibello-Filho
Keyword(s):  
Light Emitting Diode ◽  
Flow Analysis ◽  
Photometric Determination ◽  
Microfluidic System ◽  
Experimental Conditions ◽  
Light Emitting ◽  
Experimental Parameters ◽  
Led Photometer

A compact environmentally friendly microcontrolled microfluidic device ideal for in situ phosphate determination was developed based on a microsystem based on low-temperature co-fired ceramics (LTCC) coupled to a light-emitting diode (LED)–photometer with a multicommutation flow analysis (MCFA) approach. The experimental parameters of the MCFA analyzer were optimized by chemometric studies. Under the best experimental conditions, limits of detection and quantification of 0.02 mg P L–1 and 0.07 mg P L–1, respectively, and a sampling frequency of 67 h–1 were estimated. Moreover, a low sample consumption of only 60 μL per determination was the other advantage that fully meets the requirements of sustainable research and green chemistry purposes.

A novel multicommuted flow analysis strategy for the spectrophotometric determination of cadmium in water at μg L−1 levels without using a preconcentration step

2018 ◽  
Vol 10 (8) ◽  
pp. 900-909 ◽  
Author(s):  
Ticiane da Silva Magalhães ◽  
Boaventura F. Reis
Keyword(s):  
Spectrophotometric Determination ◽  
Flow Analysis ◽  
Photometric Determination ◽  
Analysis Approach ◽  
Analysis Strategy

An automated flow analysis approach for the photometric determination of cadmium in water with improved sensitivity is described.

Conductometric and Colorimetric Determination of Volatile Acidity of Vinegars by Flow-Injection Analysis

1991 ◽  
Vol 74 (2) ◽  
pp. 346-350 ◽  
Author(s):  
Matthieu Tubino ◽  
Flavio G Barros
Keyword(s):  
Acetic Acid ◽  
Colorimetric Determination ◽  
Bromocresol Purple ◽  
Water Stream ◽  
Ptfe Membrane ◽  
Volatile Acidity ◽  
Relative Standard ◽  
Significant Difference ◽  
Membrane Separator

Abstract Recent methods for determination of the volatile acidity of vinegars are relatively slow (about 40 mln) and involve techniques subject to a variety of errors (ca 2.5%). The present paper describes a method that provides results in a shorter time (ca 2 mln, Including dilution), with a smaller relative error rate (ca 1%). Conductometric analysis consists of the Injection of the sample In a deionlzed water stream that then flows past a PTFE membrane separator. Acetic acid diffuses through the membrane to another deionlzed water stream that passes through a conductivity cell. Colorimetric analysis also consists of sample injection into a deionlzed water stream that passes through the same PTFE membrane separator. However, the acetic acid diffuses into a bromocresol purple solution stream at pH 7. This solution passes through a flow cell In a spectrophotometer set at 540 nm. Before injection, samples were treated with hydrogen peroxide to ensure complete oxidation of sulfite to sulfate. Results of the proposed method were also compared with another similar method. At a 95% confidence level, the statistical t-test Indicates no significant difference between them. Typical estimates of the relative standard deviations obtained with the new methods are ca 1%. Analyses were performed with red and white wine vinegars.

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