Microdiffusion and Fluoride-Specific Electrode Determination of Fluoride in Foods

1979 ◽  
Vol 62 (5) ◽  
pp. 1065-1069
Author(s):  
Robert W Dabeka ◽  
Arthur D Mckenzie ◽  
Henry B S Conacher
Keyword(s):  
Dry Weight ◽  
Accurate Method ◽  
Standard Reference Materials ◽  
Buffer Solution ◽  
Infant Foods ◽  
Freeze Dried ◽  
Relative Standard ◽  
Petri Dishes ◽  
Absorbent Layer

Abstract A simple and accurate method was developed for routine determination of fluoride in foods. Hydrogen fluoride is diffused 20 hr at 50°C from fresh or freeze-dried samples (0.1 g dry wt) in polystyrene petri dishes containing 2 mL 40% HClO4 and 0.3 g Ag2SO4, and is absorbed on the lids, previously spotted with 0.1 mL 0.5M NaOH. The absorbent layer is dissolved in 2 mL buffer solution, and the fluoride is measured potentiometrically. The method was verified by analysis of NBS Standard Reference Materials; recovery from 28 spiked infant foods (average = 99%, range — 75-135%); and comparison of results with colorimetry results for the same diffusates, after modification to handle 1 g samples. Relative standard deviations varied from 4 to 20% day to day. Detection limits were below 0.05 μg/g dry weight.

scholarly journals Determination of 18 Intact Glucosinolates in Brassicaceae Vegetables by UHPLC-MS/MS: Comparing Tissue Disruption Methods for Sample Preparation

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 231
Author(s):  
Xiaolu Yu ◽  
Hongju He ◽  
Xuezhi Zhao ◽  
Guangmin Liu ◽  
Liping Hu ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Dry Weight ◽  
Microwave Treatment ◽  
Universal Method ◽  
Anticancer Activities ◽  
Fresh Sample ◽  
Freeze Dried ◽  
Relative Standard ◽  
Quantification Accuracy

Glucosinolates (GSLs) are important precursor compounds with anticancer activities in Brassicaceae vegetables and are readily hydrolyzed by myrosinase. Given the diversity of these species, establishing an accurate and universal method to quantify intact GSLs in different plant tissues is necessary. Here, we compared and optimized three tissue disruption methods for sample preparation. After microwave treatment for 90 s, 13 GSLs in homogenized Chinese cabbage samples were recovered at 73–124%. However, a limitation of this method was that different tissues could not be processed under the same microwave conditions. Regarding universality, GSLs in Brassicaceae vegetables could be extracted from freeze-dried sample powder with 70% methanol (v/v) or frozen-fresh sample powder with 80% methanol (v/v). Moreover, heating extraction is necessary for GSLs extracted from frozen-fresh sample powder. Average recoveries of the two optimized methods were 74–119% with relative standard deviations ≤15%, with the limits of quantification 5.72–17.40 nmol/g dry weight and 0.80–1.43 nmol/g fresh weight, respectively. Notably, the method for analyzing intact GSLs was more efficient than that for desulfo-GSLs regarding operational complexity, detection speed and quantification accuracy. The developed method was applied to identify the characteristic GSLs in 15 Brassicaceae vegetables, providing a foundation for further research on GSLs.

Development of an HPLC-UV Method for Quantification of Stattic

2019 ◽  
Vol 15 (6) ◽  
pp. 568-573
Author(s):  
Soheil Sedaghat ◽  
Ommoleila Molavi ◽  
Akram Faridi ◽  
Ali Shayanfar ◽  
Mohammad Reza Rashidi
Keyword(s):  
High Performance ◽  
Accurate Method ◽  
Plasma Samples ◽  
Promising Target ◽  
Relative Standard ◽  
Dimerization Inhibitor ◽  
Oncogenic Protein ◽  
First Time ◽  
Transcription 3

Background: Signal transducer and activator of transcription 3 (STAT3), an oncogenic protein found constitutively active in many types of human malignancies, is considered to be a promising target for cancer therapy. Objective: In this study for the first time, a simple and accurate method has been developed for the determination of a STAT3 dimerization inhibitor called stattic in aqueous and plasma samples. Methods: A reverse-phase high-performance liquid chromatography (RP-HPLC) composed of C18 column as stationary phase, and the mixture of acetonitrile (60%) and water (40%) as mobile phase with a UV detection at 215 nm were applied for quantification of stattic. The developed method was validated by Food and Drug Administration (FDA) guideline. Results: The method provided a linear range between 1-40 and 2.5-40 µg mL-1 for aqueous and plasma samples, respectively, with a correlation coefficient of 0.999. The accuracy (as recovery) of the developed method was found to be between 95-105% for aqueous medium and 85-115% for plasma samples. The precision (as relative standard deviation) for aqueous and plasma samples was less than 6% and 15%, respectively. The sensitivity of the developed method based on FDA guideline was 1 µg mL-1 for aqueous and 2.5 µg mL-1 for plasma samples. Conclusion: These results show that the established method is a fast and accurate quantification for stattic in aqueous and plasma samples.

scholarly journals Derivatization Ion Chromatography for the Determination of Monoethanolamine in Presence of Hydrazine in PHWR Steam-Water Circuits

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
Ayushi D. ◽  
Arijit Sengupta ◽  
Sangita D. Kumar ◽  
A. G. Kumbhar ◽  
G. Venkateswaran
Keyword(s):  
Ion Chromatography ◽  
Mobile Phase ◽  
Limit Of Detection ◽  
Accurate Method ◽  
Feed Water ◽  
Relative Standard ◽  
Conductometric Detection ◽  
Mode A ◽  
Eluent Acetone

A simple, rapid and accurate method for the determination of monoethanolamine (MEA) in PHWR steam-water circuits has been developed. MEA is added in the feed water to provide protection against corrosion while hydrazine is added to scavenge dissolved oxygen. The quantitative determination of MEA in presence of hydrazine was accomplished using derivatization ion chromatography with conductometric detection in nonsuppressed mode. A Metrosep cation 1-2 analytical column and a Metrosep cartridge were used for cation separation. A mixture of 4 mM tartaric acid, 20% acetone and 0.05 mM HNO3was used as eluent. Acetone in the mobile phase leads to the formation of different derivatives with MEA and hydrazine. The interferences due Na+and NH4 +were eliminated by adopting a simple pretreatment procedure employing OnGuard-H cartridge. The limit of detection limit of MEA was 0.1 μg mL−1and the relative standard deviation was 2% for the overall method. The recovery of MEA added was in the range 95%–102%. The method was applied to the determination of MEA in steam generator water samples.

Determination of the Apparent Complexing Capacity of Lake Waters

1974 ◽  
Vol 31 (9) ◽  
pp. 1515-1519 ◽  
Author(s):  
Y. K. Chau ◽  
R. Gächter ◽  
K. Lum-Shue-Chan
Keyword(s):  
Water Sample ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Accurate Method ◽  
Complexing Capacity ◽  
Ionic Copper ◽  
Relative Standard ◽  
Lake Waters

A sensitive and accurate method is described for the measurement of the apparent complexing capacity of lake waters. It is based on the measurement of labile copper by differential pulse anodic stripping voltammetry after a number of ionic copper spikes have been allowed to equilibrate with the complexing materials in a water sample. Coefficients of variation for the determination of EDTA at a level of 0.50 μmole/liter in Hamilton Harbor water were 6 and 8%. Analysis of seven replicates of a Hamilton Harbor water sample gave an apparent complexing capacity of 0.52 μmole/liter Cu equivalent with a relative standard deviation of 7.7%. Analyses of a number of samples from Lake Erie and from lakes near Sudbury, Ontario gave a range from nondetectable to 0.70 μmole/liter Cu equivalent of complexing capacity.

scholarly journals Spectrophotometric Determination of the Trace Amount of Thallium in Water and Urine Samples by Novel Oxidative Coupling Reaction

2009 ◽  
Vol 6 (4) ◽  
pp. 1153-1163 ◽  
Author(s):  
P. Nagaraja ◽  
N. Ghllab Saeed Al-Tayar ◽  
A. Shivakumar ◽  
A. K. Shresta ◽  
A. K. Gowda
Keyword(s):  
Coupling Reaction ◽  
Molar Absorptivity ◽  
Urine Samples ◽  
Standard Reference Materials ◽  
Oxidative Coupling Reaction ◽  
Relative Standard ◽  
Imipramine Hydrochloride ◽  
Optimum Reaction ◽  
Synthetic Standard

A novel, simple, rapid, sensitive and selective method has been proposed for the trace determination of thallium by spectrophotometric detection. This method is based on the oxidation of MBTH (3-methyl-2-benzothiazolinone hydrazone hydrochloride) by thallium(III) to form diazonium cation, which couples with IPH (Imipramine hydrochloride) in phosphoric acid medium at room temperature giving a blue colored species having a maximum absorption at 635 nm. The reagents and manifold variables influences on the sensitivity were investigated and the optimum reaction conditions have been established. The calibration curve was found to be linear over the range 0.1-5 μg mL-1with the molar absorptivity and Sandell’s sensitivity of 2.9x104L mol-1cm-1, 0.0071 μg cm-2respectively. The tolerance limit of the method towards various ions usually associated with thallium has been detected. The relative standard deviation for five replicate determination of 2μg mL-1thallium was 0.47%. The method has been successfully applied for the determination of thallium(ІΙΙ) and thallium(I) in synthetic, standard reference materials, water and urine samples with satisfactory results. The performance of the proposed method was evaluated in terms of student’st-test and variance ratioF-test, to find out the significance of proposed method over the reported methods.

Online Determination of Anionic Surfactant in Environmental Water

2012 ◽  
Vol 610-613 ◽  
pp. 1113-1116
Author(s):  
Liang Wei ◽  
Yi Chun Dai
Keyword(s):  
Anionic Surfactant ◽  
Sodium Dodecyl ◽  
Environmental Water ◽  
Buffer Solution ◽  
Experimental Conditions ◽  
Ethyl Violet ◽  
Relative Standard ◽  
Potassium Hydrogen ◽  
Standard Solution

It was found that ethyl violet can react with sodium dodecyl benzene sulfate (SDBS) to form ion associates in pH 2.2 ~ 2.8 of buffer solution of potassium hydrogen phthalate and hydrochloric acid in the presence of polyvinyl alcohol. Based on this, a method was proposed for online determination of anionic surfactant in environmental waterby. Under the optimum experimental conditions, Beers law was obeyed in the concentration range of 80 µg/L ~ 3500 µg/L of anionic surfactant (SDBS). The relative standard deviation of 2.1% was was obtained by injecting 800 µg/L of sodium dodecyl benzene sulfate standard solution (n=10). The detection limit calculated from three times of the average background noise was 4.39 µg/L. The proposed method had been applied successfully to the determination of anionic surfactant in environmental water and the results showed good agreement with that of the standard method.

Cloud Point Extraction and Spectrophotometry Determination of Lead in Environment Water Using 5-Br-PADAP

2013 ◽  
Vol 830 ◽  
pp. 345-348
Author(s):  
Lin Gao ◽  
Sheng Jie Chen ◽  
Fang Chen ◽  
Wen Hong Zhou ◽  
Jun Long Yao
Keyword(s):  
Cloud Point ◽  
Cloud Point Extraction ◽  
Detection Method ◽  
Low Cost ◽  
Calibration Graph ◽  
Buffer Solution ◽  
Relative Standard ◽  
Triton X ◽  
Optimized Conditions

A simple, sensitive, green and low cost detection method based on the cloud point extraction (CPE) separation and spectrophotometry was proposed for the determination of lead. In pH=9.0 H3BO3 buffer solution, Pb(II) reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in the presence of Triton X-100 yielding a hydrophobic complex, which then is extracted into micro-volume surfactant-rich phase. The calibration graph was linear in the range of 20-400 µg/L (at 560 nm). Under the optimized conditions, the detection limits of 10.94 µg/L and the relative standard deviations(RSD) of 2.0% (n=5) for Lead(II) were found, respectively. The sensitivity and absorbance of this method are at least five times higher when compared with that of usual 5-Br-PADAP spectrophotometry without CPE, and the proposed method has been applied to the determination of Lead in environment water samples with satisfactory results.

scholarly journals Spectrophotometric flow injection system for determination of Zn2+ in ophthalmic formulations using Alizarin red S

2018 ◽  
Vol 34 (2) ◽  
pp. 67
Author(s):  
Orlando Fatibello-Filho ◽  
Heberth Juliano Vieira
Keyword(s):  
Flow Injection ◽  
Sampling Rate ◽  
Alizarin Red S ◽  
Injection System ◽  
Borate Buffer Solution ◽  
Buffer Solution ◽  
Solution Ph ◽  
Alizarin Red ◽  
Relative Standard

A spectrophotometric flow injection method for the determination of Zn(II) in ophthalmic formulations was developed. In this work, Zn(II) ion was complexed with Alizarin red S in borate buffer solution (pH 9.0) and the chromophore produced was monitored at 520 nm. The analytical curve was linear in the Zn(II) concentration range from 6.05 x 10-6 to 1.50 x 10-4 mol L-1 with a detection limit of 3.60 x 10-6 mol L-1. Recoveries ranged from 96.3 to 105 % and a relative standard deviation of 1.2 % (n = 10) for 5.5x10-5 mol L-1 Zn(II) reference solution were obtained. The sampling rate was 60 h-1 and the results obtained of Zn(II) in ophthalmic products using this procedure are in close agreement with those obtained using a comparative spectrophotometric procedure at 95 % confidence level.

scholarly journals Spectrophotometric and RP-HPLC Methods for Determining Cefotaxime Sodium in Pharmaceutical Preparations

2020 ◽  
Vol 32 (6) ◽  
pp. 1314-1320
Author(s):  
Lamya A. Sarsam ◽  
Salim A. Mohammed ◽  
Sahar A. Fathe
Keyword(s):  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Pharmaceutical Preparations ◽  
Molar Absorptivity ◽  
Hplc Method ◽  
Buffer Solution ◽  
Limit Of Quantification ◽  
Rp Hplc ◽  
Relative Standard

A rapid, simple and sensitive spectrophotometric and RP-HPLC methods have been developed for the quantitative determination of cefotaxime-Na in both pure and dosage forms. The spectrophotometric method was based on diazotization of cefotaxime-Na and then coupling with 8-hydroxyquinoline in an alkaline medium. The resulting azo dye exhibited maximum absorption at 551 nm with a molar absorptivity of 0.597 × 104 L mol-1 cm-1. Beer′s law was obeyed over the range 10-700 μg/25 mL (i.e. 0.4-28.0 ppm) with an excellent determination coefficient (R2 = 0.9993). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0194 and 0.3765 μg mL-1, respectively. The recoveries were obtained in the range 97.3-102.5% and the relative standard deviation (RSD) was better than ± 1.56. The HPLC method has been developed for the determination of cefotaxime-Na. The analysis were carried out on a C18 column and a mobile phase composed of acetonitrile and phosphate buffer solution (0.024M KH2PO4 and 0.01M H3PO4) at pH 3.5 in the ratio of 60:40 (v:v), with a flow rate of 1.0 mL min-1 and UV detection at 258 nm. The proposed method showed good linearity (in a range of concentration 1.0-200 μg mL-1. The recovery percent and a relative standard deviations were found in the range 96 to 104.8% and ± 0.017 to ± 0.031%, respectively. Both methods were applied successfully to the assay of cefotaxime-Na in commercial injection preparations.

Voltammetric study of secnidazole and its determination in pharmaceutical tablet using 1, 4-benzoquinone modified carbon paste electrode

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Modified Carbon Paste Electrode ◽  
Carbon Paste ◽  
Buffer Solution ◽  
Limit Of Quantification ◽  
Pharmaceutical Tablet ◽  
Relative Standard ◽  
Paste Electrode

In this study voltammetric behaviour of secnidazole (SCZ) at 1, 4-Benzoquinone Modified Carbon Paste Electrode (1,4-BQMCPE) was investigated in Britton Robinson buffer solution using cyclic voltammetric technique. A well-defined cathodic peak was observed for the SCZ in the entire pH range. The current increases steadily with scan rate and the results indicated that the process is irreversible reduction and adsorption controlled. The number of electrons transferred and different kinetic parameters like transfer coefficient and rate constant were calculated by using cyclic voltammetry technique. Differential pulse voltammetric method has been used for the determination of SCZ content in pharmaceutical tablet. This method enabled to determine SCZ in the concentration range 1.0 × 10-8 to 4.0 × 10-4 M. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 2.13 × 10-9 and 2.85 × 10-9 respectively. The method was applied to determine the content of SCZ in different sample solutions of SCZ tablet with excellent recovery and relative standard deviation results (99.892±1.53 respectively) for spiked standard SCZ in tablet sample solutions. The selectivity of the method for SCZ was further studied in the presence of selected potential interferents such as fluconazole, azithromycin etc and confirmed the potential applicability of the developed method for the determination of SCZ in real pharmaceutical tablets.

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