Determination of subnanogram amounts of sulfur dioxide and sulfites by pneumatopotentiometry

1986 ◽  
Vol 51 (10) ◽  
pp. 2077-2082 ◽  
Author(s):  
Jan Langmaier ◽  
František Opekar
Keyword(s):  
Sulfur Dioxide ◽  
Redox Potential ◽  
Sodium Hydroxide ◽  
Porous Membrane ◽  
Membrane Electrode ◽  
Iodine Monochloride ◽  
Membrane Pores ◽  
Relative Standard ◽  
Limit Of Quantitation

Gold porous membrane electrode has been used for the potentiometric determination of small amounts of sulfur dioxide absorbed in the solutions of sodium tetrachloromercurate or sodium hydroxide. Sulfur dioxide is released by the reaction with an acid into a stream of nitrogen and led to the electrode immersed into the solution of iodine monochloride. Part of SO2 penetrates through the membrane pores into the solution where it is oxidized. The electrode redox potential change is a measure of the SO2 concentration in the absorption solution. In the solution of 1 . 10-5 M[ICl2]- in 0.02 M-HClO4 the limit of quantitation was found to be 0.07 ng SO2 . ml-1. The relative standard deviations of 1.4% and 2.5% were found for the determinations of 10 ng and 0.5 ng of SO2, respectively. Higher concentrations of H2S interfere only in the hydroxide solution. About 10 samples can be analyzed per one hour.

scholarly journals Reverse phase-liquid chromatography assisted protocol for simultaneous determination of lamivudine and tenofovir disoproxil fumarate in combined medication used to control HIV infection: an investigative approach

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Vaibhav S. Adhao ◽  
Suraj R. Chaudhari ◽  
Jaya P. Ambhore ◽  
Sunil Sangolkar ◽  
Raju R. Thenge ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Hiv Infection ◽  
Simultaneous Determination ◽  
Tenofovir Disoproxil Fumarate ◽  
Solvent System ◽  
Array Detector ◽  
Technical Requirements ◽  
Relative Standard ◽  
Limit Of Quantitation

Abstract Background Human immunodeficiency virus (HIV) causes severe life-threatening condition, i.e., AIDS. HIV destabilises an individual’s ability to prevent infection. Therefore, the combine medication lamivudine (LVD) and tenofovir disoproxil fumarate (TDF) are prescribed to suppress the amount of HIV infection in individual’s body; thus, the individual’s immune system could function properly. Consequently, the objective of present research work was to investigate robust and sensitive liquid chromatography avenue for simultaneous determination of lamivudine and tenofovir disoproxil fumarate in pure material and combined dosage form. Results The reversed-phase chromatographic separation has been performed through Hypersil BDS C18 column using solvent system composed of 10 mM potassium dihydrogen phosphate (pH 4.0): acetonitrile (60:40% v/v). The determination was executed at 30 oC at 1 mL/min rate for flow of solvent system through column. The eluents of column were monitored at 265 nm using Photodiode Array detector has revealed admirable retention times, i.e., 4.67 and 8.78 min for both drugs, respectively. The calibration curve demonstrated excellent linearity in the range of 10–50 μg/mL for lamivudine and tenofovir disoproxil fumarate with better determination coefficients was more than (r2 0.999). Conclusion The estimable method was effectively validated with respect to accuracy, precision, sensitive (limit of detection and limit of quantitation), robustness, ruggedness, and for selectivity and specificity. The value less than 2 for percentage relative standard deviation for accuracy, precision, robustness, and ruggedness satisfying the acceptance criteria as per procedure of International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use.

Simultaneous Determination of Four Herbicide and Pesticide Residues in Chinese Green Tea Using QuEChERS Purification Procedure and UPLC-MS/MS Analysis

2013 ◽  
Vol 634-638 ◽  
pp. 1586-1590
Author(s):  
Su Fang Wang ◽  
Shou Jie Zhang ◽  
Chun Hong Dong ◽  
Guo Qing Wang ◽  
Jun Feng Guo ◽  
...  
Keyword(s):  
Formic Acid ◽  
Simultaneous Determination ◽  
Green Tea ◽  
Limit Of Detection ◽  
Multiple Reaction Monitoring ◽  
Graphitized Carbon Black ◽  
Ms Analysis ◽  
Relative Standard ◽  
Limit Of Quantitation

A method for simultaneous determination of residuals of four herbicides and pesticides, simazine, carboxin, diflubenzuron and rotenone, in Chinese green tea was developed. In the proposed method, the tea powder was placed in a centrifuge tube with a plug, extracted in saturated aqueous sodium chloride solution and acetonitrile, agitated using vortex oscillator, and then centrifuged 5 min at 4000 rpm. The supernatant solution was purified by primary secondary amine (PSA) sorbent, C18 power, and graphitized carbon black powder, respectively. Then the purified extracts were dissolved with acetonitrile:0.1% formic acid aqueous solution (40:60, V/V) and agitated, filtered using a syringe with 0.22 μm nylon filter prior to UPLC-MS/MS analysis. The UPLC analysis was performed on an ACQUITY UPLC® HSS T3 column (2.1 mm×100 mm, 1.8 µm), using acetonitrile-0.1% formic acid as mobile phase with the flow rate as 0.3 mL•min-1. Injection volume was 10 µL. Positive ionization mode was applied, and the ions were monitored in the multiple reaction monitoring (MRM) mode with curtain gas 0.069 MPa, collision gas 0.052 MPa, ESI ion spray voltage 5000 V, temperature 550 °C, nebulizer gas 0.24 MPa, and turbo gas 0.28 MPa. The limit of detection (LOD) and limit of quantitation (LOQ) of the proposed method are 1 μg•kg-1and 5 μg•kg-1, respectively. The average recoveries of the four pesticides at 10, 20, and 50 µg•kg-1spiking levels range from 77.4% to 95.3%. TheSupersSuperscript textcript textrelative standard deviation (RSD) (n=6) range form 11.83% to 4.52%.

scholarly journals SENSITIVE DETERMINATION OF RELATED SUBSTANCES IN PIOGLITAZONE HYDROCHLORIDE BY HPLC

2017 ◽  
Vol 9 (2) ◽  
pp. 34
Author(s):  
N. Balaji ◽  
Sayeeda Sultana
Keyword(s):  
Mobile Phase ◽  
High Performance ◽  
Limit Of Detection ◽  
High Performance Liquid Chromatographic ◽  
Hplc Method ◽  
Internal Diameter ◽  
Related Substances ◽  
Relative Standard ◽  
Limit Of Quantitation

Objective: An efficient, high performance liquid chromatographic method has been developed and validated for the quantification of related substances in pioglitazone hydrochloride drug substance.Methods: This method includes the determination of three related substances in pioglitazone hydrochloride. The mobile phase A is 0.1% w/v triethylamine in water with pH 2.5 adjusted by dilute phosphoric acid. The mobile phase B is premixed and degassed mixtures of acetonitrile and methanol. The flow rate was 1 ml/min. The elution used was gradient mode. The HPLC column used for the analysis was symmetry C18 with a length of 250 mm, the internal diameter of 4.6 mm and particle size of 5.0 microns.Results: The developed method was found to be linear with the range of 0.006-250% with a coefficient of correlation 0.99. The precision study revealed that the percentage relative standard deviation was within the acceptable limit. The limit of detection and limit of quantitation of the impurities was less than 0.002%and 0.006% with respect to pioglitazone hydrochloride test concentration of 2000 µg/ml respectively. This method has been validated as per ICH guidelines Q2 (R1).Conclusion: A reliable, economical HPLC method was magnificently established for quantitative analysis of related substances of pioglitazone hydrochloride drug substance.

scholarly journals Development and validation of spectrophotometric method for phenylephrine hydrochloride estimation in nasal drops formulations

2008 ◽  
Vol 27 (2) ◽  
pp. 149 ◽  
Author(s):  
Ivana Savić ◽  
Goran Nikolić ◽  
Vladimir Banković
Keyword(s):  
Standard Deviation ◽  
Sodium Hydroxide ◽  
Relative Standard Deviation ◽  
Spectrophotometric Method ◽  
Molar Absorptivity ◽  
Dosage Forms ◽  
Phenylephrine Hydrochloride ◽  
Relative Standard ◽  
Development And Validation

Simple, accurate and reproducible UV-spectrophotometric method was developed and validated for the estimation of phenylephrine hydrochloride in pharmaceutical nasal drops formulations. Phenylephrine hydrochloride was estimated at 291 nm in 1 mol⋅dm-3 sodium hydroxide (pH 13.5). Beer’s law was obeyed in the concentration range of 10–100 μg⋅cm−3 (r2 = 0.9990) in the sodium hydroxide medium. The apparent molar absorptivity was found to be 1.63×103 dm3⋅mol−1⋅cm−1. The method was tested and validated for various parameters according to the ICH (International Conference on Harmonization) guidelines. The detection and quantitation limits were found to be 0.892 and 2.969 μg⋅cm−3, respectively. The proposed method was successfully applied for the determination of phenylephrine hydrochloride in pharmaceutical nasal drops formulations. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 1 %), while being simple, cheap and less time consuming, and hence can be suitably applied for the estimation of phenylephrine hydrochloride in different dosage forms.

Liquid Chromatographic Determination of Sulfentrazone in Soil

1999 ◽  
Vol 82 (5) ◽  
pp. 1214-1216 ◽  
Author(s):  
G Anthony Ohmes ◽  
Thomas C Mueller
Keyword(s):  
Chromatographic Determination ◽  
Soil Samples ◽  
Ultraviolet Detection ◽  
Liquid Chromatographic Separation ◽  
Relative Standard ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Soluble Components

Abstract A rapid method for the determination of sulfentrazone in soils is described. The method consists of extraction of soil samples with methanol, filtration, liquid chromatographic separation of methanol-soluble components through a C18 column, and ultraviolet detection at 220 nm. Recoveries from fortified surface soils were &gt;85% for sulfentrazone. Average relative standard deviations over the soils examined was 7.7%. A conservative lower limit of quantitation for sulfentrazone was 40 ng/g soil.

scholarly journals Determination of Tianeptine in Tablets by High-Performance Liquid Chromatography with Fluorescence Detection

2007 ◽  
Vol 90 (3) ◽  
pp. 720-724
Author(s):  
Sevgi Tatar Ulu
Keyword(s):  
Lower Limit ◽  
High Performance ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Linear Calibration ◽  
Fluorescence Detector ◽  
Relative Standard ◽  
Validation Parameters ◽  
Limit Of Quantitation

Abstract A sensitive and selective high-performance liquid chromatographic method has been developed for the determination of tianeptine (Tia) in tablets. The method is based on derivatization of Tia with 4-chloro-7-nitrobenzofurazan (NBD-Cl). A mobile phase consisting of acetonitrile10 mM orthophosphoric acid (pH 2.5; 77 + 23) was used at a flow rate of 1 mL/min on a C18 column. The Tia-NBD derivative was monitored using a fluorescence detector, with emission set at 520 nm and excitation at 458 nm. Gabapentin was selected as an internal standard. Linear calibration graphs were obtained in the concentration range of 45300 ng/mL. The lower limit of detection (LOD) was 10 ng/mL at a signal-to-noise ratio of 4. The lower limit of quantitation (LOQ) was 45 ng/mL. The relative standard values for intra- and interday precision were &lt;0.46 and &lt;0.57%, respectively. The recovery of the drug samples ranged between 98.89 and 99.85%. No chromatographic interference from the tablet excipients was found. The proposed method was validated in terms of precision, robustness, recovery, LOD, and LOQ. All the validation parameters were within the acceptance range. The proposed method was applied for the determination of Tia in commercially available tablets. The results were compared with those obtained by an ultraviolet spectrophotometric method using t- and F-tests.

scholarly journals Determination of 1,4-Dioxane in Household Detergents and Cleaners

2008 ◽  
Vol 91 (2) ◽  
pp. 439-444 ◽  
Author(s):  
Akiko Tanabe ◽  
Kuniaki Kawata
Keyword(s):  
Solid Phase ◽  
Stable Isotope Dilution ◽  
Household Products ◽  
Relative Standard ◽  
Limit Of Quantitation ◽  
Recovery Study ◽  
The Mean ◽  
Household Detergents ◽  
Domestic Effluent

Abstract A possible human carcinogen, 1,4-dioxane, was investigated as to its concentration levels in household detergents and cleaners currently sold in Japan. A solid-phase extraction combined with stable isotope dilution and gas chromatographic/ mass spectrometric determination was evaluated for the determination of 1,4-dioxane in household products. The evaluation of the method was performed using a recovery study of 1,4-dioxane-d8 from detergent and cleaner samples. The mean overall recovery and relative standard deviation were 78 and 15, respectively. The limit of quantitation was 0.05 mg/kg. This method was satisfactorily applied to the determination of 1,4-dioxane in household products. 1,4-Dioxane was detected in 40 out of the 51 investigated samples. The concentrations ranged from 0.05 to 33 mg/kg, and the mean was 2.7 mg/kg. The mean of the products that included anionic surfactants, i.e., alkylpoly(oxyethylene)sulfates, was 7.2 mg/kg, which was higher than the 0.39 mg/kg mean for the other surfactants. Moreover, the 1,4-dioxane load/person was estimated to be 0.061 mg/day/person in Japan, which was 27 of the load from the domestic effluent.

scholarly journals Determination of 7B3 Residues in Cotton Plants by Liquid Chromatography/Mass Spectrometry

2009 ◽  
Vol 92 (1) ◽  
pp. 302-306 ◽  
Author(s):  
Xiao-Jing Yan ◽  
Xiao-Mei Liang ◽  
Yan-Jun Xu ◽  
Shu-Hui Jin ◽  
Dao-Quan Wang
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Limit Of Detection ◽  
Reversed Phase ◽  
Liquid Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry ◽  
Relative Standard ◽  
Limit Of Quantitation ◽  
Cotton Plants

Abstract A method was developed for the determination of 7B3 (12-propyloxyimino-1,15-pentadecanlactam), a novel macrolactam fungicide, by liquid chromatography/mass spectrometry (LC/MS) with positive electrospray ionization (ESI+). The method used a reversed-phase C18 column and acetonitrilewater (60 + 40, v/v) mobile phase. The quick, easy, cheap, effective, rugged, and safe method was used for extraction of 7B3 from cotton plants, which involved the extraction of 10 g homogenized sample with 10 mL acetonitrile, followed by the addition of 4 g anhydrous MgSO4 and 1.0 g NaCl. After centrifugation, 1 mL of the buffered acetonitrile extract was transferred into a tube containing 50 mg primary secondary amine sorbent and 100 mg anhydrous MgSO4. After shaking and centrifugation, the final extract was transferred to an autosampler vial for concurrent analysis by LC/MS. The results of 7B3 determined by LC/MS in the selective ion monitoring mode were linear, and the matrix effect of the method was evaluated. The average recoveries of 7B3 fortified at different levels were within 84.1100.2, and the relative standard deviations were &lt;7.5 for all samples analyzed. The method limit of detection and the limit of quantitation values were 0.03 and 0.1 mg/kg, respectively. The proposed method was successfully applied to determine 7B3 residues in practical samples. This method is sensitive, accurate, reliable, simple, and safe.

scholarly journals Direct Determination of Free Methionine in Soy-Based Infant Formula

2004 ◽  
Vol 87 (1) ◽  
pp. 123-128
Author(s):  
Paul Johns ◽  
Rosalyn Phillips ◽  
Lobat Dowlat
Keyword(s):  
Infant Formula ◽  
Mobile Phase ◽  
Method Comparison ◽  
Water System ◽  
Direct Determination ◽  
Reversed Phase ◽  
Intermediate Precision ◽  
Relative Standard ◽  
Limit Of Quantitation

Abstract A method was developed for the direct determination of free methionine in soy-based infant formula, with analyte separation and quantitation by reversed-phase liquid chromatography (LC), and UV absorbance at 214 nm, respectively. Sample preparation required only dilution with mobile phase and syringe filtration. Using a 0.02M KH 2 PO 4 mobile phase (pH adjusted to 2.9 with 85% o-phosphoric acid) and 0.7 mL/min flow rate, methionine eluted at approximately 8 min, and total run time was 14 min after column regeneration with acetonitrile–water. System linearity was demonstrated as peak area versus analyte concentration, ranging from 80 to 120% of the formula specification for free methionine (r &gt; 0.999, and all residuals &lt;0.45%). Intermediate precision relative standard deviation values were &lt;1.5% for ready-to-feed and reconstituted powder samples, and recoveries ranged from 98.0 to 103.5% for inter-method comparison with an amino acid analyzer method. The limit of quantitation was 3 mg methionine/L in the “as fed” infant formula. Despite the relatively weak UV absorptivity of methionine, the 214 nm signal was sufficiently intense in the 30–65 mg/L (201–436 μM) range to afford quantitation by peak area proportionation versus a 2-point external standard calibration. This direct UV detection after reversed-phase LC separation provides a simple and accurate method for determining free methionine without derivatization.

scholarly journals DEVELOPMENT AND VALIDATION OF ULTRAVIOLET-SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF FEBUXOSTAT FOR CONDUCTING IN-VITRO QUALITY CONTROL TESTS IN BULK AND PHARMACEUTICAL DOSAGE FORMS

2018 ◽  
Vol 11 (9) ◽  
pp. 115
Author(s):  
Jaspreet Kaur ◽  
Daljit Kaur ◽  
Sukhmeet Singh
Keyword(s):  
Spectrophotometric Method ◽  
Limit Of Detection ◽  
Pharmaceutical Formulations ◽  
Dosage Forms ◽  
Pharmaceutical Dosage Forms ◽  
Relative Standard ◽  
Limit Of Quantitation ◽  
Development And Validation

Objective: A simple, accurate, and selective ultraviolet-spectrophotometric method has been developed for the estimation of febuxostat in the bulk and pharmaceutical dosage forms.Method: The method was developed and validated according to International Conference on Harmonization (ICH Q2 R1) guidelines. The developed method was validated statistically with respect to linearity, range, precision, accuracy, ruggedness, limit of detection (LOD), limit of quantitation (LOQ), and recovery. Specificity of the method was demonstrated by applying different stressed conditions to drug samples such as acid hydrolysis, alkaline hydrolysis, oxidative, photolytic, and thermal degradation.Results: The study was conducted using phosphate buffer pH 6.8 and λmax was found to be 312 nm. Standard plot having a concentration range of 1–10 μg/ml showed a good linear relationship with R2=0.999. The LOD and LOQ were found to be 0.118 μg/ml and 0.595 μg/ml, respectively. Recovery and percentage relative standard deviations were found to be 100.157±0.332% and <2%, respectively.Conclusion: Proposed method was successfully applicable to the pharmaceutical formulations containing febuxostat. Thus, the developed method is found to be simple, sensitive, accurate, precise, reproducible, and economical for the determination of febuxostat in pharmaceutical dosage forms.

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