Effect Of Analytical Variables Research Articles

Air-Assisted Alkanol-Based Nanostructured Supramolecular Liquid-Liquid Microextraction for Extraction and Spectrophotometric Determination of Morin in Fruit and Beverage Samples.

A new air-assisted liquid–liquid microextraction method based on alkanol nanostructured supramolecular solvents coupled to spectrometric analysis was developed for extraction, preconcentration, and spectrophotometric determination of morin. Al(III)-morin complex was performed at pH 4.5. Four different alkanol-based SUPRAS (supramolecular solvents) were prepared for the separation and preconcentration of Al-morin complex from aqueous solution by using vortex and centrifugation. Effect of analytical variables and tolerance limit of matrix ions were investigated. Under the optimum conditions, detection limit, quantification limit, relative standard deviation, preconcentration factor, and enhancement factor were found as 3.5 µg L−1, 10 µg L−1, 3.1%, 120, and 95, respectively. The accuracy of the method was performed with standard addition. The obtained results demonstrated the applicability of the method for the separation, preconcentration, and determination of morin in fruit and beverage samples. The method also complies with green chemistry principles as it uses green solvents, reduces reagent volumes, and produces low amounts of waste.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12161-021-02111-3.

Extraction, Preconcentration, and Quantification of Low Levels of Free Formaldehyde from Some Beverage Matrices by Combination of Ultrasound-Assisted-Cloud Point Extraction with Spectrophotometry

In the present study, due to use of formaldehyde (FA) as a food additive as well as its endogenous and natural occurrence in aquatic products, a new preconcentration method for the quantification of free formaldehyde (FA) in beverages was developed before analysis by spectrophotometry at 538 nm. The method is based on spontaneously Cannizzaro disproportionation of FA with Variamine blue (VBH2) in the presence of ionic surfactant, sodium dodecylsulfate (SDS) as both sensitivity enhancer and counter ion at pH 7.0, and then extraction of the formed ion-pairing complex into the nonionic surfactant, polyethylene glycol tert-octylphenyl ether (Triton X-114). The effect of analytical variables was evaluated in detail, and the optimal working conditions were established. There was a rectilinear relationship in the range of 2–400 μg L−1 with changing sensitivity. The limits of detection and quantification of the method with a sensitivity enhancement of 65 after preconcentration were 0.53 and 1.76 μg L−1, respectively. The accuracy was validated by using two spiked quality control samples in linear working range and by comparing the results obtained from the samples with those of independent method, which is known as a slight modified acetylacetone method. It has been observed that the results obtained by both methods are statistically compatible with a t value ranging from 0.09 to 0.65 (t critical 2.31). The intra-day and inter-day precisions as a result of stabilization of mixed micellar system were lower than 4.9% (as RSD%, n 5), and the recoveries were quantitatively higher than 95% for the two quality control samples spiked with 10, 25, and 50 μg L−1 with satisfactory results. The method was successfully applied to the quantification of low levels of free FA in selected beverage matrices.

Chemiluminescence Determination of Some Fluoroquinolones Using NBS-Luminol System

A new, simple, rapid and sensitive batch chemiluminescence (CL) method for determination of six fluoroquinolones (ciprofloxacin, gatifloxacin, levofloxacin, lomefloxacin HCl, ofloxacin and sparfloxacin) is proposd. The method is based on the CL generated during the oxidation of luminol by N-bromosuccinimide (NBS) in alkaline medium. The determination of the studied drugs is based on their inhibiting effect on the emission intensity of NBS-luminol chemiluminescent reaction. The effect of analytical variables on this CL system is discussed. The study was validated according to ICH guidelines. Under the optimum experimental conditions, the linear range is 50 to 400 ng/ml for ciprofloxacin, 50 to 600 ng/ml for gatifloxacin, lomefloxacin HCl and sparfloxacin and 25 to 400 ng/ml for levofloxacin and ofloxacin and the detection and quantitation limits for the studied drugs were not more than 4.88 and 14.80 ng/ml, respectively. The proposed method has been applied to detect the studied drugs in their pure forms and in different pharmaceutical formulations. The possible mechanism of the CL reaction was discussed.

Analysis of aquatic‐phase natural organic matter by optimized LDI‐MS method

The composition and physiochemical properties of aquatic-phase natural organic matter (NOM) are most important problems for both environmental studies and water industry. Laser desorption/ionization (LDI) mass spectrometry facilitated successful examinations of NOM, as humic and fulvic acids in NOM are readily ionized by the nitrogen laser. In this study, hydrophobic NOMs (HPO NOMs) from river, reservoir and waste water were characterized by this technique. The effect of analytical variables like concentration, solvent composition and laser energy was investigated. The exact masses of small molecular NOM moieties in the range of 200-1200 m/z were determined in reflectron mode. In addition, spectra of post-source-decay experiments in this range showed that some compounds from different natural NOMs had the same fragmental ions. In the large mass range of 1200-15,000 Da, macromolecules and their aggregates were found in HPO NOMs from natural waters. Highly humic HPO exhibited mass peaks larger than 8000 Da. On the other hand, the waste water and reservoir water mainly had relatively smaller molecules of about 2000 Da. The LDI-MS measurements indicated that highly humic river waters were able to form large aggregates and membrane foulants, while the HPO NOMs from waste water and reservoir water were unlikely to form large aggregates.

Simple, Rapid and Sensitive UV-Visible Spectrophotometric Method for Determination of Antidepressant Amitriptyline in Pharmaceutical Dosage Forms

The paper describes a new and simple approach for spectrophotometric determination of tricyclic antidepressant drug amitriptyline. Enhancement of the colour intensity of the Fe(III)-SCN−complex on addition of the drug amitriptyline forms the basis of the proposed method. The value of molar absorptivity of the Fe(III)-SCN−amitriptyline ion pair complex in terms of the drug lies in the range of (2.82–3.36) × 103 L·mol−1·cm−1at the absorption maximum 460 nm. The detection limit of the method was 0.3 μg·mL−1. The slope, intercept, and correlation coefficients for the present method were found to be 0.008, 0.002, and +0.998, respectively. The effect of analytical variables on the determination of the drug and the composition of the complex are discussed in the paper. The method is applicable in the determination of amitriptyline in pharmaceutical preparations.

New Approach for the Determination of Tricyclic Antidepressant Amitriptyline Using <i>β</i>-Cyclodextrin-PEG System via Spectrophotomerty

A new and simple procedure for the spectrophotometric determination of the tricyclic antidepressant drug amitriptyline is proposed. The method is based on enhancement of sensitivity of the [AMIYTP]+ β-cyclodextrin and PEG molecules involved in formation of molecules inclusion complex, in presence of polyethylene glycol (PEG) medium. The mole ratio of [AMIYTP]+ β-cyclodextrin and PEG molecules in inclusion complex were determined by the curve fitting method. The value of molar absorptivity of {[AMIYTP: (β CD)] PEG} complex in term of the drug lies in rage of (2.20 - 2.23) × 104 L·mole–1·cm–1 at absorption maximum 242 nm. The slope, intercept and correlation co-efficient were found to be 14.21, 0.0046, and 0.998, respectively. The effect of analytical variables on the determination of the drug and composition of the ion associated complex are discussed in the paper. This method is applicable in the determina-tion of amitriptyline in the pharmaceutical preparations.

Effect of colloidal β‐cyclodextrins–Fe3O4 magnetic nanoparticles on the chemiluminescence enhancement of luminol–Ag(III) complex for rapid and sensitive determination of cysteine in human serum

Colloidals solution of Fe3 O4 magnetic nanoparticles (MNPs), capped with β-cyclodextrins (β-CD) as inclusion complexes, were found to enhance the chemiluminescence (CL) intensity of the luminol-diperiodatoargentate(III) (DPA) system. On injection of cysteine into the luminol-DPA-β-CD-Fe3 O4 MNPs inclusion complexes system, the CL intensity is strongly enhanced. The enhanced CL signal is ascribed to the catalytic effect of Fe3 O4 MNPs capped with β-CD, which is assumed to stabilize the CL intermediate. Based on these findings, a rapid and sensitive assay was developed for the determination of cysteine in human serum. The effects of analytical variables on the CL signal were studied and optimized. Under the optimum conditions, the CL intensity was directly proportional to the concentration of cysteine in the range 8.0 × 10(-9) -1.0 × 10(-6) mol/L. The detection limit was 2.8 × 10(-9) mol/L (3 S(b) /m) and the relative standard deviation (RSD) for 10 replicate determinations of 1.0 × 10(-7) mol/L cysteine was 3.5%. The proposed method was applied to the sensitive determination of cysteine in human serum samples, and compared with the Ellman method with satisfactory results.

Simple and sensitive spectrophotometric method for determination of tricyclic antidepressant imipramine using Fe(III)-SCN− complex

A new simple procedure for the spectrophotometric determination of tricyclic antidepressant drug imipramine is proposed. The method is based on the enhancement of the colour intensity of the Fe(III)-SCN− complex due to the addition of the drug imipramine. The value of molar absorptivity of the Fe(III)-SCN− imipramine complex in terms of the drug lies in the range of (2.77–3.16) × 103 L/mol cm at the absorption maximum 460 nm. The detection limit of the method was 250 μg/L. The slope, intercept, and correlation co-efficient for the present method were found to be 0.008, 0.005, and 0.998, respectively. The effect of analytical variables on the determination of the drug and the composition of the complex are discussed. The method is applicable to the determination of imipramine in the drug samples.

Amperometric Enzyme Biosensor Based on the Controlled Pore Glass

A new amperometric biosensor based of glucose oxidase immobilized in aminopropyl-controlled pore glass (CPG) is reported. The glucose oxidase was linked to the CPG by covalent bonds with glutaraldehyde. The effect of analytical variables on the biosensor response was studied using experimental design methodology. Analytical properties such as linearity, detection limit, quantitation limit, range, and precision are reported. Interferences caused by compounds usually present in biological samples were eliminated.

Effects of (Pre-)analytical Variables on Activated Protein C Resistance Determined Via a Thrombin Generation-based Assay

The normalized activated protein C sensitivity ratio (nAPC-sr) determined with an assay that quantifies the effect of APC on thrombin formation initiated via the extrinsic coagulation pathway identifies hereditary and acquired defects of the protein C system. We investigated the influence of assay conditions (analytical variables) and plasma handling (pre-analytical variables) on nAPC-sr obtained with this APC resistance test. The effect of the analytical variables (CaCl2, phospholipid and APC concentrations and the concentration and source of tissue factor) was determined in pooled normal plasma. Inhibition of thrombin formation by APC was dependent on the APC concentration and was also affected by the tissue factor, Ca2+ and phospholipid concentrations. Thus, strict standardization of reactant concentrations is required to obtain reproducible nAPC-sr. Three different tissue factor preparations were compared by determining nAPCsr in plasma samples obtained from 90 healthy individuals. nAPC-sr were similar for all three tissue factor preparations although, compared with the noncommercially available tissue factor used in earlier studies, values determined with commercial tissue factor preparations showed larger variation. Pre-analytical variables, investigated in plasma of nine volunteers (3 normal individuals and 6 individuals with an APC-resistant phenotype) were: concentration of anticoagulant (3.2% vs. 3.8% trisodiumcitrate), time before processing of blood (0, 4 and 24 h), centrifugation speed, storage temperature of plasma (-20 degrees C vs. -80 degrees C) and sample thawing. Multiple linear regression analysis showed that only the citrate concentration affected the nAPC-sr, which was higher in samples collected in 3.2% trisodiumcitrate than in samples collected in 3.8% trisodiumcitrate.

A new spectrophotometric method for the determination of total and ferric iron in rain water at the ppb level.

A new, simple, selective and sensitive spectrophotometric procedure for the on-site quantification of iron at nano-gram levels in atmospheric precipitations, i.e. rain as sample source is described. It is based on the color reaction of Fe3+ with SCN- ions in the presence of a cationic surfactant, i.e. cetylpyridinium chloride (CPC), in strong HCl solution, and subsequent extraction of the complex with N-octylacetamide into toluene or chloroform. The apparent molar absorptivity of the complex is 2.60 x 10(5) L mol(-1) cm(-1) at lambdamax = 480 nm at an enrichment factor (EF) of 10. The detection limit (causing higher absorbance than the sum of the blank absorbance (0.009) and 3 SD) is 5 ng mL(-1) Fe. Ions commonly associated with iron did not interfere in the present method. The effect of analytical variables, i.e. amount and type of the reagents, acidity, solvent, temperature, dilution, etc., in the determination of iron are discussed. The validity of the present method is checked with GF-AAS. The method has been applied to the determination of iron at the ppb level in rain water samples.