American Journal of Analytical Chemistry

Journal Information
ISSN / EISSN : 21568251 / 21568278
Current Publisher: Scientific Research Publishing, Inc, (10.4236)
Total articles ≅ 875
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Léopoldine Sonfack Guenang, Prachi Gupta, Victor Costa Basseto, Milica Jovic, Ervice Ymélé, Andreas Lesch, Hubert Girault, Ignas Kenfack Tonlé
American Journal of Analytical Chemistry, Volume 11, pp 1-14; doi:10.4236/ajac.2020.111001

Abstract:In this work, a simple procedure for the preparation of an inkjet printed disposable graphene electrode is reported. Commercial graphene ink was printed on a kapton substrate and the resulting electrode was 30 min treated by oxygen plasma, then modified by a bismuth salt. The as prepared electrode was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), laser scanning microscopy (LSM) and scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDX). The sensing properties of the characterized electrodes were then investigated using cyclic voltammetry and Electrochemical Impedance Spectroscopy (EIS). Afterwards, these electrodes were exploited in a comparative way for the electroanalysis of Cadmium(II) and Lead(II) ions. An increase in the electrode sensitivity due to its modification and to the presence of bismuth was observed. Some preliminary experiments based on stripping square wave voltammetry highlighted the interest of using the proposed disposable inkjet printed electrodes for the electrochemical detection of heavy metals in tap water.
Satoshi Ikeda, Saya Morioka, Yoshihiro Kudo
American Journal of Analytical Chemistry, Volume 11, pp 25-46; doi:10.4236/ajac.2020.111003

Abstract:Ionic strength conditions in distribution experiments with single ions are very important for evaluating their distribution properties. Distribution experiments of picrates (MPic) with M = Ag(I) and Li(I)-Cs(I) into o-dichlorobenzene (oDCBz) were performed at 298 K by changing volume ratios (Vorg/V) between water and oDCBz phases, where “org” shows an organic phase. Simultaneously, an analytic equation with the Vorg/V variation was derived in order to analyze such distribution systems. Additionally, the AgPic distribution into nitrobenzene (NB), dichloromethane, and 1,2-dichloroethene (DCE) and the NaB(C6H5) 4 (=NaBPh4) one into NB and DCE were studied at 298 K under the conditions of various Vorg/V values. So, extraction constants (Kex) for MPic into the org phases, their ion-pair formation constants (KMA,org) for MA = MPic in the org ones, and standard distribution constants () for the M(I) transfers between the water and org bulk phases with M = Ag and Li-Cs were determined at the distribution equilibrium potential (dep) of zero V between the bulk phases and also the Kex (NaA), KNaA,org, and values were done at A-=BPh-4. Here, the symbols Kex, KMA,org, and or were defined as [MA] org/[M+][A-], [MA] org/[M+]org [A-]org, and [M+]org/[M+] or [A-]org/[A-] at dep = 0, respectively. Especially, the ionic strength dependences of Kex and KMPic,org were examined at M = Li(I)-K(I) and org = oDCBz. From above, the conditional distribution constants, KD,BPh4 and KD,Cs, were classified by checking the experimental conditions of the I, Iorg, and dep values.
Idris Aminu, Sani M. Gumel, Wasila A. Ahmad, Adamu A. Idris
American Journal of Analytical Chemistry, Volume 11, pp 47-59; doi:10.4236/ajac.2020.111004

Abstract:In this study, adsorption of Congo red dye onto activated carbon prepared from Jujube (Ziziphus Mauritiania) seeds with phosphoric acid as the activating agent was investigated. Batch adsorption studies were carried out to study the influence of contact time, adsorbent dosage and initial dye concentration on the adsorption. The data was analysed using pseudo-first order and pseudo-second order kinetic models. The pseudo-second order kinetic model was found to describe the adsorption more effectively with a perfect correlation coefficient of unity. The rate constant, K was obtained as 0.182 (g/mg min) and the calculated qe (9.81) is very close to the experimental value (9.78). A high correlation coefficient obtained when the data was analysed with the intraparticle diffusion rate equation, revealed the presence of intraparticle diffusion in the adsorption process even though it is not the sole controlling step as shown by the value of the intercept (C ≠ 0). Isotherm studies showed that there is high correlation in each case when the data was modelled with Langmuir, Freundlich, Temkin and Dubinin-Radushkevic isotherm models but the best fit was obtained with the Freundlich model with R2 = 0.9991, adsorption capacity, KF = 19.73 (mg/g)(mg/L)1/n and n = 1.563 indicating the adsorption is favourable and occurs on a heterogeneous surface by multilayer. The study showed that activated carbon from jujube seeds is an effective adsorbent for the removal of Congo red dye from solution.
Abdulrhman M. Dhabbah, A. Yacine Badjah-Hadj-Ahmed, Anna A. Stec, T. Richard Hull
American Journal of Analytical Chemistry, Volume 10, pp 23-37; doi:10.4236/ajac.2019.101003

Abstract:Huge amounts of various polymers are being used in many fields with numerous benefits. However, their great ability to ignition and rapid flame spreading make these materials dangerous for human life and properties due to the release of highly toxic combustion products. The present work aims to investigate several methods of sampling and identification of aromatic hydrocarbons produced by controlled burning of low-density polyethylene (LDPE) using a toxicity tube furnace. Five different sampling methods were used: solid phase micro extraction (SPME), syringe, tedlar bags, sorption tubes, and gas-solution absorbers (midget impingers). The produced hydrocarbons were analysed by gas chromatography coupled to mass spectrometry with and without pyrolysis. Among the tested techniques, the most convenient sampling method was using syringe with a glass vessel which allowed detection of the highest amount of aromatic hydrocarbons at both 800˚C and 600˚C, and then followed by SPME. On the other hand, the use of gas-solution absorber (midget impinger) showed poorer results. Regarding the use of tedlar bags and sorption tubes, they did not give satisfactory results. Several carcinogenic or possibly carcinogenic compounds were identified in the combustion products, such as benzene, naphthalene, anthracene and pyrene.
Thomas Onfroy, Olivier Marie
American Journal of Analytical Chemistry, Volume 10, pp 9-22; doi:10.4236/ajac.2019.101002

Abstract:The integrated molar absorption coefficients for ν(OH) (3655 cm−1), δ(OH) (Q branch at 1176 cm−1 or whole bands), [ν(CCring) + δ(OH)] (Q branch at 1344 cm−1 or whole bands) and γ(CH) (752 cm−1) were determined at 342 K, by recording infrared spectra of pure gaseous phenol at different partial pressure (from 0 to 33 Pa). The integrated molar absorption coefficients (ε) values were obtained with a good reproducibility and the relative uncertainty on the given values is below 2%. The influence of water on the integrated molar absorption coefficients of phenol has been investigated in a large range of nwater/nphenol values (from 0.5 to 6.1 and from 44 to 94) using distinct setups. The infrared spectra of a gas mixture containing a constant amount of phenol and different amount of water were recorded (closed cell) whereas in dynamic condition (under flow) the water partial pressure was kept constant at 1.3 kPa and the phenol partial pressure was increased from 0 to 30 Pa. It is here demonstrated that, at 342 or 355 K, the presence of water does not affect the epsilon values of δ(OH) and [ν(CCring) + δ(OH)] bands.
Lucien Murhula Namegabe, Mireille Tumusifu Kadhesi, Pacifique Murhula Hamuli, Aladdin Ombeni Mahano, Paul Brioen
American Journal of Analytical Chemistry, Volume 10, pp 415-422; doi:10.4236/ajac.2019.109029

Abstract:The present study focuses on the quality control of quinine in the compressed pharmaceutical forms circulating in eastern Democratic Republic of Congo. The analyses performed on the collected samples included disintegration of the tablets, identification of quinine in the formulations by color reaction methods and thin-layer chromatography. The quantitative analysis was performed by spectrophotometric and volumetric methods. The most significantly observed findings were abnormalities of release; underdosing, overdosing and absence of the active ingredient, Which brings us to the conclusion that more than 30% of the samples analyzed are of inferior quality and adulterated.
Carla Zarazir, Mohamad Rajab, Houssam Obeid, Joumana Toufaily, Imad Toufeili, Tayssir Hamieh
American Journal of Analytical Chemistry, Volume 10, pp 647-665; doi:10.4236/ajac.2019.1012046

Abstract:Scarce information is currently available relative to the use of polymeric materials as storage containers for extra virgin olive oil. This paper was devoted to study and compare the impact of glass and 3 types of packaging materials—polyethylene terephthalate (PET), high density polyethylene (HDPE), and polylactic acid (PLA) on Lebanese extra virgin olive oil (EVOO) up to 9 months under non-accelerated storage conditions. The acidity, peroxide value (PV), K232, K270, fatty acid profile, overall migration, and oil sorption into the packaging material were determined. Conventional titration, gas chromatography-mass spectrometry, and spectrophotometry were used to quantify the outcome measures at baseline, 3, 5, 7, and 9 months. Mixed model ANOVA was applied to assess differences according to polymer type and storage period at P 232 and K270), migration, and sorption significantly increased with increasing storage time for oil in contact with glass and plastic materials, especially between the 7th and 9th month of storage. Overall, PLA showed the least deterioration and interaction phenomena compared with PET and HDPE. While glass remains the best container for EVOO, PLA could potentially replace PET and HDPE for short-time storage under conventional storage conditions in Lebanese households.
M. Jamaluddin Ahmed, Ayesha Afrin, Mamunur Rashid
American Journal of Analytical Chemistry, Volume 10, pp 316-347; doi:10.4236/ajac.2019.108023

Abstract:A very simple, ultra-sensitive, highly selective and non-extractive new spectrofluorimetric method for the determination of arsenic at pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of Arsenic (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.025 - 0.1 M H2SO4) solution with Arsenic (V) in absolute ethanol to produce highly fluorescent oxidized product (λex = 303 nm; λem = 365 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.025 - 0.1 M H2SO4) for the period between 2 min and 24 h. Linear calibration graphs were obtained for 0.001 - 800-μgL-1 of As, having a detection limit of 0.1-ngL-1; the quantification limit of the reaction system was found to be 1-ngL-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexion agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN, etc.) do not interfere in the determination. The developed method was successfully used in the determination of arsenic in several Certified Reference Materials (alloys, steels, ores, human urine, hair, nails, bovine liver and sediments) as well as in some biological fluids (human blood, urine, hair, nail and milk), soil samples, food samples (vegetables, fruits, rice, corn and wheat), solutions containing both arsenic (III) and arsenic (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and soil samples were comparable with both ICP-OES & AHG-AAS and were found to be in excellent agreement.
Benon Ntirushize, John Wasswa, Emmanuel Ntambi, Christopher Adaku
American Journal of Analytical Chemistry, Volume 10, pp 476-487; doi:10.4236/ajac.2019.1010034

Abstract:This study was motivated by the reported accumulation of Organochlorine Pesticides (OCPs) residues in the various environmental matrices within Uganda, resulting from their use in agriculture and health sectors. This raised a concern of the likelihood of the accumulation of the OCPs residues in the honey produced within the country which would affect its purity as well as quality and consequently its competition on the world market. Sixty representative honey samples were collected from selected local beekeepers from four sampling stations in Muko sub-county, Kabale, and extracted for OCPs using a solid-phase procedure followed by a florisil column packed clean-up method and Gas Chromatography-Electron Capture Detector (GC-ECD) analysis. Confirmation of the selected samples was done using an Agilent (6890N, USA) gas chromatograph combined with a mass spectrometer. Recoveries of spiked samples ranged from 71% to 96%, except for pp-DDE (54%), with relative standard deviations from 2% to 14% in terms of repeatability, and from 4% to 17% in terms of reproducibility. Limits of quantification were from 0.003 to 0.1 mg·kg-1. Endosulfan sulfate was the most frequently detected in 38% of the samples, followed by HexaChloroBenzene (Lindane) in 21% of the samples. Residues of DDT and their metabolites were detected in 17% of the samples. Mean concentrations of the pesticide residues detected range from ND (not detected) to 1.53 μg/Kg. The acceptable Maximum residual limits (MLRs) are 200 - 300 μg·kg-1 fresh weight for dieldrin, 500 μg·kg-1 for DDT and break down products, and 50 μg·kg-1 wet weight for Lindane (WHO/FAO 2011). Results indicate that the levels of OCP residues detected in honey from the country’s South Western District of Kabale were within the acceptable limits, and hence this honey was safe for human consumption.
Miriam Muñoz Arratia, María De Lourdes Lanzagorta Rebollo, Francisco Javier Pérez Flores, Rodolfo García Contreras, José Luis Molinari Soriano, Ana María Fernández Presas, Miriam Muñ, Marí, Francisco Javier Pé, Rodolfo Garcí, et al.
American Journal of Analytical Chemistry, Volume 10, pp 629-640; doi:10.4236/ajac.2019.1012044

Abstract:5.1% of sodium hypochlorite (NaOCl) mixed with 2% of chlorhexidine (CHX) forms a brown precipitate that corresponds to para-chloroaniline (PCA), whether PCA is formed after the combination of NaOCl, CHX, and ethylenediaminetetraacetic acid (EDTA) by means of electron impact (high resolution and interlaced scanning) and ionization by fast atom bombardment (FAB), was analyzed. The brown precipitate, showed signals 127 and 153 Da, corresponding to p-chloroaniline and p-chlorophenyl isocyanate, respectively. These results were analyzed and compared with signals from the interlaced scanning program and confirmed with high resolution mass spectrometry analysis and compared with the NIST database. The mass spectra of this precipitated after different days confirmed the evolution of byproducts with the presence of a peak m/z = 127, due to the decrease of the fragment m/z = 153, which disappeared after 180 days. A blue and a white precipitate were observed by the addition of CHX (2%) with or without polyethylene glycol, respectively, EDTA (17%) and NaOCl (5.1%) precipitates contain chlorhexidine (m/z = 505), but no PCA was detected. We confirmed that PCA is not formed directly as a byproduct of CHX oxidation, but through the formation of the para-chlorophenyl isocyanate intermediate, which degrades slowly to PCA.