Publications by authors named "Ahmad Makahleh"

This study aims to explore the skills of Jordanian Arabic-speaking fourth graders with learning difficulties in terms of auditory analysis and dictation tests. It mainly aims to investigate the relationship between students' abilities to perform auditory analyses and dictation tests. The sample in the study consists of 110 Jordanian fourth graders, who are then divided into 54 students with learning difficulties who are diagnosed as having a satisfactory level of reading and writing and 56 typically developing students.

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Unlabelled: Although extensive research has been conducted worldwide to investigate the diagnostic process of Autism Spectrum Disorder (ASD), Jordanian parents' experiences have been overlooked. This study explored parents' journeys toward receiving diagnoses for their children with ASD. In particular, it aimed to provide a clear picture of the process for obtaining these diagnoses for children in Jordan.

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A rapid and green analytical method based on capillary electrophoresis with capacitively coupled contactless conductivity detection (C⁴D) for the determination of eight environmental pollutants, the biogenic amines (putrescine, cadaverine, spermidine, spermine, tyramine, 2-phenylamine, histamine and tryptamine), is described. The separation was achieved under normal polarity mode at 24 °C and 25 kV with a hydrodynamic injection (50 mbar for 5 s) and using a bare fused-silica capillary (95 cm length × 50 µm i.d.

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The measurement of α-dicarbonyls and other degradation products of sugars has become important in view of their toxicity. Although there are several methods used for their analysis, most require long reaction times to form UV absorbing or fluorescent derivatives and the nonpolar nature of commonly used derivatives necessitates relatively high concentrations of organic solvents for elution in reverse phase liquid chromatography. The present method describes the use of Girard-T reagent in a simple, one step derivatization of α-dicarbonyls and conjugated aldehydes and analysis using ion-pair reverse phase liquid chromatography.

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A vortex-assisted liquid-liquid-liquid microextraction method followed by high performance liquid chromatography-diode array detection for the determination of fourteen phenolic acids (cinnamic, m-coumaric, chlorogenic, syringic, ferulic, o-coumaric, p-coumaric, vanillic, p-hydroxybenzoic, caffeic, 2, 4-dihydroxybenzoic, sinapic, gentisic and gallic acids) in honey, iced tea and canned coffee drink samples has been developed. The separation was achieved using a Poroshell 120-EC-C18 column under a gradient elution at a flow rate of 0.6mLmin and mobile phase composed of methanol and acetic acid (1%, v/v).

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The determination of aflatoxin M in milk using high performance liquid chromatography with photochemical post-column derivatization and fluorescence detection is described. The samples were first extracted and clean-up using the immunoaffinity AFLATEST column originally targeted for aflatoxins B, B, G and G. The separation of aflatoxin M were performed using C18 Hypersil gold (150mm×4.

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A new sample preparation method, ion-pair vortex assisted liquid-liquid microextraction (VALLME-BE), for the determination of a highly polar anti-diabetic drug (metformin) in plasma sample was developed. The VALLME-BE was performed by diluting the plasma in borate buffer and extracted to 150µL 1-octanol containing 0.2M di-(2-ethylhexyl)phosphoric acid as intermediate phase.

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A novel microextraction method based on vortex- and CO2 -assisted liquid-liquid microextraction with salt addition for the isolation of furanic compounds (5-hydroxymethyl-2-furaldehyde, 5-methyl-2-furaldehyde, 2-furaldehyde, 3-furaldehyde, 2-furoic and 3-furoic acids) was developed. Purging the sample with CO2 was applied after vortexing to enhance the phase separation and mass transfer of the analytes. The optimum extraction conditions were: extraction solvent (volume), propyl acetate (125 μL); sample pH, 2.

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A new, rapid and sensitive microextraction technique named vortex-assisted liquid-liquid-liquid microextraction (VALLLME) is proposed. The complete extraction process involves two steps. First, a vortex-assisted liquid-liquid microextraction (VALLME) procedure was used to extract the analytes from a relatively large volume of sample (donor phase) to a small volume of organic solvent (intermediate phase).

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Background: A simple and sensitive hollow fiber-liquid phase microextraction with in situ derivatization method was developed for the determination of α-ketoglutaric (α-KG) and pyruvic acids (PA) in small-volume urine samples. 2,4,6-trichloro phenyl hydrazine was used as derivatization agent.

Results: Under the optimum extraction conditions, enrichment factors of 742 and 400 for α-KG and PA, respectively, were achieved.

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A new analytical method for the simultaneous determination of the antidiabetic drugs rosiglitazone (ROS) and metformin hydrochloride (MH) with marked differences in their affinity towards organic solvents (log P of 2.4 and -1.43, respectively) was developed.

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A sensitive and rapid reversed-phase ultra performance liquid chromatographic (UPLC) method for the simultaneous determination of tocopherols (α-, β-, γ-, δ-), tocotrienols (α-, β-, γ-, δ-), α-tocopherol acetate and α-tocopherol nicotinate is described. The separation was achieved using a Kinetex pentafluorophenyl (PFP) column (150 × 2.1mm, 2.

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A fast and simple solvent microextraction technique using salting out-vortex-assisted liquid-liquid microextraction (salting out-VALLME) was developed for the extraction of furfurals (2-furfural (2-F), 3-furfural (3-F), 5-methylfurfural (5-MF) and 5-hydroxymethylfurfural (5-HMF)) and patulin (PAT) in fruit juice samples. The optimum extraction conditions for 5 mL sample were: extraction solvent, 1-hexanol; volume of extractant, 200 µL; vortex time, 45 s; salt addition, 20%. The simultaneous determination of the furfurals and PAT were investigated using high performance liquid chromatography coupled with diode array detector (HPLC-DAD).

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A three phase hollow fiber liquid-phase microextraction with in situ derivatization (in situ HF-LPME) followed by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) method was developed for the trace determination of metformin hydrochloride (MH) in biological fluids. A new derivatization agent pentafluorobenzoyl chloride (PFBC) was used. Several parameters that affect the derivatization and extraction efficiency were studied and optimized (i.

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A capillary electrophoresis (CE)-capacitively coupled contactless conductivity detection (C(4)D) method for the simultaneous separation of eleven underivatized fatty acids (FAs), namely, lauric, myristic, tridecanoic (internal standard), pentadecanoic, palmitic, stearic, oleic, elaidic, linoleic, linolenic and arachidic acids is described. The separation was carried out in normal polarity mode at 20 °C, 30 kV and using hydrodynamic injection (50 mbar for 1 s). The separation was achieved in a bare fused-silica capillary (70 cm × 75 μm i.

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An in-vial liquid-liquid microextraction method was developed for the selective extraction of the phenolic acids (caffeic, gallic, cinnamic, ferulic, chlorogenic, syringic, vanillic, benzoic, p-hydroxybenzoic, 2,4-dihydroxybenzoic, o-coumaric, m-coumaric and p-coumaric) in vegetable oil samples. The optimised extraction conditions for 20 g sample were: volume of diluent (n-hexane), 2 mL; extractant, methanol: 5 mM sodium hydroxide (60:40; v/v); volume of extractant, 300 μL (twice); vortex, 1 min; centrifugation, 5 min. Recoveries for the studied phenolic acids were 80.

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A simple micellar electrokinetic chromatography (MEKC) method for the simultaneous determination of 2-furfural (2-F), 3-furfural (3-F), 5-methylfurfural (5-MF), 5-hydroxymethylfurfural (5-HMF), 2-furoic acid (2-FA) and 3-furoic acid (3-FA) in honey and vegetable oils is described. Parameters affecting the separation such as pH, buffer and surfactant concentrations, applied voltage, capillary temperature, injection time and capillary length were studied and optimized. The separation was carried out in normal polarity mode at 20 °C, 22 kV and using hydrodynamic injection (17 s).

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A hollow fiber liquid phase microextraction (HF-LPME) in conjunction with reversed phase HPLC-UV method was developed for the extraction and determination of trace amounts of the antidiabetic drug, mitiglinide (MIT) in biological fluids. The drug was extracted from 10 mL aqueous sample (donor phase (DP)) into an organic phase impregnated in the pores of hollow fiber, followed by the back extraction into a second aqueous solution (acceptor phase (AP)) located in the lumen of the hollow fiber. Parameters influencing the extraction efficiency including the kind of organic solvent, composition of DP and AP, extraction time, stirring rate and salt addition were investigated and optimized.

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Eight hydrazone-based ligands were synthesized, trapped in a silica sol-gel matrix, and were subsequently used in the micro-solid phase extraction (μ-SPE) of biogenic amines (BAs). The BAs investigated were tryptamine, phenylethylamine, putrescine, histamine, tyramine and spermidine. Prior to the extraction, dansyl chloride was added to the samples which were heated to 70°C for 10 min.

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A single line flow injection analysis (FIA) method that incorporated a preconcentrator column packed with C(18) particles and capacitively coupled contactless conductivity detector (C(4)D) was developed for the determination of free fatty acid (FFA) in vegetable oils. The carrier stream was methanol/1.5 mM sodium acetate (pH 8) 80:20 (v/v) at a flow rate of 1.

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The development of a two phase hollow fiber liquid-phase microextraction technique, followed by gas-chromatography-flame ionization detection (GC-FID) for the profiling of the fatty acids (FAs) (lauric, myristic, palmitic, stearic, palmitoleic, oleic, linoleic, linolenic and arachidic) in vegetable oils is described. Heptadecanoic acid methyl ester was used as the internal standard. The FAs were transesterified to their corresponding methyl esters prior to the extraction.

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A sorbent material based on a newly synthesized hydrazone ligand, 4-hydroxy-N'-[(E)-(2-hydroxyphenyl)methylidene]benzohydrazide was prepared by immobilizing the ligand into a silica sol-gel matrix. The capability of the sorbent material for the extraction of seven biogenic amines (BAs), i.e.

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A reversed-phase high-performance liquid chromatographic method with capacitively coupled contactless conductivity detector (C(4)D) has been developed for the separation and the simultaneous determination of five underivatized long chain fatty acids (FAs), namely myristic, palmitic, stearic, oleic, and linoleic acids. An isocratic elution mode using methanol/1mM sodium acetate (78:22, v/v) as mobile phase with a flow rate of 0.6 mL min(-1) was used.

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