Rapid and efficient determination of zinc in water samples by graphite furnace atomic absorption spectrometry after homogeneous liquid-liquid microextraction via flotation assistance

ABSTRACT. A new application of homogeneous liquid–liquid microextraction via flotation assistance (HLLME-FA) has been developed for the determination of Zn(II) in the water samples by using graphite furnace atomic absorption spectrometry (GFAAS). 1-(2-Pyridylazo)-2-naphthol (PAN) was used as a chelating reagent. In this work, low density organic solvent was used as an extraction solvent and no centrifugation was required in this method. A special extraction cell was designed to facilitate collection of the low density extraction solvent. The predominant parameters influencing the HLLME-FA procedure, such as solution pH, concentration of PAN, extraction and homogeneous solvent types and volumes, ionic strength, and extraction time have been optimized. Applying all the optimum conditions in the process, the detection limit of 0.1 μg/L, linear range of 0.5–200 μg/L, and the precision (RSD%, n = 10) of 5.7% were obtained for zinc. The proposed procedure showed satisfactory results for the analysis of tap water, well water and sea water.                 KEY WORDS: Homogeneous liquid-liquid microextraction, Flotation assistance, Zinc, Graphite furnace atomic absorption spectrometry, Water samples Bull. Chem. Soc. Ethiop. 2022, 36(1), 1-11.                                                                     DOI:  https://dx.doi.org/10.4314/bcse.v36i1.

Homogeneous liquid-liquid microextraction via flotation assistance for determination of trace amounts of manganese prior to inductively coupled plasma-mass spectrometry

86-92In the present study, homogeneous liquid-liquid microextraction via flotation assistance method is described for preconcentration of trace amounts of Mn(II). 1-(2-pyridylazo)-2-naphthol (PAN) is used as a ligand. The enriched analyte in the floated organic phase has been determined by inductively coupled plasma-mass spectrometry (ICP-MS). In this work, low density organic solvent is used and there is no need of centrifugation. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction and homogeneous solvents have been investigated and optimized. Under the optimum conditions, the linear dynamic range is 1.0-500.0 ng L-1 with a correlation coefficient of 0.9998 and the detection limit of 0.1 ng L-1. The proposed method has been successfully applied for separation and determination of manganese in different water samples

Homogeneous liquid-liquid microextraction via flotation assistance for determination of trace amounts of manganese prior to inductively coupled plasma-mass spectrometry

In the present study, homogeneous liquid-liquid microextraction via flotation assistance method is described for preconcentration of trace amounts of Mn(II). 1-(2-pyridylazo)-2-naphthol (PAN) is used as a ligand. The enriched analyte in the floated organic phase has been determined by inductively coupled plasma-mass spectrometry (ICP-MS). In this work, low density organic solvent is used and there is no need of centrifugation. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction and homogeneous solvents have been investigated and optimized. Under the optimum conditions, the linear dynamic range is 1.0-500.0 ng L-1 with a correlation coefficient of 0.9998 and the detection limit of 0.1 ng L-1. The proposed method has been successfully applied for separation and determination of manganese in different water samples

Ex Vivo Expansion of Hematopoietic Stem Cells for Therapeutic Purposes: Lessons from Development and the Niche

Expansion of hematopoietic stem cells (HSCs) for therapeutic purposes has been a “holy grail„ in the field for many years. Ex vivo expansion of HSCs can help to overcome material shortage for transplantation purposes and genetic modification protocols. In this review, we summarize improved understanding in blood development, the effect of niche and conservative signaling pathways on HSCs in mice and humans, and also advances in ex vivo culturing protocols of human HSCs with cytokines or small molecule compounds. Different expansion protocols have been tested in clinical trials. However, an optimal condition for ex vivo expansion of human HSCs still has not been found yet. Translating and implementing new findings from basic research (for instance by using genetic modification of human HSCs) into clinical protocols is crucial to improve ex vivo expansion and eventually boost stem cell gene therapy

IL3 Has a Detrimental Effect on Hematopoietic Stem Cell Self-Renewal in Transplantation Settings

The ex vivo expansion and maintenance of long-term hematopoietic stem cells (LT-HSC) is crucial for stem cell-based gene therapy. A combination of stem cell factor (SCF), thrombopoietin (TPO), FLT3 ligand (FLT3) and interleukin 3 (IL3) cytokines has been commonly used in clinical settings for the expansion of CD34+ from different sources, prior to transplantation. To assess the effect of IL3 on repopulating capacity of cultured CD34+ cells, we employed the commonly used combination of STF, TPO and FILT3 with or without IL3. Expanded cells were transplanted into NSG mice, followed by secondary transplantation. Overall, this study shows that IL3 leads to lower human cell engraftment and repopulating capacity in NSG mice, suggesting a negative effect of IL3 on HSC self-renewal. We, therefore, recommend omitting IL3 from HSC-based gene therapy protocols

Restoration of T and B Cell Differentiation after RAG1 Gene Transfer in Human RAG1 Defective Hematopoietic Stem Cells

Recombinase-activating gene (RAG)-deficient SCID patients lack B and T lymphocytes due to the inability to rearrange immunoglobulin and T cell receptor genes. The two RAG genes act as a required dimer to initiate gene recombination. Gene therapy is a valid treatment alternative for RAG-SCID patients who lack a suitable bone marrow donor, but developing such therapy for RAG1/2 has proven challenging. Using a clinically approved lentiviral vector with a codon-optimized RAG1 gene, we report here preclinical studies using CD34+ cells from four RAG1-SCID patients. We used in vitro T cell developmental assays and in vivo assays in xenografted NSG mice. The RAG1-SCID patient CD34+ cells transduced with the RAG1 vector and transplanted into NSG mice led to restored human B and T cell development. Together with favorable safety data on integration sites, these results substantiate an ongoing phase I/II clinical trial for RAG1-SCID