RESUMO
Here, a highly sensitive electrochemical sensor for detection of tryptophan (Trp) using a nitrogen defect graphitic carbon nitride-modified glassy carbon electrode (ND-CN/GCE) was introduced. ND-CN/GCE showed a higher oxidation current for Trp than the graphitic carbon nitride-modified glassy carbon electrode (g-CN/GCE) and bare glassy carbon electrode (BGCE). The synthesized nitrogen defect-rich graphitic carbon nitride (ND-CN) was characterized using X-ray photoelectron spectroscopy, X-ray diffraction spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Electrochemical impedance spectroscopy and cyclic voltammetry were used to further analyze the electrochemical properties of BGCE, g-CN/GCE, and ND-CN/GCE. The oxidation of Trp at ND-CN/GCE is a diffusion-controlled process at pH 3.0. It was calculated that the transfer coefficient, rate constant, and diffusion coefficient of Trp were 0.53, 2.24 × 103 M-1 s-1, and 8.3 × 10-3 cm2 s-1, respectively, at ND-CN/GCE. Trp was detected using square wave voltammetry, which had a linear range from 0.01 to 40 µM at pH 3.0 and a limit of detection of about 0.0034 µM (3σ/m). Analyzing the presence of Trp in a milk and multivitamin tablet sample with a percentage recovery in the range of 97.0-108% satisfactorily demonstrated the practical usability of the electrochemical sensor. The ND-CN/GCE additionally displays good repeatability and reproducibility and satisfactory selectivity.
RESUMO
BACKGROUND@#Petrol is the non-specific term for petroleum which is used for inside combustion of engines. Petrol filling workers are highly vulnerable to occupational exposure to these harmful substances which lead to hemato-toxicity and blood disorders such as leukemia, aplastic anemia, and dysplastic bone marrow. Thus, this study was aimed to assess hematological parameters of petrol filling workers in Gondar town, Northwest Ethiopia.@*METHODS@#A comparative cross-sectional study was conducted from January to March 2019 in Gondar town, Northwest Ethiopia. A total of 110 study participants comprising 55 study groups and 55 controls group were recruited by a convenient sampling technique. Socio-demographic data were collected using a structured questionnaire, and 3 ml of venous blood was collected for the determination of hematological parameters. The data were entered into Epi info 7.2.0.1 and analyzed by SPSS version of 20. Mean, standard deviation, median, and interquartile ranges were used to present the data. Independent t test and Mann-Whitney U test were used to compare the mean or median difference between parametric and non-parametric hematological parameters, respectively. Moreover, Pearson product-moment and Spearman's rank-order bivariable correlations analyses were used to describe the correlation between hematological parameters and duration of exposure to petrol. A P value of ≤ 0.05 was considered statistically significant.@*RESULTS@#The study revealed that mean red blood cell count and hemoglobin level as well as the median hematocrit, mean cell hemoglobin concentration, platelet count, absolute lymphocytes count, and red cell distribution width values of petrol filling workers showed a significant increment compared with the control group. On the other hand, the mean cell hemoglobin value of petrol filling workers showed a significant decrement compared with healthy controls. Moreover, the duration of exposure to petrol showed a significant positive correlation with red blood cell count and mean cell hemoglobin concentration; however, a significant negative correlation was observed with mean cell volume.@*CONCLUSION@#This study showed that the majority of hematological parameters of petrol filling workers showed an increment compared with healthy controls which might be associated with exposure to petrol chemicals. However, further longitudinal study with a larger sample size should be conducted to explore the impact of petrol exposure on hematopoiesis.
