د. رجبعيسى

قسم الكيمياء كلية التربية طرابلس

الاسم الكامل

د. رجب علي المختار عيسى

المؤهل العلمي

دكتوراة

الدرجة العلمية

محاضر

ملخص

رجب علي المختار عيسى هو احد اعضاء هيئة التدريس بقسم الكيمياء بكلية التربية طرابلس. يعمل السيد رجب المختار بجامعة طرابلس كـمحاضر منذ 2013-10-07 وله العديد من المنشورات العلمية في مجال تخصصه

المنشورات

Residual Bromate Assessment in Bread Samples from Tajoura city bakeries, Libya

A total of 25 randomly purchased bread samples were analyzed in this study from 25 different bakeries in Tajoura city. Bread in Libya is highly consumed among all socioeconomic groups; it is mainly consumed in breakfast, dinner and school meals. Potassium bromate is the most popular additive used in bakery industry worldwide. Bakeries in the US used Potassium bromate as bread improver since 1914 to increase bread volume and texture and improve bread production. The main aim of this study is to assess the safety of bread by the measurement of residual potassium bromate using a rapid and reliable method and to investigate the level of compliance to the ban fourteen years later. This method is based on the reaction between bromate and iodide in acidic medium to produce iodine (I2). The absorbance of I2 was measured spectrophotometrically at 488nm. The calibration curve was linear (R2=0.9996) over the range 1.0 – 5.0mg/L of potassium bromate. Despite the ban of potassium bromate in Libya since 2005 due to its classification as a potential carcinogen it is still detected in local bread loaves. All samples showed high levels of potassium bromate to be 300 to 1333 more than the permissible level set by the American Food and Drug Administration (FDA) which is highly toxic for consumers and could threaten their health over prolonged regular consumption. A continuous pursuance and implementation of the ban on use of potassium bromate in baking industry in Libya is recommended. arabic 11 English 67
RAGIAB ALI MOKHTAR ISSA(1-2020)
Publisher's website


Determination of Some Trace Elements in Different Vinegar Samples from Libyan Market using Inductively Coupled Plasma Atomic Emission Spectrometer ICP-AES

Ten vinegar samples were collected from the Libyan local market in the city of Tripoli. The elements have been investigated were:As, Pb, Cu, Fe and Zn. The samples were treated and prepared according to Indian standard IS 14703-1999, and the measurements have been done by using inductively coupled plasm – atomic emission spectroscopy (ICP-AES) available in the Libyan Petroleum Institute. The analysis indicated that the concentration of Arsenic of all the samples was less than 0.02mg/kg whereas, the concentration of lead is less than 0.03mg/kg. The concentration ranges of Cu, Fe and Zn were 0.11-0.59mg/kg, 0.72-2.67mg/kg and 0.08-0.28mg/kg respectively. The concentrations of the elements AS, Pb, Cu, Fe and Zn are within the limits of a variety of standards such as Libyan, Indian and Pakistani ones. arabic 21 English 134
ABUBAKER A BASHIR ATRROG, RAGIAB ALI MOKHTAR ISSA, ِAburawi Mohammed Aburawi Algornazi(11-2020)
Publisher's website


أسس الكيمياء التحليلية العمليه

يساعد الكتاب في فهم ألاسس العملية للكيمياء التحليلية بطريقة سهلة الفهم والاستيعاب arabic 57 English 0
د رجب علي المختار عيسي(1-2019)


Assessment of Heavy Metals in Roadside Soil Samples in Zawia City, Libya

This report is based on the assessment of four heavy metals: lead, chromium, nickel, and copper, in thirty-two roadside soil samples, one of which was a virgin soil, in Zawia City, Libya. During spring 2019, soil samples were collected from five sites along Jamal Street starting from the old university building to Al-Shuhadaa Square. The atomic absorption spectrometer Perkin Elmer AAnalyst 400 was used in this study using absorption mode, except for the use of Cu emission mode due to the unavailability of the Cu lamp. Results showed that the highest concentrations of the investigated elements were: 36 mg/kg for Pb, 15.6 mg/kg for Cr, 8.3 mg/kg for Ni, and 50 mg/kg for Cu. These values are in agreement with the allowable values of heavy metal concentration of soils in some European countries (i.e. Austria, Germany, and France). However, the concentration values for Pb, Cr, Ni, and Cu were 5.2, 2.9, 2.3, and 7.8 fold higher, respectively, than that of the virgin soil sample collected about 10 km away from the city centre. The sample preparation method used in this work was demonstrated to be suitable, showing acceptable recovery values (R%) of 94.6%, 81.9%, 87.6%, and 90.7% for Pb, Cr, Ni, and Cu, respectively.
Ragiab A M Issa(4-2020)


Spectrophotometric determination of iron in dietary supplements in Libyan market

In most cases dietary supplements especially in Libya are consumed without prescriptions and the public has very limited any awareness of their health risk. The lack of quality control on numerous brands of dietary supplements in pharmacies of Libya today may result in a serious health problem. The aim of this study is to determine the iron content using a fast and accurate method for quality control of some imported dietary supplements, based on spectrophotometric measurement of iron after complexation with 1, 10-phenanthroline in an acidic medium. Eight types of vitamin supplementary tablets were randomly collected from the Libyan market and analyzed for the iron content. The analysis showed an average value of 61mg Fe/pill for the range of 40.07-112.63 mg Fe/pill. Results showed that 75% of the samples were lower in iron content than that recorded on the dietary products.
Ragiab A. M. Issa(4-2020)


تقدير تركيز فيتامين C في عينات من أصناف الليمون والبرتقال بالطريقة الحجمية

أجري هذا البحث لتقدير فيتامين C في العصائر الطازجة لبعض عينات الليمون والبرتقال المحلي. وتم تقدير تركيزالفيتامين بطريقة المعايرة باستخدام محلول اليود القياسي وأظهرنتائج هذا البحث أن كمية الفيتامين تختلف باختلاف العينة وحتى في عينات نفس النوع، حيث وجد أن تركيز فيتامين C بوحدة ملغ\100مل لعينتين من نفس النوعللبرتقال الدمي (37 و 76) وبرتقال أبو سرة (33 و 64) وللبرتقال الحلو (28 و 40) ولليوسفي (17 و 28) وللبرتقال المر (24.7 و 48) وللبرتقال الحامض (31 و 58) ولليمون (21 و 41) وأعلى تركيز كان لعينة البرتقال الدمي وأقل تركيز كان لعينة الليمون.
رجب علي المختار عيسى(1-2021)


MATERIALS CHARACTERIZATION BY COMBINED THERMOVOLTAIC DETECTION (TVD) AND THERMAL ANALYSIS (DTA) TECHNIQUES

The thermovoltaic detection (TVD) technique is based on measurement of the EMF generated by two dissimilar metal electrodes in contact with the specimen. This technique has recently been applied when investigating different types of materials involving thermal decomposition reactions which have more normally been studied by conventional thermal analysis techniques, such as DTA, TG, etc. This paper reports the application of the combined TVD and DTA techniques for thermal characterization of materials. The Harrop DTA system has been modified such that measurements by the two techniques can be made simultaneously in the same environment. Data have been obtained on different types of materials, e.g., NiSO,.6H,O and CoSO,.7H,O, etc., at a programmed heating rate of 10” C rnin- ‘. Results obtained by these techniques are discussed and compared with the corresponding values in the literature.
Ragiab Ali Mokhtar(5-1990)


An investigation on Libyan olive oil in the western region

Thirteen Olive oil samples were collected from five different places in the western Libyan region with different cultivation periods. The physical and chemical properties of samples were investigated and classified whether they comply with the Libyan standard specification number 8/2002 or not. The density and refractive index of almost all samples were found within the normal range (0.908-0.919) and (1.4688-1.4705) respectively whereas the chemical properties showed a range of fluctuated values such as peroxide number (11.20-60.40), acidity value (0.737-17.94), saponification number (185.34-199.65), esterification number (173.84-194.36) and iodine number (71.00-94.10). A third of the investigated samples are considered to be of good quality mainly the newer samples
Ragiab A. M. Issa(9-2017)


Reversibility in radionuclide/bentonite bulk and colloidal ternary systems

Ternary systems of 152Eu(III), bulk bentonite and ethylenediaminetetraacetic acid (EDTA) ([Eu] = 7.9 × 10−10 M; pH = 6.0–7.0) have been studied. Without EDTA, there was slow uptake in a two-stage process, with initial rapid sorption of Eu(III) (96%), followed by slower uptake of a much smaller fraction (3.0% over a period of one month). The reversibility of Eu(III) binding was tested by allowing Eu(III) to sorb to bentonite for 1–322 days. EDTA was added to the pre-equilibrated Eu bentonite systems at 0.01 M, a concentration that was sufficient to suppress sorption in a system where EDTA was present prior to the contact of Eu(III) with bentonite. A fraction of the Eu was released instantaneously (30‒50%), but a significant amount remained bound. With time, the amount of Eu(III) retained by the bentonite reduced, with a slow fraction dissociation rate constant of approximately 4.3 × 10−8 s−1 (values in the range 2.2 × 10−8 – 1.0 × 10−7 s−1) for pre-equilibration times ≥7 days. Eventually, the amount of Eu(III) remaining bound to the bentonite was within error of that when EDTA was present prior to contact (4.5% ± 0.6), although in systems with pre-equilibration times >100 days, full release took up to 500 days. Europium interactions with colloidal bentonitewere also studied, and the dissociation rate constant measured by a resin competition method. For the colloids, more Eu was found in the slowly dissociating fraction (60–70%), but the first-order dissociation rate constant was faster, with an average rate constant of 8.8 × 10−7 s−1 and a range of 7.7 × 10−7–9.5 × 10−7 s−1. For both bulk and colloidal bentonite, although slow dissociation was observed for Eu(III), there was no convincing evidence for ‘irreversible’ binding.
RAGIAB ISSA(1-2021)