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Register a new userChoising the alternative conditions for the continuity of the work of the nitrate-selective electrode
اختيار الشروط البديلة لاستمرارية عمل مسرى النترات الانتقائي
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تناولت الدراسة إيجاد شروط بديلة تحليلية وتقنية لاستمرار عمل مسرى النترات الانتقائي، نظراً لغياب الشروط التشغيلية و المحاليل المرفقة بها مجهولة الهوية. جرى العمل على اختبار أكثر من الكتروليت مثل كبريتات الأمونيوم، خلات الأمونيوم و كلوريد الأمونيوم. وتبين من خلال الشروط التقنية و التحليلية أن إضافة 0.5ml من الكتروليت كبريتات الأمونيوم بتركيز 3mol/l أعطت أفضل استجابة و ميل نرنستي للمسرى كما أعطت زمن تجاوب 20secو بقيت القيم ثابتة لمدة 15sec. كما بينت دراسة مجال الـpH أن المسرى يعمل ضمن مجال pH(2-8) و أن أفضل استجابة كانت عندpH=5.5 بوجود المحلول المنظم حمض الخل-خلات الصوديوم. دُرس تأثير درجة الحرارة على كمون المسرى و وجد أن الاستجابة نرنستية عند مجال درجة حرارة (18-37)C0. أما عند دراسة إعاقة بعض الأيونات (OH-,HCO3-,CO32-,(NO2-,Cl- على عمل المسرى فقد بينت القيم المنخفضة لمعامل الانتقائية الذي لم يتعد 3×10-2 عدم تأثر المسرى بوجود هذه الأيونات. جُربت الشروط المختارة على محاليل عيارية، فلحظ أن المسرى يعمل ضمن مجال تراكيز (10-4-10-1)mol/l أما عند التراكيز من مرتبة 10-5mol/lفما دون كان لابد من نقع المسرى بمحلول ذي تركيز منخفض لمدة ساعة على الأقل و تمديد الحجوم المأخوذة عشر مرات .طبقت هذه الشروط التقنية و التحليلية على محاليل عيارية و واقعية (عينات مائية)، فأعطت نتائج قياس دقيقة و صحيحة و ذات مصداقية.
Due to the absence of operational requirements and its unidentified solutions ,this study presented definition alternative analytical and technical conditions for the continuation of nitrate-selective electrode working. Many electrolytes were tested (ammonium sulfate, ammonium acetate and ammonium chloride). The technical and analytical conditions shows that the best response which give the Nernst slope of the electrode had been obtained by adding 0.5ml of ammonium sulfate (3mol / l), and the response time was 20sec, by the time that values stabilized for 15sec. The study of pH effect on the electrode response also showed that electrode works within the range (2-8) of pH and that the best response was at pH = 5.5 by using acetic acid-sodium acetate buffer. The effect of temperature on the potential electrode was studied ,it showed that the Nernest electrode response realized within the range (18-37) C0of temperature.While Studying the effect of some interfering ions such as (OH-, HCO3 -, CO3 2-,Cl-,NO2 -) on the work of the electrode showed low values of the coefficient of selectivity, which did not exceed 3×10-2 that the electrode was not affected by the presence of these ions. The chosen conditions were experimented on standard solutions, which showed that the electrode is working within the range (10-4-10-1) mol / l of concentrations. When the concentrations was about 10-5mol/l or less than that, it was necessary to soak the electrode in solution which has low concentration for at least one hour, and diluted the taken volumes ten times . These technical and analytical conditions was applied on standard solutions and environmental samples(water), which showed the accuracy ,correctly and authenticity of the measurements.
References used
COMELIA.M; PETRU.N;MIHAELA.C; LAVINIA.L;IOAN.U; GIANNIN.M. Studies Regarding the Ground Water Pollution in a Rural Area. Chem.Bull, Romania, 2006, Vol.51(65),1- 2, 75-78
SIMON.V; CAMPEANU.GH; VASILE.G; ARTIMON.M; CATANA.L; NEGOTTA.M. Nitrate and nitrite accumulation in tomatoes and derived products.Bucharest University, Romania, 2008, Vol. 3, No.4, pp. 3785-3790
IARC Working Group .Ingested Nitrate and Nitrite, and Cyanobacterial PeptideToxins. World health organization international agency for research on, France, 2010, Vol94
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