No abstract

A simple, rapid, sensitive and inexpensive approach is described in this work based on a combination of solid‐phase extraction of 8‐hydroxyquinoline (8HQ), for speciation and preconcentration of Cr(III) and Cr(VI) in river water, and the direct determination of these species using a flow injection system with chemiluminescence detection (FI–CL) and a 4‐diethylamino phenyl hydrazine (DEAPH)–hydrogen peroxide system. At different pH, the two forms of chromium [Cr(III) and Cr(VI)] have different exchange capacities for 8HQ, therefore two columns were constructed; the pH of column 1 was adjusted to pH 3 for retaining Cr(III) and column 2 was adjusted to pH 1 for retaining of Cr(VI). The sorbed Cr(III) and Cr(VI) species were eluted from columns using 3.0 ml of 0.1 N of HCl and 3.0 ml of 0.1 N of NaOH, respectively. The flow injection–chemiluminescence (FI–CL) method is based on light emitted due to the oxidation of DEAPH by the H2O2 in the presence of Cr(III), which catalyzes the reaction. The flow cell is a transparent coiled tube made from glass (2.0 × 4.0, inner and outer diameter) and located close to the photodetector. The flow parameters: flow rate, sample volume, flow cell length, and distance to the CL detector were studied and optimized. Under optimum flow conditions, the Cr(III) concentration can be determined over the range 5–350 μg L−1 with a limit of detection of 1.2 μg L−1, as the Cr(III) concentration is proportional to the intensity of the CL signal. The relative standard deviations (%) for 10 and 50 μg L−1 Cr(III) were 1.2% and 3.2%, respectively. The effects of Al(III), Cd(II), Zn(II), Hg(II), Pb(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), and Fe(III) were investigated. The proposed method is highly selective and sensitive, enabling a rapid determination of the Cr(III) amount in the presence of other interfering metals. Finally, the FI–CL method was examined in five river water samples with excellent recoveries.

بينت التطورات العلمية الحديثة وجوب ايجاد طرق قياس تمتاز بالدقة ، البساطة والسرعة وتدخل ضمن الكيمياء الخضراء . في هذه الدراسة تم استحداث طريقة لقياس تركيز ايون المنغنيز الثنائي في ازهار بعض النباتات الطبية بأستعمال تقنية الحقن الجرياني المستمر باستعمال بيروكسيد الهيدروجين في وسط قاعدي لأكسدة المنغنيز الموجود في النبات الى Mn+7 (برمنجنات البوتاسيوم) ذات اللون البنفسجي حيث تم قياسه بواسطة منظومة محلية الصنع عند طول موجي 540 نانومتر وتحت ظروف قياسية حيث كانت سرعة الجريان 1.8 مل / دقيقة لبيروكسيد الهيدروجين وهيدروكسيد البوتاسيوم. وكانت لهذه الطريقة خطية ضمن المدى من 0.10 الى 36.0 ملغم/لتر، مع حدود كشف 1.080 ملغم/لتر ونسبة استردادية مؤوية (RDS %) 1.7 %. تم اخذ نموذج 10 ملغم من الازهار المجففة المطحونة لاربعة نباتات طبية مختلفة ( Matricaria recutita, Lavandula angustifolia , Viola , Gardenia ) ان هذه الطريقة المطورة كانت ناجحة بتقدير المنغنيز فقد اظهرت المقارنة الاحصائية بين الطريقة المستحدثة  والطريقة القياسية , طيف الامتصاص الذري , انه لا يوجد فرق معنوي بين الطريقتين لذلك من الممكن استعمال الطريقة المستحدثة كبديل للطرق التحليلية المثبتة في الدساتير العالمية لتقدير المنغنيز.

In this study, a new flow injection analysis (FIA) based on a microfluidic flow cell (MFC) with a sample capacity of 40 µL is described. A Tungsten lamp directs light from a typical 2100P Portable Turbidimeter apparatus into a quartz flow cell through a round sidewall aperture of 2.0 mm and emerges through the identical aperture on the opposite side of the flow cell, where a photodiode array (light detector) detects the passing light. When compared to a traditional cuvette (25 mm x 60 mm round) with the same nominal route length, this technique improves sensitivity by around 4.0. This improvement is due to the use of a short, narrow internal diameter microfluid as the flow cell, which reduces physical dispersion. The designed flow cell has been evaluated by developing a turbidimetric method for the detection of promethazine in pure form or pharmaceutical dosages. The developed method is based on forming of a yellowish ion-pair association complex due to the reaction of promethazine and sodium tetraphenylborate (STPB) in an acidic medium. At the flow optimum conditions, the calibration curve (CC) and the LOD for promethazine were obtained 0.5-90 µg mL-1 and 0.35 µg mL-1, respectively (R2 = 0.9955).