نبذة عن FLAME PHOTOMETRY

الموضوع في 'كيمياء تحليلية' بواسطة chemistry, بتاريخ ‏نوفمبر 24, 2008.

  1. chemistry

    chemistry مستشار كلية العلوم النهرالخالد إداري

    إنضم إلينا في:
    ‏فبراير 5, 2007
    المشاركات:
    12,616
    الإعجابات المتلقاة:
    5,276
    نقاط الجوائز:
    128
    الجنس:
    ذكر
    مكان الإقامة:
    أم الدنيا مصـر


    [​IMG]

    [​IMG]


    نبذة عن

    FLAME PHOTOMETRY


    Background
    Flame photometry is an atomic emission method for the routine detection of metal salts, principally Na, K, Li, Ca, and Ba. Quantitative analysis of these species is performed by measuring the flame emission of solutions containing the metal salts. Solutions are aspirated into the flame. The hot flame evaporates the solvent, atomizes the metal, and excites a valence electron to an upper state. Light is emitted at characteristic wavelengths for each metal as the electron returns to the ground state. Optical filters are used to select the emission wavelength monitored for the analyte species. Comparison of emission intensities of unknowns to either that of standard solutions, or to those of an internal standard, allows quantitative analysis of the analyte metal in the sample solution.
    Flame photometry is a simple, relatively inexpensive, high sample throughput method used for clinical, biological, and environmental analysis. The low temperature of the natural gas and air flame, compared to other excitation methods such as arcs, sparks, and rare gas plasmas, limit the method to easily ionized metals. Since the temperature isn't high enough to excite transition metals, the method is selective toward detection of alkali and alkali earth metals. On the other hand, the low temperatures renders this method susceptible to certain disadvantages, most of them related to interference and the stability (or lack thereof) of the flame and aspiration conditions. Fuel and oxidant flow rates and purity, aspiration rates, solution viscosity, concomitants in the samples, etc affect these. It is therefore very important to measure the emission of the standard and unknown solutions under conditions that are as nearly identical as possible.
    This experiment will serve as an introduction to sodium analysis by flame emission photometry and will demonstrate the effects of cleanliness and solution viscosity on the observed emission intensity readings. The instrument is calibrated with a series of standard solutions that cover the range of concentrations expected of the samples. Standard calibrations are commonly used in instrumental analysis. They are useful when sample concentrations may vary by several orders of magnitude and when the value of the analyte must be known with a high degree of accuracy. This experiment does not produce hazardous waste.

    Procedure
    Consult your Teaching Assistant for operating instructions for the Buck PFP-7 Flame Photometer. Allow a sufficient warm-up period. Be sure to aspirate deionized-distilled water between samples to clean out the sample tube and aspirator. Sodium is ubiquitous. It is imperative that you use scrupulously cleaned glassware to obtain good results.

    Standard Preparations
    Prepare sodium chloride standard solutions by volumetric dilution of the stock solution. The following approximate concentrations should be made: 5, 10, 25, 50, 75, and 100 mg/mL as Na. Be sure to use clean methods. Use ultra-pure deionized-distilled water to clean your glassware and for dilution of the 1000 mg/mL standard. Prepare these standards in scrupulously clean volumetric glassware and transfer the solutions to plastic bottles. Glass often is made from high sodium glass. Allowing extremely high or low pH solutions to stand in glass could alter the sodium concentrations in solution. Prepare 25 mg/mL Na solutions in other solvents, 10% Ethanol, 50% Ethanol, 50% Glycerin. Standard solutions may be pre-prepared by the laboratory instructor or may be made up as a class or group project.


    Unknown Preparation
    Obtain a sodium unknown from your instructor in a scrupulously clean 50 mL volumetric flask. Dilute to the mark with distilled water.

    Instrument Calibration
    Set the readout to zero using distilled water as a blank. Set the peak reading according to the instrument instructions using the most concentrated sodium solution (100 mg/mL). Measure the emission intensity of each of the remaining sodium standard solutions, and of the sodium unknown solution. Check for accuracy and repeatability by measuring the standards several times. Be sure to aspirate deionized distilled water between measurements.

    Cleanliness Check
    Dip two fingers into a clean beaker containing about 20 mL of distilled water. Measure and record the sodium emission intensity. Measure and record the sodium emission intensity of tap water. Be sure to aspirate deionized distilled water between measurements.

    Viscosity Variations
    Measure and record the sodium emission intensity of each of the 25 mg/mL Na solutions in various solvents. Be sure to aspirate deionized distilled water between measurements.

    Reproducibility Check
    Remeasure the emission intensity of two or three of the standard solutions. If a significant change has occurred, READJUST the zero and peak readings, and RE-MEASURE the emission intensity of the standards and the unknown.

    Results
    Plot a working curve from the data obtained in the Instrument Calibration step. Calculate and report the sodium concentration of the unknown, "fingered" solution, and tap water in units of mg/ml.
    Plot intensity reading as a function of viscosity for the data of Viscosity Variation step.
    Turn in the two graphs and the sodium concentrations of the unknown, "fingered" solution, and tap water. Grades will be based 80% on the reported unknown concentration and 20% on graphs. Tap water and "fingered" solution data is for our future reference.





    Reference
    • Sawyer, Heineman, Beebe, Chemistry Experiments for Instrumental Methods, Wiley, New York, 1984.
    • D. C. Harris Quantitative Chemical Analysis 4th Ed., W. H. Freeman and Company, New York 1995 Chapter 21
    لا تنسوا ذكرالله

    الملفات المرفقة:

    Alhashemiah ،kream ،semamedo و 3آخرون معجبون بهذا.
  2. مهند حازم

    مهند حازم Well-Known Member

    إنضم إلينا في:
    ‏يناير 6, 2008
    المشاركات:
    1,040
    الإعجابات المتلقاة:
    39
    نقاط الجوائز:
    63
    الوظيفة:
    طالب جامعي
    مكان الإقامة:
    لبنان


    بارك الله فيك
  3. chemistry

    chemistry مستشار كلية العلوم النهرالخالد إداري

    إنضم إلينا في:
    ‏فبراير 5, 2007
    المشاركات:
    12,616
    الإعجابات المتلقاة:
    5,276
    نقاط الجوائز:
    128
    الجنس:
    ذكر
    مكان الإقامة:
    أم الدنيا مصـر


    جزيت الجنة أخى مهند
  4. عمر اليحيى

    عمر اليحيى Active Member

    إنضم إلينا في:
    ‏مايو 28, 2008
    المشاركات:
    576
    الإعجابات المتلقاة:
    66
    نقاط الجوائز:
    43
    الجنس:
    ذكر
    الوظيفة:
    ماجستير كيمياء تحليلية
    مكان الإقامة:
    العراق


    مشكور دكتور على المواضيع الرائعة
  5. سامح اليمني

    سامح اليمني Member

    إنضم إلينا في:
    ‏يناير 19, 2008
    المشاركات:
    212
    الإعجابات المتلقاة:
    5
    نقاط الجوائز:
    18


    شكرا جزيلا

    بارك الله فيك اخي
  6. khanssa

    khanssa Active Member

    إنضم إلينا في:
    ‏سبتمبر 1, 2008
    المشاركات:
    423
    الإعجابات المتلقاة:
    75
    نقاط الجوائز:
    28
    الوظيفة:
    chemistry
    مكان الإقامة:
    عربي المنشا وافتخر


    مشكور اخي الكريم
  7. ندى النديه

    ندى النديه New Member

    إنضم إلينا في:
    ‏يونيو 9, 2008
    المشاركات:
    16
    الإعجابات المتلقاة:
    3
    نقاط الجوائز:
    3
    الوظيفة:
    مساعد باحث


    Thanks, brother
  8. Alhashemiah

    Alhashemiah مشرفة بالمنتدى ملكة كتاب العرب إداري

    إنضم إلينا في:
    ‏أغسطس 15, 2007
    المشاركات:
    11,168
    الإعجابات المتلقاة:
    3,450
    نقاط الجوائز:
    128
    الجنس:
    أنثى
    الوظيفة:
    دكتوراه في الكيمياء
    مكان الإقامة:
    KSA


    بارك الله فيك اخي كميستري
  9. chemistry

    chemistry مستشار كلية العلوم النهرالخالد إداري

    إنضم إلينا في:
    ‏فبراير 5, 2007
    المشاركات:
    12,616
    الإعجابات المتلقاة:
    5,276
    نقاط الجوائز:
    128
    الجنس:
    ذكر
    مكان الإقامة:
    أم الدنيا مصـر


    بارك الله فيكم أحبتى فى الله وكل عام وانتم بخير
  10. Dr.Refat

    Dr.Refat New Member

    إنضم إلينا في:
    ‏أكتوبر 26, 2008
    المشاركات:
    53
    الإعجابات المتلقاة:
    4
    نقاط الجوائز:
    0
    مشكور دكتور على المواضيع الرائعة وربنا يخليك
  11. kream

    kream Active Member

    إنضم إلينا في:
    ‏يونيو 11, 2008
    المشاركات:
    380
    الإعجابات المتلقاة:
    39
    نقاط الجوائز:
    28
    مشكوررررررررررررررررررررررررررررررررررررررررررررررررررررررررررررررررررررر جدا

مشاركة هذه الصفحة