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Chlorophyll Extraction and Measurement
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Chlorophyll Extraction and Measurement

Created by
@EndearingWildflowerMeadow2200

Questions and Answers

What is the primary purpose of using a combination of Lovibond slides in the colorimetric method?

  • To identify the concentration of chlorophyllin.
  • To determine the purity of chlorophyll samples. (correct)
  • To create a new chlorophyll standard.
  • To match the exact color of the chlorophyll solution.

    • Why is it impractical for each worker to prepare their own pure chlorophyll?

  • Pure chlorophyll is too expensive to produce.
  • Pure chlorophyll is not readily available commercially. (correct)
  • Pure chlorophyll is not considered an essential component.
  • Each preparation method greatly differs from one another.

    • Which of the following steps follows the evaporation of ether in the chlorophyll extraction process?

  • Colorimetric matching against a new set of standards.
  • Saponification using concentrated hydrochloric acid.
  • Filtration to remove any particulates.
  • Addition of distilled water to adjust final volume. (correct)

    • What variations are noted in the chlorophyll solutions when conducting quantitative work on fresh green leaves?

    <p>Variations in the green pigments are substantially more pronounced.</p> Signup and view all the answers

    What method is used to dissolve pure chlorophyll prior to its analysis?

    <p>Dissolution in ether.</p> Signup and view all the answers

    Why is the exact color matching of chlorophyll solutions to Lovibond slides noted as impossible?

    <p>Different samples have varying tint intensities.</p> Signup and view all the answers

    What is the expected outcome with regards to the availability of pure chlorophyll in the near future?

    <p>Companies will soon commercially produce it.</p> Signup and view all the answers

    What does the process of saponification of chlorophyll involve?

    <p>The addition of an alkaline solution for chlorophyll conversion.</p> Signup and view all the answers

    What is the width of the absorption band for potassium chlorophyllin?

    <p>32 mp</p> Signup and view all the answers

    At what concentration does the colorimeter yield the best results?

    <p>0.05 gm per liter</p> Signup and view all the answers

    Which method shows a maximum error at a concentration of 0.05 gm per liter?

    <p>Colorimeter</p> Signup and view all the answers

    What is the maximum error percentage for the spectrometer at a concentration of 0.15 gm per liter?

    <p>18.9 per cent</p> Signup and view all the answers

    What was the determined amount of chlorophyll in the solution from spectrometer results?

    <p>0.08 gm per liter</p> Signup and view all the answers

    Which concentration yields the probable error closest to zero for the spectrometer?

    <p>0.10 gm per liter</p> Signup and view all the answers

    Which of the following statements is accurate regarding error percentages?

    <p>At 0.20 gm per liter, the colorimeter has a maximum error greater than the spectrometer.</p> Signup and view all the answers

    What is the probable error at the lowest concentration measured by the colorimeter?

    <ul> <li>3.3</li> </ul> Signup and view all the answers

    What was the highest reading at a concentration of 0.10 g/L?

    <p>19.6</p> Signup and view all the answers

    What is the maximum difference in readings for the concentration of 0.15 g/L expressed as a percentage?

    <p>28 per cent.</p> Signup and view all the answers

    At a concentration of 0.05 g/L, what is the average reading?

    <p>31.9</p> Signup and view all the answers

    What was the probable error in percent for the concentration of 0.10 g/L?

    <p>7.0</p> Signup and view all the answers

    In the spectrometric method, what was the slit opening set to?

    <p>5</p> Signup and view all the answers

    Which concentration had the maximum reading difference of 0.062 g/L?

    <p>0.20 g/L</p> Signup and view all the answers

    What was the lowest reading for a concentration of 0.05 g/L?

    <p>28.6</p> Signup and view all the answers

    Which concentration showed the highest probable error?

    <p>0.20 g/L</p> Signup and view all the answers

    Why should saponified chlorophyll solutions not be allowed to stand for a long time?

    <p>The saponified chlorophyll is rather unstable.</p> Signup and view all the answers

    What is the current status of data for the spectrophotometric method in determining chlorophyll?

    <p>The data for the method are yet to be obtained.</p> Signup and view all the answers

    Which of the following claims about saponified chlorophyll solutions is incorrect?

    <p>They can be stored indefinitely without losing properties.</p> Signup and view all the answers

    What might be a potential benefit of the spectrophotometric method for chlorophyll measurement?

    <p>It offers great promise of being very accurate.</p> Signup and view all the answers

    Which substance is mentioned as a method for saponification in the provided content?

    <p>Methyl alcoholic potash.</p> Signup and view all the answers

    What is implied about chlorophyll extraction methods discussed in the references?

    <p>Several different methods are explored for accuracy.</p> Signup and view all the answers

    Which claim about chlorophyll solutions is least valid based on their properties?

    <p>They can be effectively used after prolonged standing.</p> Signup and view all the answers

    In the context of chlorophyll methods mentioned, what challenge remains?

    <p>Obtaining consistent data for the spectrophotometric method.</p> Signup and view all the answers

    What is required before satisfactory solutions of chlorophyll a or b can be prepared?

    <p>Obtaining pigments of undoubted purity</p> Signup and view all the answers

    Why is preparing a solution of chlorophyll considered challenging?

    <p>There is little knowledge about its spectral transmission properties</p> Signup and view all the answers

    What is the expected outcome of obtaining complete spectrophotometric curves for chlorophyll?

    <p>It will enhance the understanding of chlorophyll's role in nature</p> Signup and view all the answers

    What must be taken into consideration before accurate quantification of chlorophyll can be achieved?

    <p>The need for more information about chlorophyll</p> Signup and view all the answers

    What does the successful preparation of pure food dyes indicate for chlorophyll studies?

    <p>It demonstrates the difficulty of preparing pure pigments</p> Signup and view all the answers

    What is the main challenge associated with chlorophyll studies as noted in the content?

    <p>The high cost and effort needed for spectrophotometric curves</p> Signup and view all the answers

    Which aspect of chlorophyll analysis requires meticulous chemical technique?

    <p>Preparation of pure pigments for analysis</p> Signup and view all the answers

    What outcome can result from improved methods for the quantitative determination of chlorophyll?

    <p>Greater insights into the ecological role of chlorophyll</p> Signup and view all the answers

    Study Notes

    Chlorophyll Extraction and Measurement

    • Pure chlorophyll is dissolved in ether and saponified with cold concentrated methyl alcoholic potash.
    • Ether is removed through evaporation under reduced pressure.
    • Potassium chlorophyllin solution is prepared by adding distilled water to the residue, resulting in a final volume of 250 cc.
    • Chlorophyll concentration is assessed through colorimetric and spectrometric methods.

    Colorimetric Method

    • Solutions are diluted, and absorbance readings are taken using Lovibond color slides.
    • A combination of blue and yellow slides helps standardize color measurements.
    • Direct matching to slides is challenging; the method focuses on tint variation for purity assessment.
    • Measuring chlorophyll concentrations yields variability due to differing ratios of chlorophyll types a and β.

    Measurement Data

    • Colorimetric readings are listed in a table, comparing highest, lowest, and average values for different concentrations (0.20, 0.15, 0.10, 0.05 grams per liter).
    • Calculated maximum differences in readings indicate variability in chlorophyll concentration: 0.062 for 0.20 g/L, with corresponding error percentages ranging from 14% to 37%.

    Spectrometric Method

    • Similar solutions used in the colorimetric method apply to the spectrometric analysis.
    • Absorption bands are evaluated using a defined slit opening and a powerful light source.
    • Examples illustrate how to derive chlorophyll concentration from the width of absorption bands in the spectrometer.

    Accuracy Comparison

    • Error rates for colorimetric and spectrometric methods differ.
    • Colorimeter shows better accuracy at approximately 0.05 gm/L, whereas the spectrometer is more reliable at 0.10 to 0.15 gm/L.
    • Maximum errors recorded for each method are detailed, indicating complexities in measurements.

    Need for Pure Standards

    • Challenges exist in obtaining pure chlorophyll for standard reference due to limitations in commercial availability and preparation techniques.
    • A U.S. company is working towards producing pure chlorophyll for accurate measurements.
    • Current understanding of chlorophyll spectra is limited; further research is essential for better methodologies.

    Importance of Accurate Measurement

    • Precise determination of chlorophyll and related pigments is critical for understanding plant physiology and its ecological roles.
    • Saponified chlorophyll should be measured quickly after preparation to reduce instability.

    Future Directions

    • The spectrophotometric method holds potential for enhanced accuracy, but data collection is ongoing.
    • Complete spectrophotometric curves for both chlorophyll a and β are needed to advance in chlorophyll analysis research.
    • Understanding the properties of chlorophyll can help elucidate its vital role in photosynthesis and plant function.

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    Description

    This quiz covers the process of extracting chlorophyll and measuring its concentration using a colorimetric method. It details the saponification process with methyl alcoholic potash and the subsequent preparation of potassium chlorophyllin. Test your understanding of these techniques and their applications in biochemistry.

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