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  • Measuring on your own scale

    • 　So far, you have learned about measurement precision, sensitivity, quantitation by measuring standard samples, and how to determine the quantifiable range. You have also learned about the importance of blank measurements when quantifying small signal intensities and how to improve sensitivity. In this report assignment, you will put these into practice through "measuring things on your own scale and quantitatively evaluating their sensitivity and precision".
       

      　A self-scale is a length scale, such as the width of an outstretched arm, the width of a goofy hand, the width of a fingertip, or the length of a stride. It can also be a scale of weights that rely on your senses, such as the weight of a pinch of salt, a teaspoon full of salt, or the weight of an object in your hand. Use your own scale to measure the objects around you. Make an analytical chemistry calibration curve, establish a lower limit of quantitation, or evaluate the results.

    • แหล่งข้อมูล icon
      Measuring objects on your own scale (download description file) แหล่งข้อมูล
      358.2 กิโลไบต์ เอกสาร pdf Uploaded 26/04/2023 12:03

      Instructions will be distributed as a Word file and PDF.

    • Folder icon
      How to draw a calibration curve and define the lower limit of quantitation (Excel file download and instructional video) Folder

      　Accuracy evaluation (coefficient of variation) will be done based on the results of 10 repeated measurements of standard samples (10 types). You will also learn how to create a calibration curve and quantify concentrations from regression equations. Download the Excel file and view the explanatory video.

    • URL icon
      This video explains the limit of detection. URL
    • URL icon
      This video explains the range of quantification. URL

      This is an explanatory video of the concentration quantification Excel file.

    • Example of own scale (stride length)：

      　In analytical chemistry, signal intensity corresponds to the number of steps. There is reliable distance information (certified value by a standard sample), and measuring the number of steps for that distance is equivalent to the measurement of a standard sample. The number of steps of an unknown sample is measured and the result is converted (quantified) into a distance.

      Fig. 1


      　For certified distance information, you can read the distance from Google Maps, use a track ground, car meter, tape measure, etc. The number of steps can be counted by recitation or by using the pedometer function of a smartphone. You may need to take into account the error in the certified distance to be used as the standard sample, and the error in the step count measurement by your smartphone. If you repeat the standard measurement on the same day, the error will be smaller due to the experience (memory) of that day. Repeating the standard measurement over several days will provide a more realistic accuracy assessment. The same is true in analytical chemistry.


      　If you want to quantify with the smallest possible signal intensity (fewer steps), it is essential to evaluate blank measurements. If the beginning of the walk is not good enough, the lower limit of quantification should be larger. Can we improve the sensitivity?

      Fig. 2


      　Would an upper limit of quantification exist?　If the measurement device (human) were to walk indefinitely, there might not be an upper limit of quantitation. Assuming various measurement environments and required precision, the evaluation of upper and lower quantitation limits makes sense. For example, when measuring the distance of a snow-covered mountain ridge on a self-scale, the life of the measurer would be a criterion for the upper limit of quantification. In other words, the upper quantitative limit is due to time constraints and fatigue before sunset.

      　The "matrix effect" in analytical chemistry must also be taken into account. The conditions for measuring standard stride lengths under ideal conditions (a well-maintained athletic field) are too different from those for measuring an unknown sample on a frozen surface containing contaminants.

      　Assuming a certain measurement environment (conditions), evaluate the measurement using your own scale.


      I gave it for a report assignment in the Marine Biology course offered by the Faculty of Fisheries Science (2nd year), and they reported a unique own scale. Unique and scientific is good.