1. Write down the equation from the trendline fit of the standard curve data tha

Question

1. Write down the equation from the trendline fit of the standard curve data that will be used to determine the concentrations of the unknowns.

2. Determination of the concentration of the unknown sample using the trendline fit.
Show an example calculation.

Illustrations Chart 4 1 Group A 0 Group B o 0 -0.001 -0.004 0 -0.033 0 0.004 0 -0,036 2 0.077 0.500 2 0.049 2 0.080 2 0.056 0.067 0.050 4 0400 0.169 4 0.140 4 0.148 4 0.138 6 0.265 4 0.134 6 0.269 6 0.228 0,300 0.239 6 0.228 0.315 0.313 0.328 8 0.317 0.287 0.347 2 0.100 16 0.439 10 0.400 0.462 10 0.403 10 0.388 10 0.410 0.000 21 unknown [A] 0.376 Unknown [D 0.350 22 unknown [B 0.272 Unknown [E 0.271 23 unknown [C] 0.13 Unknown [F] 0.097 25 29 A820 Biuret O Ask me anything Charts E! Add-in Tours Sparkline Biuret y 0.0425x -0. y 0.0436x -0.0304 Concentration mg/mL e Group A Group B Linear (Group A) Linear (Group B) Linear (Group Bl

Explanation / Answer

Ans. 1. Trendline equation of the graph is-

I. Y = 0.0425 X – 0.0077          - for group A

II. Y = 0.0436 X – 0.0304         - for group B

Ans. 2. Ans. In the graph, Y-axis indicates absorbance and X-axis depicts concentration. That is, according to the trendline (linear regression) equation Y = 0.0425 X – 0.0077 obtained from the graph, 1 absorbance unit (1 Y = Y) is equal to 0.0425 times 1 units on X-axis (concentration) minus 0.00077.

For example, consider the unknown 2 from group A :

            Trendline equation for group A is Y = 0.0425 X – 0.0077  

            Absorbance of unknown 2 (or, B) = 0.272

Now,

Putting the value of absorbance of unknown (Y = 0.272) in the trendline equation -

            0.272 = 0.0425 X – 0.0077                  ; (Absorbance of unknown is Y = 0.272)

            Or, 0.272 + 0.0077 = 0.0425 X

            Or, X = 0.2797 / (0.0425)

            Or, X = 6.58

Therefore, an absorbance of 0.272 indicates a value of 6.58 concentration units.

So,

Concentration of the unknown = 6.58 unit

                                                = 6.58 mg/ mL                      ; [concentration unit = 1 mg/mL]

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