混合物の分光光度法分析

連立方程式を用いて二成分混合物を分解する

Colorimetry Advanced (University) 75 分 ~$12.00

目的

二つの波長での吸光度測定と連立方程式を用いて混合溶液中の二種の色素の個別濃度を決定する。

背景

When a solution contains two absorbing species with overlapping spectra, a single wavelength measurement cannot determine both concentrations. However, by measuring absorbance at two wavelengths (ideally the λmax of each component) and applying the additive property of absorbance (Beer-Lambert), a system of two simultaneous equations can be solved. This technique is the basis of multicomponent analysis in spectrophotometry.

安全上の警告

  • Indicator dyes stain clothing
  • Handle cuvettes by frosted sides only to avoid fingerprints
  • Clean spills immediately

必要なPPE

goggles lab_coat

材料

  • Methyl orange solution (0.01%) (100 mL)
    Component A
  • Bromothymol blue solution (0.01%) (100 mL)
    Component B
  • Unknown mixture of both dyes (50 mL)
    Prepared by instructor
  • Distilled water (200 mL)

器具

UV-Vis spectrophotometer Cuvettes (matched pair) Volumetric flasks (50 mL, 6 total) Pipettes Calculator

手順

1

Scan pure methyl orange from 350–700 nm. Record λmax (approximately 464 nm in acidic pH).

8 分
2

Scan pure bromothymol blue from 350–700 nm. Record λmax (approximately 615 nm at neutral pH).

7 分
3

Prepare 3 standard concentrations of each pure dye. Measure absorbance of each at both λmax values (464 and 615 nm).

15 分
4

Calculate the molar absorptivity (ε) for each dye at each wavelength from the standard curves: ε(A,464), ε(A,615), ε(B,464), ε(B,615).

15 分
5

Measure the absorbance of the unknown mixture at both wavelengths.

5 分
6

Set up the simultaneous equations: A(464) = ε(A,464)·C(A) + ε(B,464)·C(B), A(615) = ε(A,615)·C(A) + ε(B,615)·C(B). Solve for C(A) and C(B).

15 分
7

Verify your results by comparing the calculated total absorbance at several wavelengths with the measured mixture spectrum.

10 分

予想される結果

The simultaneous equations yield positive concentrations for both dyes. The reconstructed spectrum (sum of individual contributions) should closely match the measured mixture spectrum, validating the Beer-Lambert additivity principle.

後片付け

Pour dilute dye solutions down the drain with running water. Rinse all cuvettes and volumetric flasks thoroughly.

詳細

カテゴリ
Colorimetry
難易度
Advanced (University)
所要時間
75 分
推定費用
$12.00
ステップ数
7
材料
4

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Frequently Asked Questions

What is the objective of 混合物の分光光度法分析?
二つの波長での吸光度測定と連立方程式を用いて混合溶液中の二種の色素の個別濃度を決定する。
How difficult is 混合物の分光光度法分析?
This experiment is rated as Advanced (University). It takes approximately 75 minutes to complete.
What safety precautions are needed for 混合物の分光光度法分析?
Key safety precautions include: Indicator dyes stain clothing; Handle cuvettes by frosted sides only to avoid fingerprints; Clean spills immediately.
What materials are needed for 混合物の分光光度法分析?
The main materials required are: Methyl orange solution (0.01%), Bromothymol blue solution (0.01%), Unknown mixture of both dyes, Distilled water.
What results should I expect from 混合物の分光光度法分析?
The simultaneous equations yield positive concentrations for both dyes. The reconstructed spectrum (sum of individual contributions) should closely match the measured mixture spectrum, validating the Beer-Lambert additivity principle.