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Numbers come from the W7 teaching-material calculation checks (40:1 maple mass balance, US11099127 two-wavelength background subtraction, DuBois 1956 phenol–sulfuric acid method at 490 nm, and the Class B Somogyi method comparison).
Interactive calculators: handheld NIR two-wavelength simulator & phenol–sulfuric acid calibration curve with standard bias
Adjust the light intensities at 875 nm (sugar O-H absorption) and 1050 nm (scattering background reference) to verify A = log₁₀(I₀/Iₛ), x₁ = A₈₇₅ − A₁₀₅₀ and Ŷ = b₀ + b₁·x₁ in real time:
A₈₇₅ = 0.3010 ｜ A₁₀₅₀ = 0.0969 ｜ x₁ = 0.2041 → Ŷ = 12.08 °Brix
Switch the standard slope (glucose S=0.0085 vs fructose S=0.0112 mL/μg, blank σ=0.003) and watch the systematic bias when the unknown's A₄₉₀ is converted back to concentration:
Calibrated conc. = 52.9 μg/mL (stock 52.9 mg/mL) ｜ fructose true value 40.2 μg/mL (bias +31.8%) ｜ LOD = 1.16, LOQ = 3.53 μg/mL
Teaching notes & sources
Each act follows predict → observe → explain → compare → apply: act 1 only records your prediction (no answer yet); the middle acts ask their question after the animation, and a correct answer unlocks the next act; the last act has two questions in turn. The stage, captions and progress bar share one paused timeline, so nothing animates on its own; leaving the page or switching tabs pauses it.
Orange juice Brix 11.5 vs phenol–sulfuric acid total sugar 9.5 g/100mL; NIR simulation A875=0.3010, A1050=0.0969, x1=0.2041, Ŷ=12.08 °Brix.
This version uses synchronized text captions and has no narration; the pre-lab video and this page share the same storyboard and drawing components.
W7 Sugar: Brix and phenol–sulfuric acid total sugar (online material) · ATAGO patent US11099127B2