Domain: Engineering — Food and Bioprocess Engineering
Target concept: Determination of Vitamin B3 (Spectrophotometric Method with P-Aminobenzenesulfonic Acid)

Video generation prompt: Place 2 mL of peanut extract into a test tube, and add one drop of sulfanilic acid and acetic anhydride solution. Heat the test tube in a boiling water bath for 1 minute.

Evaluation guide:
(i) Target concept: Heat-driven, König-type reaction in which niacin's pyridine ring is opened and condenses with the aromatic amine sulfanilic acid to build a stable yellow polymethine-type chromophore in the peanut-extract solution; this is NOT diazotization, since no nitrite/nitrous acid is present to generate a diazonium ion.
Minimum mechanism: Peanut extract must contain free niacin (nicotinic acid); sulfanilic acid, the aromatic amine, must be present to condense with the ring-opened niacin intermediate and build the extended yellow chromophore; acetic anhydride must help activate the pyridine ring toward opening and/or acetylate competing free amines in the extract so they do not consume the sulfanilic acid; boiling-bath heat must be sustained long enough to drive the ring-opening/condensation reaction to completion; the resulting yellow product must stay water-soluble and hold its color under the observation lighting.
(ii)Storyline: [Frame 0–2] Static shot of upright test tube containing pale liquid (peanut extract); [Frame 3–4] Droplet of sulfanilic acid/acetic anhydride solution released from above, descending vertically; [Frame 5] Droplet impacts liquid surface causing transient meniscus deformation; [Frame 6–8] Tube lowered into steaming water bath; [Frame 9–10] Uniform yellow color emerges synchronously with full submersion and persists; all events occur from fixed frontal viewpoint with consistent lighting and no occlusion.

Manual:
Experimental Procedure
1. Place 2 mL peanut extract into a clear test tube.
2. Add one drop of sulfanilic acid and acetic anhydride solution to the extract.
3. Immediately place the test tube in a boiling water bath for 1 minute.
Observation of Experimental Phenomena
A uniform yellow color develops in the solution during heating in the boiling water bath.
Summary of Experimental Principles
Niacin (vitamin B3) in peanut extract undergoes heat-driven opening of its pyridine ring, which then condenses with the aromatic amine sulfanilic acid (with acetic anhydride assisting ring activation and/or acetylating competing amines) to form a yellow polymethine-type chromophore — a König-type reaction, not a diazotization — detectable spectrophotometrically.

Prompt Grounding rubric:
level_1: No test tube is shown; or no pale peanut-extract liquid is visible inside it; or no droplet of the sulfanilic acid/acetic anhydride solution is added; or no boiling water bath scene appears; or the order is broken (e.g., the tube is heated before the droplet is added, or the droplet is skipped entirely)
level_2: The test tube holds a liquid, but it is not visually distinguishable as the pale peanut extract (e.g., shown as clear water with no context); the reagent droplet is missing or its arrival at the liquid surface is not shown; a boiling/steaming water bath appears on screen but the test tube is never placed into it
level_3: A test tube holding a pale liquid (the peanut extract) is shown; one distinct droplet is seen contacting the liquid surface; the tube is placed into a visibly steaming water bath; the heating step is implied by the tube's continuous presence in the bath; the three actions (droplet addition, placement in the bath, and heating) occur in that order
level_4: Everything in score 3 holds, and additionally: the droplet is clearly seen merging into the extract (contact is unambiguous); the tube stays fully submerged and upright in the boiling bath for the whole heating step; no extraneous object (glove, pipette, stand, etc.) blocks or dominates the view of the tube, extract, droplet, or bath
level_5: Everything in score 4 holds, and additionally: the test tube is the sole focal object with steady, consistent framing throughout; the droplet's fall, impact, and spread into the liquid look like a normal aqueous reagent addition; steam stays continuously visible above the bath at a level matching the water surface; no cut, zoom, or reframe breaks the single continuous shot of the droplet-addition-to-heating sequence

Scientific and Causal Correctness rubric:
level_1: The pale peanut-extract liquid never develops any yellow tint by the end of the clip (it stays pale/colorless throughout, or turns blue, purple, green, black, or brown instead); or a solid precipitate settles out; or the water bath is shown bubbling before the sulfanilic acid/acetic anhydride droplet has touched the extract
level_2: A yellow tint appears, but only before the droplet reaches the extract, or only after the tube has been lifted back out of the boiling bath, or it stays confined to the small spot where the droplet landed instead of spreading through the liquid, or it appears briefly then fades back toward colorless while the tube is still submerged
level_3: While the tube is submerged in the boiling water bath, the liquid turns a uniform yellow across its full volume, and that yellow color holds for at least a second without the liquid turning cloudy, separating into layers, or forming a precipitate
level_4: Everything in score 3 holds, and additionally: the yellow only begins after the droplet has visibly mixed into the extract and only while the tube is in the boiling bath (not earlier, not after removal); the yellow looks equally deep and bright everywhere in the liquid, with no streaks, blotches, or a darker ring at the droplet's landing spot; the liquid stays clear rather than hazy as it turns yellow
level_5: Everything in score 4 holds, and additionally: the yellow hue and its intensity look identical across the entire liquid volume, its onset lines up closely with both full submersion and droplet mixing with no visible lag between the two, and no glare, reflection, or color fringing on the glass makes the true liquid color hard to judge

Spatiotemporal Consistency rubric:
level_1: The test tube's position or tilt changes abruptly between moments with no visible motion connecting the two states (e.g., upright, then suddenly tilted or off-screen); or the extract's liquid level jumps up or down with no visible cause; or the droplet is shown already inside the liquid with no preceding fall or splash; or the steam column over the water bath switches fully on or off between one moment and the next with no gradual build-up or fade; or the room lighting shifts abruptly between frames (e.g., a bright shot cutting straight to a dark one) with no visible cause such as a light being turned off.
level_2: The test tube visibly rotates or shifts by a large angle within one continuous shot without any smooth in-between motion linking the two positions; the droplet's fall bends sideways or skips a stage of drop-contact-splash rather than tracing one continuous downward arc; the steam plume rises at an angle that does not match a heat source directly beneath the tube (e.g., drifting sideways with no draft shown)
level_3: The test tube stays upright in the same spot for the whole clip; the droplet falls straight down and its contact with the extract surface produces a brief, visible ripple that settles back to a flat surface; the steam plume rises continuously upward from the water bath surface without switching on or off mid-clip; lighting and shadows stay stable across the whole clip, with no unexplained shift in brightness or shadow direction.
level_4: Everything in score 3 holds, and additionally: the ripple from the droplet's impact spreads outward and flattens smoothly rather than freezing mid-ripple or vanishing instantly; the steam plume's thickness and rise speed stay roughly even through the clip rather than surging or thinning erratically; a thin condensation film builds up gradually on the tube's inner wall as heating continues, rather than appearing all at once
level_5: Everything in score 4 holds, and additionally: the tube, the falling droplet, the settling ripple, and the rising steam all move with smooth, unbroken continuity frame-to-frame (no jump-cut repositioning or duplicated frames); condensation collects only on the part of the tube wall above the waterline, leaving the submerged portion clear; the steam plume keeps one coherent rising column rather than splitting, forking, or drifting sideways away from the bath