Domain: Healthcare — Nutrition and Food Hygiene
Target concept: Tetrodotoxin Detection

Video generation prompt: Ten milliliters of aqueous extract from a seafood sample containing tetrodotoxin were placed in a test tube, followed by the addition of concentrated potassium hydroxide solution; the tube was then heated in a boiling water bath for 5 minutes and examined under an ultraviolet lamp in a darkened setting.

Evaluation guide:
(i) Target concept: Alkaline-heat degradation of tetrodotoxin into a fluorescent quinazoline derivative (the "C9 base"), visualized as fluorescence under ultraviolet light, a classical wet-chemistry screening method for tetrodotoxin-class toxins predating modern chromatographic assays.
Minimum mechanism: Tetrodotoxin's intact guanidinium/ring structure must be present in the extract; strong base (KOH) combined with sustained heat breaks the toxin down into a smaller fluorescent degradation product; this product only fluoresces under ultraviolet excitation; under ordinary room light the tube looks unchanged; both heat and base are required (neither alone triggers visible fluorescence); the fluorescent product stays dissolved in the liquid rather than forming a solid.
(ii)Storyline: [Frame 0–2] Static shot: upright test tube containing ~10 mL colorless liquid (aqueous seafood extract) under ordinary room light. [Frame 3–4] Potassium hydroxide solution is dispensed into the tube, causing a visible meniscus rise and brief swirling as it mixes. [Frame 5–8] The tube is lowered into a heated water bath; bubbling of the surrounding bath water and rising steam are visible; the tube's own liquid stays clear under room light throughout. [Frame 9] Room lights dim and an ultraviolet lamp is switched on, aimed at the tube. [Frame 10+] The liquid inside the tube glows blue under the UV light while the tube walls and surrounding air stay dark; the glow persists as long as the UV lamp remains on. Perspective: fixed side-view throughout, no cutaways or external annotations; tube remains stationary, liquid surface horizontal.

Manual:
Experimental Procedure
1. Place 10 mL of colorless aqueous extract from a seafood sample into a clean, upright test tube.
2. Add concentrated potassium hydroxide solution to the tube.
3. Heat the tube in a boiling water bath for 5 minutes.
4. Dim the room lights and illuminate the tube with an ultraviolet lamp.
Observation of Experimental Phenomena
Under ordinary light, the solution looks unchanged before and after heating. Once illuminated with the ultraviolet lamp, the heated solution glows blue; without both the potassium hydroxide and the heating step, no glow appears under the same UV light.
Summary of Experimental Principles
Hot, strongly basic conditions break tetrodotoxin down into a smaller fluorescent compound. This compound is invisible under ordinary light but fluoresces blue under ultraviolet light, providing a simple presumptive screening indicator for tetrodotoxin-class toxins in seafood extracts.

Prompt Grounding rubric:
level_1: No test tube is shown; no colorless aqueous extract is visible in it; no potassium hydroxide solution is added; no heating step is shown; no ultraviolet lamp appears anywhere in the clip; none of these core elements (tube, extract, KOH, heat source, UV lamp) are present in recognizable form.
level_2: Only one of the core elements is correctly shown (for example a test tube with clear liquid, or a water bath, or a UV lamp), while the others are missing or clearly wrong; the sequence of steps is not recognizable as extract-then-KOH-then-heat-then-UV.
level_3: A test tube holding roughly 10 mL of colorless liquid, a KOH solution being added into that tube, a water bath or heat source under the tube, and a UV lamp near the tube by the end of the clip are all present and visually distinguishable from one another; the KOH addition happens before the heating step, matching the setup described in the prompt.
level_4: All conditions for score 3 are met, and the room's ambient light is visibly dimmed or turned off just before the UV lamp is switched on; the tube is clearly still resting in the same fixed position when the UV lamp is introduced; no extra unlabeled containers or unrelated liquids appear in the frame at any point.
level_5: All conditions for score 4 are met, and the sequence's order is unambiguous and never reversed (extract already in the tube, then KOH added, then heating, then the UV lamp), with no step shown out of order or skipped; the test tube, extract, KOH solution, water bath, and UV lamp are each visible clearly enough that a viewer could point to each one without confusion.

Scientific and Causal Correctness rubric:
level_1: The liquid glows under the UV lamp even though no KOH was added, or before any heating occurred; or the liquid never glows under the UV lamp at all despite both KOH addition and heating; or the liquid appears to change color under ordinary room light rather than only under UV illumination.
level_2: The liquid glows under UV light, but the glow appears before the heating step finishes, or without the KOH having been added first; or the glow is a color other than blue (e.g., red, green, or white) with no visible blue component.
level_3: The liquid stays visually unchanged under ordinary room light throughout, both before and after heating; once the KOH has been added and the tube has been heated, the liquid glows blue specifically when the UV lamp illuminates it; the glow is not visible while the room lights are still on.
level_4: All conditions for score 3 are met, and the blue glow appears only in the liquid itself, not as a general haze filling the whole tube or spilling onto the outside glass; the glow holds steady in brightness for as long as the UV lamp stays on, without flickering out or fading right after the lamp turns on.
level_5: All conditions for score 4 are met, and the blue glow is confined strictly to the liquid inside the tube with no glow on the tube's outer surface, the surrounding air, or the water bath; the glow is visible only in the frames after the UV lamp is switched on and never bleeds into or appears during the earlier room-light frames, confirming the effect depends on the UV light itself rather than an ordinary color change.

Spatiotemporal Consistency rubric:
level_1: The test tube vanishes and reappears at some point in the clip; the liquid's level changes with no visible KOH being added or liquid being removed; the tube appears already glowing before the UV lamp is ever switched on; the camera cuts abruptly between unrelated angles or distances; the room brightness jumps between fully lit and fully dark within a single frame with no dimming transition.
level_2: One clear inconsistency appears: for example the KOH solution seems to enter the tube after the heating step rather than before; the tube rotates by a large angle with no hand or tool visible causing it; steam rises from the water bath while the bath itself shows no visible bubbling; the liquid volume drops noticeably with no evaporation or spill cues shown.
level_3: The test tube stays in view and in the same general position throughout; the liquid's volume looks the same aside from the visible addition of KOH; the KOH visibly enters the tube and raises the liquid level before any heating begins; the water bath shows continuous bubbling and rising steam while the tube sits in it; the UV lamp switches on only after the heating step is shown as complete; all from one fixed camera view with no sudden angle changes.
level_4: All conditions for score 3 are met, and the KOH solution flows smoothly into the tube with no floating, no instant absorption, and no splashing outside the tube; the bubbling in the water bath rises steadily rather than starting and stopping erratically; the room dimming and UV lamp activation happen as one smooth transition rather than a sudden cut; the tube's shape and position stay consistent frame to frame.
level_5: All conditions for score 4 are met, and there is no frame duplication, stutter, or repeated motion anywhere in the clip; the tube's glass appears at a consistent angle and size throughout (no unexplained shifts in its apparent tilt or distance from the camera); the blue glow, once it appears, stays anchored to the same region of the tube rather than drifting or flickering across different parts of the frame.