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

Video generation prompt: Ten milliliters of the Liliaceous plant extract containing colchicine were placed in a test tube, to which a few drops of concentrated nitric acid were added. The mixture was gently mixed and allowed to stand.

Evaluation guide:
(i) Target concept: Visual confirmation of colchicine presence via its characteristic violet color reaction with concentrated nitric acid, a colchicine-specific identification test used in pharmacognosy.
Minimum mechanism: Colchicine must be present in the extract; concentrated nitric acid must be added and allowed to react at room temperature, an oxidative color reaction, not a precipitation reaction; colchicine's nitrogen is a non-basic acetamide, so it does not reliably give the usual basic-nitrogen alkaloid-precipitant reactions (e.g., Dragendorff's/potassium iodobismuthate), which is why this test relies on nitric-acid oxidation rather than ionic precipitation.
(ii)Storyline: [Frame 0–1] Static shot: upright test tube containing pale-yellow liquid (extract). [Frame 2–3] Dropper enters frame; several discrete droplets of concentrated nitric acid descend and contact the liquid surface. [Frame 4–6] Tube is gently mixed: liquid swirls without splashing. [Frame 7–9] Tube returns upright and holds still; the liquid gradually develops a violet color, uniformly through the column, with no precipitate or turbidity. Perspective: fixed frontal view, centered on test tube, full tube visible, no occlusion, consistent lighting.

Manual:
Experimental Procedure
1. Place 10 mL Liliaceous plant extract into a clean test tube.
2. Add several drops of concentrated nitric acid.
3. Mix gently.
4. Stand tube upright and observe the color change.
Observation of Experimental Phenomena
A violet color develops uniformly throughout the liquid column; no precipitate or turbidity forms.
Summary of Experimental Principles
Colchicine has a non-basic (acetamide) nitrogen and does not reliably give the typical basic-nitrogen alkaloid-precipitation reactions (e.g., Dragendorff's/potassium iodobismuthate). Instead, concentrated nitric acid oxidizes colchicine to produce a distinctive violet coloration — a colchicine-specific identification test used in pharmacognosy and food-hygiene screening for toxic Liliaceous alkaloids.

Prompt Grounding rubric:
level_1: No test tube is shown; no pale-yellow Liliaceous extract is visible inside it; no acid or dropper appears; no mixing or standing phase occurs; none of these elements (tube, extract, acid, mixing) appear.
level_2: A test tube appears, but no extract liquid is visible inside it; or the acid is never added; or no mixing action is shown; or the sequence is out of order (e.g., the liquid already shows a developed color before any acid is added).
level_3: The test tube contains a pale-yellow liquid (the extract); a dropper delivers liquid into the tube (the acid); the liquid is mixed after the addition; the tube is then held upright and still; these steps (placement, addition, mixing, standing) occur in that order.
level_4: All conditions of the 3-point level hold, and in addition: the acid is delivered via a dropper rather than poured from a wide vessel; the tube is upright and stationary during the standing phase; the mixing action visibly disturbs the liquid (more than a faint surface ripple) before the tube is set down to stand.
level_5: All conditions of the 4-point level hold, and in addition: the tube is held vertically for the entire sequence; the extract fills roughly a third to half of the tube's height before the acid is added; the acid enters as at least three distinct droplets rather than a continuous stream; the tube is visibly returned to a still, upright position (held motionless for a couple of seconds) before any color change is shown developing.

Scientific and Causal Correctness rubric:
level_1: No color change occurs at all; the liquid stays pale-yellow (or clear) from start to finish, with no visible link between adding the acid and any change in the liquid's appearance.
level_2: A color change does occur, but it is not violet: for example the liquid turns green, blue, or brown instead; or a precipitate or cloudy solid forms rather than a smooth color change; or the color changes before the acid is added, contradicting an acid-triggered reaction.
level_3: The liquid develops a violet hue after the acid is added and mixed in; the color change happens only after the acid contacts the extract, not before; the liquid stays a clear solution throughout, with no precipitate or cloudiness accompanying the color change.
level_4: All conditions of the 3-point level hold, and in addition the violet color is even throughout the liquid column, without patches, streaks, or a top-to-bottom gradient, and is clearly distinguishable from the extract's original pale-yellow shade.
level_5: All conditions of the 4-point level hold, and in addition the violet color becomes visible shortly after mixing (within roughly the first few seconds of the standing phase, not after a long unexplained delay) and stays fully saturated and uniform through to the end of the clip rather than fading back toward yellow or separating into layers.

Spatiotemporal Consistency rubric:
level_1: The test tube jumps between two different positions from one shot to the next with no motion carrying it there; the liquid inside disappears and reappears; the frame goes abruptly dark or overexposed, hiding the tube; the tube appears to bend, crack, or change shape in a way no physical tube would; or the footage freezes or strobes/skips abruptly at a critical moment.
level_2: The tube shifts position noticeably between two consecutive frames with no visible motion causing it; the stream of acid from the dropper seems to detach from the dropper tip mid-air; the mixing motion starts or stops abruptly with no visible acceleration or deceleration; during the standing phase the tube appears to vibrate or flicker slightly even though nothing is touching it.
level_3: The tube stays in the same place in the frame throughout; the liquid's surface moves continuously while being mixed and comes to rest smoothly rather than stopping instantly; the droplet stream from the dropper to the liquid surface is unbroken; nothing about the tube or liquid warps or flips in perspective.
level_4: All conditions of the 3-point level hold, and in addition the camera viewpoint never pans, tilts, or zooms; the tube keeps the same vertical orientation throughout; the way the liquid's surface curves while being mixed looks physically reasonable (no upside-down or inside-out curvature); no ghosting or blur obscures the moment the violet color starts appearing.
level_5: All conditions of the 4-point level hold, and in addition the liquid's motion while being mixed shows natural momentum (it keeps moving briefly and settles rather than stopping instantly); the surface settles within about a second of the mixing ending, with no visible residual ripple; the violet color spreads through the liquid in a steady, continuous way rather than jumping or blinking into place.