Domain: Engineering — Food and Bioprocess Engineering
Target concept: Vitamin D Assay (Colorimetric Method)

Video generation prompt: Pipette 2 mL of fish liver oil extract into a dry test tube, and add 3 mL of antimony trichloride-chloroform solution. Mix thoroughly.

Evaluation guide:
(i) Target concept: Visual confirmation of a Vitamin D colorimetric screening test using antimony trichloride (SbCl₃) in anhydrous chloroform, applied to fish liver oil extract.
Minimum mechanism: Fish liver oil extract must contain bioavailable Vitamin D; SbCl₃ must be dissolved in anhydrous chloroform (water inactivates the reagent) and delivered into a dry tube to preserve reactivity; anhydrous conditions and immediate mixing are needed to stabilize the transient complex; a bluish-purple hue arises from the Vitamin D–SbCl₃ adduct once mixing is complete and is not produced by lipids, solvents, or impurities alone.
(ii) Storyline: [Start] Dry test tube shown empty and upright → [Event 1] Pipette draws and dispenses amber-yellow fish liver oil extract into tube → [Event 2] Separate reagent container delivers colorless-to-pale-yellow antimony trichloride-chloroform solution into same tube → [Event 3] Tube is mixed (vortex/swirl) with both liquids fully contained → [Event 4] Uniform bluish-purple color emerges exclusively after mixing completes and persists → All events occur in fixed side-on view with no occlusion; lighting remains constant; camera does not pan, zoom, or rotate; tube remains stationary except for controlled mixing motion.

Manual:
Experimental Procedure
1. Pipette 2 mL of fish liver oil extract into a dry test tube.
2. Add 3 mL of antimony trichloride-chloroform solution to the same tube.
3. Mix thoroughly by vortexing or swirling.
Observation of Experimental Phenomena
A distinct bluish-purple color develops uniformly throughout the mixture only after mixing is complete — this is the positive color reaction for Vitamin D.
Summary of Experimental Principles
Vitamin D (cholecalciferol/ergocalciferol) reacts with antimony trichloride in anhydrous chloroform to form a bluish-purple complex once the two liquids are fully mixed; color intensity correlates with Vitamin D concentration.

Prompt Grounding rubric:
level_1: No dry test tube is visible; no pipette delivers liquid into a tube; no antimony trichloride-chloroform solution container is visible; no mixing action is shown at any point.
level_2: A test tube is visible but is wet, stoppered, or already contains liquid before the sequence begins; or a pipette appears without ever dispensing the amber-yellow fish liver oil extract into the tube; or the antimony trichloride-chloroform solution container appears but its contents are never poured into the tube; or a swirling/vortexing motion occurs before both liquids are together in the tube.
level_3: An empty, dry test tube is shown at the start; a pipette delivers the amber-yellow fish liver oil extract into the tube; a second container delivers the antimony trichloride-chloroform solution into the same tube after the oil; both liquids are added before any mixing motion begins; the pipette, test tube, and reagent container are all visible in the scene.
level_4: All conditions of score 3 are met, and additionally: the fish liver oil extract is visually distinct (amber-yellow, oily) from the antimony trichloride-chloroform solution (colorless-to-pale-yellow, thin); the reagent is dispensed from a clearly separate container (dropper or bottle) rather than appearing to come from the same source as the oil; the vortex/swirl mixing motion begins only once both liquids share the tube; no unrelated object or hand action interrupts the pipetting, reagent addition, or mixing.
level_5: All conditions of score 4 are met, and additionally: the pipette tip is shown entering the tube mouth before the oil is dispensed, and dispensing ends with no oil dripping outside the tube; the antimony trichloride-chloroform solution is added strictly after the fish liver oil extract, never before or simultaneously; mixing begins within about a second of the second liquid's addition and continues until the contents look uniformly blended; the camera keeps a fixed side-on framing of the tube, pipette, and reagent container for the entire sequence with no cut or repositioning between the pipetting, adding, and mixing steps.

Scientific and Causal Correctness rubric:
level_1: No bluish-purple color ever appears: the liquid stays amber-yellow, or shifts to an unrelated hue such as red, green, or brown; OR the color appears before mixing is complete or without both liquids present.
level_2: A color appears in the tube but is incorrect (e.g., red, green, yellow-only, or brown); or the shift toward bluish-purple begins before mixing is complete; or the hue fades or disappears during mixing rather than stabilizing.
level_3: Both liquids are visually distinguishable before mixing (fish liver oil extract: amber-yellow viscous liquid; antimony trichloride-chloroform solution: colorless-to-pale-yellow mobile liquid); a uniform bluish-purple color appears in the tube only once mixing is complete, and persists afterward.
level_4: Everything described for score 3 holds, and in addition: the bluish-purple color occupies the entire liquid volume uniformly (no phase separation, streaks, or cloudiness); the color does not appear until mixing has fully finished; no unintended color shift (e.g., to pink, gray, or orange) occurs.
level_5: Everything described for score 4 holds, and in addition: the bluish-purple color is stable and persists without fading, darkening, or lightening over the remainder of the video; color intensity is consistent across the liquid column (no gradient or meniscus discoloration); no precipitate, turbidity, or interfacial ring forms.

Spatiotemporal Consistency rubric:
level_1: The test tube, pipette, or reagent container abruptly appears in a new position or disappears from one frame to the next; the fish liver oil extract or the antimony trichloride-chloroform solution jumps straight from its container into the tube with no visible pouring path; the lighting abruptly shifts brighter or darker, or the background flickers or warps, between frames with no cause shown; the tube's tilt flips by more than 90 degrees between adjacent frames with nothing on screen to explain it.
level_2: The pipette tip is inside the tube in one moment and, in the very next frame, is several centimeters away with no visible path connecting the two positions; the vortex/swirl motion appears to start before the second liquid has fully entered the tube; the tube's tilt changes noticeably between frames with no corresponding hand or mixing motion visible.
level_3: The test tube, pipette, and reagent container keep consistent relative positions and scale across the sequence; the fish liver oil extract and the antimony trichloride-chloroform solution each travel along a continuous, visible path from their source container into the tube; the mixing motion at the tube's mouth or walls looks smooth rather than a sudden state change; no object appears to stretch, clip through another, or resize suddenly.
level_4: All conditions of score 3 are met, and additionally: the pipette's approach and withdrawal follow a natural hand-guided arc rather than a straight-line jump; the swirling motion stays confined to the tube's interior without the tube itself jumping sideways; the tube stays fully framed and centered throughout pipetting, reagent addition, and mixing; no part of the background shifts independently of the camera.
level_5: All conditions of score 4 are met, and additionally: the pace of pipetting, pouring, and mixing stays even throughout with no sudden speed-ups or freezes; no frame appears to repeat or skip; the liquid surface inside the tube moves the way a real oil-solvent mixture would, settling and swirling rather than behaving like a rigid solid or perfectly flat plane; the tube's edges and the pipette's outline stay clearly defined throughout the mixing action.