Domain: Healthcare — Clinical Laboratory Science
Target concept: Creatinine Test (Picric Acid Method)

Video generation prompt: Collect 100 μL of serum from a patient with elevated creatinine levels, add 2 mL of picric acid reagent, mix thoroughly, and let stand for 10 minutes. Place the solution in the spectrophotometer, set the wavelength to 510 nm, and observe the color change and absorbance readings.

Evaluation guide:
(i) Target concept: Jaffé reaction kinetics under controlled stoichiometry and timing
Minimum mechanism: Picric acid must be in excess, serum creatinine must be non-negligible (>1.5 mg/dL), reaction requires alkaline pH (implied by reagent formulation), and color development is time-dependent (≥5 min for detectable change, complete by 10 min)
(ii)Storyline: [Frame 0–2] Serum vial and calibrated pipette enter view → pipette aspirates liquid → serum level drops visibly. [Frame 3–4] Picric acid bottle enters → reagent pours into same tube → meniscus rises steadily. [Frame 5–6] Tube inverted twice → liquid swirls uniformly → meniscus deforms and recovers. [Frame 7] Tube held motionless → no ripple for ≥3 frames. [Frame 8] Tube opened → mixture transferred to a clear cuvette → cuvette inserted fully into spectrophotometer. [Frame 9] Spectrophotometer panel shows “510 nm” and absorbance digit “1.23”; background remains fixed viewpoint, front-lit, shallow depth of field focusing on cuvette and display.

Manual:
Experimental Procedure
1. Pipette 100 μL serum into clean test tube.
2. Add 2 mL picric acid reagent; mix thoroughly by inversion.
3. Let stand 10 min.
4. Transfer mixture to spectrophotometer cuvette; insert into instrument set to 510 nm.
Observation of Experimental Phenomena
Picric acid (yellow-orange) + serum → homogeneous brick-red color; spectrophotometer displays absorbance value >0.8.
Summary of Experimental Principles
Creatinine reacts with picric acid under alkaline conditions to form a red-orange complex; absorbance at 510 nm is proportional to creatinine concentration.

Prompt Grounding rubric:
level_1: No serum sample, no picric acid reagent vial, no spectrophotometer visible; or all objects present but zero correct actions (e.g., no pipetting, no mixing, no instrument placement, no wavelength setting).
level_2: At least one correct object present (e.g., serum vial OR picric acid bottle OR spectrophotometer), and at least one action vaguely resembling pipetting or pouring, but no sequence alignment with posted_prompt: e.g., pipette used to dispense into wrong container, or spectrophotometer shown before reagent addition.
level_3: All three core objects present (serum sample, picric acid reagent vial, spectrophotometer); correct sequential order of actions visible: (1) 100 μL serum collected (pipette tip visibly entering serum vial and withdrawing liquid), (2) 2 mL picric acid added (reagent poured from labeled bottle into same tube), (3) mixing shown (vortexing or inversion motion), (4) solution placed into spectrophotometer cuvette holder; wavelength setting is not required at this level.
level_4: The serum sample, the picric acid reagent, and the spectrophotometer are all present, and the same action sequence as the level above is shown (100 μL of serum collected, 2 mL of picric acid added, the tube mixed, and the mixture placed in the spectrophotometer's cuvette holder), and in addition the display panel clearly reads 510 nm with legible digits and the nm unit visible; the cuvette sits fully seated in the holder with no partial insertion or crooked alignment; no gloves, labels, or timers block the view of the vial, pipette, tube, or display.
level_5: Everything above is shown, and further: the pipette barrel or a digital readout visibly indicates 100 μL; the picric acid bottle's label reads 2 mL or 2.0 mL, or a fill mark on the tube lines up with the liquid's meniscus while it is poured; the tube is inverted at least twice, each inversion covering a similarly full rotation; the cuvette used for the final measurement is clear, uncolored glass or plastic (not tinted amber or brown), consistent with getting an accurate 510 nm absorbance reading; the shot has no flicker, jump cut, on-screen overlay text, or sudden zoom.

Scientific and Causal Correctness rubric:
level_1: The picric-acid-and-serum mixture stays colorless, or turns an implausible color for this reaction (blue, green, or bright red) instead of orange-red or brick-red; or an absorbance reading is displayed while the cuvette still holds an uncolored liquid; or the serum looks visibly turbid or hemolysis-red before the reagent is even added, and nothing changes after mixing.
level_2: The picric acid solution shows its own bright yellow-orange color before it is mixed with serum, but no further color change happens once mixing occurs; or the cuvette is placed in the spectrophotometer before the required 10-minute stand time has visibly elapsed, with no still period shown; or the displayed absorbance value is below 0.1 or above 2.5 with nothing in the video explaining why.
level_3: Orange-yellow picric acid solution visibly mixed with colorless or straw-colored serum → the resulting mixture becomes distinctly orange-red or brick-red within the video; the color change is uniform, with no phase separation or streaking; the cuvette containing the final mixture is placed into the spectrophotometer; an absorbance reading is not required at this level.
level_4: Everything at the level above holds, and in addition a stillness period is visually confirmed: the solution sits motionless in the tube or cuvette for at least 3 continuous seconds after mixing and before it is placed in the spectrophotometer (no hand movement, vibration, or swirling); the spectrophotometer display then shows a numeric absorbance value between 0.2 and 2.0, with the decimal point legible and no units other than Abs or none at all.
level_5: Everything above holds, and further: the picric acid is a bright, unfaded yellow-orange before mixing; the serum is pale straw-colored rather than hemolyzed red or lipemic milky-white; the post-mix color reads as a homogeneous brick-red (not orange-brown, not pink), with no discoloration ring at the meniscus or along the cuvette walls; the absorbance value shown is noticeably higher than any baseline shown, or at least 0.8, consistent with the elevated-creatinine sample described in the prompt.

Spatiotemporal Consistency rubric:
level_1: The serum vial or the reaction tube swaps position, or is missing from the shot, between the pipetting and mixing steps with no hand shown carrying it there; the 100 μL of serum or the 2 mL of picric acid is shown already inside the tube before the pipette or bottle has ever touched it; the liquid's color jumps straight from clear/pale-yellow to brick-red in a single cut with no mixing shot in between; or the spectrophotometer's 510 nm/absorbance readout is visible before any cuvette has been inserted.
level_2: The pipette tip hovers near the serum vial's opening without ever dipping below the liquid surface even though the serum level is shown dropping; the picric acid bottle tips to pour but the liquid level in the tube does not rise to match; the tube is inverted for mixing but the liquid inside stays perfectly flat with no swirl; or the cuvette is seated in the spectrophotometer holder in one frame and pulled back out in the very next frame with no hand shown doing it.
level_3: The pipette visibly dips below the serum's surface and the serum meniscus drops as it withdraws; the picric acid stream visibly enters the tube and the combined liquid's meniscus rises to match; each inversion of the tube produces a visible swirl that settles back to a level surface; the cuvette's insertion into the spectrophotometer lines up with the slot opening; none of the core objects (vial, pipette, bottle, tube, or cuvette) is hidden or cut away during these actions.
level_4: Everything above holds, and the order of actions stays unbroken: the inversion/mixing motion fully stops, the tube then sits with a flat, undisturbed surface for a clearly sustained pause, and only after that pause is the mixture poured into the cuvette and the cuvette inserted: no frame shows a hand steadying the mixing tube while also inserting the cuvette; the picric acid's pour rate and the pipette's aspiration speed each stay visually constant rather than suddenly speeding up or slowing down partway through a single action.
level_5: The pipette tip reads as nearer or farther from the camera consistent with its actual depth in each shot, rather than looking flatly pasted on; the liquid meniscus in the vial, tube, and cuvette always curves consistent with gravity instead of sitting flat; the cuvette's curved edges show the brick-red mixture refracting slightly; the hand's motion pouring the 2 mL of picric acid is visibly slower and more deliberate than the quick, firm motion used to seat the cuvette in the spectrophotometer; no core object's outline blurs or smears enough to make it unrecognizable during any of these actions.