Domain: Healthcare — Pharmaceutical Chemistry
Target concept: Identification of Cephalosporin Drugs (Ferric Hydroxamate Colorimetric Method)

Video generation prompt: Place the cephalosporin sample solution into a test tube. Add hydroxylamine hydrochloride solution, followed by sodium hydroxide solution, and gently mix. After the reaction is complete, add dilute hydrochloric acid to acidify the mixture, then add ferric chloride solution dropwise. Use a test tube, pipette, and water-soluble reagents to clearly demonstrate the process of sequential addition and mixing.

Evaluation guide:
(i) Target concept: Visual verification of ferric hydroxamate colorimetric assay for cephalosporins.
Minimum mechanism: Hydroxylamine must react with β-lactam under alkaline conditions to generate hydroxamate; the alkaline mixture must then be acidified with dilute hydrochloric acid before Fe³⁺ is introduced (adding FeCl₃ directly to a still-alkaline solution would precipitate Fe(OH)₃ instead of forming the colored complex); Fe³⁺ must then bind to hydroxamate under the resulting acidic conditions to form the chromophore; color development requires all four reagents (hydroxylamine HCl, NaOH, dilute HCl, FeCl₃) in correct sequence; purple must appear exclusively after acidification and FeCl₃ addition.
(ii)Storyline: [Start] Clear test tube with colorless/pale yellow cephalosporin solution → [Event 1] Pipette delivers hydroxylamine HCl solution into tube → [Event 2] Pipette delivers NaOH solution into same tube → [Event 3] Tube is gently swirled (liquid motion visible, no splashing) → [Event 4] Pipette delivers dilute hydrochloric acid into the tube to acidify the mixture → [Event 5] Pipette delivers FeCl₃ solution dropwise → [Event 6] Purple/violet color emerges uniformly in liquid phase, persisting for remainder of video; all events occur in fixed-frame, front-facing, eye-level perspective; no occlusion of test tube contents during any event; lighting remains constant and diffuse to ensure color fidelity.

Manual:
Experimental Procedure
1. Place cephalosporin sample solution into a clear test tube.
2. Using a pipette, add hydroxylamine hydrochloride solution to the test tube.
3. Using the same pipette, add sodium hydroxide solution to the test tube.
4. Gently mix the mixture by swirling the test tube.
5. Using a pipette, add dilute hydrochloric acid to the mixture to acidify it.
6. Using the pipette, add ferric chloride solution dropwise to the acidified mixture.
Observation of Experimental Phenomena
A distinct purple or violet color develops in the test tube only after ferric chloride is added to the acidified mixture; no purple color is present before this step.
Summary of Experimental Principles
Cephalosporins contain β-lactam rings that, under alkaline conditions with hydroxylamine, form hydroxamic acids; after the mixture is acidified, these hydroxamic acids chelate Fe³⁺ ions to produce a stable purple-violet ferric hydroxamate complex.

Prompt Grounding rubric:
level_1: No test tube is visible, or the cephalosporin sample solution is missing, or none of the reagents (hydroxylamine hydrochloride, sodium hydroxide, hydrochloric acid, ferric chloride) appear anywhere, or no pipette is used, or the order in which anything is added cannot be determined at all.
level_2: The test tube and at least one reagent container are visible, but the pipette is never seen touching or dispensing any liquid, or a reagent is shown near the test tube without ever being added into it, so no clear sequence of additions can be followed.
level_3: The test tube holds the initial cephalosporin sample solution; a pipette visibly dispenses hydroxylamine hydrochloride solution into the tube, then dispenses sodium hydroxide solution into the same tube, and a gentle swirling/mixing motion follows those two additions; all three actions are visible and happen in this order, even if part of a pour is briefly out of view.
level_4: All requirements for the 3-point level are met, and additionally: a pipette adds dilute hydrochloric acid to acidify the mixture, followed by ferric chloride solution added dropwise into the same tube; the full six-step sequence (sample, hydroxylamine hydrochloride, sodium hydroxide, mixing, acid, ferric chloride) is present and in the correct order, with the test tube, pipette, and all five liquids each clearly present in their own distinguishable container.
level_5: All requirements for the 4-point level are met, and additionally: each of the five liquids (sample, hydroxylamine hydrochloride, sodium hydroxide, hydrochloric acid, ferric chloride) is visually distinguishable from the others by its container or its own appearance; the pipette tip visibly touches the liquid surface for every addition; the mixing step clearly follows the sodium hydroxide addition and clearly precedes the acid and ferric chloride additions in that order; no tool or container unexpectedly leaves or enters the frame; the test tube, pipette, and reagent containers stay visible and in the same relative arrangement throughout.

Scientific and Causal Correctness rubric:
level_1: The liquid in the test tube never turns purple/violet at any point, or it ends up a different final color (e.g., stays yellow-brown or turns rust-colored), or a purple/violet tint shows up before ferric chloride is added, or purple appears without hydroxylamine hydrochloride and sodium hydroxide having been added beforehand.
level_2: A purple/violet color does appear at some point, but before the ferric chloride addition, or at the same moment as an earlier reagent addition, or without any mixing step having happened first, or the resulting color reads closer to red/brown/yellow than to purple/violet, or the purple fades away again before the clip ends.
level_3: The liquid turns purple/violet only after ferric chloride is added to the mixture; the color change stays confined to the liquid inside the test tube; no purple tint appears at any point before the ferric chloride step; the mixing step is visibly finished before ferric chloride goes in; once formed, the purple color persists for the rest of the video rather than fading.
level_4: All requirements for the 3-point level are met, and additionally: the purple color visibly develops as a gradual transition (e.g., from pale yellow through to a distinct purple/violet) within the same test tube right after ferric chloride is added to the acidified mixture; no rust-brown precipitate, green, or blue color competes with or replaces the purple; the background behind the tube stays neutral so it doesn't tint the apparent liquid color.
level_5: All requirements for the 4-point level are met, and additionally: the purple/violet color is even and fully dissolved throughout the liquid, with no streaking, layering, or cloudy precipitate that would suggest an insoluble byproduct rather than the dissolved ferric-hydroxamate complex; the hue reads as a genuine purple/violet under the clip's lighting rather than being distorted by glare or an obvious color cast.

Spatiotemporal Consistency rubric:
level_1: The test tube vanishes from view and reappears somewhere else in the frame, or the pipette instantly jumps from one position to another with no travel shown, or the liquid level inside the test tube jumps up or down between frames with no pipette action to explain it, or the lighting changes abruptly (a flash, flicker, or sudden shadow sweep) with no visible cause, or the camera cuts or zooms partway through the sequence.
level_2: The test tube stays in frame but its position shifts noticeably between one reagent addition and the next; or the pipette's travel from a reagent container to the test tube looks jerky, stopping and restarting mid-motion; or the swirling motion looks rigid and stop-start rather than fluid; or a shadow cast by the hand or pipette moves independently of the hand/pipette itself.
level_3: The test tube stays completely fixed in the frame with no sliding, rotating, or resizing; the pipette travels in one continuous motion from each reagent container to the test tube opening for every addition; the swirling motion is smooth and stays confined to the test tube; the light source's direction on the tube and liquid stays the same from the first addition to the last; no reagent container, pipette, or the test tube itself flickers or disappears at any point.
level_4: All requirements for the 3-point level are met, and additionally: the pipette tip holds a steady, natural orientation as it approaches, touches, and withdraws from the liquid at every step, with no unnatural twisting; the liquid surface visibly dips or dimples realistically when the pipette tip enters it; the pipette never appears to pass through the glass wall of the test tube; the test tube, pipette, and reagent containers keep the same spatial arrangement relative to each other across the whole clip.
level_5: All requirements for the 4-point level are met, and additionally: the pipette in the foreground appears to move faster across the frame than the test tube and containers in the background, consistent with real depth; focus and occlusion cues between the pipette, tube, and containers stay consistent as they move; the speed of each addition and the mixing motion looks even from one step to the next rather than some steps looking sped up or slowed down; no component's edges look doubled or blurred from frame to frame.