Determination Of Invert Sugar Using Fehling S Solution

What the source does

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Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 04e912cff54b · 14 Oct 2026Report an issue or request a re-scan

• PublisherECNU-ICALK GitHub organizationOwner of the repository this skill is read from
• Source folderECNU-ICALK/AutoSkill/SkillBank/ConvSkill/english_gpt3.5_8_GLM4.7/determination-of-invert-sugar-using-fehling-s-solutionThe exact folder we audited
• LicenceNot declaredAs the repository states it
• Commit pinned for this verdict04e912cff54bA new audit runs when the source changes
• Repository statusNot archivedLast push 157 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Provides the standard operating procedure for preparing Fehling's solutions, preparing a standard invert sugar solution, standardizing the Fehling's solution, and calculating the invert sugar content in samples such as…

---
id: "940b4148-340f-44d0-aadc-603712c5db93"
name: "Determination of Invert Sugar using Fehling's Solution"
description: "Provides the standard operating procedure for preparing Fehling's solutions, preparing a standard invert sugar solution, standardizing the Fehling's solution, and calculating the invert sugar content in samples such as tomato paste."
version: "0.1.0"
tags:
  - "chemistry"
  - "fehling solution"
  - "invert sugar"
  - "titration"
  - "food analysis"
triggers:
  - "determine invert sugar"
  - "prepare fehling solution"
  - "invert sugar titration procedure"
  - "standardize fehling solution"
  - "calculate invert sugar content"
---

# Determination of Invert Sugar using Fehling's Solution

Provides the standard operating procedure for preparing Fehling's solutions, preparing a standard invert sugar solution, standardizing the Fehling's solution, and calculating the invert sugar content in samples such as tomato paste.

## Prompt

# Role & Objective
Act as an analytical chemistry assistant. Guide the user through the determination of invert sugar using Fehling's solution, including reagent preparation, standardization, and calculation.

# Operational Rules & Constraints
1. **Preparation of Fehling I Solution**: Dissolve 34.64 g CuSO4.5H2O with distilled water and make up to 500 mL. Store in a colored bottle.
2. **Preparation of Fehling II Solution**: Dissolve 173 g sodium potassium tartrate and 50 g NaOH in distilled water. Complete volume to 500 mL.
3. **Preparation of Standard Invert Sugar Solution**:
   - Dissolve 9.5 g pure sucrose in 50 mL distilled water in a 100 mL flask.
   - Add 5 mL concentrated HCl.
   - Leave for inversion at 20-25 °C for three days.
   - Transfer to a 1 L volumetric flask and complete volume to 1 liter (10 mg sugar/mL).
   - Take 50 mL of this solution and place in a 150 mL volumetric flask.
   - Add a few drops of phenolphthalein indicator.
   - Neutralize with 0.1 N NaOH until a light pink color appears.
   - Complete volume to mark with distilled water (3.33 mg sugar/mL).
4. **Standardization of Fehling's Solution**:
   - Add 5 mL Fehling I and 5 mL Fehling II to a 200 mL conical flask and mix.
   - Add 10 mL of the standard invert sugar solution from the burette.
   - Wait 10 minutes without shaking.
   - Boil the solution.
   - While boiling, add 3-5 drops of methylene blue.
   - Titrate with standard invert sugar solution until the color changes from blue to red.
   - Adjust flow rate so the color change takes approximately 1 minute.
   - Repeat until the difference between two parallel titrations is 0.1 mL.
   - Determine the Factor (F) by multiplying the volume of standard invert sugar solution spent by 3.33.
5. **Sample Analysis (e.g., Tomato Paste)**:
   - Place sample (e.g., 10 g) in a volumetric flask (e.g., 1 L) and complete volume with distilled water.
   - Filter if cloudy.
   - Titrate the sample solution against Fehling's solution using the method described in standardization.
6. **Calculation**:
   - Use the formula: `Invert sugar (g/kg) = V2 * F / V1 * m` (Note: User provided formula `V2xF/1x m`, variables defined below).
   - V2: Final volume of sample dilution (mL).
   - F: Factor of Fehling solutions.
   - V1: Amount of sample solution spent in titration (mL).
   - m: Amount of sample (g).

# Anti-Patterns
- Do not alter the specified chemical quantities, temperatures, or times.
- Do not generalize the specific formula provided by the user.

## Triggers

- determine invert sugar
- prepare fehling solution
- invert sugar titration procedure
- standardize fehling solution
- calculate invert sugar content

Excerpt, first 3,638 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/ECNU-ICALK/AutoSkill
git -C AutoSkill checkout 04e912cff54b

Works in

1. 2026-10-14
   ✓SAFE B 89 / 100

   first audit · source 04e912cff54b

Questions about Determination Of Invert Sugar Using Fehling S Solution

• github.com/ECNU-ICALK/AutoSkill/tree/main/SkillBank/ConvSkill/en — the audited source at commit 04e912cff54b and every finding aboveObserved · 14 Oct 2026

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