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Determination of Acid Value
1. Aim
To determine acid value from a supervised, validated analytical record. Actual sample and result must be entered in the student record.
2. Requirements
Authenticated oil or fat sample record, validated method sheet, labelled blank and sample titres, standardized reagents, balance record, calculator, protective equipment, and waste instructions. Required inputs: Blank-corrected alkali volume V, standardized normality N, and sample mass W. Follow the chosen method sheet for reagent amounts, concentrations, and timings. Any assay acceptance limit is to be recorded from the assigned current monograph or approved college method in the student record against the current approved method or monograph.
3. Theory
Acid value is the milligrams of potassium hydroxide equivalent to free acids in 1 g of sample. The exact solvent, endpoint, blank correction, and acceptance limit depend on the method and sample. A high or low result has no quality meaning until compared with an applicable specification.
4. Procedure
- Identify the authenticated sample, current method, safety controls, and reporting units.
- Check the balance, reagent standardization, and blank records before using any titre.
- Have the instructor perform or supervise the exact validated analytical procedure; do not substitute an illustrative value for a laboratory setting.
- Record original sample and blank readings, including any replicate and validity check.
- Apply the formula only to accepted readings and compare the result with the applicable specification, if supplied.
5. Observation and calculation
| Student record field | Entry |
|---|---|
| Case or product | Record here |
| Method | Record here |
| Observation | Record here |
| Inference | Record here |
| Supervisor check | Record here |
| Outcome | Record here |
Assumed values for calculation practice only: assumed blank-corrected V = 1.20 mL, assumed N = 0.10, and assumed W = 2.00 g. Assumed acid value = 56.1 × 1.20 × 0.10 / 2.00 = 3.366 mg KOH/g. These invented inputs and output are not a real result, preparation instruction, or acceptance limit. Source formula: Acid value = 56.1 × V × N / W, in mg KOH per g. Actual measurements must be entered in the student record.
6. Output or final result
Report the value, unit, method, and validity check for the real sample. Actual result for determination of acid value: Record here.
Teaching-lab safety: Titrants and solvents require instructor supervision, ventilation appropriate to the method, and chemical waste collection. Do not prepare reagents from assumed examples.
This page is a supervised-activity guide; it does not report a completed case.
7. Sources
- PharmacoLearn Pharm.D Year 2 syllabus
- PCI Pharm.D Regulations and Syllabus
- WHO Quality Control Methods for Herbal Materials
- Official method or compendial chapter
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