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Determination of Ester Value

1. Aim

To determine ester 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: Validated saponification value and acid value for the same sample, with their worksheets. 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

Ester value represents alkali consumed by esterified acids. It is calculated as saponification value minus acid value when both values are measured on the same sample using compatible methods and units. A mismatch in sample or units invalidates subtraction.

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 saponification value = 190 mg KOH/g and assumed acid value = 5 mg KOH/g for the same assumed sample. Assumed ester value = 190 − 5 = 185 mg KOH/g. These invented inputs and output are not a real result, preparation instruction, or acceptance limit. Source formula: Ester value = saponification value − acid value, 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 ester 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

← Determination of Saponification Value and Unsaponifiable MatterDetermination of Acid Value →

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