Automatic Potentiometric Titrator for Acid and Peroxide Value

What is the Automatic Potentiometric Titrator for Acid and Peroxide Value?

An automatic potentiometric titrator determines acid value and peroxide value in edible oils by detecting endpoints with electrodes instead of color indicators. It gives objective results for dark or turbid oils and supports batch testing in refinery and quality laboratories.

Overview

For acid value, the oil is dissolved in a neutral ethanol and diethyl ether or isopropanol and toluene mixture and titrated with 0.1 mol/L potassium hydroxide while a nonaqueous pH electrode tracks potential. For peroxide value, the oil reacts with potassium iodide in acetic acid and chloroform or isooctane, and liberated iodine is titrated with sodium thiosulfate using a platinum redox electrode. The instrument finds the equivalence point from the first derivative of the titration curve and calculates the result from titrant volume, concentration and sample mass. Automatic dosing, stirring and endpoint recognition remove subjectivity, particularly for pigmented palm, olive or used frying oils where colored endpoints are hard to see. A sample changer allows unattended operation of batches.

How does it work?

Edible oil quality is defined by hydrolytic, oxidative and compositional indicators. Free fatty acids are measured by titrating the oil dissolved in an ethanol-ether or isopropanol mixture with standard potassium hydroxide, and expressed as acid value in mg KOH/g. Peroxide value is determined by iodometric titration of the iodine liberated from potassium iodide by hydroperoxides, expressed in meq O2/kg. Fatty acid composition is obtained by converting triglycerides to methyl esters and separating them on a polar capillary GC column with flame ionization detection. Oxidative stability is tested by bubbling heated air through the oil and monitoring conductivity of volatile acids formed. Total polar compounds in frying oil are estimated from dielectric constant changes or measured by silica column chromatography. Color is graded by transmittance against Lovibond or CIE scales.

What are the key features?

• Dual measurement of acid value and peroxide value with one titrator
• Nonaqueous pH and platinum redox electrodes included
• Automatic equivalence point detection from titration curve
• Preloaded methods for ISO 660, ISO 3960 and GB 5009
• Optional sample changer for 12 to 20 beakers

What are the technical specifications?

A typical automatic potentiometric titrator for acid and peroxide value configuration offers burette volume of 10 mL or 20 mL, dosing resolution of 1/20,000 of burette volume, acid value range of 0.05–50 mg KOH/g, peroxide value range of 0.1–100 meq O2/kg, potential resolution of 0.1 mV and sample mass of 1–20 g. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Automatic Potentiometric Titrator for Acid and Peroxide Value is used in oil refinery batch release, incoming crude oil acceptance and storage stability monitoring. Across the wider Edible Oil Analysis class, laboratories also deploy it for oil refinery batch quality control, shelf-life and storage studies and frying oil change decisions in food service.

Which standards and certifications apply?

Relevant standards and methods include ISO 660, ISO 3960, ISO 6886, ISO 12966-2, ISO 6320, AOCS Cd 12b-92, AOCS Cd 20-91, GB 5009.229 and GB 5009.227. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Keep edible oil samples cool, dark and sealed, since light, air and metal contact accelerate oxidation and distort peroxide results. Use reagents of specified grade and prepare titrants fresh; standardize potassium hydroxide and sodium thiosulfate regularly. Electrodes for titration need conditioning for nonaqueous media. GC columns, septa and liners need routine replacement, and methylation reagents such as boron trifluoride require fume-hood handling. Oxidative stability testers need accurate heating-block temperature calibration and clean reaction vessels. Frying oil sensors should be verified against reference oil or column chromatography. Follow laboratory safety rules for solvents and food-sample hygiene.

How do I select the right Automatic Potentiometric Titrator for Acid and Peroxide Value?

Select the titrator when acid and peroxide value are routine batch-release tests and color endpoints are unreliable. Specify the required methods (ISO 660, ISO 3960, GB 5009.229, GB 5009.227), burette size, electrodes, sample changer and reagent handling needs. It cannot give polar compounds or fatty acid profiles.

How does it compare with other Edible Oil Analysis variants?

Decide first which decision the result supports. Refiners and oil mills need acid value, peroxide value, color and moisture for every batch; an automatic titrator reduces subjectivity compared with color-indicator titration. Frying operators need fast total polar compound readings at the fryer, where a handheld sensor is enough and a laboratory method confirms disputes. Shelf-life and formulation work need a conductometric oxidative stability tester that runs several samples at defined temperatures. Authenticity, nutritional labeling and trans-fat determination need GC fatty acid analysis. Match the instrument to the standard used in your market, such as ISO 660, ISO 3960, ISO 6886, ISO 12966 or GB 5009, and check sample throughput, detection limits, operator skill requirement and reagent costs.