The full specification, COA and Amine Value Pack for MEA 99% industrial grade defines the lot-specific release envelope used for stoichiometric calculations in amidation, ethoxylation, and acid-gas neutralization. Monoethanolamine, CAS 141-43-5, has a molecular weight of 61.08 g/mol, a primary amine functionality, and a theoretical total amine value of 918.5 mg KOH/g. An industrial-grade release is not judged by assay alone: water, color, diethanolamine, triethanolamine, ammonia, density, and total amine value constitute a multi-parameter control because each impurity consumes active equivalents, alters reaction kinetics, or increases corrosion potential. The typical release envelope for drummed and bulk isotank material is shown below.

The total amine value in this specification is not a separate indicator of generic quality; it is the lot-level titration total of primary, secondary, and tertiary amine species expressed as mg KOH per gram of sample. Bulk isotank deliveries often require a tighter water limit of ≤0.2 wt% because headspace moisture ingress during unloading can push a marginally wet lot above downstream anhydrous requirements in fatty acid amidation and narrow ethoxylation systems.

What Does the Certifying Laboratory Report in a Lot-Specific COA for Industrial MEA?

A COA for MEA 99% industrial grade is a tabulated record of measured results for an identified batch, not a reprint of the specification. The certifying laboratory reports the batch number, date of manufacture, retest or expiry interval, sampled container, and test data for assay, water, color, individual homologues, ammonia, density, and total amine value. When the Amine Value Pack is specified, the COA is expanded with titration normality, sample mass, burette volume, and the calculated total amine value. Release is completed under ISO 9001:2015 Clause 8.6 only when all specified criteria are within the release envelope. If a parameter is outside specification, the lot is assigned a nonconforming product status and is not released without documented rework or customer concession. The COA therefore functions as the controlled analytical boundary between production and formulation, and a missing amine value entry should be treated as a documentation gap in molar-ratio-sensitive applications.

Because the primary amine hydrogen is the reactive center in amidation, ethoxylation, and acid-gas neutralization, measured total amine value provides a direct check on stoichiometric availability. Non-aqueous titration per ASTM D2074-07, adapted for alkanolamine matrices, dissolves the specimen in a solvent system of isopropanol and glacial acetic acid, then titrates with perchloric acid in glacial acetic acid using a potentiometric autotitrator with a double platinum-pin electrode. The result is calculated as total amine value = (V × N × 56.1) / m, where V is titrant volume in mL, N is perchloric acid normality, 56.1 is the molar mass of potassium hydroxide in mg/mmol, and m is specimen mass in grams. For pure MEA the theoretical value is 918.5 mg KOH/g; for a lot with 99.6 wt% assay, 0.10 wt% water, and minor residual DEA and TEA, the expected wet total amine value is approximately 915–916 mg KOH/g. The Amine Value Pack combines this titration with GC purity, water, and color so that a formulator can convert charged mass into available amine equivalents without retesting incoming lots.

Amine Value Drift During Storage and the Correction Logic in the Pack

MEA 99% is hygroscopic and absorbs carbon dioxide from ambient air; both processes alter the measured total amine value and shift the stoichiometric basis of downstream batching. In open-head IBC storage at relative humidity above 60%, water uptake can occur rapidly, and dissolved CO₂ forms carbamate species that reduce free amine value. Published data for this specific plant configuration is limited, but the operative control in bulk storage is a nitrogen blanket with a supply dew point below -40°C and a tank headspace pressure of 0.5–1.0 kPa gauge. The pack correction logic is not a recalculation of assay; it is the use of the delivered COA amine value and water content as the baseline for retest comparison after any storage event. If retest amine value falls by more than 1.0 mg KOH/g relative to the COA, the lot is normally quarantined for drying or nitrogen sparging before use in molar-ratio-sensitive syntheses. Prolonged contact with copper and zinc should be avoided because MEA forms amine complexes that accelerate metal ion contamination and color development.

In gas sweetening, MEA 99% is diluted with demineralized water to 15–30 wt% active amine for CO₂ and H₂S absorption in packed columns or tray towers. Lean amine loading is typically controlled at 0.10–0.15 mol CO₂/mol amine, and rich loading is kept below 0.35–0.45 mol/mol because hot carbonate and carbamate species increase carbon steel corrosion rates. Reboiler bulk temperature is limited to 118–120°C; tube skin temperatures above 127°C accelerate thermal degradation to 2-oxazolidone and heat-stable salts. The rich/lean exchanger velocity in carbon steel lines is maintained below 1.8 m/s to limit erosion corrosion. Lean amine cooler outlet temperature is often set at 45–55°C to balance viscosity and absorption efficiency, and rich solution flash tanks operate at 500–700 kPa gauge to remove dissolved methane before regeneration. Gas sweetening systems using MEA require continuous filtration and a thermal reclaimer slipstream; without reclamation, heat-stable salt accumulation raises amine consumption and reboiler duty. The choice of MEA over formulated solvents is governed by acid gas ratio, CO₂ slip requirements, and the facility’s ability to manage corrosion and degradation within the regeneration circuit.

When Ethoxylation Reactors Run on MEA Instead of Diethanolamine

The substitution of MEA for DEA changes the initiation sequence and the thermal profile of the ethoxylation reactor. MEA is a primary amine and adds ethylene oxide at the amine hydrogen before the hydroxyl sites; the first EO addition is strongly exothermic, and the reactor must be capable of removing the heat of reaction through jacket and external loop cooling. In a 10 m³ stainless steel autoclave, initial EO addition is ramped at 0.5–1.0 mol EO/mol MEA per hour until the first molar equivalent has reacted, with the batch temperature held between 120–150°C under a nitrogen pad. Water above 0.1 wt% in the MEA feed initiates ethylene glycol and polyethylene glycol formation, broadening the molar mass distribution and lowering the surfactant cloud point. Catalysis is normally potassium hydroxide at 0.1–0.3 wt% of the final charge; higher hydroxide levels increase ethoxylate color and dioxane byproducts. The resulting monoethanolamine ethoxylates have different foaming and wetting behavior than diethanolamine ethoxylates because the nitrogen remains in the chain and can be quaternized or neutralized. Process safety documentation must account for the autocatalytic polymerization of ethylene oxide if the initial primary amine addition is bypassed by poor mixing; published data for this reactor configuration is limited, and full reaction calorimetry is required before scale-up.

In aqueous metalworking fluid concentrates, MEA 99% is added at 2–8 wt% to buffer pH between 9.0 and 9.5 and to form ethanolamine borate when combined with boric acid at 1–3 wt%. The borate ester acts as a ferrous corrosion inhibitor and biostat; the pH window is narrow because above 9.5 the fluid can stress copper alloys and below 9.0 the borate ester hydrolyzes. Fluid formulators use the COA water and amine value to adjust the neutralization equivalent of the alkanolamine/boric acid complex; a shift of 1.0 mg KOH/g in total amine value changes the required MEA charge by approximately 0.11 g per 100 g of concentrate. MEA in metalworking fluids is not compatible with strong oxidizing biocides or nitrosating agents; if the fluid is treated with a separate nitrite source, nitrosamine formation becomes an industrial hygiene constraint. The amine also complexes cobalt from tungsten carbide tooling, which can deplete the available amine and produce colored metal complexes; this is a documented operational limitation in high-speed machining operations.

Across a compiled set of release records for drummed MEA 99% industrial grade, a representative COA with the Amine Value Pack is provided below. The data are not a specification guarantee; they summarize observed lot-level variability for a single production train.

The observed amine value is lower than the pure-component theoretical value because the measured assay is not 100% and because DEA and TEA have lower molar contributions to the KOH equivalence per gram than MEA. Batch-to-batch variance in this production train is reported as 0.2% absolute for assay and 1.0 mg KOH/g absolute for total amine value.