NEMI Method Summary

Method Summary Information

Method Number: D4983 Media: WATER
Revision: Reapproved 1996. Current edition approved Nov. 10, 1989. Published March 1990.
Method Source: ASTM International
Subcategory: ORGANIC Analytes in this method
Official Name: Standard Test Method for Cyclohexylamine, Morpholine, and Diethylaminoethanol in Water and Condensed Steam by Direct Aqueous Injection Gas Chromatography
Descriptive Name Volatile Amines in Condesates
Source Info: ASTM International
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Citation: ASTM Volume 11.02
 
Brief Method
Summary:
 Prior to analysis the pH is raised to > 10.0. After centrifugation, the sample is analyzed by direct aqueous injection gas chromatography using an alkaline polyethylene glycol liquid phase and a flame-ionization detector.
When high levels of these amines (> 15 mg/L) are found in water samples, positive identification of the component(s) is required by supplemental testing, such as the use of different gas chromatographic column packings, a nitrogen-specific detector, derivatization, mass spectrometry, or a combination of these techniques should also be used.
In this test method, the elution profile of the subject amines occurs in the order: morpholine, cyclohexylamine, and diethylaminoethanol.
Scope And
Application:
 This test method covers the general considerations for the qualitative and quantitative determination of volatile amines such as cyclohexylamine, morpholine, and diethylaminoethanol in steam condensates and surface water by gas-liquid chromatography.
Applicable
Conc Range:
 2 - 15 mg/L
Interferences: Inorganic Cations Capable of Complexing with Amines: Particulate Matter - Usually oxides from metal surfaces and other solid impurities may remain in the sample as particulate or suspended matter and therefore must be removed without the loss of analyte. This is accomplished generally by centrifugation. Varying amounts of polyvalent metal ions, specifically ferric cations, present in the sample may likely chelate or complex with the amines. This prevents quantitative elution of the amines from the column. Prior to the analytical step, since the sample may have a pH greater than 10.0, the ferric hydroxide formed will entrap varying amounts of the amines. This will cause irreproducible results, produce nonuniform injection by fouling the microsyringe, and contaminate the glass liner of the injection port of the gas chromatograph.
Identical Retention Times: Neutral and Basic Organic Compounds - Identical retention times will cause inteferences.
Acidic Organic Compounds - Before analysis when the sample is brought approximately to pH > 10, components such as organic and inorganic acids, phenolic compounds, etc., are converted to their respective salts. The solution containing these salts is then flash-evaporated onto the inner walls of the glass liner in the injection port. If the salt build-up is very high, the amines may be irreversibly adsorbed or decomposed by the salts at high temperatures.
Ghosting - Ghosting is evidenced by an interference peak that occurs at the same retention time as that of the component of interest or was carried from previous analyses, or both. Repeated injections with 5 mL of water between every sample and standard run will usually eliminate ghosting problems.
Delayed Elution - High-boiling contaminants in the sample may unpredictably elute several chromatograms later and therefore act as interferences. This is particularly true with boiler waters that are fed with reclaimed, industrial waste waters.
QC Requirements:
Sample Handling: Collect the water samples in accordance with Practice D 1066, Practices D 3370, and Practice D 2908, as applicable. The sample is preserved by adjusting the pH to 3.0 by addition of phosphate solutions.
Sampling Procedure for Steam - Prior to sampling condensed steam, open the valve leading to the sample nozzle for a maximum rate of flow of steam, during which time the cooling water surrounding the condensing coil is drained. This will remove any material that might have previously deposited in the lines. When the actual sampling is carried out, cool the condensing coil with running cold water. After rinsing the bottle twice with approximately 10 mL of condensed water, collect 115 +/- 5 mL of the sample in amber glass bottles. Immediately after the samples are collected, treat with approximately 1 mL of phosphate solution (8.7.1) followed by the addition of a few drops of phosphoric acid solution (8.7.2) to bring the pH approximately to 3. Stopper the containers tightly with TFE-fluorocarbon-laminated silicone septa and with screw caps. Centrifuge the samples using 40-mL heavy-duty borosilicate glass centrifuge tubes at 3000 r/min for about 15 min to pelletize the particulates. Transfer 10-mL aliquots of the supernatant liquid into rinsed 1 0-mL centrifuge tubes.
Store the samples and standards at 4 to 6oC at all times prior to analysis.
Max Holding Time:
 
Relative Cost: Unknown
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