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1.1 This procedure covers the determination of diethanolamine, triethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine (referred to collectively as ethanolamines in this test method) in surface water by direct injection using liquid chromatography (LC) and detected with tandem mass spectrometry (MS/MS). These analytes are qualitatively and quantitatively determined by this method. This method adheres to single reaction monitoring (SRM) mass spectrometry.
1.4 The Detection Verification Level (DVL) and Reporting Range for the ethanolamines are listed in Table 1.
1.4.1 The DVL is required to be at a concentration at least 3 times below the Reporting Limit (RL) and have a signal/noise ratio greater than 3:1. Fig. 1 displays the signal/noise ratios at the DVLs and at higher concentrations for N-methyldiethanolamine.
1.4.2 The reporting limit is the concentration of the Level 1 calibration standard as shown in Table 2 for diethanolamine, triethanolamine, and N-ethyldiethanolamine and Level 2 for N-methyldiethanolamine. The reporting limit for N-methyldiethanolamine is set at 50 μg/L due to poor sensitivity at a 5 μg/L concentration which did not meet the DVL criteria. The DVL for N-methyldiethanolamine is at 10 μg/L, which forces a raised reporting limit (chromatograms are shown in Fig. 1). However, the multi-laboratory validation required a spike of all target analytes at 25 μg/L. The mean recovery for N-methyldiethanolamine at this level was 88 % as shown in Table 3. If your instrument’s sensitivity can meet the requirements in this test method, N-methyldiethanolamine may have a 25 μg/L reporting limit.
|Engelse titel||Standard Test Method for Determination of Diethanolamine, Triethanolamine, N-Methyldiethanolamine and N-Ethyldiethanolamine in Water by Single Reaction Monitoring Liquid Chromatography/Tandem Mass Sp|