Description

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.

1.2 This test method has been developed by US EPA Region 5 Chicago Regional Laboratory (CRL).

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

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.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

TABLE 1 Detection Verification Level and Reporting Range

Analyte	DVL (μg/L)	Reporting Range (μg/L)
Diethanolamine	5	25-500
Triethanolamine	5	25-500
N-Ethyldiethanolamine	5	25-500
N-Methyldiethanolamine	10	50-500

TABLE 2 Concentrations of Calibration Standards (PPB)

Analyte/Surrogate	LV 1	LV 2	LV 3	LV 4	LV 5	LV 6	LV 7
Diethanolamine	25	50	75	150	250	350	500
Triethanolamine	25	50	75	150	250	350	500
N-Ethyldiethanolamine	25	50	75	150	250	350	500
N-Methyldiethanolamine	25	50	75	150	250	350	500
Diethanolamine-D₈ (Surrogate)	25	50	75	150	250	350	500

TABLE 3 Multi-Laboratory Recovery Data in Reagent Water

Analyte	Spike Conc. (ppb)	# Results	# Labs	Bias			Precision
Analyte	Spike Conc. (ppb)	# Results	# Labs	Mean Recovery (%)	Min Recovery (%)	Max Recovery (%)	Overall SD (%)	Pooled within-lab SD (%)	Overall RSD (%)	Pooled within-lab RSD (%)
Diethanolamine	25	24	6	96.34	51.00	156.96	31.31	10.96	32.50	9.49
Diethanolamine	50	24	6	101.41	54.00	154.80	29.54	7.97	29.13	7.91
Diethanolamine	200	24	6	101.57	61.00	138.00	20.98	10.50	20.66	10.85
Diethanolamine	425	24	6	102.06	70.00	138.82	17.98	5.90	17.61	5.70
Triethanolamine	25	24	6	87.70	35.96	157.20	27.00	25.18	30.79	27.48
Triethanolamine	50	24	6	94.95	67.00	121.66	16.39	9.57	17.26	9.66
Triethanolamine	200	22	6	105.00	79.50	132.00	14.06	11.81	13.39	11.52
Triethanolamine	425	24	6	96.94	40.00	144.94	27.56	4.41	28.43	5.76
N-Ethyldiethanolamine	25	24	6	90.61	31.00	132.00	39.42	7.47	43.51	10.42
N-Ethyldiethanolamine	50	23	6	111.88	49.00	146.00	28.71	7.19	25.66	7.56
N-Ethyldiethanolamine	200	24	6	106.20	60.00	134.00	23.09	11.96	21.74	12.23
N-Ethyldiethanolamine	425	24	6	99.67	51.00	130.00	23.07	4.68	23.15	6.01
N-Methyldiethanolamine	25	24	6	88.43	41.72	133.60	25.24	13.29	28.55	16.70
N-Methyldiethanolamine	50	24	6	102.28	56.00	153.80	25.85	8.73	25.27	8.22
N-Methyldiethanolamine	200	24	6	101.02	59.00	136.50	20.07	9.51	19.87	9.54
N-Methyldiethanolamine	425	24	6	94.75	63.00	115.76	15.02	3.34	15.85	3.72
Diethanolamine-D₈ (Surrogate)	200	96	6	103.02	60.00	151.95	21.13	9.40	20.51	9.25