Method 552.2: Determination of Haloacetic Acids and Dalapon Analysis in Drinking Water by Ion Exchange Liquid-Solid Extraction and GC with an Electron Capture Detector

Haloacetic acids are a byproduct of chlorinated disinfection of drinking water. Historically, there has been some concern that these analytes may represent a chronic risk to human health, and toxicological evidence suggests that some of them are possible human carcinogens. Elevated levels of haloacetic acids in drinking water could pose acute human risk because of their corrosive nature. Using Method 552.2 and an appropriate GC column set, such as the Rtx-CLPesticides and the Rtx-CLPesticides2 columns, environmental chemists can achieve accurate analysis of haloacetic acids and dalapon.

Haloacetic acid analysis can be performed on a variety of GC column phases. However, an important criterion for column selection is the degree of resolution between the methylated haloacetic acid compounds and known interference compounds like bromoform. Bromoform may be present due to the partial decarboxylation of tribromoacetic acid that can occur during a methylation step that uses acidic methanol. As shown below, the Rtx-CLPesticides and Rtx-CLPesticides2 columns provide the necessary resolution for this GC-ECD analysis in less than 12 minutes, using the same instrument setup as several other EPA methods.

Comparison based on published competitor data. All columns tested were 0.32 mm ID. NDP = no data published

	Peaks	Conc. (µg/mL)
1.	Methyl monochloroacetate	1.2
2.	Methyl monobromoacetate	0.8
3.	Methyl dichloroacetate	1.2
4.	Dalapon methyl ester	2
5.	Methyl trichloroacetate	0.4
6.	1,2,3-Trichloropropane (IS)	4

	Peaks	Conc. (µg/mL)
7.	Methyl bromo(chloro)acetate	0.8
8.	Methyl bromodichloroacetate	0.8
9.	Methyl dibromoacetate	0.4
10.	Methyl chlorodibromoacetate	2
11.	Methyl 2,3-dibromopropionate (SS)	2
12.	Methyl tribromoacetate	4

Columns	Rtx-CLPesticides2 30 m, 0.32 mm ID, 0.25 µm (cat.# 11324)
	and Rtx-CLPesticides 30 m, 0.32 mm ID, 0.32 µm (cat.# 11141)
	using Rxi guard column 5 m, 0.32 mm ID (cat.# 10039)
	with deactivated universal “Y” Press-Tight connector (cat.# 20405-261)
Standard/Sample	Haloacetic acid methyl ester mix #2
	Dalapon methyl ester (cat.# 32057)
	Methyl-2,3-dibromopropionate (cat.# 31656)
	1,2,3-Trichloropropane (cat.# 31648)
Diluent:	Methyl tert-butyl ether (MTBE)
Injection
Inj. Vol.:	1.0 µL splitless (hold 0.75 min)
Liner:	Cyclo double taper (4 mm) (cat.# 20896)
Inj. Temp.:	250 °C
Oven
Oven Temp.:	35 °C (hold 4 min) to 250 °C at 15 °C/min (hold 5 min)
Carrier Gas	He, constant flow
Linear Velocity:	25 cm/sec

Detector

Micro-ECD @ 300 °C

Notes

Standard cat.# 31647 was used to produce this chromatogram, but has since been discontinued. For assistance choosing a replacement for this application, contact Restek Technical Service or your local Restek representative. - - - - - - This chromatogram was obtained using an Agilent micro-ECD. To obtain comparable results, you will need to employ a micro-ECD in addition to confirmational dual columns connected to a 5-meter guard column using a “Y” Press-Tight connector.

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