Horizon Technology, Inc.

	Drinking water is an important part of environmental exposure, especially for small children. Countries around the world have put regulations in place to monitor drinking water quality for a wide range of hazardous compounds. Methods such as SL 392-2007 in China, the EN methods in Europe, and US methods such as method 525.2, cover a large suite of analytes of concern, extracted using solid phase extraction (SPE) disks and using GC–MS for detection.

	US EPA method 525.2 may use SPE to extract the analytes of interest from water samples. It includes a variety of quality control measures to ensure the method is under control throughout the analysis (1). The SPE-DEX

 5000 was used in this study to extract the EPA Method 525.2 analytes from six prepared water samples as described in section 9.3, Initial Demonstration of Laboratory Accuracy and Precision. The test involves measuring 4–7 samples of reagent water spiked at approximately the mid-point of the calibration curve, 2–5 µg/L of the full suite of analytes. For each analyte and surrogate, the spike recovery, expressed as a percentage of the true value, should be 70–130% and the relative standard deviation (RSD) should be <30% to meet method criteria. All six samples were extracted using the same procedure and calibration parameters.

	Extraction was performed with the SPE-DEX 5000 Automated Disk Extraction System (2). The SPE-DEX

 5000 is an automated system that conditions the solid phase extraction disk, loads the sample through the disk, rinses the sample bottle, and elutes the sample all without user intervention. Atlantic

 C18 high capacity SPE disks were used, DryDisk membrane drying was used to remove residual water from the extract, and GC–MS was used for analysis. Results are shown in Table I for six replicate preparations and show excellent recovery and precision.

	Method 525.2, Determination of Organic Compounds in Drinking Water by Liquid-Solid Extraction and Capillary Column Gas Chromatography/Mass Spectrometry, US EPA 

https://www.epa.gov/sites/production/files/2015-10/documents/method_525-2_rev-2_1995.pdf

	Extraction of a Full Suite of Semivolatile Compounds from Drinking Water using Automated Solid Phase Extraction, AN1141703_01, available from 

Articles

Drinking water is an important part of environmental exposure, especially for small children. Countries around the world have put regulations in place to monitor drinking water quality for a wide range of hazardous compounds.

Extraction of a Full Suite of Semivolatile Compounds from Drinking Water Using Automated Solid-Phase Extraction

The compound 4-methylimidazole (4-MEI) is formed as a by-product in some foods and beverages. Caramel coloring Type III and Type IV in beverages is one of the ingredients which may contain 4-MEI and it may be found in products such as certain colas, beers, soy sauces, breads, coffee, ammoniated livestock feed, and others. There has been an increase in concern lately about 4-MEI being a suspected carcinogen. Europe has regulated the amount of 4-MEI allowed in coloring used in food products. The state of California has added 4-MEI to its proposition 65 list of known carcinogens. California now requires products with an exposure potential of >29 µg/day to carry warning labels.

	This work will demonstrate a simple methodology using automated solid-phase extraction (SPE) and HPLC coupled with mass spectrometric detection.

 Cartridge Extractor was used with a Waters Oasis

 MCX 3 cc (60 mg) cartridge. The extraction method was optimized using a series of conditions and collecting fractions on the SmartPrep (1).

	The samples for this experiment were common soft drinks containing caramel coloring. The point of purchase and original product production site are variables in 4-MEI levels. Some of the beverages were purchased in New England and others in California, in common supermarkets and their bottling origin is listed with the results.

					Figure 1: Mexican soda sample, S/N = 383 for quantitation ion.

	A sensitive method for 4-MEI detection was developed using HPLC–MS, showing adequate measurement below the California Prop 65 requirements of 29 µg per day. Solid-phase extraction was shown to adequately concentrate the 4-MEI from the soft drinks analyzed and provide clean-up. Two samples were shown to exceed the daily exposure limits in Prop 65 with one serving.

		“A Simple Analysis of 4-Methylimidazole Using Automated Solid Phase Extraction and High Performance Liquid Chromatography with MS-MS and MS-SIM Detection,” AN1111606_01, available from 

This work will demonstrate a simple methodology using automated solid-phase extraction (SPE) and HPLC coupled with mass spectrometric detection.
This work will demonstrate a simple methodology using automated solid-phase extraction (SPE) and HPLC coupled with mass spectrometric detection.
This work will demonstrate a simple methodology using automated solid-phase extraction (SPE) and HPLC coupled with mass spectrometric detection.

A Simple Analysis of 4-Methylimidazole Using Automated Solid-Phase Extraction and High Performance Liquid Chromatography with MS-MS and MS–SIM Detection

	The US EPA has implemented an exposure research program aimed at conducting drinking water research on methods as part of the Microbiological and Chemical Exposure Assessment. This research is aimed at evaluating the chemical pollutants and their role and levels in which there is an unacceptable risk to either humans or wildlife, as well as evaluating the methodologies currently being used to determine levels of chemical pollutants. 

	Alachlor is listed as a regulated contaminant under the US Safe Drinking Water Act with a maximum contaminant level of 0.002 mg/L. Several of the other analytes listed in the EPA method are on the contaminant list for unregulated contaminant monitoring rule 3 (UCMR-3), and may require monitoring for occurrence determination. In Europe, the regulatory approach is different and individual pesticides cannot be present at greater than 0.1 µg/L or a total of all pesticides cannot exceed 0.5 µg/L. Pesticides are defined in Europe as insecticides, herbicides, fungicides, and related categories.

	Enabling automation to perform the tedious manual SPE procedure can increase the efficiency of a laboratory’s work flow and allow other technician activities to be accomplished during the SPE process. In this application note, determination of chloroacetanilide and acetamide degradates was performed using the automated SmartPrep® Extractor SPE cartridge system according to US EPA 535 prior to LC–MS-MS analysis, with the intent to generate results within the acceptance criteria of the EPA 535 method.

	Purified laboratory water samples of 250 mL each were spiked at 2.5 ng/mL in triplicate with an herbicide compound mix and the recoveries are shown in the accompanying table.

	Solid-phase extraction provided excellent recoveries within the specifications of the EPA 535 method of these more difficult compounds. Automation of the extraction procedure offered reproducible performance with less technician intervention. Analysis of the herbicides using LC–MS-MS indicated that all produced LC–MS-MS results passed the requirements for mean recovery of water samples being 50–150% of the true spiked value of each of the 12 herbicide compounds, as well as passed the requirements for meeting the <20% RSD criteria for the precision criteria of the same water samples. Low detection limits required by the method were met, as shown by the passing recoveries and excellent precision in the table. Blank injections resulted in no quantifiable herbicide compounds to report, with detection levels down to 0.6 ppb.

	(1) “US EPA Method 535, Measurement of Chloroacetanilide and Other Acetamide Herbicide Degradates in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC–MS-MS),” April 2005.
	(2) “Solid Phase Extraction of US EPA 535 for Chloroacetanilide and Acetamide Degradates in Drinking Water Samples Prior to Liquid Chromatography/Tandem Mass Spectrometry,” AN0901407_01, 

	Horizon Technology, Inc.
	16 Northwestern Drive, Salem, NH 03079
	tel. (603) 893-3663, fax (603) 893-4994
	Website: www.horizontechinc.com

The US EPA has implemented an exposure research program aimed at conducting drinking water research on methods as part of the Microbiological and Chemical Exposure Assessment. This research is aimed at evaluating the chemical pollutants and their role and levels in which there is an unacceptable risk to either humans or wildlife, as well as evaluating the methodologies currently being used to determine levels of chemical pollutants.

Solid-Phase Extraction of US EPA 535 for Chloroacetanilide and Acetamide Degradates in Drinking Water Samples Prior to Liquid Chromatography/Tandem Mass Spectrometry