1.1This procedure covers the determination of thiodiglycol (TDG) in surface water by direct injection using liquid chromatography (LC) and detected with tandem mass spectrometry (MS/MS). TDG is qualitatively and quantitatively determined by this test method. This test method adheres to single reaction monitoring (SRM) mass spectrometry.

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

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

1.4The detection verification level (DVL) and reporting range for TDG are listed in Table 1.

Analyte	DVL (μg/L)	Reporting Range (μg/L)
Thiodiglycol	20	100-10000

1.4.1The 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 ratio at the DVL.

FIG. 1Example SRM Chromatograms Signal/Noise at Detection Verification Level

1.4.2The RL is the concentration of the Level 1 calibration standard as shown in Table 2. The reporting limit for this test method is 100 μg/L.