This paper presents a method for determining sub-ppb levels of perchlorate anion using ion chromatography/mass spectrometry (IC/MS). The IC/MS method follows EPA Method 314 methodology originally developed for IC with conductivity detection at the single ppb range [1]. The IC/MS method is not affected by the addition of the interference matrix described in Method 314 on perchlorate recoveries throughout the measurable range. Typical recoveries are 90%–105% at the 0.5 and 1-ppb level in synthetic drinking and waste waters with the method detection limit (MDL) less than 100 ppt.
This document describes a method for the determination of perchlorate anion at sub ppb levels using ion chromatography/mass spectrometry (IC/MS). The method follows EPA Method 314 methodology and is designed to be unaffected by interference matrices that typically affect conductivity detection. Typical recoveries are reported between 90% and 105% at 0.5 and 1 ppb levels in synthetic drinking and waste waters, with a method detection limit (MDL) less than 100 ppt.
The analytical system consists of a modular ion chromatograph (Metrohm-Peak, Inc.) and an Agilent 1100 MSD SL Quad mass selective detector. The method utilizes a 4-mm id column to reduce matrix suppression and employs a suppressor to remove cations from the eluent stream. Instrumental parameters, including flow rates, column specifications, and mass spectrometer settings, are detailed in the text.
| Injection loop size | 100 pL |
|---|---|
| Column | MetroSep ASUPP-5 (4 mm x 100 mm) |
| Eluent | 3/7 v/v MeOH/30 mm NaOH |
| Flow rate | 0.8 mL/min |
| Veap | 1400 V |
| Drying gas flow | 9 L/min |
| Nebulizer pressure | 20 psig |
| Fragmentor | 140V |
| Dwell time m/z 99 | 1s |
| Dwell time m/z 101 | 1s |
Typical recoveries are 90% to 105% at the 0.5 and 1-ppb level in synthetic drinking and waste waters.
The method detection limit is less than 100 ppt.
The flow rate is 0.8 mL/min.