Purge-and-trap Determination of Ammonia in Water Samples Using Needle-type Extraction Coupled with Gas Chromatography–Barrier Discharge Ionization Detection

Abstract

This manuscript describes the determination of ammonia (NH₃) in aqueous samples by purge-and-trap extraction using a needle-type extraction device with gas chromatography–barrier discharge ionization detector (GC-BID). NH₃ was purged from the aqueous samples in basic conditions and then salted out with sodium chloride. Purged ammonia was trapped onto non-volatile carboxylic acid-coated macroporous terephthalic acid particles, which were contained within the needle-type extraction device. The analyte (NH₃) was thermally desorbed by heating the extraction needle in the GC injection port, and detected by BID. After the optimization of both purge and extraction conditions, the linearity and sensitivity of the proposed method were evaluated. The limit of detection was found to be 2.0 mg L⁻¹ at a headspace sampling volume of 100 mL. The method applicability was confirmed by the determination of spiked NH₃ in tap water and river water samples.