A flow system coupled with on-line solid phase extraction (SPE) and liquid waveguide capillary cell (LWCC) spectrophotometric detection has been established to simultaneously determine nanomolar levels of nitrite and nitrate in surface seawaters. The azo-compound that formed from nitrite could be quantitatively extracted on HLB SPE cartridge, and then eluted and detected in a LWCC detector of 16 cm path length. In a separated portion of sample, nitrate was reduced to nitrite with a Cu–Cd reduction column. The initial and reduced nitrite together formed azo-compound in a parallel flow channel, and the azo-compound formed was extracted, eluted and detected via the same way as that of nitrite. Due to the hyphenation of SPE and LWCC, the matrix interferences to the performance of LWCC could be avoided. Limit of detections at the nanomolar level (0.3 nmol L⁻¹ for nitrite and 1.5 nmol L⁻¹ for nitrate) were obtained. Application to seawater analysis showed good agreement with an alternative analytical configuration.

Item Type:	Refereed Article
Keywords:	nitrite, nitrate, liquid waveguide capillary cell, on-line solid phase extraction, seawater
Research Division:	Chemical Sciences
Research Group:	Analytical chemistry
Research Field:	Flow analysis
Objective Division:	Environmental Management
Objective Group:	Marine systems and management
Objective Field:	Measurement and assessment of marine water quality and condition
UTAS Author:	Zhang, M (Dr Min Zhang)
ID Code:	104701
Year Published:	2009
Web of Science® Times Cited:	27
Deposited By:	Chemistry
Deposited On:	2015-11-18
Last Modified:	2016-03-30
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