Talanta 64 (2004) 534–537 Determination of glyphosate mono-isopropylamine salt in process samples using flow injection analysis with tris(2,2 ′ -bipyridyl)ruthenium(II) chemiluminescence detection Jacqui L. Adcock a , Neil W. Barnett a , Richard D. Gerardi b , Claire E. Lenehan a , Simon W. Lewis a,∗ a Centre for Chiral and Molecular Technologies, School of Biological and Chemical Sciences, Deakin University, Geelong 3217, Vic., Australia b Nufarm Limited, Laverton North 3026, Vic., Australia Received 14 December 2003; received in revised form 9 March 2004; accepted 9 March 2004 Available online 18 May 2004 Abstract The mono-isopropylamine salt of glyphosate was selectively determined directly in industrial and commercial formulations using flow injection analysis with tris(2,2 ′ -bipyridyl)ruthenium(II) chemiluminescence detection without the need for separation. Glyphosate and its mono-isopropylamine salt furnished detection limits of 7 × 10 -9 and 3.5 × 10 -10 M and relative standard deviations of 0.4% at 1 × 10 -7 M and 0.8% at 5 × 10 -8 M, respectively. The methodology is robust and reliable with samples subjected only to aqueous dilution prior to analysis. © 2004 Elsevier B.V. All rights reserved. 1. Introduction Glyphosate [N-(phosphonomethyl)glycine] (see Fig. 1), is a well known, broad-spectrum herbicide [1]. As the free amino acid exhibits poor aqueous solubility its ammonium, potassium and mono-isopropylamine salts are commonly used as the active ingredient in commercially available prod- ucts [1]. Various ion exchange [2–5] and gas [6] chromato- graphic methods have been reported for the determination of glyphosate in environmental matrices and some repre- sentative examples of these [2–6] have been summarised in Table 1. To the best of our knowledge, the only previous use of chemiluminescence detection was that by Ridlen et al. [3] who used tris(2,2 ′ -bipyridyl)ruthenium(III) to determine glyphosate and some related compounds in standard solu- tions. This type of chemiluminescence has also been em- ployed for the sensitive and/or selective detection of various classes of analytes using either flow analysis or HPLC [7]. ∗ Corresponding author. Tel.: +61-3-52271365; fax: +61-3-52271040. E-mail address: swlewis@deakin.edu.au (S.W. Lewis). Nufarm Limited, produce proprietary glyphosate-based herbicide formulations and the quality assurance of these processes is currently monitored using standard HPLC methodology with conductivity detection [8]. This paper describes, for the first time, a simple approach to the de- termination of glyphosate mono-isopropylamine salt in commercial formulations using flow injection analysis with tris(2,2 ′ -bipyridyl)ruthenium(II) chemiluminescence detection. 2. Experimental 2.1. Instrumentation and procedure A two-line flow injection analysis manifold was used. A Gilson Minipuls 3 peristaltic pump (John Morris, Australia) with PVC pump tubing (1.85 mm i.d., A.I. Scientific, Aus- tralia) propelled the carrier and sample streams at a maxi- mum total flow rate of 6 ml min -1 . The manifold tubing was PTFE (0.5mm i.d., Chromalytic Technology, Australia). The reagent solution, tris(2,2 ′ -bipyridyl)ruthenium(III) 0039-9140/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2004.03.024