The paper presents the determination of the pesticide 3-indolyl acetic acid based on its native fluorescence; the method has been optimised either in a flow injection analysis (FIA) assembly or in batch. Maximum fluorescence intensity was observed at basic pH solutions at lambda(exc) = 280 nm and lambda(em) = 364 nm. The influence of different empirical parameters as pH, surfactants presence, solvent polarity, solved oxygen amount, and temperature was studied; highest outputs only required the pH in aqueous solutions to be adjusted over the range 9.5-10.5. Different calibration ranges were obtained by working with three different sensitivity scales of the fluorimeter either in flow injection analysis or batch. With the high sensitivity scale and FIA, the linear dynamic range was from 0.005 to 0.6 mg L(-1) 3-indolyl acetic acid; with an relative standard deviation (RSD) of 4.9% inter-day reproducibility. A large series of potential interferents was studied and finally, the method was applied to several water samples.

No abstract

No abstract

IntroductionBromoxynil (3,5-dibromo-4-hydroxybenzonitrile) is a nitrile herbicide 1 that is used for the post-emergent control of annual broad-leaf weeds, especially in cereal, corn, sorghum, flax, onions, mint and non-cropland. This pesticide acts to inhibit photosynthesis in the target plants. The molecular structure is shown in Fig. 1.Most of the reported analytical methods for the determination of Bromoxynil are chromatographic, often in tandem with mass spectrometry, with UV detection, or even a combination of both.2 There are methods for the determination in atmospheric samples (gas and particles), 3 crops, 4 water, 5-11 from biological origins, 12 wines with a solid-phase extraction (SPE), 13 soils, [14][15][16] foodstuffs 17,18 or plants. 15 Electrochemical detection has been combined with HPLC for the determination of Bromoxynil and Ioxynil in barley. 19Two capillary electrophoresis methods 20,21 provided with solid-phase extraction have been proposed for Bromoxynil determination in the analysis of water samples.Although separative methods are by far the most commonly used; some attempts for direct determination have been published. Abubaker et al. 22 proposed peroxyoxalate chemiluminescence for the determination of phenol herbicides in soil. An ester is formed by a reaction with anhydride triethylamine and oxalyl chloride in tetrahydrofuran (THF). After eliminating of the supernatant liquid phase under a vacuum, a re-dissolution in THF containing 9,10-diphenylanthracene was implemented and the injection of H2O2 into a standard quartz spectrophotometer cell yielded light emission, which was measured at two different time intervals of 1 and 3 s. However, the linear range was observed for quite high concentrations, over the range of 10 -100 mg l -1 .Phosphorescence has been also used. 23 The spectra (264 and 420 nm for excitation and emission, respectively) were recorded in ether-isopentane-ethanol (5:5:2) at 77 K. A linear behavior was found in the range from 0.2 (quantitation limit) to 7.5 mg l -1 of Bromoxynil. Finally, a Photosystem II-based biosensor have been proposed by Koblizek et al. 24 This present paper contributes to the non-separation methods for the Bromoxynil determination. The selected detector was a luminometer; due to direct chemiluminescence, it provides a strong oxidant and has proved to be a highly sensitive method that is applicable over a wide range of concentrations and with very low detection limits. 25,26 To obtain the emitter product, online irradiation with UV light was used, as a clean reactive for derivatization. The UV irradiation proved to be an easy and clean way of derivatization to obtain fluorometric 27-29 or chemiluminescent structures. 30-32 A discussion of possible photoproducts is included. In order to automate the method, a flow injection analysis (FIA) manifold was developed. A new, robust and simple method is proposed for the chemiluminescent determination of the pesticide Bromoxynil. The empirical procedure is performed with the aid of a flow-injection manifol...

No abstract