DETERMINATION OF BORON IN LIGHT-WATER AND HEAVY-WATER SAMPLES BY FLOW-INJECTION ANALYSIS WITH INDIRECT UV VISIBLE SPECTROPHOTOMETRIC DETECTION

A flow injection analysis (FIA) system was built to determine boron in aqueous samples using indirect UV-visible detection. The analyzer consists of a two-line manifold in which the sample (300 muL) is introduced into a water carrier stream and the buffered chromotropic acid reagent constitutes the second channel. The merging point of the two streams appears just in front of the reaction coll, thus ensuring a constant reagent dilution. The reactor is made of 10-m packed Teflon tubing followed by 3-m open Teflon tubing, both in series. With a flow rate of 0.3 mU(min/channel), the sample dispersion is about 2 and the residence time is 7 min, allowing a sample throughput of 15 samples/h. The response is linear over the concentration range of 40-6000 mug/L, and at levels up to 10 000 mug/L a third-order polynomial can be used. The precision is 3 % in the low end of the concentration range (< 1000 mug/L) and 1 % at higher levels with a relative accuracy better than 6 % and a detection limit of 8 mug of boron per liter (SA/N = 2). The precision and accuracy were validated by a comparison of interlaboratory analytical performances. The new analyzer has been successfully applied for the boron determination in moderator and primary heat transport system samples which are collected al Hydro-Quebec's Gentilly 2 nuclear power station. The results presented in this paper demonstrate that these samples can be analyzed without any interference from ions potentially found in those systems.