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An automated colorimetric method for determining dissolved boron in water is described. The boron is complexed with azomethine H, which is readily available as the condensation product of H acid (8-amino-l-naphthol-3,6-disulfonic acid) and salicylaldehyde. The absorbance of the yellow complex formed is then measured colorimetrically at 410 nm. Interference effects from other dissolved species are minimized by the addition of diethylenetriaminepentaacetic acid (DTPA); however, iron, zinc, and bicarbonate interfere at concentrations above 400 pg/L, 2000 pg/L, and 200 mg/L, respectively. The bicarbonate interference can be eliminated by careful acidification of the sample with concentrated HCl to a p H between 5 and 6. Thirty samples per hour can be routinely analyzed over the range of from 10 to 400 pg/L boron.Since its chemical behavior in water is not well known, boron is assumed to exist primarily as the undissociated form of orthoboric acid (HSBO~) at the pH range of ordinary natural water and a t concentrations less than 1.0 mg/L ( I ) . It is probable that complex solute species occur in natural waters draining evaporated boron deposits and in sewage and industrial wastes.Several complexing agents are commonly used for the spectrophotometric determination of boron in water including curcumin, carmine, and dianthrimide. However, their adaptation to automated procedures is not feasible because either an evaporation to dryness or a strong acid medium is required prior to color development.The condensation product of H acid (8-amino-1-naphthol-3,6-disulfonic acid) and salicylaldehyde, azomethine H , was used by Shanina e t al. (2) for the manual determination of boron in complex borenes and boranes. Basson et al. (9) successfully adapted azomethine H into an automated procedure for determination of boron in aqueous plant tissue extracts. Basson et al. ( 4 ) later incorporated an in situ preparation of azomethine H into the manifold to circumvent the time required for outside preparation of the complexing reagent.The purpose of this study was to adapt the azomethine H procedure for the routine determination of dissolved boron in natural water samples. The in situ preparation of azomethine H was found to be suitable for the boron concentration range 1 to 6 mg/L ( 4 ) , but it failed to provide the required sensitivity for determining boron concentrations normally present in natural waters (

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This sixteenth review of the literature of analytical chemistry applied to water analysis covers the period from October 1972 through September 1974. The present review follows the plan of the previous reviews, the last of which appeared in Analytical Chemistry for April 1973 (.11); however, the editors of ANALYTICAL CHEMISTRY requested that the review authors cover their respective fields in a critical, selective manner, and mot attempt to provide an all-inclusive bibliography. The material used in preparing this review comes mainly from major analytical journals titration with potassium ferrocyanide. Anfalt and Jagner (2A) determined the potassium content of sea water potentiometrically by standard addition with a potassium-selective valinomycin electrode. A computer-processed titration procedure is used.An indirect polarographic method for determining potassium in waters of high salinity is reported by Marczak and 334 R .