Determination of Available Boron in Soil by ICP-OES with Hot Water Bath Extraction

At present, the main methods of soil available boron analysis are spectrophotometry and inductively coupled plasma-optical emission spectrometry (ICP-OES). The spectrophotometric method has a long process, cumbersome operation, low analysis efficiency and easy environmental pollution, high requirements on the experience of the analyst, and unstable measurement results. The existing ICP-OES method has shortcomings such as long extraction time and high extraction temperature. It has low efficiency in analyzing large quantities of samples, wastes electrical energy and has the risk of scalding during operation.

In order to improve the ICP-OES method with water bath extraction for determination of available boron in soil.

The polyethylene stoppered plastic bottle was used instead of a quartz conical flask and a reflux device. Ultrapure hot water was added as the extractant. After leaching in a hot water bath, the ICP-OES method was used to determine the available boron content.

The optimal extraction conditions were determined through experiments: using 85℃ ultrapure hot water as the extractant, soil-liquid ratio of 1∶2, water bath extraction temperature of 85℃, extraction time of 6min, using ICP-OES method after hot centrifugation to determine the available boron content. The detection limit of the method was 0.02mg/kg, the precision (RSD, n=12) was less than 3%, and the standard substances NSA-1, NSA-2, NSA-3, NSA-6 and GBW07497 (HTSB-5) and GBW07498 (HTSB-6) were tested, and the relative errors of the measurement results were all less than 4%, which was consistent with the recommended value.

This method can be used to determine available boron in soil with quick, efficient, safe and cost-effective potentials.