Test of ferroboron for casting tractor case and cylinder block

Working conditions of ICP inductively coupled plasma spectrometer

The working conditions of ICP ICP ICP spectrometer are: high frequency power, atomizer pressure, atomization efficiency (pump speed), integration time (exposure time), etc. Considering the small interference effect and strong and stable analysis strength, the working conditions of the instrument are optimized.

Selection of analytical spectral lines

In the instrument, there are several recommended spectral lines for boron. The same spectral line has different levels, and the intensity of different levels is also different. Using the information of spectral lines, the samples were scanned. Observe and analyze the interference of each spectral line, select the spectral line with good peak shape, high sensitivity, small spectral interference and easy to be deducted. In the experiment, the intensities of boron lines from high to low are b249.772, b249.677, b208.956, b208.890 and b182.641 nm. B249.772 nm and b249.677nm are relatively strong and sensitive, but fe249.782nm will produce background interference; b208.956 nm will be interfered by mo208.952 nm; b182.641 nm is low in intensity and interfered by s182.624 nm, so the analytical line of boron is 208.890 nm.

Working curve

There are two methods to draw the working curve: standard solution and reference material. When ICP ICP-AES is used for high content analysis, small influence factors will bring large analysis error. Therefore, the analysis error caused by directly using standard solution is larger than that by using reference material to draw working curve. This method uses reference materials to draw the working curve.

0.100 g of national standard sample gsb03-2599-2010 (boron: 20.58%) was weighed and treated by alkali melting method and microwave digestion method respectively, and the final volume was fixed in a 100 ml volumetric flask. Because the sample is a volumetric flask with a constant volume of 250 ml, the boron content in the national standard sample gsb03-2599-2010 is 51.45% (20.58% × 2.5) for the sample. Then the working curve was made by separating gsb03-2599-2010 solution (51.45%).

According to the best working conditions of the instrument, the spectral line intensity of boron in the working curve solution is determined from low to high. The working curve of boron is drawn with boron concentration (percentage content) as abscissa and spectral line strength as ordinate (see Fig. 1). The working curve was linear (r = 0.999).

Interference cancellation

The main matrix elements of ferroboron samples are iron and boron, the content of boron is usually 9% – 22%, and the rest is mainly iron. The elimination method is: adding the corresponding amount of iron matrix in the standard solution or selecting the same kind of ferroboron standard sample to make the working curve to eliminate the interference. In this method, the standard sample of ferroboron is used as the working curve, which can not only reduce the interference of iron matrix, but also reduce the measurement error caused by the difference of matrix composition (the main coexisting elements are Si, Al and some trace elements). The same method can be used to treat the sample at the same time, which can eliminate the error caused by sample processing. In order to eliminate the influence of interference lines and reagents, the blank test was carried out at the same time.