With the development of the experimental technology and experimental equipment update, there will always be 2 or a plurality of simultaneously in the same project detection phenomenon. However, in the use of different instruments of the same sample were detected, only the instrument detection result is consistent to ensure the accuracy of test results and reliability, which requires regular detection of the same project instrument to carry on the contrast. We therefore in 2008 July by V apodest12 nitrogen determination apparatus for reference, K06A type automatic azotometer contrast instrument, on agricultural soil constituents analysis of total nitrogen content in 6 samples of standard sample and random sampling are analyzed, report the result as follows now.

Materials and methods 1

1.1 the tested sample and instrument

The samples tested for 6 soil samples were randomly collected, cataloged as 20082T 2003, 20082T 2005, 20082T 2007, 20082T 2010, 20082T 2012, 20082T 2015, is provided by the Jingtai County Agricultural Technology Extension Center; standard sample for agricultural soil composition analysis standard substance GNJ ö BW 2002, containing N (0.59 ± 0.07) g ö kg, water and soil and fertilizer management station provided by agriculture agricultural testing center of Gansu Academy of Agricultural Sciences of Gansu province. The tested instrument Kjeldahl apparatus for V apodest12, imported from Germany, in 2007 October by the Baiyin Bureau of quality and technical supervision appraisal; full automatic azotometer type K06A, analytical instruments Co. Ltd Shanghai Shengsheng automation, 2008 January purchase of new, unidentified.

The 1.2 method

V apodest12 the fixed half Kelvin trace method to automatic distillation using nitrogen analyzer, distillate manual titration; full automatic azotometer by Kelvin trace method automatic distilling and titrating K06A. Each sample 4 times repeated, take 2 repeated in one instrument determination, the remaining 2 repeated in other instruments determination, with the average of 2 repetitions for comparison. In the standard samples of 2 instruments were measured continuously for 4 times.

2 results and analysis

Determination of total nitrogen content of 2.1 standard samples

The standard soil samples were used in V type apodest12 nitrogen determination apparatus and K06A type automatic azotometer determination. It is seen from table 1, use K06A type automatic azotometer results difference with the standard value of 0.01 ~ 0.04 g ö k g; V apodest12 type difference measured nitrogen analyzer is 0.01 ~ 0.07 g ö K G. Detection of two instruments result errors are within the allowable range, measured results are in good agreement.

Determination of total nitrogen content of 2.2 samples

3 summary and discussion

The experimental results show that, automatic deviation is small, stable, determination of total nitrogen in soil nitrogen instrument type K06A better repeatability, the results and the V type apodest12 nitrogen determination apparatus are in good agreement. Although the Vapodest12 type manual titration distillate by nitrogen instrument, but it is the periodic evaluation reference instrument, detection results comparable. The purchase of new equipment of K06A type automatic azotometer can improve the testing laboratory, and ensure that the results are accurate and reliable, can be used in the experimental testing, is an ideal instrument for soil and agricultural chemistry analysis.

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