Purification And Analysis Of Pyrimidinyl Sulfonylurea Herbicides

The spectroscopic analyses of pyrimidinyl-sulfuron herbicides were studied represented by nicosulfuron, amidosulfuron and ethoxysulfuron. In this basis, the purification method and reversed phase high performance liquid chromatography analysis method were established. Farther, the purification and quantitative analysis of nicosulfuron, amidosulfuron and ethoxysulfuron were completed.The UV absorption spectrums of pyrimidinyl-sulfuron herbicides were obtained in HPLC - PDA. The maximum absorption wavelength of nicosulfuron, amidosulfuron and ethoxysulfuron was 236.1 nm, 237.1 nm and 237.1 nm respectively. The infrared absorption spectrums were measured with KBr pellet, their characteristic absorption peaks were 1720 cm -1, 1600 cm -1, 1360 cm -1, and 1200 cm -1. Mass spectrum obtained with LC - MS show that urea linkage is easy to break mostly, and the fragment of m / z 182 is their common features. Nuclear magnetic resonance spectrum was gotten with deuterated acetone as the solvent to collect 1HNMR and ¹³CNMR signals. 1HNMR characteristic peaks wereδH 3.9,δH 5.9,δH 9.6,δH 13.0; ¹³CNMR characteristic peaks wereδC 54.3,δC 84.0,δC 149.0,δC 156.3,δC 171.7.The analysis method of pyrimidinyl-sulfuron herbicides by HPLC was developed. Sample dissolved in acetonitrile, with acetonitrile / water as mobile phase, 10 mmol. L -1 ammonium formate and 20 mmolï¹’L -1 formic acid were regulators. C8 column, photo diode array detector for quantitative determination, identified the chromatographic behavior of nicosulfuron, amidosulfuron, ethoxysulfuron and their degradation products. At the same time, another method with evaporative light scattering detector was established for amidosulfuron using for degradation products without UV absorption.Nicosulfuron, amidosulfuron and ethoxysulfuron were purified by recrystallization, liquid chromatography preparation, or wash with water. Pyrimidinyl-sulfuron herbicides were slightly soluble in common solvent and instable when were heated, so the purity was difficult to be improved by recrystallization. Nicosulfuron, amidosulfuron and ethoxysulfuron were washed with water and then with acetone, and the purity of them were 99.12 %, 99.18 %, 99.35 %, respectively.Nicosulfuron was quantitatively determinated with dimethyl phthalate as internal standard. The proportion of acetonitrile was 30 % in eluent, and determination wavelength was 232 nm. In the range of 25 - 500 mgï¹’L -1, the peak area ratio of nicosulfuron and internal standard to the ratio of their mass is linear, the linear equation Y = 1.122 4 X +0.005 6, r = 0.999 2. The recovery of low concentration was 99.79 %, while 99.84 % of high concentration, and the RSD was 0.27 %.Amidosulfuron were detected by HPLC - PDA - ELSD, with the internal standard was methyl p - hydroxybenzoate, the ratio of acetonitrile in eluent was 40 %, extraction wavelength was 230 nm. The peak area ratio of nicosulfuron and internal standard was linear with the ratio of their mass, and the linear equation was Y = 1.104 2 X +0.015 2, r = 0.999 9 in 25 - 500 mgï¹’L -1. The recovery was 99.37 - 99.43 %, RSD was 0.85 %. While the recovery of external standard method was 98.86-101.19 %, RSD was 0.94 %. When amidosulfuron was detected by ELSD, The linear equation was Y = 2 918.856 X - 2 319 548.767,r = 0.986 5. The recovery was 99.47-100.36 %,RSD 2.59 %.Ethoxysulfuron was detected by HPLC - PDA at 222 nm, with dimethyl phthalate as internal standard also. The ratio of acetonitrile and buffer solution was 55 : 45. In the concentration range of 25-500 mgï¹’ L -1, the linear relationship between ethoxysulfuron and the internal standard peak area ratio As / Ai and their mass ratio ms / mi was good, with the linear equation Y = 0.760 6 X +0.006 4, r = 0.999 8. The recovery of low concentration was 99.09 %, and 99.38 % of high concentration, RSD was 0.46 %. When it was 98.72-102.04 %,RSD was 1.23 % of external standard method.Taking into account the economic value of pyrimidinyl-sulfuron herbicides, the internal standard method was recommended to be used in the analysis of technical pesticides.