Journal of Science and Applications: Biomedicine

Volume 03 Issue 06 Pages:88-95.

Current progress on the detection of glyphosate in environmental samples

Jing Ding 1, Hao Guo 1*, Wen-wen Liu 1, Wen-wen Zhang 2 and Jun-wei Wang 1*

1 Chongqing Institute of Forensic Science, Chongqing 400000, China.
2 Department of Fiber and Polymer science, College of Textiles. North Carolina State University. Raleigh. USA.

* Corresponding Author: Hao Guo and Jun-wei Wang. E-mail:babyfast1982 @126.com, Phone: 86-23-63764388.

Abstract

     Glyphosate is widely used in herbicides and is toxic to organism. Therefore accurate detection of glyphosate content is important for public health and food security. In this paper, methods such as gas chromatography (GC), high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC/MS), liquid chromatography-mass spectrometry (LC/MS), ion chromatography (IC), capillary electrophoresis (CE), enzyme-linked immunosorbent assay (ELISA) and other kinds of analytical methods used for determination of glyphosate were reviewed. The characters of these methods were described to provide consultation for further research.
Published by www.inter-use.com. Available online Oct. 15, 2015, Vol. 3 Iss. 6, Page 88-95.

Keywords:

G1yphosate, Environmental samples, Determination method


Introduction
     Glyphosate is a non-selective and internal adsorption herbicide. It is widely applied in agriculture industry due to less toxicity to the mammal animals compared with other herbicide. According to the statics reported in 2014, both the sales and production of glyphosate were highest among all commercial herbicides [1]. However, it is crucial to detect the glyphosate residue in biological, natural water resources, and soils due to the following facts. First, it is directly toxic to the amphibian in end uses. Secondly, glyphosate migrates fast in soils due to the good solubility in water [2].
It is a challenge to detect glyphosate residue due to its poor solubility in common organic solvents, difficult evaporation, high polarity, and absences of chromophores and fluorophores [3]. In the most recent years, scholars explored many approaches to detect glyphosate residues including Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC), Gas Chromatography-Mass Spectrometry (GC/MS), Liquid Chromatography-Mass Spectrometry (LC/MS), Ion Chromatography (IC), and Capillary Electrophoresis (CE). Here are the simple introductions of those methods:

1. GC
     Glyphosate is of high polarity and high boiling temperature due to hydrogen group and amino group in the molecule structure, which makes it impossible to detect residues by using GC directly. Therefore, the structure of glyphosate needs to be derivatived by disabling polar groups. The evaporation properties have been improved by most researchers through esterification and acylation [4]. As described in Table 1, the recycle ratios of glyphosate in different samples modified by different reagents are close to or higher than 90%.


 

     In GC, the columns and the detectors are selected according to the properties of each sample, as summarized in Table 2. Generally, the column are selected from mid-polar to non-polar range for the GC testing of derivatived glyphosate. Electron Capture Detector (ECD), Nitrogen Phosphorous Detector (NPD), Flame Photometric Detector (FPD) and Flame Ionization Detector (FID) are commonly used for the detection of glyphosate due to the existence of C, H and P. The lowest limit of detection (LLOD) for glyphosate in soil sample and water sample are 12 μg/kg and 0.5 ng/L, respectively. However, GC is not commonly used in practice due to the complicated derivatization procedure of the detection of glyphosate. 


 

 2. HPLC
     Unlike GC, HPLC is a common method for detecting the glyphosate residue. However, derivatization procedure including pre-column derivatization and post-column derivatization need to be conducted due to the absences of fluorophore and chromophore, as mentioned earlier [2]. The detection methods of glyphosate derivatived before columns in HPLC are summarized in Table 3 according to different samples, columns, mobile phases, and derivatization reagents.

    The UV detector and fluorescence detector (FLD) can be used in the HPLC detection of glyphosate. The derivatization reagents for UV detector [14-15, 17-18] include p-toluenesulphonyl chloride, o-nitrobenzenesulfonyl chloride and 2,5-dimethylbenzenesulfonylchloride. However, 9-fluorenylmethylchoroformate (FMOC) and o-phthalaldehyde are used on FLD detections [11-13, 16, 19-21]. As stated in Table 3, the LLOD for glyphosate samples from soil and water are 0.02 mg/kg and 0.02 μg/L, respectively.
Similar to Table 3, the detection methods of glyphosate using post-column derivatization in HPLC are summarized in Table 4.
    As described in Table 4, the FLD detector is used in post-column derivatization for the detection of glyphosate. Two types of reagent are often used. One is a common oxidation reagent named sodium hypochlorite, the other is a mixture of o-phthalaldehyde and mercaptoethanol. The LLOD of aqueous sample is 2 μg/L, as listed in Table 4. Compared with pre-column derivatization, the post-column derivation is more precise due to the difficulty in controlling derivatization reaction in the reflux system of HPLC for post column.
     HPLC can provide fast, precise, repeatable data in glyphosate residue detection. However, as we summarized in Table 3 and Table 4, the pre-column derivatization and post-column derivatization are complicated in practical applications for most end users.

3. Chromatography-mass spectrometry
    Chromatography-mass spectrometry is a most recent technique with the capabilities of separation and detection. Glyphosate is an ionic compound with high polar, high solubility and hard gasification, which limits the applications of common GC through standard derivatization. Therefore, GC/MS are rarely reported in the detection of glyphosate residue.
     The glyphosate residue in water sample was tested using GC-IT-MS by Royer et al [30]. The derivatization reagents are trifluoroacetic anhydride (TFAA) and 2,2,3,3,4,4,4-heptafluoro-1-butanol (HFB). Elisabet et al [31] determined the LOD of GC/MS is 0.1 µg/L in water, and 0.006 µg/L in soil. Philip et al [32] found that the LOD glyphosate in soil is 0.01mg/kg using GC/MS under SIM. The derivatization reagents in their study are also TFAA and HFB. Cheng et al [33] reported the LOD in water sample is 0.3µg/L using same characterization method.
     Until now, chromatography-mass spectrometry methods reported in the detection of glyphosate from environmental samples are mostly LC/MS and LC/MS/MS, which not only avoid the derivatization procedure but also improve the sensitivity of the detection. These methods are listed in Table 5 with a detailed description of columns, mobile phase.
As showed in Table 5, the common ion source is ESI in LC/MS characterization of glyphosate sample, which can also be used to determine new chemistry structures [43-44]. Mass spectrometry mode are mainly MRM or SRM. The LLOD is 0.06 μg/L for glyphosate samples filtered by 0.02 μm filter. Derivatization is not required in the detection of glyphosate using LC/MS, which simplifies the testing procedure. However, it has not been widely used in the detection of glyphosate due to the cost of LC/MS and the interface technology problem.

4. IC
     IC is a branch of HPLC, which is a brand new separation and analysis technique based on ion exchange chromatography. Anion-exchange column and alkaline buffer can be used as the column and eluent due to glyphosate is an ionic compound. However, it is easily hydrolyzed in waters containing chloride, which affects the shape, qualitative and quantitative data of the peaks. Therefore, dechlorination is a necessary step in determining the glyphostate in drinking water by adding ascorbic acid or sodium thiosulfate in order to improve the precision. In IC, the LLOD of detectability of glyphosate in water and in soil are17.4 μg/L and 3.2 μg/L respectively. The summaries of the reported methods using IC in glyphosate detection are reported in Table 6.
     At the same time, instead of using anion suppression conductometric detectors in IC characterization of glyphosate, You et al [65] built an IC-CNLSD detector which can be used to detect the glyphosate in water samples. Derivatization, pre-concentration and mobile phase conductivity inhibition are not required in this method. The LOD in water sample is 53 μg/L. Guo et al [66] built an IC-ICP method in order to determine the glyphosate residue in water sample. Dionex Ion Pac AS16, 250 mm×4 mm, ICP and 20mM eluent were applied in this method. The reported LOD is 0.7 μg/L.
The greatest advantage of IC testing is the simple treatment for samples. However, it is only applied in water and soil analysis. Compared with GC, HPLC, and LC/MS, IC has lower sensitivity and higher LOD, which make it hard to spread in practices.

5. CE
     Until now, CE has not been used commonly in the detection of glyphosate residue. As described in Table 7, the detection of glyphosate requires derivatization procedure in CE characterization in order to improve the sensitivity of detection. However, it is not required in CE/MS. The LLOD of detectability are 3.2 ng/kg and 0.005 μg/L respectively for glyphosate residue in the soil sample and water sample.

6. Other detection methods
     Recently, emerging detection methods for glyphosate residue were applied, such as immunoassay, oscillographic polarography and diffuse reflection spectrophotometric, which have simpler procedure, less work load and higher efficiency. Clegg et al [74] used CI-ELISA to determine the glyphosate residue in water with the LOD of 76 μg/L. In order to lower the LOD and improve the sensitivity, Rubio et al [75] used ELISA and made the LOD approach 0.6 μg/L. Lee et al [76] improved the LOD to 0.1 μg/L by adopting L-ELISA. Based on ELISA, Miguel [77] improved the LOD to 0.021 μg/L by using a self-invented glyphosate sensor.
Sun et al [78] obtained 96 μg/L as the LOD using single scan oscillographic polarography after the nitroso glyphosate derivatization, which is a simple and fast way to determine the glyphosate residue in soil samples. Silva et al [79] invented a small and potable equipment based on diffuse reflection spectrophotometry method, which can be used in common samples.

7. Conclusion and Future Study
     Compared all the currently applied methods in glyphosate detection, Chromatography including HPLC, IC and LC-MS are widely used based on the physical and chemical properties of glyphosate. GC and GC-MS are rarely used in practice.
     Among all these methods summarized in this paper, derivatization is necessary in GC, HPLC. However, it is not required in LC/MS and CE-MS characterization. At the same time, LC/MS and CE-MS can characterize time retention and MS qualitatively and quantitatively, which leads to a wide and promising market. More importantly, simplifying the sample treatment procedure, speeding up detection time and improving the sensitivity and efficiency are the directions that require continues development based on the smart materials [80-82] and a better working interface.

8. Acknowledgement
     This research was supported by the grants supported by Chongqing Public Security Bureau (G2014-16).

References
[1] Ma WM, Lin XH, et al. Research progress on the detection method of glyphosate and aminomethylphosphonic acid residues. Agrochem. 2008;47(8):554-557.
[2] Pan XP, Lou JJ, et al. Research progress on the detection method of glyphosate residue. Chin J Hangzhou Univ. 2011;10(6):506-509.
[3] Xiang Y. A review on the detection methods of glyphosate and aminomethylphosphonic acid residues. Chin J Jilin Police Acad. 2011;2:68-71.
[4] Li XJ, Zhou XK, Meng PJ. Detection method of glyphosate and its metabolites. Research progress on chemical problems in public safety. 2014;98-102.
[5] Tsunoda N. Simultaneous determination of the herbicides glyphosate, glufosinate and bialaphos and their metabolites by capillary gas chromatography-ion-trap mass spectrometry. J Chromatogr A. 1993;637(2):167-173.
[6] Lou ZY, Zhu GN, Wu HM. Study on the detection method of glyphosate in pond water. Chin J Ningbo Acad. 2001;13(Suppl.):142-145.
[7] Hiroyuki K, Sunhi R, et al. Simple and rapid determination of the herbicides glyphosate and glufosinate in river water, soil and carrot samples by gas chromatography with flame photometric detection. J Chromatogr A. 1996;726(1-2):253-258.
[8] Zbigniem HK, Dorota KG, et al. Novel approach for the simultaneous analysis of glyphosate and its metabolites. J Chromatogr A. 2002;947(1):129-141.
[9] Pei MQ, Lai J. Qualitative and quantitative analysis of glyphosate. Chin J Guangdong Police Sci Technol. 2004;1:14-15.
[10] Hu JY, Zhao DY, et al. Determination of glyphosate residues in soil and apples by capillary gas chromatography with Nitrogen Phosphorus Detection. Chin J Pestic Sci. 2007;9(3):285-290.
[11] Zhou YM, Li N, et al. Determination of glyphosate residues in water by liquid chromatography. China Meas Technol. 2007;33(3):114-116.
[12] Liu ZZ, Li L, et al. Determination of organophosphorus herbicide in water by high performance liquid chromatography pre-column derivatization. Environ Monit in China. 2009;25(5):35-38.
[13] Ma JM, Gong WJ, et al. Determination of glyphosate in water by high performance liquid chromatography-fluorescence detection with pre-column derivatization and solid-phase extraction. Chin J Health Lab Technol. 2014;24(18):2599-2601.
[14] Si YB, Sang ZY, et al. Determination of glyphosate in soil by high performance liquid chromatography after derivatization with p-toluenesulphonyl chloride. Chin J Anhui Agric Univ. 2009;36(1):136-139.
[15] Fang F, Xu H, et al. Determination of glyphosate by high performance liquid chromatography with o-notrobenzenesulfonyl chlride as derivatization reagent. Chin J Instrum Anal. 2011;30(6):683-686.
[16] Li JP, Liang ZH, et al. Determination of glyphosate in water by high performance liquid chromatography with pre-column derivatization. Chin J Environ Health. 2012;29(1):73-74.
[17] Fang F, Wei RQ, et al. Determination of glyphosate by HPLC with a novel pre-column derivatization reagent. Chin J Bioprocess Eng. 2014;12(3):69-73.
[18] Kawai S, Uno B, Tomita M. Determination of glyphosate and its major metabolite aminomethylphosphonic acid by high-performance liquid chromatography after derivatization with p-toluenesulphonyl chloride. J Chromatogr A. 1991;540:411-415.
[19] Hidalgo C, Carolina Rios C, et al. Improved coupled-column liquid chromatographic method for the determination of glyphosate and aminomethylphosphonic acid residues in environmental waters. J Chromatogr A. 2004;1035(1):153-157.
[20] Sancho JV, Hernández F. Rapid determination of glufosinate, glyphosate and aminomethylphosphonic acid in environmental water samples using precolumn fluorogenic labeling and coupled-column liquid chromatography. J Chromatogr A. 1996;737(1):75-83.
[21] Nedelkoska TV, Low GK, et al. High-performance liquid chromatographic determination of glyphosate in water and plant material after pre-column derivatisation with 9-fluorenylmethyl chloroformate. Anal Chim Acta. 2004;511(1):145-153.
[22] Hou ZW, Wang ZH. Determination of glyphosate in water by HPLC. Chin J Forensic Sci Technol. 2003;6:9-10.
[23] Wang L, Zeng JM, et al. Determination of glyphosate and phosphonic acid in drinking water by direct injection HPLC-post column derivation. Chin J Mod Sci Instrum. 2010;6:99-100.
[24] Wang C, Liu YC, et al. Determination of glyphosate in the water of farmland ditch by HPLC-post column derivation. Chin J Plant Prot. 2012;38(5):96-99.
[25] Wang XY, Wang L. Determination of glyphosate in drinking water by liquid chromatography. Chin J City & Town Water Supply. 2011;5:52-53.
[26] Su BY, Huang SF, et al. Determination of glyphosate and AMPA in water by direct injection HPLC-post column derivation. Chin J Strait Prev Med. 2014;20(3):46-47.
[27] Chen J, Yuan XJ, et al. Determination of glyphosate in water by HPLC-post column derivation. Chin J Chem Manage. 2014;9:44-45.
[28] Waters Beijing Lab. Determination of glyphosate in drinking water by liquid chromatography. Chin J Environ Chem. 1995;14(6):554-555.
[29] Abdullah MP, Daud J, et al. Improved method for the determination of glyphosate in water. J Chromatogr A. 1995;697(1-2):363-369.
[30] Royer A, Beguin S, et al. Determination of glyphosate and aminomethylphosphonic acid residues in water by gas chromatography with tandem mass spectrometry after exchange ion resin purification and derivatization application on vegetable matrixes. Anal Chem. 2000;72(16):3826-3832.
[31] Elisabet B, Torstensson L, et al. New methods for determination of glyphosate and (aminomethyl)phosphonic acid in water and soil. J Chromatogr A. 2000;886(1-2):207-216.
[32] Philip LA, Yutaka I. Determination of glyphosate and (aminomethyl) phosphonic acid in soil, plant and animal matrixes, and water by capillary gas chromatography with mass-selective detection. J Agric Food Chem. 1994;42(12):2751-2759.
[33] Cheng XM, Zhou M. Determination of glyphosate and it metabolite in banana and water by gas chromatography-tandem mass spectrometry. Chin J Chromatogr. 2004;22(3):288.
[34] Zheng HH, Zhang J, et al. Determination of glyphosate and carbofuran in water with direct injection by ultra high performance liquid chromatography-tandem mass spectrometry. Chin J Anal Lab. 2008;27(Suppl.):68-70.
[35] Zheng HH, Li J, et al. Determination of glyphosate, carbofuran and 2,4-D in water with direct injection by liquid chromatography-tandem mass spectrometry. Chin J Health Res. 2009;38(3):302-303.
[36] Liu QM, Ye FT. Determination of glyphosate residues in water by Thermo TSQ liquid chromatography-tandem mass spectrometry. Chin J Food in China. 2013;9:56-57.
[37] Guo H, Zhang S, et al. Determination of glyphosate residues in fishpond water using hydrophilic interaction chromatography-tandem mass spectrometry. Chin J Anal Lab. 2013;32(6):93-96.
[38] Guo Z, Duan JP, et al. Determination of glyphosate in drinking water with direct injection by liquid chromatography-tandem mass spectrometry. Chin J Health Lab Technol. 2013;23(7):1683-1685.
[39] Zheng HH, Bian ZQ, et al. Determination of glyphosate and 2,4-D in water by normal-phase chromatography electrospray ionization tandem mass spectrometry. Chin J Environ Hyg. 2014;4(4):395-397.
[40] Li BR, Jiang JH, et al. Determination of toxicants in drinking water by high performance liquid chromatography-tandem mass spectrometry. Chin J Health Lab Technol. 2008;18(8):1513-1517.
[41] Kang L, Liu HH, et al. Determination of four pecticides in drinking water and source water by high performance liquid chromatography-tandem mass spectrometry. Chin J Health Lab Technol. 2013;23(14):2871-2873.
[42] Hao C, Morse D, et al. Direct aqueous determination of glyphosate and related compounds by liquid chromatography/tandem mass spectrometry using reversed-phase and weak anion-exchange mixed-mode column. J Chromatogr A. 201; 1218(33):5638-5643.
[43] Zhang W, Vinueza NR, Datta, P and Michielsen S. Functional dye as a comonomer in a water-soluble polymer. J Polym Sci A Polym Chem. 2015;53:1594-1599.
[44] Wu J, Fang L, Su YL. Determination of 2,4-D and glyphosate in water by ion chromatography. Chin J Water & Wastewater Eng. 2008;34(2):30-31.
[45] Song YY, Li X, Tang JC. Determination of glyphosate in drinking water by ion chromatography. Chin J Pract Prev Med. 2009;16(4):1267-1269.
[46] Ye ML, Hu ZY, Pan GW. Determination of trace iodide, thiocyanate and glyphosate in drinking water by capillary ion chromatography. Chin J Anal Chem. 2011;39(11):1762-1765.
[47] Liu MP, Xu R, et al. Determination of glyphosate in water by ion-exchange chromatography. Chin J Water Supply Technol. 2011;5(4):52-54.
[48] Liu YX, Li J, et al. Determination of glyphosate in drinking water by ion-exchange chromatography. Chin J Rock & Mineral Anal. 2011;30(3):361-363.
[49] Zhong XL. Determination of glyphosate in water by Ion Chromatography with suppressed conductance. Chin J Environ Chem. 2012;31(11):1831-1832.
[50] Zhang XB, Wu ML. Study on determination of glyphosate in drinking water by Ion Chromatography. Chin J Guangdong Chem. 2010;37(6):206-207.
[51] Wang Y, Wei HZ, Ma Y. Determination of glyphosate in environmental and drinking water by Ion Chromatography. Chin J Water Supply Technol. 2012;6(1):53-55.
[52] Wang HT, Zhao W, et al. Detection of glyphosate in water using Ion Chromatography with on-line eluent generator. Chin J food Res Dev. 2013;34(22):43-45.
[53] Li L, Zhang W, et al. Detection of glyphosate in drinking water using Ion Chromatography. Chin J Health Lab Technol. 2015;25(8):1152-1156.
[54] Zhang PZ, Wu J, et al. Determination of glyphosate in soil by Ion Chromatography. Chin J Instrum Anal. 2003;22(4):89-90.
[55] Su YL, Wu J, Fang L. Determination of 2,4-D, glyphosate and bentazone in water by Ion Chromatography. Chin J Water Pur Technol. 2008;27(3):51-52.
[56] Fang L, Su YL, Wu J. Detection of glyphosate in drinking water by Ion Chromatography. Chin J Modern Sci Instrum. 2008;2:54-55.
[57] Wang J, Hou X P. Determination of glyphosate by Ion Chromatography. Chin J Forensic Sci Technol. 2009; 3: 67-68.
[58] Li XP, Qi JY, Chen Y H. Determination of haloacetic acids and glyphosate in environmental water by Ion Chromatography. Chin J Appl Chem. 2009;26(4):447-450.
[59] Qi RP, Qu XF, et al. Determination of glyphosate in water by Ion Chromatography. Chin J Health Lab Technol. 2011;21(4):820-821.
[60] Wu YQ, Guo LI, Xie LZ. Determination of glyphosate in drinking water by Ion Chromatography. Chin J Guangdong Chem. 2012; 39(6): 224-225.
[61] Wang YG, Chen SS, Wang JB. Determination of glyphosate in drinking water using carbonate eluent systems. Chin J Health Lab Technol. 2012;22(2):394-396.
[62] Qiu L, Deng J. Simultaneous determination of glyphosate, 2,4-D and bentazone in drinking water by Ion Chromatography. Chin J Guangdong Agrochem Sci. 2013;2:93-95.
[63] Coutinho CFB, Coutinho LFM, et al. Rapid and direct determination of glyphosate and aminomethylphosphonic acid in water using anion-exchange chromatography with coulometric detection. J Chromatogr A. 2008;1208(1-2):246-249.
[64] Zhu Y, Zhang FF. Determination of glyphosate by ion chromatography. J Chromatogr A. 1999;850(1-2):297-301.
[65] You J, Koropchak JA, et al. Condensation nucleation light scattering detection with ion chromatography for direct determination of glyphosate and its metabolite in water. J Chromatogr A. 2003;989(2):231-238.
[66] Guo ZX, Cai QT, et al. Determination of glyphosate and phosphate in water by ion chromatography-inductively coupled plasma mass spectrometry detection. J Chromatogr A. 2005;1100(2):160-167.
[67] Hsu CC, Whang C, Wen, et al. Microscale solid phase extraction of glyphosate and aminomethylphosphonic acid in water and guava fruit extract using alumina-coated iron oxide nanoparticles followed by capillary electrophoresis and electrochemiluminescence detection. J Chromatogr A. 2009;1216(49):8575-8580.
[68] See HH, Hauser PC, et al. Dynamic supported liquid membrane tip extraction of glyphosate and aminomethylphosphonic acid followed by capillary electrophoresis with contactless conductivity detection. J Chromatogr A. 2010; 1217(37): 5832-5838.
[69] Lee G, James RS, et al. Analysis of glyphosate and glufosinate by capillary electrophoresis-mass spectrometry utilising a sheathless microelectrospray interface. J Chromatogr A. 2003;1004(1-2):107-119.
[70] Chiu HY, Lin ZY, et al. Analysis of glyphosate and aminomethylphosphonic acid by capillary electrophoresis with electrochemiluminescence detection. J Chromatogr A. 2008;1177(1):195-198.
[71] Kawai M, Yoshiaki I, et al. Analysis of phosphorus-containing amino acid-type herbicides by sheathless capillary electrophoresis/electrospray ionization–mass spectrometry using a high sensitivity porous sprayer. Anal Sci. 2011;27:857-860.
[72] Cao LW, Deng T, et al. Determination of herbicides and its metabolite in soil and water samples by capillary electrophoresis-laser induced fluorescence detection using microwave-assisted derivatization. Anal Sci. 2014;30(7):759-766.
[73] Cao LW, Liang SL, et al. Capillary electrophoresis analysis for glyphosate, glufosinate and aminomethylphosphonic acid with laser-induced fluorescence detection. Chin J Chromatogr. 2012;30(12):1295-1300.
[74] Clegg BS, Stephenson G R, et al. Development of an enzyme-linked immunosorbent assay for the detection of glyphosate. J Agric Food Chem. 1999;47(12):5031-5037.
[75] Rubio F, Veldhuis LJ, Clegg BS, et al. Comparison of a direct ELISA and an HPLC method for glyphosate determinations in water. J Agric Food Chem. 2003;51(3):691-696.
[76] Lee EA, Zimmerman L R, Bhullar BS, et al. Linker-Assisted immunoassay and liquid chromatography/mass spectrometry for the analysis of glyphosate. Anal Chem. 2002;74(19):4937-4943.
[77] González-Martínez MA, Brun EM, Puchades R, et al. Glyphosate immunosensor: Application for water and soil analysis. Anal Chem. 2005;77(13):4219-4227.
[78] Sun N, Hu B X, Mo W M. Single sweep oscillopolarographic technique for the determination of glyphosate after derivatization with sodium nitrite. Agrochem. 2007;46(9):609-611.
[79] Silva A, Fernandes F, Fernandes FCB, et al. A simple and green analytical method for determination of glyphosate in commercial formulations and water by diffuse reflectance spectroscopy. Spectrochim Acta Part A. 2011;79:1881-1885.
[80] Yao L, Jiang M, Zhou D, Xu F, Zhao D, Zhang W, et al. Fabrication and characterization of microstrip array antennas integrated in the three dimensional orthogonal woven composite. Composites Part B. 2011.
[81] Zhou D, Yao L, Liang F, Zhao D, Jiang M, et al. Tensile and shear properties of three dimensional orthogonal woven basalt/kevlar hybrid composites. Fiber Compos. 2010.
[82] Kitamura T, Suzuki M, Nishimatsu H, Kurosaki T, Enomoto Y, Fukuhara H, Kume H, Takeuchi T, Miao L, Jiangang H . Final report on low-dose estramustine phosphate (EMP) monotherapy and very low-dose EMP therapy combined with LH-RH agonist for previously untreated advanced prostate cance. Aktuelle Urologie.2010 Suppl 1:S34-40.

 

Copyright © 2013 International Union of Science & Education All rights reserved.