【正文】 HLB SPE. The result showed that HLB was more effect, and the recovery was over 90 %. In this experiment, HLB SPE and mol/L methanol oxalic acid were used. In one way, it is good enough to recover the drug, and in another way, it is easy to concentrate.CTC, ECTC and ICTC were the wellknown pounds forming chelates with divalent and trivalent cations,additionally they also strongly interacted with the silanols groups locating in the chromatographic stationary silanol groups and metal impurities in column materials caused peak broadening and tailing on reversedphase sorbents, which made it impossible to achieve chromatographic separations suitable for residue analyse of tetracycline antibiotics. Usually, the chromatographic columns packed with highly purified silica or polymer sorbents were used for the chromatographic separations of CTC and other pounds from the tetracycline family. In order to avoid forming chelates, reversed phase chromatography column used mobile phases with low pH environment. In our experiment, we pared the % formic acid % formic acid water with % formic acid water. The column pressure is lower when we choose acetonitrile instead of methanol as mobile phase, it is propitious to conserve for column, an Agilent C8 column was used, the acetonitrile % formic acid water used as mobile phase and it is good enough to separate CTC, ECTC and ICTC which was in fig. 2. Mass spectrometry The MS/MS spectra of ECTC, ICTC and CTC were obtained by direct infusion of a standard solution of mg/L into the ESI source. First, we set parent ion full scan, in order to determine the molecular ions of CTC, ECTC and ICTC, then set its molecular ions as parent ion to full scan for its daughter ion, then selected the abundance of strong, small interfering ions of three pairs as the qualitative ions, then set multiple reaction monitoring (MRM) with positiveion electro spray ionization to optimize fragment and Collision Energy. Dongguan city vegetable base of tetracyclines in content and distributionAbstract：The concentration and distribution offour tetracycline antibiotics(TCs)including tetracycline(TC)，oxytetracycline(OTC)，chlortetracycline(CTC)and deoxytetracycline(DC)in soils from 24 typical vegetable fields in 18 towns ofDongguan city using highperformance liquid chromatographytandem mass spectrometry(HPLC—MS／MS)was discussed．The total concentrations of four tetracycline antibiotics(ETCs)ranged from 0(below LOQ)to ,which predominated with under10ug/kg and averaged at ~89％ of the samples ranged from 0(below LOQ)to ．Oxytelracycline which averagedat ,followed by chlortetracycline and deoxytetracycline which averaged at ．The concentration and constitute of tetracycline poun ds in soils from different vegetable fields varied greatly,consistingmainly offour models，．The first one dominated with oxytetracycline，the second one dominated with dexyteracycline．the third one dominated with deoxytetracycline,andthelastone dominated with both oxytetracycline and deoxytetracycline．However,the concentrations and constitute of tetracycline pounds in soils grown different cultivars within the same vegetable fields varied weakly．The concentrations oftetracycline antibiotics in soils from vegetable fields ofDongguan city were generally lower and less ecotoxic risk for soil ecosystem．But it should not be ignored as to bined toxicefectand resistance ofvarious pounds．Key words： vegetable field； soil；pollution； tetracycline antibiotics； monitoringAll kinds of antibiotics in the scale of animal breeding for disease prevention cure diseases, improve the utilization rate of feed and promote animal growth. After use antibiotics are usually to drugs with excrement discharge . prototype research show scale breeding animal manure is generally rich in antibiotic,And widely used as organic fertilizer used in agricultural production, especially by In the vegetable and fruit production L8J, can cause soil pollution with. at present about antibiotic pollution research work mainly focus on water pollution and its ecological effect on. To the soil pollution and its ecological effect less research in,Our country is rarely reported 39。l country is big country of antibiotic production and use, there is excessive use of antibiotics. There have been reports of the Pearl River Delta region of city sewage,The antibiotic content higher , through the sewage irrigation water caused soil pollution, and the application of manure as the important source. Therefore, this study selects the vegetable bases of Dongguan City and shared by people and animals of tetracycline antibiotics as the research object, discuss regional agricultural antibiotics in soil content and spatial distribution characteristics of antibiotics, pollution control and safety of agricultural products to provide scientific basis.1. Materials and methods sample collection and pretreatmentVegetable production base in Dongguan city is mainly posed of farmer production by camp, with pound fertilizer, irrigation water water, reservoir water,Water and wastewater. According to the base type (normal, without vegetable base pollution vegetable base), size, environmental quality and the greens varieties of dishes and other factors, the choice of the Dongguan City 18 District in the town of 24 generation list of vegetable base, were collected from surface soil (020cm) l 5 a sample, by global positioning system positioning based on environmental monitoring requirements, Multiplies collecting soil position of mixed samples, according to the four law reduced, a total of 37 samples, in the indoor dry grinding have 60 heads sieve sample method of references. accurate weighing about soil samples under 10mL centrifugal bottle, adding methanol / EDTAMcllvaine (volume ratio: 1:1) buffer mixture of 5mL, followed by vibration swing and ultrasonic extraction from the 15min, t~, (4500r / min) collection liquid residue by the above method. Repeated extra