A simple and sensitive cloud point extraction high-performance liquid chromatography method is proposed for the determination of isoniazid in blood. The procedure is based on the product of the reaction of isoniazid with benzaldehyde. It can be validated that there is a linear relationship between the signal of isonicotinyl hydrazone and the concentration of isoniazid. A cloud point extraction system of nonionic surfactant Triton X-100 is applied for preconcentration of isonicotinyl hydrazone. Then the analytes in surfactant-rich phase are detected with HPLC-UV system. calibration graph was obtained in the range of 2.0 × 10(-3)-0.5 mg/L, the detection limit was 5.0 × 10(-4) mg/L. Method validation is performed on serum samples spiked at two levels, the recoveries ranging from 82.17-83.81%, with relative standard deviations from 2.45% to 3.89%.

A new method for the determination of nine organophosphorus pesticides (OPPs): Dichlorvos, methamidophos, acephate, diazinon, dimethoate, chlorpyrifos, parathion-methyl, malathion and parathion-ethyl in concentrated fruit juice was developed using the cloud point extraction coupled with ultrasonic-assisted back-extraction prior to gas chromatography with flame photometric detection (GC-FPD) analysis. The parameters and variables that affect the extraction were investigated. Under optimum conditions: a solution containing 6% (W/V) polyethylene glycol 6000 (PEG 6000) and 20% (W/V) Na(2)SO(4) for the extraction of the OPPs. The coacervation phase obtained was back extracted with ethyl acetate. The upper ethyl acetate solution was centrifugated simply for further cleanup for the sake of automatic injection. A preconcentration factor of 50 was obtained for these nine pesticides. Using this method, the limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.5-3.0 and 1.5-9.0μgkg(-1) in concentrated fruit juice, respectively; the relative standard deviations (RSD) were <9%.

A novel method was used to detect reduction benzidine by microchip capillary electrophoresis with an end-column amperometric detector at the three-electrodes system.According to the fact that trichlorfon has the capacity to catalyze the oxidation of benzidine in the presence of sodium perborate,a linear relationship between the concentration of trichlorfon and the decreasing concentration of benzidine was obtained.Based on this,a method for the indirect determination of trichlorfon was developed.The effect of experimental factors,such as concentration and pH of buffer solution,injection time,separation voltage and detection potential,on separation efficiency and amperometric response were assessed and optimized.Under the optimized experimental conditions,there is a linear relationship between trichlorfon in the concentration range of 20-400 μg/L and the peak areas of benzidine(r=0.991 3).The limit of detection was 10 μg/L.

An electrospinning polystyrene nanofiber is used for materials of solid phase micro-extraction (SPME).By using 10% acetone aqueous solution as a carrier liquid and acetone as an eluent,trace SudanⅡ in chili powder are enriched.SudanⅡ shows a sensitive reduction peak at-0.93 V on its linear sweep polarogram in a buffer solution of borax-NaOH (pH 11.5) with acetone as a co-solvent to dissolve it.The peak current is linearly proportional to the concentration of sudanⅡin the range from 2×10-2 to 2×10-1 mg/L with a correlation coefficient of 0.9947.The detection limit is 3×10-3 mg/L.This method is applied to the determination of sudanⅡ in chili powder with the recoveries of 78.0%～85.7%.

A cloud point extraction(CPE) method was used to separate and concentrate malachite green(MG) and crystal violet (CV) in shrimp samples followed by HPLC-diode-array detector(DAD) analysis was developed.The effects of surfactant,salt additive,equilibration time and the equilibration temperature on extraction efficiency were studied.The method was applied to determine residues in shrimp samples.Under optimum conditions,recoveries of spiked shrimp sample,relative standard deviations (RSD) and the limit of detection of MG were 75.5%-80.2%,2.3%-3.1%and 2.0μg·kg~(-1),and CV were 81.4%-89.6%, 1.5%-3.3%and 1.0μg·kg~(-1),respectively.The results obtained by the proposed method were suitable for the requirements of China and EU.

Melamine shows a polarographic wave at-0.34 V(vs.SCE) in a solution of KOH-Na2SO3,and the second derivative peak current of the wave is linearly proportional to the melamine concentration in the range from 1.0×10-2 to 10.0 mg/L(r=0.9992).Melamine in milk samples can not be directly determined by the polarographic method because of the interference of colloidal protein in milk.In this paper,many methods were studied for dispelling the interference.When the concentration of NaCl in milk was 150 g/L and the solution was kept at 100 ℃ for 10 min,the interference of colloidal protein could be avoided.In the case,the linear sweep polarographic method could be used for the determination of melamine in milk.The peak current was linearly proportional to the melamine concentration in the range of 0.4～10.0 mg/L with the detection limit of 0.1 mg/L.The recoveries were between 78.2% and 92.5%.The whole determination procedure could be completed in 20 min.

阐述高等农林院校基础化学实践教学改革的重要意义,重点介绍了南京农业大学在建立和优化农林院校化学实践性教学的新课程体系和教学内容,加强化学实验、实训、实习等实践教学诸环节,培养在化学实践方面具有厚基础、宽知识、实践能力强、重创新的新世纪农林院校本科人才等方面取得的初步成效。

An electrospunpolymer nanofiber was used for materials of solid phase extraction.The pyrethroid pesticides in tea samples were directly extracted with the fiber,and the target compounds were monitored by a gas chromatography with an electron capture detector.Parameters of influencing the performance of the fiber were investigated.Under the optimized conditions,the maximun absorption capacities of the fiber for bifenthrin,permethrin,fenvalerate,deltamethrin,and fenpropathrin were 7.8、 7.5、 7.2、 6.6、 7.0 μg/mg,respectively.The five pyrethroids in three mixed standard solutions were extracted by nanofibers.The extraction recoveries were 65.5%～89.0%,RSD 1.2%～3.0%.Tea samples sprayed five pesticides were determined with above method,The extraction recoveries were 61.3%～87.1%,RSD 0.9%～2.8%.The limits of detection(LODs) were in the range of 1.0×10-4～1.0×10-2 mg/kg.Compared to C18 sorbent,this method has been used for detection of multiple pyrethroid pesticides in tea samples,and proved to be cheap,simple and consuming less organic solvent.

Cloud point extraction (CPE) was carried out to extract malachite green (MG) from aqueous solution and shrimp samples using a series of polyethylene glycol (PEG) surfactants: PEG10000, PEG6000, PEG2000 and PEG600. The adsorption mechanism between PEG micelles and MG molecules was studied. The data of equilibrium concentrations and adsorption amounts in the four PEG–MG systems followed the Langmuir type isotherm. On some assumptions, a developed Langmuir isotherm was used to calculate the feed surfactant concentration required for the removal of MG up to an extraction efficiency of 90%. The calculated PEG concentrations were used in CPE process, and other influence factors on phase behavior were investigated. Under the optimal conditions, recoveries of MG were 82.16–92.41% in aqueous solution and 78.16–86.54% in shrimp samples.

A highly sensitive method for the determination of arprocarb (AC), carbofuran (CF), isoprocarb (IC), and fenobucarb (FC) is proposed. The method is based on alkaline hydrolysis of the four carbamate pesticides, and the resultant hydrolysis products are reacted with 4-aminoantipyrene (AP) to give four red color products. The colored compounds are enriched and separated by cloud point extraction (CPE) method, and the coacervate phase containing the compounds is determined with a high-performance liquid chromatography (HPLC) system in the visible region. AC, CF, IC, and FC were determined on the basis of a linear correlation between the signals of the colored compounds and the concentrations of the pesticides. The method is applied to determine the four pesticides in corn samples; the limits of detection are 2.0 x 10(-4) mg L(-1) for AC, CF, and IC and 5.0 x 10(-4) mg L(-1) for FC, with recoveries ranging between 84.8 and 93.0%, at spiking levels of 5 x 10(-3), 2 x 10(-2), and 0.2 mg kg(-1), respectively.

A method was developed for the determination of pyrethroid pesticides:bifenthrin(BF),fenpropathrin(FP),cyhalothrin(CH),permethrin(PM),fenvalerate(FV)and deltamethrin(DI)in tea proposed using the cloud point extraction(CPE)coupled with ultrasonic-assisted back-extraction prior to gas chromatography with electron capture detection.A pyrethroid solution containing 1.2%(m/V)polyethylene glycol 6000(PEG 6000)and 40%(m/V)(NH4)2SO4 was heated for the extraction of the pyrethroid pesticides.The coacervation phase obtained was back extracted with isooctane.The upper isooctane solution was centrifugated simply for further cleanup.A preconcentration factor of 75 was obtained for these six pesticides.The limits of detection(LODs)were 0.4 μg/kg for BF,FP and CH,2.1 μg/kg for FV and 3.0 μg/kg for PM and DI respectively.Six pyrethroid pesticides,BF,FP,CH,FV,DM and DI,were determined,the amounts were 4.17,4.15,4.09,4.01,3.93 and 3.51 μg/kg.Six pyrethroid pesticides standards of 20 μg/kg were added in the tea samples mentioned above,the spiked recoveries were 72.3%-85.6% and the relative standard deviations were 2.2%-5.6%.

Isoniazid (IN) can not be sufficiently extracted by the cloud point extraction (CPE) of polylethyleneglycol (PEG) 6000, and reacts with para-chlorobenzaldehyde to form a derivative (para-chlorobenzaldehydeisonicotiny-hydrazone, CIH). It was proven that there was linear relationship between the signal of CIH and the concentration of IN. A cloud point extraction system of polylethyleneglycol 6000 (NH4)(2)SO4 coupled with high performance liquid chromatography was developed for the separation and the simultaneous determination of isoniazid (IN), pyrazinamide (PZ) and rifampicin (RF). Under the optimum conditions, the analytes were eluted with a gradient mode and detected with a UV-detector at 310 nm, the retention time of isoniazid, pyrazinamide and rifampicin was 14.5, 34.4 and 38.1 min, respectively, the linear calibration curves in the range of 0.01 - 10 mg/L for isoniazid and 0.05 - 20 mg/L for pyrazinamide and 0.08 - 25 mg/L for rifampicin, respectively (r > 0.99). Average recoveries of three drugs ranged from 91.5% to 98.6% with relative standard deviations from 0.2% to 1.5%. The limits of detection of IN, PZ and RF was 4 x 10(-3), 2 x 10(-2) and 3 x 10(-2) mg/L, respectively. The CPE-HPLC-UV method had been applied to the determination of IN, PZ and RF in pharmaceuticals and in urine samples.

Carbofuran can be hydrolysed to from 2,3-dihydro-2,2-dimethyl-7-benzofuranol (BF). BF is coupled with 4-aminoantipyrene (AP) in presence of potassium ferricyanide (K3Fe(CN)6) to generate red coloured derivative(BFAP)having λmax 530nm. Cloud point extraction (CPE) methodology and using surfactant Triton X-100 as extractant was applied as a preconcentration step prior to HPLC, the surfactant-rich phase containing BFAP was then analysed by HPLC in visible region. The high back ground absorbance of Triton X-100 in UV region was completely avoided. A new visible detection method with high-performance liquid chromatography (HPLC) has been developed for the determination of carbofuran. Using this method, we found that carbofuran residues could be determined with recoveries ranging from 80.4% to 84.5%, relative standard deviations in the range of 2.51–3.26% for three fortified rice levels, and the limit of detection as 5.0×10−4cJ/cK.

将电纺纳米纤维用于萃取分离拟除虫菊酯农药。实验发现电纺纳米纤维对甲氰菊酯、高效氯氟氰菊酯、溴氰菊酯、氰戊菊酯、氯菊酯和联苯菊酯农药有较好的吸附能力,对6种拟除虫菊酯农药的最大吸附容量分别为5.4、5.8、6.0、6.5、6.5和8.0μg/mg。应用电纺纳米纤维固相萃取-高效液相同时测定蔬菜样品中6种拟除虫菊酯农药。在优化实验条件下,6种拟除虫菊酯类农药分离效果较好,并在（0.01～0.04）～10mg/L浓度范围内与峰面积呈良好的线性关系（r2=0.9995～0.9999）;方法的最小检测限为5～12μg/L,其加标回收率在85.8%～96.6%之间。

A high performance liquid chromatography(HPLC) method was developed for the determination of five organophosphorus pesticides,including methidathion,malathion,phoxim,profenofos and chlorpyrios,in cabbage samples.An electrospunpolymer nanofiber loaded into a tiny tip was used for solid phase extraction materials due to its less fiber amount but large surface areas and strong absorption ability.The five organophosphorus pesticides in cabbage samples was directly extracted with the fiber and eluted by methanol.The detection of the target compounds was performed by LC with UV detector.Experimental parameters influencing the performance of the fiber,such as extracted times,extracted solutions,elutions and pH values were investigated.Under the optimized conditions,the maximum absorption capacities of the fiber for methidathion,malathion,phoxim,profenofos,chlorpyrios were 2.9,3.5,5.6,3.7,7.8 mg/g,respectively.The five organophosphorus pesticides of three concentration standard solutions were extracted by nanofibers,and the extraction recoveries were 68%-97% with RSDs of 1.6%-4.7%.The calibration curves showed good linearity in the concentration range of 0.05-10 mg/L for methidathion,0.5-10 mg/L for malathion and 0.1-10 mg/L for rest of analytes.The limits of detection ranged from 0.02 to 0.1 mg/kg for five organophosphorus pesticides.The spiked recoveries were in the range of 65%-93% with RSDs of 1.6%-4.0%.The method was effective,simple and sensitive for detection multiple organophosphorus pesticides.The result also indicated that,compared with usual liquid-liquid extraction and solid phase extraction,the present method offers the advantages of low consumption of organic solvent and less harm to environment and humanity.

Isoniazid (INH) reacted with p-dimethylaminobenzaldehyde (DABD) in the presence of trichloroacetic acid to give isonicotinylhydrazone (INZ) having λmax 365nm. Cloud point extraction (CPE) is carried out to extract INH and IHZ in aqueous solutions using surfactant poly(ethylene glycol) 4000 (PEG4000), respectively. Langmuir model is used to study the adsorption behaviors of the two solutes on micelles of PEG4000. A linear correlation is found between variation of PEG4000 concentration required for feed concentration of the two solutes and used to predict PEG4000 concentration required for extracting INH and IHZ in CPE procedure. The results calculated show that, for a desired recovery level of 90%, only can IHZ be sufficiently extracted by PEG4000. In this experiment, the feed concentration of PEG4000 is defined by above-mentioned correlation, and the effects of other operating parameters, e.g., concentration of salt, pH and centrifugation time on extraction of PEG4000-IHZ system have also been studied in detail. The proposed CPE method coupled with HPLC-UV system is successfully used for the determination of INH in urine sample.

Derivative polarographic analysis is developed for the determination of isoniazid(INH) in serum.It is based on the formation of the hydrazone with isoniazid and benzaldehyde in the presence of trichloroacetic acid.The sensitive second derivative polarographic wave of isoniazid-benzaldehyde hydrazone is obtained at-0.848 V(vs.SCE).A sensitivity of the hydrazone is 50 times larger than that of isoniazid under optimum conditions and the peak current is proportional to the concentration of isoniazid over the range from 1.0×10-4 mg/L to 3.5×10-2 mg/L(r2=0.9989) with limit of detection of 2×10-5 mg/L.This method has potential to be used for analysis of isoniazid in serum.

A novel method of the determination of thiram was proposed based on its polarographic catalytic wave in the presence of persulfate.In 0.2 mol·L-1 C4H6O6-C4H4O6KNa(pH 5.5)+1.5×10-3 mol·L-1 K2S2O8 base solution,the peak potential of the polarographic catalytic wave was at-0.5 V(vs.SCE),and the 2nd-order derivative peak current of the catalytic wave was linearly proportional to the thiram concentration in the range of 5.0×10-8-3.0×10-6 mol·L-1.The detection limit was 1.0×10-8 mol·L-1,and the relative standard deviations was 1.27%(n=11).The sensitivity of the catalytic wave of thiram was 25 times higher than that of the corresponding reduction wave.The recovery was between 90.29%-96.10% in detection samples.The method was sensitive,simple,rapid.