Development of an efficient extraction method for oxytetracycline in animal manure for high performance liquid chromatography analysis

Oxytetracycline (2-(amino-hydroxy-methylidene)-4-dimethylamino-5,6,10,11,12a-pentahydroxy-6-methyl-4,4a,5,5a-tetrahydrotetracene-1,3,12-trione) is a major member of the tetracycline antibiotics family of which are widely administered to animals in concentrated animal feeding operations for purposes of therapeutical treatment and health protection. With the disposal of animal manure as fertilizer into agricultural land, tetracyclines enter the environment. However, tetracyclines chelate with multivalent cations and proteins, resulting in low extraction efficiencies from animal manure for tetracycline residue analysis. In this study an efficient extraction method for oxytetracycline from steer manure using methanol/water solution amended with chelating organic acid was developed for the analysis of high performance liquid chromatography. The effect of species and amount of amendment acids, shaking time, methanol/water ratio, manure weight, and repeated times of extraction was investigated. It was optimized to amend 2.5 g citric acid and 1.1 g oxalic acid with 10.0 g manure sample in a 50-ml centrifuge tube and extract with 15 ml methanol/water (9:1 in volume) by vigorously shaking for 30 min in a reciprocating shaker. After centrifugation at 11,000 rpm, supernatant is collected. Sample was extracted for a total of 3 times. The developed extraction method was further applied to extract oxytetracycline from fresh and aged cow manure, swine and poultry manure, and soil. Satisfactory recoveries ranging from (84.1 ± 2.4) % to (102.0 ± 3.1) % were obtained, demonstrating that the optimized extraction method is robust for oxytetracycline from different manure sample matrixes.     

Simultaneous determination of organophosphorus and organonitrogen pesticides residues in Angelica sinensis

Gas chromatography with nitrogen phosphorus detector (GC-NPD) was applied to the simultaneous determination of 15 organophosphorus and 6 organonitrogen pesticides residues in Angelica sinensis. The pesticides were extracted by microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) techniques, respectively. The experimental variables were optimized through orthogonal array experimental design. Cleanup of extracts was performed with column chromatography using florisil and neutral aluminum as the sorbents. The determination of pesticides in the final extracts was carried out by GC-NPD. Under optimized conditions, the average recoveries obtained from MAE and UAE are in the range of 75.1–129% and 70.6–129%, respectively, and the relative standard deviations of MAE and UAE were 3.1–10.6% and 1.0–17.8%, respectively.     

A method for the analysis of organophosphorus pesticide residues in Mexican axolotl

A method based on matrix solid-phase dispersion (MSPD) was developed for quantitative extraction of three organophosphorus pesticides (OPPs) from the Mexican axolotl, Ambystoma mexicanum. The determination was carried out using high- performance liquid chromatography (HPLC) with diode array spectrophotometric UV detection (DAD). The MSPD extraction with octadecylsilyl (C18) sorbent combined with a silica gel clean-up and acetonitrile elution was optimised for chlorpyrifos, fenthion and methyl parathion. The method was validated, yielding recovery values higher than 90%. The precision, expressed as the relative standard deviation (RSD), was less than or equal to 6% in muscle samples at spiking levels of 10 and 5 ppm. Linearity was studied from 15 to 60 ppm for chlorpyrifos and fenthion, and from 7.5 to 30 ppm for methyl parathion. The limits of detection (LODs) were found to be less than or equal to 0.5 ppm_.This method was applied to the analysis of samples from a chlorpyrifos-exposed axolotl, demonstrating its use as an analytical tool for toxicological studies.     

Extraction procedure optimization for perfluorooctane sulfonate and perfluorooctanoic acid in food packaging determination by LC-MS/MS

This research aimed to optimize the extraction method parameters for sample pretreatment and determine the levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) contamination in food packaging made of paper. Techniques used were pressurized liquid extraction (PLE) followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Influence parameters of PLE were carefully evaluated for extracted concentration of samples in low level (ng g^?1). The study found that the optimal conditions for PLE were 30 min static extraction time with a flush volume of 100% cell volume and one extraction cycle at 80°C and 1,000 psi. The extraction technique validated the absolute recovery from PFOS and PFOA fortified control samples at three different levels (5, 50, and 200 ng g^?1), with seven repeats at each fortification level. The average recoveries were 79% or higher, with relative standard deviation (RSD) less than 11%. Optimization of the PLE method was established based on recovery data, accuracy, precision, and repeatability of the method. Using optimal PLE technique, PFOS and PFOA were extracted from 34 food-packaging samples collected in Thailand. PFOS and PFOA were detected in all kinds of collected samples, with average concentrations of 4.89 and 2.87 ng g^?1, respectively. The concentrations of PFOS and PFOA were highest in fast-food container samples: 36.99 and 9.99 ng g^?1, respectively.     

Microwave/SPME method to quantify pesticide residues in tomato fruits

A new analytical method using focused microwave-assisted extraction (FMAE), coupled with solid phase micro-extraction (SPME), has been elaborated to determine 25 pesticides used in tomato cultivation. Microwave energy was used for a fast and controlled heating of solvent to selectively extract compounds. Calibration curves were plotted from blank tomato samples spiked at different concentrations with standards. A linear response was obtained between 10 and 1000 μ g/Kg for pyrethroids and between 0.1 and 5000 μ g/Kg for other compounds. For all studied substances, the resulting correlation coefficient (r²) was greater than 0.99. Limits of detection (LOD) and quantification (LOQ) were measured lower than 8 and 25 μ g/Kg, respectively. The relative standard deviation (RSD) was determined below 15% for all pesticides. Field incurred tomato samples were used to validate the new FMAE/SPME method. Observed analysis results by using this technique were in good agreement compared to those obtained by two accredited trading laboratories using traditional methods. Four tomato samples, bought in a local market, were also tested with the FMAE/SPME method.     

罐底含油污泥萃取溶剂的选择与优化

针对某炼化企业在石油储运过程中产生的罐底油泥,进行了油泥样分析和不同萃取剂萃取回收油分实验.经分析该罐底油泥含水率约16.1％,总有机物含量约34.8％,其中可萃取石油类物质约占总有机物成分的67.0％.考察不同溶剂的萃取效果,结果表明,石脑油90 ～ 110℃沸程段的馏分油的萃取效果和工艺可操作性优越于其他常用溶剂,其萃取效果排序为石脑油90～ 110℃沸程段的馏分油＞120#溶剂油＞正庚烷＞石油醚(90 ～ 120℃)＞石油醚(60 ～ 90℃);用石脑油90 ～ 110℃沸程段的馏分油在优化萃取工艺条件下,经两次萃取可分离出大于96％的可萃取油分,罐底油泥中有机物的萃出率可达64％以上,比120#溶剂油萃取效果高出约3％～5％,实现了罐底油泥更深程度的萃取和资源化利用.     

剩余污泥中微生物絮凝剂的提取方法比较

分别采用低浓度和高浓度剩余污泥对剩余污泥中微生物絮凝剂(MBF)的多种提取方法(超声法、树脂法、超声-树脂法、树脂-超声法、超声-树脂-超声法和树脂-超声-树脂法等)进行了比较研究.结果表明,各种复合形式的提取效果均优于超声法或树脂法单独使用的提取效果.在各种复合形式中,以树脂-超声法所提取MBF的含量最高且絮凝效果最好.此外,所提取的MBF浓度与污泥浓度正相关.从剩余污泥中直接提取MBF,在降低MBF生产成本的同时实现了污泥的资源化利用.     

离子液体萃取法回收废水中的醋酸丁酯

利用离子液体1-己基-3-甲基咪唑六氟磷酸盐萃取模拟废水中的醋酸丁酯。萃取液经减压蒸馏回收醋酸丁酯,离子液体也得到再生。实验结果表明:萃取率随废水与离子液体体积之比(相比)的增加而减小,随萃取时间的延长而增大,随萃取温度的升高而增大;在相比为6∶1、萃取时间为40min、萃取温度为50℃的条件下,萃取率达98.98%,醋酸丁酯纯度达99.8%;回收后离子液体可重复使用且萃取率基本不变。     

络合萃取法处理2-萘酚生产废水

采用络合萃取法处理2-萘酚生产废水,比较了分别以三辛胺、十二烷基二甲基胺（十二叔胺）、三烷基胺作为萃取剂的萃取效果,其中三辛胺萃取效果最佳,三烷基胺次之,十二叔胺的萃取效果最差。处理2-萘酚生产废水的最佳工艺条件为：以三辛胺作为萃取剂,萃取剂加入量为8.5%,废水pH为1.0。在此最佳工艺条件下废水的COD去除率可达97.2%。采用NaOH溶液反萃取后的萃取剂用于第二次萃取,COD去除率为96.4%,再反萃取后用于第三次萃取,COD去除率为94.9 %。萃取剂可重复使用。