超声波萃取/气相色谱质联用仪分析电动牙刷中的多溴联苯及多溴联苯醚

本研究中,以超声波萃取技术为样品处理方法和气相色谱—质谱法对电动牙刷材料中的多溴联苯(PBBs)和多溴二苯醚(PBDEs)进行分析。在超声波萃取中,分别对萃取时间和溶剂量进行优化,萃取率高达99%以上。采用该方法对电动牙刷的PBBs和PBDEs的含量进行测定,回收率在92.0%~111.5%之间;RSD(n=5)为3.00%~4.86%。并和索氏提取法/气相色谱一质谱联用法进行对照实验,证明该方法的可行性。     

超声波萃取-高效液相色谱测定电子产品中多溴二苯醚

文章采用超声波萃取-高效液相色谱建立了测定电子电器产品中的方法：选用正丙醇作为萃取剂,采用超声波萃取装置对电子电器产品中的溴系阻燃剂,以甲醇/超纯水为流动相,在反相C18色谱柱上进行梯度淋洗,检测波长226 nm,该方法对于9种目标多溴二苯醚的回收率为92%~96%,相对标准偏（RSD）均小于5%,该方法的检测限为〈0.1 mg/kg,具有良好的准确性和精密度。可以满足RoHS指令中溴阻燃剂的测定分析。如用该方法对普通电路板进行测定,可知道其中PBDE-209的含量约为314.7436 mg/kg。     

塑料制品中溴代阻燃剂多溴联苯醚的检测

多溴联苯醚(PBDEs)是一类性能优异的阻燃剂。研究表明,PBDEs是持久性有机污染物(POPs)。本文建立了气相色谱-质谱联用法测定塑料制品中多溴联苯醚的方法。以二氯甲烷为提取溶剂,超声提取塑料中多溴联苯醚(PBDEs),提取2次,合并提取液后用氮吹浓缩,再进样气相色谱-质谱法(GC-MS)检测。SCAN和SIM同时扫描,采用特征离子定量分析。结果表明:10种多溴联苯醚(PBDEs)的线性关系(r~2=0.9985~0.9997)、检出限(8.2×10~(-3)~8.9×10~(-3))回收率和精密度符合要求,RSD为2.25%~5.31%,回收率在82.97%~109.9%之间。本方法前处理简便,灵敏度高,定性、定量分析准确可靠,且分析时间短,适用于塑料制品中PBDEs的测定。     

高效液相色谱法测定百菌清中六氯苯、十氯联苯

[目的]建立高效液相色谱法测定百菌清中六氯苯、十氯联苯的方法。[方法]采用Waters 2998高效液相色谱仪(配备Waters Symmetry C18不锈钢色谱柱),以甲醇-四氢呋喃-水为流动相,在217 nm波长下对百菌清中六氯苯、十氯联苯含量进行测定。[结果]在0.05~2.0 mg/L范围内,六氯苯、十氯联苯线性关系良好,平均回收率为98.5%和97.9%,六氯苯的相对标准偏差为3.4%。[结论]该方法能快速、准确测定百菌清中六氯苯和十氯联苯的含量。     

高效液相色谱法测定溴氰虫酰胺可分散油悬浮剂中有效成分含量

[目的]建立溴氰虫酰胺可分散油悬浮剂中有效成分含量的测定方法。[方法]采用高效液相色谱法,使用C18色谱柱,以甲醇-醋酸水溶液为流动相,在270 nm波长下对溴氰虫酰胺进行分离和定量分析。[结果]方法的线性相关系数r为0.999 9,定量检测限为2.73 mg/L,标准偏差为0.025 3,变异系数为0.245%,平均回收率为101.9%~102.1%。[结论]方法具有快速、准确,适用于溴氰虫酰胺制剂的定量分析。     

GC/MS法测定电子电气塑料件中的限用含溴阻燃剂

建立了电子电气产品塑料部件中限用含溴阻燃剂多溴二苯醚(PBDE)和多溴联苯(PBB)的气相色谱/质谱(GC/MS)联用检测方法,成功应用于10种PBDE和8种PBB化合物的检测。样品经索氏提取器提取、固相硅胶净化小柱净化后,用GC/MS联用仪进行定性和定量特征离子分析。PBDE和PBB的线性分析范围为3.3~3 300 ng(绝对进样量),3种代表性化合物四溴联苯、十溴联苯和十溴二苯醚的加标回收率为76.4%~99.2%,十溴二苯醚的方法精密度为1.3%。结果表明,本方法应用于电子电气产品塑料部件中限用含溴阻燃剂的检测,操作简单,分析结果稳定,重现性好。     

一种高哌嗪溴盐的液相分析新方法

建立了一种高效液相色谱法测定高哌嗪溴盐的新方法,确定了最优的色谱条件,色谱柱采用岛津VP-ODS色谱柱,柱长为250 mm,内径为4.6 mm;流动性采用V(甲醇)∶V(水)=10∶90(水相含30 mmol/L磷酸二氢钾,稀酸调p H=3.5);检测波长为220 nm;流速为1.0 m L/min;进样量为2.0μL。该分析方法填补了国内空白,分离度R≥1.5,线性相关系数达到了0.999以上,标准偏差均小于1.4%,加标回收率在98%~103%之间。实验结果表明,该方法能够满足工艺中控分析的需要。     

高效液相色谱法测定30%乙羧·氟磺胺水剂

采用二极管阵列检测器和C18色谱柱,以联苯为内标,甲醇+乙腈+0.3%磷酸水溶液(体积比35︰40︰25)为流动相,在检测波长为230 nm,流速为1.0 m L/min条件下,高效液相色谱法测定30%乙羧·氟磺胺水剂中有效成分的质量分数。结果表明,氟磺胺草醚和乙羧氟草醚的回收率分别为99.52%~100.75%和99.21%~100.14%,变异系数分别为0.30%和1.15%,线性相关系数分别为0.999 7和0.999 6。     

液相色谱-串联质谱法测定苹果、甘蓝和番茄中的溴氰虫酰胺

建立了液相色谱–串联质谱测定苹果、甘蓝和番茄中的溴氰虫酰胺的残留检测方法。样品经过改进的QuEChERS(快速、简单、廉价、高效、灵活和安全)方法提取,采用乙腈提取,NaCl盐析,PSA净化,以Agilent Zarbax SB C18色谱分离柱,用乙腈和0.1%甲酸溶液进行梯度洗脱,电喷雾正离子(ESI+)多反应模式监测,液相色谱–串联质谱测定。在本方法条件下,溴氰虫酰胺在0.025~5.0μg/m L浓度范围内均呈现良好的线性关系(R~20.996),检测限和定量限分别为0.0015和0.005 mg/kg。在0.005、0.05和0.5 mg/kg三个添加水平下,溴氰虫酰胺在苹果、甘蓝和番茄中日内平均回收率75.44%~89.76%,日内相对标准偏差为2.32%~7.56%;日间平均回收率80.70%~93.05%,日间相对标准偏差为3.40%~11.96%,能满足苹果、甘蓝和番茄中溴氰虫酰胺检测的要求。     

气相色谱法测定洗油中萘及联苯含量

确立了使用气相色谱法(GC)定量测定洗油中萘及联苯的方法,该法以甲苯为溶剂,正十二烷为内标物,用内标法对萘及联苯含量进行测定;并采用气相色谱质谱联用法(GC/MS)对洗油化学成分定性分析,共鉴定出14个主要组分。结果表明,洗油中各组分能很好地分离,其中萘质量浓度平均为0.072 4g/mL,相对标准偏差(RSD)为0.70%~1.76%,加标回收率为95.46%~102.86%;联苯质量浓度平均为0.041 8g/mL,RSD为1.18%~3.83%,加标回收率95.19%~103.49%。     

Chemistry of Color Fixation in Crude,Physically Refined and Chemically Refined Rice Bran Oils upon Heating

Compared to other vegetable oils, rice bran oil (RBO) has a characteristic dark color which further deepens upon heating or frying of foods in the oil. Darkening of the oil during heating has been studied. The dark color‐causing material in crude, chemically refined and physically refined rice bran oils was separated using a silica gel column for a hexane‐eluted oil fraction and a methanol eluted fraction. The methanol eluted fraction for all the above three types of RBO produced a dark color upon heating, hence the physically refined RBO methanol fraction was investigated further and contained monoglycerides (23.4 %) and diglycerides (67.4 %) of linoleic + linolenic acids in its methanol fraction as analyzed by column chromatography and HPLC which decreased in concentration after heating. The linoleic acid level of 37.7 % in the methanol fraction was reduced significantly to 18 % after heating (52.3 % reduction). The IR and NMR spectra were similar to those of a monoglyceride/diglyceride with NMR spectra indicating a lower amount of olefinic protons for the heated sample. These results showed that the darkening of RBO was due to the oxidation and polymerization of monoglycerides/diglycerides containing linoleic acid/linolenic acid.     

反相高效液相色谱法直接测定离子液体中咪唑杂质含量

研究了高效液相色谱法测定离子液体中的杂质(4-甲基咪唑)含量的测定方法。在不同色谱条件下,分离效果不同。在AllsphereODSC18色谱柱上,以水-甲醇为流动相,两者流速比为水∶甲醇=1∶9,流速为1.0mL/min,在215nm处进行紫外检测,离子液体能与4-甲基咪唑很好的分离。另外,在HypersilBDSC18色谱柱上用类似的条件分离效果也较好。采用该法的线性范围,检出限分析考察,结果表明,其灵敏度高、定量准确、重现性好,适合于离子液体中4-甲基咪唑这种杂质含量的测定。     

辣椒红油膏中有机溶剂残留的测定方法

以甲醇、乙醇、丙酮为标准液,毛细管柱作分离柱,顶空气相色谱法测定辣椒红油膏中的溶剂残留。3种溶剂在0~2 000μg范围内线性关系良好(R=0.999 6~0.999 8);样品最低检测限为1.67 mg/kg;甲醇、乙醇、丙酮的回收率分别为91.7~109.7%、92.7%~105.4%、91.4%~105.9%。甲醇、乙醇、丙酮的RSD分别为2.86%~5.79%、2.98%~4.75%、2.68%~4.96%。     

高效液相色谱测定环境水中2，4-二氯苯氧乙酸的方法研究

建立了以高效液相色谱法进行分离和检测环境水中2,4-二氯苯氧乙酸的方法。环境水中的2,4-二氯苯氧乙酸用SPE C18小柱进行固相萃取。液相色谱的条件是：色谱柱：SPE C18 150mm×4．6mm;流动相：甲醇：水（9：1,V／V）;流速：3mL·min^-1;柱温：40℃;检测器：UV 282nm;进样量10μL。回收率〉98％,最低检测限为0．01mg·L^-1。本法具有良好的灵敏度和重现性。     

甲醇和三甲氧基硅烷共沸物分离过程模拟和优化

三甲氧基硅烷（trimethoxysilane）是合成功能性有机硅化合物的重要中间体。在以甲醇和硅为原料合成三甲氧基硅烷的工业化生产过程中,过量的甲醇和产物三甲氧基硅烷会形成最高共沸物。本文探究了变压精馏、萃取精馏和隔壁塔萃取精馏三种分离提纯甲醇和三甲氧基硅烷的工艺,以最小年度总费用（TAC）为目标函数,运用混合整数非线性规划（MINLP）对三种流程进行了优化,比较了三种流程的效率和二氧化碳排放量。结果表明,与变压精馏相比,通过隔壁塔萃取精馏分离甲醇与三甲氧基硅烷共沸物具有明显的优势。分离100kmol/h甲醇（摩尔分数50.00%）和三甲氧基硅烷的TAC从198.84万美元/年降低到98.93万美元/年,降幅高达50.25%,效率从8.17%提高到13.82%,二氧化碳排放量从1217.53kg/h减少到684.22kg/h,减少了43.80%。     

10.8%精喹禾灵水乳剂的高效液相色谱分析

采用高效液相色谱法对10.8%精喹禾灵水乳剂进行定量分析。使用CHIRALCEL OJ-H手性柱,以V(甲醇)∶V(水)=60∶40为流动相,流速为1.8 mL/min,柱温为35℃,紫外检测波长为237 nm。结果显示,精喹禾灵的线性相关系数为0.999 9,标准偏差为0.048,变异系数为0.44%,平均回收率为98.8%。     

高效液相色谱法测定化妆品中的保泰松

建立了化妆品中保泰松的高效液相色谱分析法.采用甲醇超声提取样品,氨基固相小柱净化富集,以C18色谱柱(4.6 mm×250 mm,5μm)分离,流动相为20 mmol/L乙酸铵水溶液、甲醇和乙腈,流速1.0 mL/min,检测波长270 nm,柱温25℃,进样量10 μL.该方法的检出限为2.0 mg/kg,线性范围0.2～100.0μg/mL,加标回收率86.1％ ～90.5％,相对标准偏差为5.79％～9.21％.     

Continuous production of biodiesel fuel from vegetable oil using immobilized Candida antarctica lipase

Candida antarctica lipase is inactivated in a mixture of vegetable oil and more than 1∶2 molar equivalent of methanol against the total fatty acids. We have revealed that the inactivation was eliminated by three successive additions of 1∶3 molar equivalent of methanol and have developed a three-step methanolysis by which over 95% of the oil triacylglycerols (TAG) were converted to their corresponding methyl esters (ME). In this study, the lipase was not inactivated even though 2∶3 molar equivalent of methanol was present in a mixture of acylglycerols (AG) and 33% ME (AG/ME33). This finding led to a two-step methanolysis of the oil TAG: The first-step was conducted at 30°C for 12 h with shaking in a mixture of the oil, 1∶3 molar equivalent of methanol, and 4% immobilized lipase; the second-step reaction was done for 24 h after adding 2∶3 molar equivalent of methanol (36 h in total). The two-step methanolysis achieved more than 95% of conversion. When two-step reaction was repeated by transferring the immobilized lipase to a fresh substrate mixture, the enzyme could be used 70 cycles (105 d) without any decrease in the conversion. From the viewpoint of the industrial production of biodiesel fuel production, the two-step reaction was conducted using a reactor with impeller. However, the enzyme carrier was easily destroyed, and the lipase could be used only several times. Thus, we attempted flow reaction using a column packed with immobilized Candida lipase. Because the lipase packed in the column was drastically inactivated by feeding a mixture of AG/ME33 and 2∶3 molar equivalent of methanol, three-step flow reaction was performed using three columns packed with 3.0 g immobilized lipase. A mixture of vegetable oil and 1∶3 molar equivalent of methanol was fed into the first column at a constant flow rate of 6.0 mL/h. The eluate and 1∶3 molar equivalent of methanol were mixed and then fed into the second column at the same flow rate. The final step reaction was done by feeding a mixture of eluate from the second column and 1∶3 molar equivalent of methanol at the same flow rate. The ME content in the final-step eluate reached 93%, and the lipase could be used for 100 d without any decrease in the conversion.     

反相高效液相色谱法测定化妆品中羟基喹啉

采用反相高效液相色谱法测定化妆品中羟基喹啉的含量.色谱条件为:Kromasil C18色谱柱(250 mm×4.6 mm i.d.,5μm),流动相为V(甲醇):V(0.01 mol/L癸烷磺酸钠溶液(磷酸调pH=2.25))=62:38的混合溶液,流速1.0 mL/min,检测波长240 nm,柱温25℃,进样量20μL.结果表明,该方法的检出限为2.254 μg/g,线性范围为1.0～100.0μg/mL,回收率为95.5％～100.1％,RSD为0.07％～2.18％.     

Hydraulics and efficiency of screen trays for distillation

Screen trays are proprietary devices similar to sieve trays which are used in distillation and absorption applications. The pressure drop, liquid holdup and entrainment are measured for screen trays in an air/water column and compared to results obtained with sieve trays. The effciencies of both types of trays were compared in a distillation column using systems of various physical properties (methanol/water, acetic acid/water and cyclohexane/n-heptane mixtures). It was found that the screen tray has a lower dry pressure drop, higher liquid holdup, lower entrainment and weeping, and higher jet flooding capacity than the sieve tray. However, the effciencies of both trays are similar for the systems studied. A model was developed for predicting total pressure drop for screen trays using an air/water column. The model was tested using results for methanol/water, cyclohexane/n-heptane and acetic acid/water systems at total reflux. The deviations are within +/- 20% for 90% of the data points. The effect of a bed of mesh packing on the screen tray was also studied. It was found that the packing led to a higher tray effciency, but resulted in a higher tray pressure drop.