亚临界条件下地沟油制备生物柴油副产物中有机氯化物的定性检测及来源分析

该文介绍了一种生物柴油副产物粗甘油和拔出轻组分中有机氯化物的气相色谱-质谱（GC-MS）定性检测方法。样品来自于亚临界条件下地沟油与甲醇的酯交换反应，总氯含量较高。在GC-MS分析之前采用正己烷萃取脱除样品中的脂肪酸甲酯和游离脂肪酸等脂溶性干扰组分，对参考标准样品3-氯代甘油和2-氯代甘油以及样品的脱脂水相部分进行苯硼酸衍生化、正己烷萃取、浓缩等处理，经正己烷复溶后进行GC-MS分析。结果表明，生物柴油副产物中的有机氯化物主要为3-氯代甘油和2-氯代甘油。参考已有文献的研究结果和生物柴油制备工艺对有机氯化物的来源进行了讨论，推断原料地沟油中存在的大量无机氯盐是导致产生3-氯代甘油和2-氯代甘油的主要原因。     

三甲基硅烷衍生化-气相/质谱联用法分析尿中7-氨基硝西泮

 建立了分析尿中硝西泮主要代谢物 7 氨基硝西泮 (7 ANIZ)的三甲基硅烷衍生化 气相 /质谱联用方法。尿样经乙醚 乙酸乙酯 (体积比为 99∶1 )萃取后 ,用N ,O 双 (三甲基硅 )三氟乙酰胺进行衍生化 ,检测衍生物的总离子流。根据 7 ANIZ衍生物质谱中主要特征离子的相对丰度及其质量的保留时间进行定性分析 ;用 7 氨基氯硝西泮做内标 ,根据衍生物基峰离子的质量进行定量分析。本方法中 7 ANIZ的萃取率为 82 8% ,线性范围为 1 0 μg/L～ 50 0 μg/L,检出限为 1 2 μg/L,定量限为 3 5μg/L。     

Trace level determination of substance P using capillary electrophoresis and laser-induced fluorescence

An analytical method was developed to determine the undecapetide substance P (SP) based on capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection. SP was derivatized with the fluorogenic reagent 2,3-naphthalenedicarboxaldehyde (NDA) prior to injection into the CE-LIF system. The pre-column derivatization scheme combined with injection enhancement techniques extends the detectability of SP to the subnanomolar level. Limit of detection (LOD) of 100 pM was achieved without pre-concentrating the sample prior to injection. The reproducibility for six different preparations of a standard sample containing 5 nM of SP was 6.8% RSD and that of the CE migration time was 0.08% RSD. The method was used to determine SP in a saliva sample.     

Sensitive analysis of amino acids in injection liquor by reversed-phase HPLC

A convenient derivatization method of amino acids with l-fluoro-2,4-dimtrobenzene as reaction reagent and a separation system were described. The derivative amino acids were separated on a specific chemically bonded phase column with a simple linear gradient elution consisting of aqueous buffer and methanol. The eluate was detected by common ultraviolet absorption detector at 360 nm. The detection limits of amino acids were as low as 10 picomole. This method has been successfully applied to assay amino acid injection liquor used in hospital. It has good repro-ducibility and precision. The procedures avoid the requirements of particular derivative equipment and analyzer employed in conventional amino acid analysis.     

Derivatization of Humic Compounds: An Analytical Approach for Bound Organic Residues

Abstract

Bound residues of pesticides and their metabolites are defined as being nonextractable with organic solvents, but partly extractable together with the humic matrix by NaOH or other solvents suitable to extract humic compounds. Recently, an improvement in humus extraction from soils was achieved upon derivatization of the organic matter with silylating reagents at room temperature. By this method 70–90% of the organic carbon or nitrogen either from soil or from humin became soluble in organic solvents. The extracts were analyzed by means of ¹³C NMR-spectroscopy. The spectra were well resolved with signal-separation of less than 1 ppm. The extracted humic compounds were of rather low molecular weight, ranging from 300 to 4000 to 6000 d or more.

¹⁴C-labeled residues of pesticides or other xenobiotics found to be nonextractable after exhaustive organic solvent extraction became readily dissolved along with most of the humic matrix using this derivatization procedure. Between 60–80% of ¹⁴C anilazine residues or of ¹⁴C-labeled chlorinated phenols or anilines originating from both previously solvent extracted soil samples or from humin became solubilized in organic solvents.     

Constant pressure-assisted head-column field-amplified sample injection in combination with in-capillary derivatization for enhancing the sensitivity of capillary electrophoresis

In this work, a novel method combining constant pressure-assisted head-column field-amplified sample injection (PA-HC-FASI) with in-capillary derivatization was developed for enhancing the sensitivity of capillary electrophoresis. PA-HC-FASI uses an appropriate positive pressure to counterbalance the electroosmotic flow in the capillary column during electrokinetic injection, while taking advantage of the field amplification in the sample matrix and the water of the “head column”. Accordingly, the analytes were stacked at the stationary boundary between water and background electrolyte. After 600 s PA-HC-FASI, 4-fluoro-7-nitro-2,1,3-benzoxadiazole as derivatization reagent was injected, followed by an electrokinetic step (5 kV, 45 s) to enhance the mixing efficiency of analytes and reagent plugs. Standing a specified time of 10 min for derivatization reaction under 35 °C, then the capillary temperature was cooled to 25 °C and the derivatives were immediately separated and determined under 25 °C. By investigating the variables of the presented approach in detail, on-line preconcentration, derivatization and separation could be automatically operated in one run and required no modification of current CE commercial instrument. Moreover, the sensitivity enhancement factor of 520 and 800 together with the detection limits of 16.32 and 6.34 pg/mL was achieved for model compounds: glufosinate and aminomethylphosphonic acid, demonstrating the high detection sensitivity of the presented method.     

Silylation–desilylation of quinones and their derivatives

The silylation of quinones and their substituted derivatives for the protection of the reactive quinonic moiety and/or reactive substituents (in particular hydroxyl groups) is discussed in view of the wide applicability of the reaction for synthetic, biological and analytical purposes. Furthermore, the most common and efficient methods for the subsequent desilylation of the silylated quinones and their derivatives to the parent quinones or to the corresponding hydroquinones are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

液相色谱-串联质谱法测定面粉及其制品中的联二脲

建立了面粉及其制品中联二脲的液相色谱-串联质谱（LC-MS/MS）测定及确证方法。采用纯水振荡提取样品中的联二脲,联二脲经高锰酸钾氧化后,转变为偶氮甲酰胺,再加入对甲苯亚磺酸钠使偶氮甲酰胺衍生为对甲苯磺酰氨基脲。以乙腈和2 mmol/L乙酸铵溶液（含0.2%（v/v）甲酸）为流动相进行梯度洗脱,经Shimpak XR-ODSⅡ色谱柱（150 mm×2.0 mm,2.2 μm）分离,电喷雾正离子模式电离（ESI⁺）,多反应监测（MRM）模式检测,同位素内标法定量。方法的线性范围为1~20000 μg/kg,相关系数为0.9999,定量限为5 μg/kg;当添加水平为5.0、10.0与50.0 μg/kg时,联二脲的平均回收率为78.3%~108.0%,相对标准偏差（RSDs）不大于5.73%。本方法新颖、可靠、灵敏、线性范围广,而且实用性强,可用于面粉及其多种制品中联二脲的测定和确证。     

柱前衍生高效液相色谱法测定减肥药中的芬氟拉明

建立了柱前衍生反相高效液相色谱—紫外检测方法用于测定减肥药中的芬氟拉明。样品用三氯甲烷萃取,异丙醇转溶,再在四氢呋喃中和60℃下,用苯异氰酸酯衍生35min,然后用甲醇／水(72／28,V／V)为流动相和Kromasil C18分离柱,在240nm检测衍生物。方法的线性范围在2．52—126mg／L(r=0．9994),检出限和定量限分别为0．36ng(S／N=3)和1．2ng(S／N=10),平均回收率为98．4％,相对标准偏差(RSD)小于3．00％。     

对甲苯胺衍生高效液相色谱法测定夏桑菊中熊果酸的含量

建立了柱前衍生高效液相色谱紫外可见检测夏桑菊中熊果酸的分析方法。在CSz介质中用对甲苯胺衍生熊果酸,于C18柱上,以pH=6．2的甲醇-水(80：20,V／V)为流动相,290nm检测衍生物,熊果酸在0．3～30．0mg／L范围内与色谱峰高呈良好线性关系,r=0．9986,检出限为2．46μg／L。平均回收率为101．2％(n=5),相时标准偏差为2．5％。方法易行,可用于该制剂的质量控制。