碱蒸馏/超声波衍生化-气相色谱-质谱法测定土壤中的偏二甲肼

建立了碱蒸馏/超声波衍生化预处理的气相色谱-质谱法测定土壤中偏二甲肼的分析方法。通过碱蒸馏预处理方法,以水杨醛为衍生化试剂,采用超声波加速衍生化反应,在选择离子检测( SIM)模式下进行定量分析,衍生化产物的特征离子为m/z 164。考察了碱蒸馏、超声波衍生化条件的影响,并对衍生化条件进行优化,方法的线性范围在0.4~30 mg/L之间,方法检出限为0.0078 mg/kg。以此方法测定已知浓度的土壤样品,目标化合物的含量在10~100 mg/kg之间,回收率在76％~108％之间,相对标准偏差在12％~19％之间。与分光光度法、索氏提取/超声波衍生化-气相色谱-质谱法相比较,本方法检出限显著优于二者。     

柱上衍生-气相色谱-质谱法测定纺织织物中的痕量全氟辛基磺酸

建立了柱上衍生-气相色谱-质谱法测定憎水憎油纺织织物中痕量全氟辛基磺酸(PFOS)的检测方法,运用超声-微波协同提取技术,使用四丁基氢氧化铵(TBAH)为衍生化试剂,与PFOS形成铵盐,并在柱上进行原位裂解烷基化反应,所得PFOS丁酯利用气相色谱-质谱法进行分离和分析,采用选择离子(SIM)模式检测,特征离子分别为m/z 57,69,131,169和449。本方法的加标回收率为83.6%～91.7%,相对标准偏差(RSD)小于7.34%,检出限为59 mg/L。运用本法对憎水憎油纺织织物样品进行检测,PFOS含量在0.063～13.9 mg/kg之间。     

气相色谱-质谱法测定大气中偏二甲肼

利用气泡吸收器富集大气中的偏二甲肼气体,以水杨醛与水以体积比1比50混合的溶液作为吸收液,偏二甲肼经水杨醛于50℃下衍生化3 h后,供气相色谱-质谱法分析检测。结果表明:当采集流量为0.2 L.min-1时,吸收器对偏二甲肼的吸附效率为95%~98%。偏二甲肼的质量浓度在40.0 mg.L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)为0.878 mg.L-1。测定结果的相对标准偏差(n=6)为2.96%~4.09%,加标回收率为88.0%~93.0%。     

固相微萃取-GC-MS法测定水中的三苯胂和二苯胂酸

建立了一种同时测定水中痕量三苯胂和二苯胂酸的方法,使用巯基乙酸甲酯作为二苯胂酸测定的衍生化试剂,固相微萃取耦合气相色谱-质谱法(选择离子监测)同时测定三苯胂和二苯胂酸。优化了萃取纤维丝、萃取时间、衍生化等操作条件。同时对混合物测定的回收率、相对标准偏差和最低检测限进行了研究。方法的回收率大于95%,最低检测质量浓度分别为0.0005和0.0003 mg/L,6次测定的相对标准偏差分别为5.3%、7.6%。     

SPME/GC-MS测定水中痕量二苯氰胂的方法研究

采用衍生化固相微萃取-气相色谱-质谱(GC-MS)监测技术,对水中痕量二苯氰胂进行了测定,考察了衍生化试剂、萃取纤维、萃取时间等因素对方法灵敏度的影响.测定二苯氰胂的线性范围为2.14～137 μg/L,检出限为0.2 μg/L,相对标准偏差为10.4%,回收率为97%～102%.     

SPME/GC-MS测定水中痕量二苯氯胂

采用衍生化固相微萃取/气相色谱-质谱(GC-MS),对水中痕量二苯氯胂进行测定,考察了衍生化试剂、萃取纤维、萃取时间等因素对方法灵敏度的影响。测定二苯氯胂的线性范围为1.8~216μg/L,检出限为0.3μg/L(S/N=3),相对标准偏差为7.63%,回收率为95%~103%。     

Tenax采样管富集气相色谱-质谱法测定空气中的痕量酚类化合物

建立了Tenax采样管富集气相色谱-质谱测定空气中痕量酚类化合物的方法。用Tenax采样管吸附环境空气中的痕量酚类化合物,用甲醇淋洗解吸酚类化合物,洗脱液加入萘-D8作为内标,利用气相色谱-选择离子监测质谱(GC-MS/SIM)进行检测,内标法定量。该方法定性、定量准确,线性响应良好,回归曲线的线性相关系数均大于0.999,平均回收率为92.4%～102%,测定干扰小,检测灵敏度高,按采样10 L计算,空气中最低检测浓度可达0.001 mg/m3。用于实际样品测定,完全能满足环境空气中痕量酚类化合物监测的要求。     

萘基衍生化-GC/MS/MS法测定血中的氰离子

在血液检材中,采用萘胺和亚硝酸盐形成的重氮盐与CN~-发生亲核取代反应,生成衍生物萘甲腈,然后用气相色谱—质谱法进行测定。结果表明,衍生化产物在0.1~10μg/m L范围内的线性关系良好,检测限为0.014μg/m L,定量限为0.047μg/m L,相对回收率为97.4%,相对标准偏差为3.1%。方法具有较强专属性,适用于生物检材中CN~-的检验。     

气相色谱电子捕获检测器检测蟑螂头部痕量章鱼胺的衍生物

章鱼胺(OA)是昆虫体内的痕量神经活性物质。本实验研究了蟑螂头部基质中OA的提取、章鱼胺与五氟丙酸酐的衍生化反应,优化了最佳衍生反应条件。建立了适合于昆虫样本中OA痕量测定的衍生化气相色谱-电子捕获检测方法。昆虫头部匀浆样本在10 ng/g OA添加浓度时回收率在89%~118%;该方法的最低检出浓度为1.7ng/g。采用GC-MS对衍生化产物进行了定性确证分析。     

衍生化-液液萃取气相色谱法测定环境水体中苦味酸

建立衍生化-液液萃取气相色谱法测定环境水体中的苦味酸。环境水体中的苦味酸经次氯酸钠氯化衍生后,用正己烷提取后进行气相色谱分析。对萃取溶剂、衍生化反应温度和时间、衍生试剂(次氯酸钠)的加入量、色谱柱的选择以及色谱分析条件进行了优化,采取正己烷作为萃取试剂,加入次氯酸钠溶液2.0 mL,选择衍生化反应温度为35℃,反应时间为50 min,DB-5细管柱(30 m×0.32 mm,0.25μm)作为分离柱,当取样体积为10 mL时,方法检出限为0.2μg/L。用该方法对实验用水做了高、中、低质量浓度水平的加标回收试验,回收率为85.5%~105.6%,相对标准偏差为2.93%~4.49%(n=6)。     

固体吸附-毛细管气相色谱法测定环境空气中的偏二甲肼

采用固体吸附-毛细管气相色谱法测定环境空气中偏二甲肼的含量,色谱峰高与偏二甲肼浓度在0～13．8mg／L范围内线性关系良好,当采样体积为60L时,检出限和测定下限分别为0．37μg／m^3和1．2μg／m^3。低、中、高3种浓度的偏二甲肼标准溶液测定结果（n=6）的相对标准偏差分别为3．5％,2．6％,1．9％,样品加标回收率为84．5％～101．0％。     

两种采样方法检测空气中偏二甲肼含量的精密度检验

以自制的偏二甲肼动态配气系统配制已知浓度空气样品为测试环境,采用溶液吸收法采样并简化了G JB2373-1995的分析步骤,使用改进方法与标准方法分别进行实验。用F检验法比较两种方法所对应的两组检测数据,结果表明,两种方法的精密度相当,而溶液吸收法省时、省力。     

Precolumn derivatization with glyoxal as a new approach to the highly sensitive HPLC-UV determination of unsymmetrical dimethylhydrazine

A procedure has been developed for the determination of unsymmetrical dimethylhydrazine (UDMH) based on precolumn derivatization with glyoxal and determination of the produced derivative, mono-1,1-dimethylhydrazone of glyoxal, by reversed-phase HPLC (RP-HPLC) with UV detection at 305 nm. It has been demonstrated that the reaction of UDMH with an excess of glyoxal in solution quantitatively yields one stable product within 20 min at 25°C at pH 3.5. To increase the sensitivity of UDMH determination it has been proposed to perform solid-phase extraction preconcentration of the derivative from a 25-mL sample portion on cartridges containing Strata SDB-L polymer adsorbent. The analytical range of UDMH determination in water is 0.5–10000 μg/L or 0.01–20 μg/L using preconcentration. The relative standard deviations of UDMH determination (n = 3) do not exceed 0.12 and 0.25 without and with preconcentration, respectively. The accuracy of UDMH determination is confirmed by the analysis of spiked samples and by RP-HPLC determination with preliminary derivatization with 4-nitrobenzaldehyde as independent method.     

Electrophysical properties of In2O3-and WO3-based gas-sensitive semiconducting films as sensors for unsymmetrical dimethylhydrazine in air

Some n-type semiconductor metal oxide sensors based on WO₃ and In₂O₃ were studied in detecting unsymmetrical dimethylhydrazine (UDMH) vapors. The sensors are highly sensitive to the presence of UDMH vapors in air at concentrations equal to or lower than the MPC. They have short response and relaxation times in detecting UDMH vapors in air. It was found that, when ammonia was present in air in concentrations comparable to those of UDMH, it did not affect the electrophysical properties of the semiconductor sensors.     

Catalytic oxidation of unsymmetrical dimethylhydrazine on Pt/SiO<Subscript>2</Subscript>

Specific features of oxidation of unsymmetrical dimethylhydrazine on a Pt-containing catalyst were studied. The temperature dependence of the unsymmetrical dimethylhydrazine conversion was determined, and the main intermediate and final reaction products were identified. Platinum behaves in the process as a multifunctional catalyst participating in dehydrogenation, hydrogenolysis, and oxidation. A new method was suggested for detecting unsymmetrical dimethylhydrazine in air. It consists in catalytic conversion of unsymmetrical dimethylhydrazine and detection of the nitrogen dioxide formed with semiconductor gas sensors. The method was successfully used for detecting unsymmetrical dimethylhydrazine in air at concentrations in the range 0.1–10 mg m^–3.     

Detection and determination of formaldehyde dimethylhydrazone in mixtures with 1,1-dimethylhydrazine

Small amounts of formaldehyde dimethylhydrazone (FMDH) present as impurity in unsymmetrical dimethylhydrazine (UDMH) give a yellow color (λ_max = 456 nm) on heating with excess of sulphuric acid; the detection limit is 50 μg ml^? FDMH. Differences in the basicity of the two compounds in anhydrous acetic acid and in methanol are used to determine the two compounds in mixtures containing ? 5% (w/w) FDMH.     

液体推进剂偏二甲肼自动电位滴定分析方法的建立

设计了Metrohm809型自动电位滴定仪分析液体推进剂偏二甲肼的应用程序,解决了程序设计中滴定模式和终点确定方式选择、滴定速度确定等关键性技术问题,考察了环境温度对分析结果的影响,确定了最佳条件,实现了液体推进剂偏二甲肼的自动电位滴定分析。重复性试验和准确度试验表明,自动电位滴定法分析偏二甲肼具有准确度高、精密度好等优点,测量结果完全符合GJB753-89的要求：     

Analysis of cigarette mainstream smoke for 1,1-dimethylhydrazine and vinyl acetate by gas chromatography-mass spectrometry

1,1-Dimethylhydrazine, also known as unsymdimethylhydrazine (UDMH) and vinyl acetate (VA), are both classified by the International Agency for Research on Cancer as 2B carcinogens (possibly carcinogenic to humans) and listed as cigarette smoke constituents; however, there is little or no quantitative data available on them. For UDMH in cigarette smoke, neither a yield nor a method has been published. For VA, the most recent information on yields dates back to 1965. To bridge this gap, we have developed new gas chromatographic-mass spectrometric methods for both compounds to determine their yields in cigarette smoke. UDMH is determined by derivatization with 2-nitrobenzaldehyde in methanol and is not found in cigarette smoke at levels above the detection limit of 19 ng/cig. In further experiments, when UDMH is added to the smoke stream or air stream of lit or unlit cigarettes, the derivative 2-nitrobenzaldehyde-2,2-dimethylhydrazone is found only in the air stream of the unlit cigarettes. From this, we conclude that UDMH is either not formed during smoking at all or, if it is, it reacts immediately and quantitatively with other smoke constituents (e.g., aldehydes) and is therefore not detectable in cigarette smoke. VA is determined by trapping in acetone at -78 degrees C and is found at a concentration of 270 ng/cig for a standard reference cigarette with a cellulose acetate filter (the reference cigarette 1 R4F). In the literature, VA is reported at concentrations of 1.6 microg/cig for a cigarette with a cellulose acetate/charcoal filter and 4 microg/cig for a cigarette with a cellulose acetate filter and for an unfiltered cigarette.     

Effect of sample preparation conditions on the determination of the total concentrations of unsymmetrical dimethylhydrazine in soils

It is shown that, for a correct determination of the total concentration of unsymmetrical dimethylhydrazine (UDMH) in soil, it is necessary to consider the simultaneous presence of active products of its transformation, capable of hydrolysis to the parent compound, such as formic acid 1,1-dimethylhydrazide (FADMH). A comparative study is performed of the methods known in the literature for sample preparation to select conditions for the quantitative extraction of UDMH bonded by various mechanisms to organic and mineral fractions of soil, as well as FADMH as one of the most common active transformation products. It is found that the distillation with a 40% NaOH solution with an addition of Na₂S enables the quantitative recovery of UDMH and FADMH from soils of all types and the determination of the maximum concentration of UDMH in the analysis of real samples of contaminated soils, which allows us to recommend this option to determine the total concentration of UDMH.