双内标毛细管GC-MS定量分析尼古丁

建立了以樟脑和间甲酚为双内标物毛细管GC-MS定量分析尼古丁的方法.色谱分析数据表明:色谱条件不变时,双内标得到的尼古丁定量曲线的线性相关系数明显优于单内标法.这可能是由于双内标可使样品分压在进样室快速均匀分布所致.文中还讨论了内标物浓度以及内标物相对分析物的出峰位置对方法线性的影响.结果表明,采用双内标法进行毛细管定...     

空气中偏二甲肼气体标准物质的研制

采用称量法制备空气中偏二甲肼气体标准物质,分别用F检验和回归曲线法对研制的标准物质进行均匀性和稳定性检验。结果表明,研制的空气中偏二甲肼气体标准物质具有良好的均匀性和稳定性,定值结果分别为10,500μmol/mol,定值结果的相对扩展不确定度为2%(k=2)。该标准物质可用于偏二甲肼报警器的检定或校准。     

乳酸甲酯脱水体系中丙烯酸甲酯的气相色谱分析

用气相色谱测定了乳酸甲酯脱水体系中丙烯酸甲酯的含量。样品用乙醚稀释,改性聚乙二醇FFAP毛细管柱分离,经FID检测器检测,以丙烯酸乙酯为内标,采用内标标准曲线法定量,丙烯酸甲酯的线性范围为0~53 mg.L-1,相关系数为0.999 4,检出限为0.001 5 mg.L-1(S/N=2),样品的回收率为96.8%~99.0%,相对标准偏差为1.55%~3.12%(n=7)。     

锶内标法在溶液法制样-X射线荧光光谱法测定天然铀产品(U3O8)中铀的可行性研究

建立了溶液法制样-X射线荧光光谱法(XRFS)测定天然铀产品(U_3O_8)中铀元素的含量,并从样品中锶含量水平、锶元素分析谱线的选择、锶内标化合物的选择、样品中硫含量对锶的影响等角度探讨了锶内标法的可行性。将0.600 00 g干燥后的内标物碳酸锶与1.000 00 g天然铀产品(U_3O_8)混合,用磷酸和硝酸在电炉上加热消解,吸取20 g消解液于塑料样杯中,按照优化的XRFS仪器工作条件测定。以标准物质GBW 04205配制的标准溶液系列制作标准曲线,并引入了标准曲线的参数建立校正公式,以消除基体效应。结果显示:样品中锶的质量分数不大于8.0μg·g~(-1),硫的质量分数小于2.00%,均不影响锶内标法对铀的测定;内标物碳酸锶的用量为0.600 00 g时,以锶元素的K_α作为内标特征线测定,锶元素和铀元素的荧光强度及吸收-增强效应基本一致,且不受样品溶液的定容体积、进样量和仪器波动的影响;铀标准曲线的线性范围为78.78%～87.25%;对标准物质GBW 04205平行分析11次,测定值的相对标准偏差(RSD)为0.061%,测定值(84.722%)与认定值(84.711%)的绝对差值为0.011%,小于天然铀产品(U_3O_8)贸易检测中铀元素的质控指标(0.1%);方法用于6个实际样品的分析,测定值与国家标准GB/T 11848.1-1989中的电位滴定法所得的测定值基本一致。     

电感耦合等离子体原子发射光谱法测定轴承用铜钢复合双金属板中的镧、铈量

轴承用铜钢复合双金属板样品经硝酸、盐酸溶解后,以铑为内标,用电感耦合等离子体原子发射光谱仪测定试料溶液中待测元素特征谱线的强度,通过内标标准曲线法计算出试料中镧、铈量, 轴承用铜钢复合双金属板 1#、2#样品的精密度(RSD值)为0.98%～1.08%,加标回收率为97.0%～104.6%,说明本方法准确可靠。     

发射光谱法测定人发样品中七种元素

应用发射光谱法一次性同时测定了人发样品中Zn、Ca、Mg、Fe、Cu、Mn、Pb七种元素含量。选用含5%SiO2的光谱纯石墨粉作基体配制人工标准,样品放于570℃马福炉中灰化,加入以石墨粉为主体的缓冲剂,Sb、Pd为内标,光谱法测定,使用国家人发标准样校正标准曲线,以保证分析结果的准确度,经10多万份样品分析,方法稳定可靠。     

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。     

X-射线衍射内标法定量滑石粉中的温石棉

对比α-氧化铝、氧化镁、硅粉三者的结晶属性,选择晶相良好且与温石棉特征峰无重叠的单质硅为内标物,建立温石棉衍射吸收标准曲线,该曲线在温石棉含量0%～9.3%具有较好的回归性。使用曲线分析已知温石棉含量的分析样品,测得温石棉含量为1.70%,与理论值(温石棉添加量:1.68%)的相对误差RE为0.99%。分析该方法检出限与定量限分别为0.10%和0.30%。与以金属基底建立曲线的石棉定量方法相比,内标法有较好灵敏度和准确度,是一种准确可靠的石棉定量方法。     

NMR定量测定片剂中的对乙酰氨基酚

以基准试剂邻苯二甲酸氢钾为内标,采用1H NMR法建立了对乙酰氨基酚片剂中对乙酰氨基酚含量的测定方法。考察了延迟时间、脉冲宽度和采样次数对测定结果的影响。选定核磁共振参数延迟时间1 s、脉冲宽度3μs、采样次数16次。结果显示,测定内标与标样的NMR峰面积比均小于0.4%,方法具有很好的重复性。将内标与标样的NMR峰面积比对其质量比绘制标准曲线,相关系数为1.000 0,内标的质量浓度为6 g/L时,对乙酰氨基酚的线性范围为2～10 g/L。用标准曲线法和绝对定量模式(内标法)测定了3种不同厂家的片剂中对乙酰氨基酚的含量。结果表明此方法与紫外分光光度法的测定结果一致,方法简单易行、结果准确。     

毛细管电泳检测酚基体中对甲苯磺酸

以苯酚（phenol)和对甲苯磺酸（para toluene sulfonic acid,PTSA)的混合物为模拟样品,毛细管电泳检测了苯酚体中的对甲苯磺酸。考察了磷酸缓冲溶液的浓度和pH对分离的影响,选择性桂皮酸作为内标法和标准曲线法得到了对甲苯磺酸在50mg/L苯酚基体中的标准曲线,其线性范围为1.25-12.5mg/L（R=0.9999),检测限为0.75mg/L(S/N)=3,讨论了毛细管电泳中的基体效应,并应用标准加入法测定了4个实际样品。     

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：     

Gas Chromatography–Mass Spectrometry Quantification of 1,1-Dimethylhydrazine Transformation Products in Aqueous Solutions: Accelerated Water Sample Preparation

The use of highly toxic rocket fuel based on 1,1-dimethylhydrazine (UDMH) in many types of carrier rockets poses a threat to environment and human health associated with an ingress of UDMH into wastewater and natural reservoirs and its transformation with the formation of numerous toxic nitrogen-containing products. Their GC-MS quantification in aqueous samples requires matrix change and is challenging due to high polarity of analytes. To overcome this problem, accelerated water sample preparation (AWASP) based on the complete removal of water with anhydrous sodium sulfate and transferring analytes into dichloromethane was used. Twenty-nine UDMH transformation products including both the acyclic and heterocyclic compounds of various classes were chosen as target analytes. AWASP ensured attaining near quantitative extraction of 23 compounds with sample preparation procedure duration of no more than 5 min. Combination of AWASP with gas chromatography–mass spectrometry and using pyridine-d₅ as an internal standard allowed for developing the rapid, simple, and low-cost method for simultaneous quantification of UDMH transformation products with detection limits of 1–5 μg L⁻¹ and linear concentration range covering 4 orders of magnitude. The method has been validated and successfully tested in the analysis of aqueous solutions of rocket fuel subjected to oxidation with atmospheric oxygen, as well as pyrolytic gasification in supercritical water modelling wastewater from carrier rockets launch sites.     

Square-wave voltammetric determination of daminozide

A novel electrochemical method is described for the determination of the growth regulator, daminozide. Daminozide is hydrolyzed in alkaline aqueous media to form 1,1-dimethylhydrazine (UDMH). The UDMH is oxidized at ?0.38 V vs. Ag/AgCl at the hanging mercury drop electrode and detected by square-wave voltammetry. The sensitivity is about 2.3 nA 1 mg^?1 and the standard deviation (n = 8) for different standard solutions is 2.9 nA. Results obtained with apples after steam distillation agreed well with results obtained with a previously published method.     

Application of the localized surface plasmon resonance of gold nanoparticles for the determination of 1,1-dimethylhydrazine in water: Toward green analytical chemistry

Localized surface plasmon resonance (LSPR) is an optical phenomena generated by light when it interacts with conductive nanoparticles that are smaller than the incident wavelength. In this work, we proposed a simple, fast, and green method for spectrophotometric determination of unsymmetrical 1,1-dimethylhydrazine (UDMH) based on LSPR property of gold nanoparticles (AuNPs). An LSPR band is produced via reduction of Au³⁺ ions in solution by UDMH as active reducing agent in the presence of cetyltrimethylammonium chloride as a capping agent. Some important parameters in the formation of LSPR including Au(III) concentration, pH, concentration of stabilizer, and reaction time were studied and optimized. Under optimum conditions, the LSPR intensity displays linear response with the increasing UDMH concentration in the range from 0.5–10 μg/mL at 550 nm with a detection limit of 0.2 μg/mL. Also, the relative standard deviation for ten replicate determination of 5.0 μg/mL of UDMH was 3%. Usage of AuNPs as new nontoxic reagent instead of hazardous reagents in the spectrophotometric determination of UDMH is a step toward green analytical chemistry. The proposed method was successfully applied for determination of UDMH in water and wastewater samples.     

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.     

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.     

Ion chromatography as a tool for the investigation of unsymmetrical hydrazine degradation in soils

A new procedure for the determination of 1,1-dimethylhydrazine (UDMH) in soil samples was developed. This involves the distillation of UDMH from an alkaline suspension of soil and ion chromatographic analysis of the distillate. The separation was performed on a silica cation-exchanger column with ammonium acetate buffer solution as mobile phase and amperometric detection at +1.2?V. Hydrazine (Hy) and methylhydrazine (MH), which are decomposition products of UDMH, can be determined simultaneously. The limits of detection in aqueous solutions were 0.2, 0.5 and 1?µg?L^?1 for Hy, MH and UDMH, respectively. The developed technique was used for investigating the behaviour of UDMH in spills of rocket fuels on soils. It was found that the addition of 4?kg?m^?2 UDMH resulted in a 0.02% residue one year after the soil treatment. The vertical migration of UDMH in soil was less than 50?cm.     

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。     

气相色谱/质谱法测定空气中痕量偏二甲肼

建立了气相色谱/质谱法测定空气中痕量偏二甲肼的分析方法。以2-硝基苯甲醛为衍生化试剂,以含有衍生化试剂的甲醇溶液为吸收液,气体发生装置发生的偏二甲肼气样用吸收液直接吸收后,与衍生化试剂在甲醇中发生反应,对气体采样和衍生化反应条件进行了优化,考察了气相色谱/质谱法测定空气中痕量偏二甲肼的加标回收率为75%～92%;检出限(S/N=3)为0.019mg/L。采样2L时,最低检测浓度为9.5ng/m3。当采样流量为0.2L/min时,平均采样效率为99%。本方法灵敏快速,简便易行,可实现对空气中痕量偏二甲肼的检测。     

偏二甲肼渗透管标准物质的制备及其均匀性稳定性研究

以精馏和光解纯化工艺获得的高纯偏二甲肼为原料,制备了渗透率范围为0.5-30μg/min的偏二甲肼渗透管标准物质.经过均匀性、稳定性检验,结果表明:该标准物质均匀性、稳定性良好,为航天作业环境中各类快速检测仪的监控准确性提供了判定依据.