原油中硫化氢含量检测方法

分析了目前利用水提取法、氮气吹脱-离子色谱法、氮气吹脱-XVI总硫分析仪法、氮气吹脱-碘量法等方法测定原油中硫化氢含量存在的问题,推荐并进一步从检测装置、操作步骤、计算公式等方面完善了氮气吹脱-碘量法测定原油中硫化氢的方法。     

应用FTIR分析硫磺中残留硫化氢及多硫化氢

硫磺中硫化氢（Ｈ２Ｓ）和多硫化氢（Ｈ２Ｓｘ）的残留量是硫磺产品质量控制指标之一。介绍了利用傅立叶变换红外光谱仪（ＦＴＩＲ）定量分析硫磺中残留Ｈ２Ｓ和Ｈ２Ｓｘ的方法,并对影响分析的主要因素－温度进行了讨论,给出了温度的选择方法,该分析方法简单,快速,且分析范围,检测下限低。     

天然气或液体燃料现场制氢新工艺

采用常规浸渍法制备了经氧化镧改性的Ni-La/MgAl2O4催化剂,采用共沉淀方法制备了经氧化镧改性的Ni-La/Al2O3催化剂.通过氧分布器向催化剂床层分布引入氧气,研究了天然气催化部分氧化与水蒸气重整耦合绝热反应制氢的性能,结果说明,Ni-La/MgAl2O4催化剂对于天然气绝热转化制氢具有高的催化活性、选择性和稳定性.采用常规固定床反应器研究了氨分解反应的性能,结果说明,Ni-La/Al2O3催化剂对于氨分解制氢具有高的催化活性,以非贵金属镍基催化剂替代贵金属钌基催化剂,用于较低温度下氨分解制氢是可行的.对于液态烃类制氢,采用预转化与带有氧分布器的绝热转化集成工艺,可以从根本上解决催化剂积碳问题.以氧化铝多孔陶瓷管做为支撑体,通过对其表面进行有效修饰和控制制备的技术关键,可以制备高效复合金属钯膜.以氨分解制氢与钯膜分离氢进行技术集成,在维持氢回收率为84%的前提下,在实验的500小时内,氢气的纯度始终保持在～99.97%,透氢量始终保持在30 m3/m3·h附近,说明氨分解催化剂和复合金属钯膜具有长期稳定性.所制备的复合金属钯膜在含有～2%CO的混和气体中可以稳定地用于分离氢气.     

顶空色谱法测定脱硫胺液中CO_2和H_2S的含量

建立了一种测定脱硫胺液(30%(w)的N-甲基二乙醇胺(MDEA)溶液)中CO2和H2S含量的顶空色谱法;考察了试样处理方法、标准溶液配制方法、顶空瓶隔垫的吸附性、环境中的CO2等因素对测定结果的影响;测定了顶空色谱法的重复性和准确性。实验结果表明,试样中加入过量的稀硫酸,可使CO2和H2S从试样中解吸出来;试样的最佳处理条件为:n(硫酸)∶n(MDEA)=2、反应温度为常温、反应时间2 min、平衡时间1.0 min;用脱硫胺液完全吸收标准气体试样中的CO2和H2S,可准确配制含量接近实际试样的标准溶液。采用该方法测定脱硫胺液中CO2和H2S的含量,相对标准偏差小于4%,定量下限均为0.1 g/L,分析时间为6 min,测定结果不受亚硫酸盐等的干扰,方法准确度高,可在常温下进行试样处理,操作简单,色谱柱和进样口不受脱硫胺液的污染。     

Determination of methenamine residues in edible animal tissues by HPLC-MS/MS using a modified QuEChERS method: Validation and pilot survey in actual samples

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was developed for the determination of methenamine in edible animal tissues by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Samples were extracted with acetonitrile, and cleaned with anhydrous sodium sulfate and primary secondary amine (PSA) sorbent. An isotope dilution mass spectrometry technique was applied to compensate for matrix effect. The separation was performed on a HILIC column, and the mobile phase composed of acetonitrile-0.1% of formic acid and 5.0 mmol/L of ammonium acetate in water. The method showed a linear relationship in the range of 1.0–20.0 μg/L for methenamine, and the determination coefficients (R²) ranged from 0.9939 to 0.9995. The limit of detection (LOD) and quantification (LOQ) for methenamine in animal tissues sample was 1.5 μg/kg and 5.0 μg/kg, respectively. The average recoveries were 86.7–109.5% at spiked levels of 5.0, 25.0, 100.0 μg/kg. The intra-day precision ranged from 2.6 to 7.0%, and the inter-day precision ranged from 4.9 to 11.3%. The validated method was successfully applied to determination of methenamine in swinish muscle, kidney and liver.     

Determination of multi-mycotoxin occurrence in maize based porridges from selected regions of Tanzania by liquid chromatography tandem mass spectrometry (LC-MS/MS), a longitudinal study

Residents of certain areas of Tanzania are exposed to mycotoxins through the consumption of contaminated maize based foods. In this study, 101 maize based porridge samples were collected from villages of Nyabula, Kikelelwa and Kigwa located in different agro-ecological zones of Tanzania. The samples were collected at three time points (time point 1, during maize harvest; time point 2, 6 months after harvest; time point 3, 12 months after harvest) over a 1-year period. Ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was used to detect and quantify 9 mycotoxins: aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), aflatoxin G₁ (AFG₁), aflatoxin G₂ (AFG₂), fumonisin B₁ (FB₁), fumonisin B₂ (FB₂), deoxynivalenol (DON), ochratoxin A (OTA) and zearaleneone (ZEN) in the samples following a QuEChERS extraction method. Eighty two percent of samples were co-contaminated with more than one group of mycotoxins. Fumonisins (FB₁ + FB₂) had the highest percentage occurrence in all 101 samples (100%) whereas OTA had the lowest (5%). For all three villages the mean concentration of FB₁ was lowest in samples taken from time point 2. Conversely, In Kigwa village there was a distinct trend that AFB₁ mean concentration was highest in samples taken from time point 2. DON concentration did not differ greatly between time points but the percentage occurrence varied between villages, most notably in Kigwa where 0% of samples tested positive. ZEN occurrence and mean concentration was highest in Kikelelwa. The results suggest that mycotoxin contamination in maize can vary based on season and agro-ecological zones. The high occurrence of multiple mycotoxins found in maize porridge, a common weaning food in Tanzania, presents a potential increase in the risk of exposure and significant health implications in children.