顶空固相微萃取-气相色谱法测定水中氯苯类化合物

采用顶空固相微萃取（HS －SPME）技术萃取水中6种氯苯类化合物，全面分析对目标物萃取效率的影响因素，并确定萃取试验的最佳条件。用顶空固相微萃取联合气相色谱法（HS －SPME －GC）测定水中6种氯苯类化合物，方法在0.500 ng／L～2.00×10^5 ng／L范围内线性良好，检出限为0.05 ng／L ～2000 ng／L，空白样品加标回收率为69.8％～121％， RSD为4.8％～18.3％。用该方法测定实际水样，平行双样的相对偏差低于20％。     

气相色谱-高分辨双聚焦磁质谱测定水中超痕量多氯萘

采用固相萃取法处理水样，气相色谱-高分辨双聚焦磁质谱法测定水中超痕量多氯萘，同位素内标法定量，并对样品前处理条件和仪器条件进行优化。试验表明：方法在0．500 ng/L～500 ng/L范围内线性良好；当取样体积为1 L时，方法检出限为0．005 ng/L～0．01 ng/L；对实际水样进行2个质量浓度水平的加标回收试验，平行测定6次的 RSD为2．7％～8．7％，回收率为70．2％～110％。方法适用性试验表明，水样中复杂的基质对测定无影响。     

Application of the QuEChERS method for the determination of organochlorine pesticide residues in Brazilian fruit pulps by GC-ECD

The Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was applied to the extraction of 14 organochlorine pesticides (OCPs) residues from commercial fruit pulps available in supermarkets in Fortaleza, Northeastern Brazil. The analyses were carried out by gas chromatography (GC), coupled to an electron-capture detector (ECD), and were confirmed by GC-tandem mass spectrometry (MS). The parameters of the analytical method, such as accuracy, precision, linear range, limits of detection and quantification, were determined for each pesticide. The results showed good linearity (R² ≥ 0.9916) and the overall average recoveries were considered satisfactory obtaining values between 69 and 110%, RSD of 2–15 %, except for hexachlorobenzene (HCB) in açai, acerola and guava pulp samples. The OCPs were detected in guava (α–HCH; lindane) and soursop (α, β–HCH isomers) samples. The QuEChERS method and GC–ECD were successfully used to analyze OCPs in commercially available Brazilian fruit pulps and can be applied in routine analytical laboratories.     

降水中甲酸、乙酸和草酸的离子色谱法测定及样品保存研究

甲酸、乙酸和草酸是降水中有机酸的主要成分。研究选用离子色谱法同时测定降水中的甲酸、乙酸和草酸,并对降水样品中3种有机酸的保存条件进行了研究。优化后的色谱条件为4. 0 mmol/L Na_2CO_3和1. 2 mmol/L NaHCO_3混合淋洗液,淋洗液流速为1. 0 m L/min,进样体积为200μL,电导池温度为30℃,柱温为室温。甲酸、乙酸和草酸的检出限分别为0. 002、0. 005、0. 005 mg/L,实际降水样品测定时平行样的相对标准偏差为1. 4%～12%,加标回收率为95%～118%。样品采集后需尽快用0. 45μm聚醚砜微孔滤膜过滤,4℃以下冷藏密封保存,2 d内测定。若用氢氧化钠溶液调节p H至8～10,样品可保存7 d。     

顶空-气相色谱法(氮磷检测器)测定固定污染源废气中三甲胺

建立了顶空-气相色谱法测定固定污染源废气中三甲胺的分析方法。弱酸性吸收液采集固定污染源废气中的三甲胺,碱液中和后顶空进样气相色谱仪氮磷检测器分析。并对平衡温度、平衡时间、盐析效应、氨水和氢氧化钠条件实验进行优化,在最佳实验条件下,三甲胺的方法检出限为0. 46μg/m~3(以采集20 L空气样品计),加标回收率为97%～107%,相对标准偏差在9. 26%以下。利用该方法对垃圾焚烧发电厂厂界空气及鱼粉厂有组织废气中三甲胺进行检测分析,该方法能够满足国家标准及上海地方标准中三甲胺排放限值的要求。     

A product analysis-based study on the mechanism of inflammable gas explosion suppression

To study the mechanism of the suppressing effect of Expanded Aluminium (EA) on the premixed gas explosion, premixed methane-air and propane-air gases were undergone explosion reaction in the presence of EA in a self-designed closed pipeline with the overpressures and the compositions, rates and sensitivities of products analyzed. The results showed that the 9.5% methane-air and 5% propane-air explosions produced peak pressures decreased by 79.3% and 65.6%, and residual methane and propane contents increased by 270% and 560% respectively than without EA. In addition, the results revealed that the explosions of propane in the presence of EA produced less methane and carbon oxides contents, but more ethylene and propylene contents. The simulation showed that H, O, and OH are the key factors affecting the rate of products. The product compositions, together with other parameters, suggested that EA decreased temperature, inhibited chain initiation and propagation reaction, but facilitated chain termination reaction by advancing and accelerating the gas phase and wall destruction reaction of radicals, especially collisions and concentration of key free radicals. This new research method based on the analysis of explosion products can be used for in-depth research into gas explosion features and shed light on the suppressing mechanism of EA in flammable gas explosion.     

Research based on double coverage rate and reliability of gas detector layout optimization

The gas detector layout should be highly attuned to combustible gas leakage and attain a good reliability in avoiding detector malfunction, which is an important guarantee for the normal production of the chemical industry and other related enterprises. Herein, a gas detector layout optimization method based on double coverage and reliability is proposed. The key gas leakage monitoring area is determined through layout scene field investigation. To improve the detection probability and detection system reliability, the dual coverage target and voting mechanism are set, and the gas detector layout is determined with the ray-casting algorithm according to the coverage target. Combined with FLACS software to simulate a variety of typical leakage conditions under different layout scenarios, the relationship between the leaked gas concentration detected by gas detectors in each layout scheme and time is obtained, and the gas leakage detection probability in each layout scheme, number of detectors that can trigger the alarm, shortest time to trigger the alarm and reliability are comprehensively evaluated. The decision-maker selects the final gas detector layout plan according to the evaluation results and actual site needs. The study shows that the detection probability of each layout scheme set according to the double coverage is high, and multiple detectors can trigger the alarm (up to 100%), which ensures that the alarm can be triggered within 10 s under all applicable conditions. According to the evaluation results, the decision-maker can obtain a layout scheme that not only agrees with the actual site conditions but also attains a high detection probability, short detection time and strong reliability.     

An LC-MS/MS method for creatine and creatinine analysis in paraquat-intoxicated patients

Abstract

A sudden increase in serum creatinine after paraquat intoxication has been reported in several clinical studies. However, this dramatic change of creatinine may be possibly due to an interconversion of creatine-creatinine in relation to paraquat toxicity. In order to investigate the creatine-creatinine relationship, a liquid chromatography tandem mass spectrometry in combination with electrospray ionization was developed and validated for simultaneous determination of creatine and creatinine in the serum. The chromatographic separation was achieved on a Gemini® C₆-Phenyl column with a gradient elution consisting of 0.1% formic acid in ultrapure water and methanol as the mobile phase. The method yielded suitable levels of specificity and selectivity, and calibration curves of creatine and creatinine in serum were linear over the concentration range of 0.5–200?µg mL^?1. The limit of quantification of both compounds was 0.5?µg mL^?1, and the method was accurate within the recovery range of 96.23–102.75%, indicating the robustness of the method. The method was successfully applied to toxicological samples from paraquat-intoxicated patients, and the concentrations of creatine and creatinine were quantified. High creatine concentrations in serum samples were observed which may lead to high serum creatinine despite normal kidney function as creatine is converted to creatinine in proportion to its concentration.     

苦味酸测定中关键问题的研究

目前测定苦味酸的国标方法为《生活饮用水标准检验方法有机物指标》(GB/T 5750.8—2006)中的衍生物-液液萃取-气相色谱法,在实际测试过程中,发现水样pH值和基质效应会影响苦味酸测定。当pH值为8~12时,生成的氯化苦响应强度变化不大;在pH约为13时,响应强度最大。水质中除腐殖酸、硝基甲烷及2,4,6-三硝基甲苯会影响苦味酸测定外,硝基酚类和甲基酚类同样起到正干扰作用,因此,国标方法不能全面和准确地测定水中的苦味酸含量。     

云南曲靖某煤化工基地及周边土壤中多环芳烃的检测研究

采用快速溶剂提取处理土壤样品,利用气相色谱质谱内标法测定土壤中多环芳烃,其检出限范围为2.01~3.68μg/kg,相对标准偏差为2.6%~14.7%,加标回收率为67.1%~119%。结果表明,此方法具有良好的灵敏度、准确度和精密度。本研究对11个不同采样点土壤进行了检测分析,并考察了土壤中多环芳烃的污染水平。