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气相色谱法检测大气中N2O浓度 总被引:14,自引:0,他引:14
由于受大气中O2、H2O和氯氟烃的干扰,大气中的N2O难于用简单的气相色谱法连续观测。实验中对带有电子捕获检测器的气相色谱仪(G-ECD)进行了改进,系统中安装了10通进样反吹阀和4通切换阀,色谱系统中同时采用两根PoraPakQ填充柱,并在进样系统中安装了水蒸汽和CO2过滤吸收器。这样,干扰物不进入检测器,对N2O信号没有干扰,从而提高了N2O分析灵敏度和精确度。从1992年11月起,我们开始对北京大气N2O浓度进行长期定位测检。用这种方法测得的北京大气N2O月平均浓度介于301±9.8ppbv至335±22.5ppbv之间,平均值为317±12.8ppbv。 相似文献
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中国大气中氧化亚氮浓度及土壤排放通量的测定 总被引:2,自引:0,他引:2
收集和分析了中国不同地区的大气样品并且得出了痕量气体N_2O的浓度。用箱式法对种植不同作物农田释放N_2O的通量进行了测定。测得我国本底站N_2O大气浓度为308±5ppb(1989年),这和世界其它本底站N_2O浓度相同。在其它城、乡地区测定的N_2O浓度则较高。不同农田释放N_2O的通量虽有差异,但数值大致相当。农业活动和天气条件影响土壤释放N_2O的大小。计算得出,1990年我国来自农业源(土壤和含氮化肥释放)的N_2O平均排放量为122GgN_2O-N。 相似文献
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SDE-GC-ECD分析水体中有机氯农药 总被引:4,自引:0,他引:4
运用单滴溶剂萃取-气相色谱-微池电子捕获检测器(SDE—GC—μECD)联用技术对水体中有机氯农药进行了分析,优化了影响单滴溶剂萃取的多种因素。该方法除了对P,P′-DDD的线性范围在0.4~4ng/mL之间外,其余的七种目标物(α-666,β-666,γ-666,δ-666,P,P′-DDE,0,P′-DDT,P,P′-DDT)线性范围均在0.04~4.0ng/mL之间,相关系数为0.9976~0.9999,回收率范围为83.3%~96.1%,相对标准偏差为2.1%~7.8%。与传统的液液萃取相比,单滴溶剂萃取不仅准确度、精密度相当,而且还具有省时、省溶剂的优点。 相似文献
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农产食品中菊酯类农药残留量的气相色谱快速分析方法 总被引:11,自引:0,他引:11
1 前言菊酯类农药是一种广泛应用于农业和家庭防虫的化学品,由于具有杀虫谱广、施用量小、杀虫速效、持效期长而低残毒等特点,其使用愈来愈普遍[1]。本文介绍了用一根色谱柱同时测定食品中的菊酯类农残的快速分析方法,样品中的菊酯类农残经丙酮-石油醚萃取,用无水硫酸钠-中性氧化铝净化,加入活性炭粉脱色,用气相色谱-电子捕获检测器测定。其回收率范围为90.2%-109.1%,检测限范围为0.0005mg/kg-0.002mg/kg,能满足残留量分析的要求。2 实验部分[2-8]2.1 主要仪器和试剂2.1.1 仪器岛津GC-7AG气相色谱仪附电子捕获检测器(ECD)、高速组织… 相似文献
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对比研究了吹扫捕集/气相色谱-质谱法(PT/GC-MS)和液液萃取-气相色谱/电子捕获检测器(LLE-GC/ECD)检测饮用水中碘代三卤甲烷(I-THMs)的分析方法。结果表明,采用甲基叔丁基醚(MTBE)作为萃取剂直接液液萃取,LLE-GC/ECD检测更适于I-THMs的分析。在选定条件下,内标法定量,6种ITHMs在0.5~1 000μg/L范围内线性关系良好,相关系数均大于0.99,相对标准偏差(RSD,n=7)为3.9%~6.4%,方法检出限为0.05~0.11μg/L。0.5,2.0,10.0μg/L加标水平下,分别对某地表水、水厂滤后水和自来水进行I-THMs的加标回收实验,平均回收率为81.2%~108.6%,RSD为2.6%~7.7%。结果表明,该方法简便、快速、灵敏,适用于饮用水中新兴消毒副产物I-THMs的检测。 相似文献
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用吸收液采集废气样品,顶空进样,采用气相色谱法测定进样气体中吡啶的含量。用DB-FFAP毛细管色谱柱分离,氢火焰离子化检测器测定。优化的试验条件如下:①采用多孔玻板吸收瓶采集样品;②吸收液的体积为45mL;③采样流量为0.5L·min^-1;④样品在4℃下,7d内完成分析;⑤吸收液的pH大于12;⑥加入3g氯化钠调节吸收液离子强度;⑦顶空温度为80℃,顶空平衡时间为30min。吡啶的质量浓度在100mg·L^-1以内与其对应的峰面积呈线性关系,检出限为0.05 mg·m^-3。对3个不同浓度水平的吡啶标准气体进行测定,相对误差为-8.0%^-4.7%,测定值的相对标准偏差(n=6)为1.3%~7.8%。 相似文献
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R. K. Wells J. P. S. Badyal 《Journal of polymer science. Part A, Polymer chemistry》1992,30(13):2677-2681
Strips of polystyrene held in a flowing O2 or N2O atmosphere have been exposed to 240-600 nm radiation. The extent of photooxidation has been followed by x-ray photoelectron spectroscopy (XPS). Although N2O is a more reactive gas than O2, it produces a less oxidized polymer surface. This surprising observation can be correlated to the photochemistry occurring at the gas/polystyrene interface. © 1992 John Wiley & Sons, Inc. 相似文献
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借助NO和NO2的相关反应,对空气中O2含量测定的实验进行改进,测得空气中O2的平均体积分数为21.15%,在实验过程中培养学生从定性到定量的化学思维能力。 相似文献
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The total conductivity (σT) in bcc γ-Bi2O3 doped with V2O5 system has been measured in the composition range between 1 and 7 mol% V2O5 at different temperatures. Phase transitions for different addition amounts depending on the temperature were investigated
by quenching the samples. According to the XRD and DTA/TG results, this bcc type solid solution was stable up to about 720°C and the solubility limit was found at ˜7 mol% V2O5 in γ-phase. This system showed predominantly an oxide ionic conduction. As the V2O5 addition increased, the ionic conduction increased up to 5 mol% V2O5 at which the highest conductivity was found to be 8.318·10-2 Ω-1 cm-1 at 700°C and then decreased. It has been proposed that γ-Bi2O3 phase contains a large number of oxide anion vacancies and incorporated vanadium cations at tetrahedral sites which affect
the oxygen sublattice of the crystal structure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Pyatnitskii Yu. I. Raevskaya L. N. Bostan A. I. Borisenko M. V. 《Theoretical and Experimental Chemistry》2004,40(3):172-176
It is shown that at relatively low temperatures the rate of oxidation of methane by nitrous oxide over the catalyst V2O5/SiO2 exceeds the rate of oxidation of methane by oxygen, whereas at higher temperatures the opposite relation is observed between the comparative rates of the reactions. This effect is explained on the basis of a heterogeneous chain mechanism for the oxidation of methane. 相似文献
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Aleksey A. Yaremchenko Vladislav V. Kharton Evgeny N. Naumovich Alim A. Vecher 《Journal of Solid State Electrochemistry》1998,2(3):146-149
The minimum concentration of niobium to stabilize the fluorite-type f.c.c. phase in the Bi2O3–Nb2O5 oxide system at temperatures below 996 K was ascertained to be about 10 mol%. Thermal expansion, electrical conductivity
and crystal lattice parameters of the Bi(Nb)O1.5+δ solid solutions decrease with increasing niobium content. Thermal expansion coefficients were calculated from the dilatometric
data to be (10.314.5)×10−6 K−1 at temperatures in the range 300–700 K and (17.526.0)×10−6 K−1 at 700–1100 K. The conductivity of the Bi1−
x
Nb
x
O1.5+δ ceramics is predominantly ionic. The p-type electronic transference numbers of the Bi(Nb)O1.5+δ solid solutions in air were determined to be less than 0.1. Annealing at temperatures below 900 K results in a sharp decrease
in conductivity of the Bi1−
x
Nb
x
O1.5+δ ceramics.
Received: 18 August 1997 / Accepted: 20 October 1997 相似文献
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将导热性能良好的泡沫铝作为载体,羰基钌为前驱体制备了一系列不同形态的钌基催化剂应用于N2O的低温催化分解研究.采用XRD、XPS、SEM、TEM、BET、H2-TPR等方法对催化剂进行了表征,于石英管固定床反应器上对催化剂性能进行了评价.重点考察了泡沫铝作为催化剂载体的可行性、载体的处理方法对催化剂活性的影响以及RuO2、Ru、Ru3(CO)12所表现出的活性差异.结果表明:泡沫铝作为催化剂载体,能够促进N2O的催化分解;泡沫铝经H2O2处理有利于提高其对活性中心的附着力,提高催化活性;N2O浓度为1%,Ru负载量为0.3%,活性中心分别为Ru3(CO)12、Ru、RuO2时,N2O完全转化温度依次为285、380和415℃;活性较高的Ru3(CO)12/泡沫铝催化剂在长时间作用后活性组分转变为RuO2. 相似文献