复合式气体报警器检定装置的研制

提出一种新型复合式气体报警器检定方法,根据此方法设计一套复合式气体检测报警器检定装置。该检定装置由工作柜、气瓶存储柜、气体输送气路、流量控制器、气体稀释装置、旋转工作台6部分组成。其中气体输送气路共有6路通道,气体稀释装置的重复性不大于0.5%。旋转工作台可同时对多台仪器进行测量,另外还配备了证书编辑软件。该装置检定结果的扩展不确定度不大于5%(k=2),其中:用于0~100%LEL CH4检定的扩展不确定度为3.0%(k=2);用于0~100μmol/mol H2S检定的扩展不确定度为5.0%(k=2);用于0~100μmol/mol CO检定的扩展不确定度为4.2%(k=2);用于0~20.9%O2检定的扩展不确定度为3.4%(k=2)。该检定装置工作效率高,采用PLC和上位机的控制方式能够实现检定过程自动化测量。该装置主要适用于CH4,H2S,CO,O2气体报警器的检定。     

高温傅里叶变换红外气体分析仪研制与应用

为了满足固定污染源在线分析仪器比对和现场环境监督检查的需要,研制了一种基于傅里叶红外(FTIR)光谱分析技术的高温便携式红外气体分析仪。在实验室模拟烟气条件下,采用该分析仪进行SO_2和NO标气检测,其示值绝对误差分别小于1.5μmol/mol和1.0μmol/mol。该设备在某垃圾焚烧厂的脱硝前烟气进行监测,监测结果的趋势变化与在线监测结果具有较好的对应性,其监测结果平均值的绝对误差在标准容许误差范围内,表明该分析仪具有较好的准确性和现场应用能力,能够满足检测需求。     

解吸法校准微量溶氧仪

基于气体溶解定律,提出了校准微量溶氧仪的解吸方法,设计制造了解吸法溶解氧分析仪检定装置,通过理论计算确定了检定装置的技术指标及溶氧水的测量不确定度,并通过实验验证了该方法的可行性。     

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。     

气相色谱法测定大气中的CO、CO_2以及低级烃类物质

建立了运用气相色谱对大气中一氧化碳、二氧化碳以及3种低级烃类甲烷、乙烯和乙炔进行同时分析的方法。气相色谱分析系统由自动进样器、1个十通阀协同1个六通阀,以及1个十通阀协同1个四通阀组成,可以实现进样、分离和反吹功能。HP-PLOT Q开口毛细管柱用于5种气体的分离,柱后连接热导检测器;分离完成后,一氧化碳和二氧化碳通过甲烷转化炉中的镍催化作用转化为甲烷,用氢火焰离子化检测器进行检测。5种目标分析物在9 min内完全分离。一氧化碳、甲烷、二氧化碳、乙烯以及乙炔的线性范围分别为3.3~4 990.0、3.3~5 010.0、6.6~4 990.0、4.2~5 080.0、3.9~5 030.0μmol/mol,检出限为1.0~2.0μmol/mol,相关系数不低于0.997,相对标准偏差(RSD,n=5)不大于3.5%。该方法简单、准确,可操作性强。     

氢同位素气体在线分析装置研制及分析方法建立

为了实现氢同位素气体在线检测,利用气体低气压辉光放电性质,设计加工了氢同位素在线测定装置并建立了辉光放电原子光谱法在线测定氢同位素的分析方法。该装置由辉光放电管、激发光源、真空–微量进气系统、光谱仪及数据采集系统等部件组成。采用不同含量的系列氕氘气体作为标准气体,绘制标准工作曲线,建立了氢同位素在线检测分析方法,氕氘气体的检出限均为0.04%,氕浓度、氘浓度和氕氘浓度比测量的相对标准偏差分别为3.6%,5.2%和2.4%(n=6)。该分析装置性能稳定可靠,操作简单,可实现氢同位素气体在线检测。     

氮中1μmol·mol-1氧硫化碳气体标准物质长期稳定性研究

本文考察了低浓度氧硫化碳气体标准物质的长期稳定性,并对其长期稳定的影响因素进行探究。实验中采用称量法制备氮中1μmol·mol^-1氧硫化碳气体标准物质,分别使用内壁涂氟处理和普通铝合金无缝气瓶两种包装容器进行充装,考察了该标准物质连续6个月的长期稳定及变化规律。研究证明,在内壁未作处理的普通铝合金无缝气瓶内,微量水分会与氧硫化碳发生化学反应,导致氧硫化碳浓度降低;在内壁涂氟处理的铝合金无缝气瓶内,氧硫化碳能够保持良好的稳定性。     

痕量臭氧标准气体发生装置的研制

研制了一种新型的痕量臭氧标准气体发生装置,可输出设定量值的稳定臭氧标准气体,24 h连续运行,输出量值相对标准偏差小于1.2%。发生臭氧浓度范围为25～1 000 nmol/mol。该装置可输出一组按顺序增大或减小的臭氧标准气体,可与被校准仪器连接进行比对试验或检定校准。与美国国家标准局(NIST)臭氧基准测量装置SPR41比对试验研究表明,研制的臭氧标准气体发生装置具有很好的准确性,定值不确定度小于1%(k=2)。     

甲烷中微量噻吩气体标准物质研制

研制了甲烷中噻吩气体标准物质。以高纯噻吩、高纯甲烷为原材料，包装容器为4 L内壁经抛光处理的铝合金瓶，通过微量转移与常规相结合的方法完成了甲烷中微量噻吩气体标准物质制备。利用气相色谱法对标准物质进行了均匀性检验及稳定性考察。F检验和回归曲线法实验结果表明，该气体标准物质在压力为0.5～10 MPa范围内，均匀性良好，在常温条件下保存12个月稳定。采用称量法对该气体标准物质进行了定值，并对定值、均匀性和稳定性引入的不确定度进行了评定，该系列甲烷中微量噻吩气体标准物质标称摩尔分数为1.00～10.0μmol/mol，定值结果的相对扩展不确定度为2%(k=2)。     

二氧化碳中一氧化氮气体标准物质研制

研制二氧化碳中一氧化氮气体标准物质。以高纯二氧化碳和一氧化氮气体标准物质为原料,采用称量法制备二氧化碳中一氧化氮气体标准物质,用气体分析仪对制备的标准物质浓度进行检测,并对该标准物质定值结果的不确定度进行评定。研制的二氧化碳中一氧化氮气体标准物质中一氧化氮的浓度为5,25,50 μmol/mol,相对扩展不确定度为3.0% (k=2)。该气体标准物质具有良好的均匀性和稳定性,可用于食品级二氧化碳分析方法的确认和评价。     

电化学电极气体氧分析器计量标准不确定度的评定

简述电化学电极气体氧分析器的计量检定方法及过程。给出了检定过程中测量误差的数学模型及电化学电极气体氧分析器计量标准不确定度的来源，并对各不确定度分量进行了评定。电化学电极气体氧分析器计量标准的扩展不确定度小于5％。     

口腔气体检测仪校准装置的研制

利用研制的三通道渗透管装置发生摩尔分数范围为0.1~1.0μmol/mol的硫化氢、甲基硫醇、二甲基硫醚混合气体,用于校准检测口腔气体检测仪。校准装置可以在固定输出总流量不变的情况下,快速改变发生硫化物的摩尔分数。对校准装置的温控系统和流量系统进行了测试,通过总硫分析仪对校准装置发生的低含量硫化物的量值进行了比较和验证。该校准装置发生的低含量硫化物量的相对扩展不确定度不大于6.8%(k=2)。     

气相色谱法测定丙烯中的微量氧

用气相色谱法分析丙烯中的微量氧。先将液态丙烯汽化成气态,用气体进样阀将气态丙烯样品进样到气相色谱仪中,由5A分子筛填充柱进行分离,用TCD检测器检测,外标法定量。标准气体测定结果的相对标准偏差不大于1.076%(n=5),丙烯样品中氧含量的检出限为1.0mL/m3。用该方法对实际丙烯样品进行了分析。     

Dual-purpose gas chromatographic injection device for pressurized liquid and gas injection

A dual-purpose gas chromatographic injection device, capable of injecting pressurized liquid sample of up to 5000 psig and gas sample with a volume as high as 5000 μL, has been successfully developed and implemented. The injection device is synergized by the effectiveness of a classical flash vaporization of a syringe injection and the reliability of a proven rotary valve. Depending on the matrix involved, this injection device employs either a commercially available four-port internal valve for liquid sampling or a six-port external valve for gas sampling, a modified removable needle used in standard liquid syringe, and an auxiliary flow stream that can be either mechanical or electronic flow controlled for solute transfer. For pressurized liquid, the device was found suitable of up to nC₁₆ hydrocarbon with no observable carry-over despite the injection device was operating at ambient temperature. A relative standard deviation of less than 2% (n = 20) was obtained for hydrocarbon compounds ranging from nC₈ to nC₁₆. For gas injection, the device performed well even under difficult chromatographic conditions such as with a low column inlet pressure of less than 1 psig. A relative standard deviation of less than 0.5% (n = 10) was obtained for reactive sulfur compounds such as alkyl mercaptans. The device can be operated manually or automated with pneumatic or electrical actuator, is platform neutral, and can be moved amongst instruments without hardware modification as well as implemented for on-line or in situ applications. In this paper, the utility of the device was also demonstrated with selected GC applications of industrial significance.     

Automated high-speed analysis of selected organic compounds in urban air by on-line isotopic dilution cryofocusing gas chromatography/mass spectrometry

An automated environmental air monitor has been developed to measure selected organic compounds in urban air. The instrument is based on a cryofocusing-thermal desorption gas chromatographic mass spectrometry technique where the mass spectrometer is a slightly modified residual gas analyzer (RGA). The RGA was chosen as a detector because the whole system must be robust for long periods, with 24-h continuous air monitoring. RCA are extremely simple and seemed the most reliable mass spectrometers for this purpose. Moreover, because they have no physically limited ion source, contamination is considerably reduced, so maintenance intervals are longer. The gas chromatograph is equipped with a computer-controlled six-way sampling valve, with a 100-mL sampling loop and thermal desorption cold trap injector. Environmental air is enriched with an isotopically labeled internal standard in the sampling line. This internal standard is added with a validated, custom-made, permeation tube device. The “on-line” internal standard provides for high quality quantitative data because all variations in instrument sensitivity in cryofocusing or in thermal desorption efficiency are taken into account. High repetition rates (down to 5 min for a full analytical cycle) are obtained with the use of an isothermal gas chromatography program, microbore capillary column, and environmental air sampling during the gas chromatography run.     

等离子体发射检测器在检测高纯氦气中微量氖气的应用

采用等离子发射检测器(PED)和氦离子放电检测器(DID)对重量法制备的氦气中微量氖气进行了检测,对比了微量氖气在两种检测器上的灵敏度和重复性。结果显示,PED对氖气的检测灵敏度较高,氖气含量在0.03~0.3μmol/mol范围与响应值呈良好的线性关系,r2=1.000,检测限小于1 nmol/mol,测定结果的相对偏差小于2%(n=6)。利用大气压离子质谱仪对检测限测试结果进行了验证。采用等离子发射检测器检测氦气中微量氖气的方法,可以降低微量氖气标准物质的定值不确定度,为研制高准确度微量氖气标准物质奠定基础。     

On-line determination of trace sulfur dioxide in air by integrated microchip coupled with fluorescence detection

A microchip-based method was developed for on-line determination of trace sulfur dioxide (SO₂) in air. Gaseous SO₂, which diffused through the porous glass materials on the microchip, was absorbed into an absorption solution of triethanolamine (TEA) as sulfite ions and reacted with N-(9-acridinyl)maleimide (NAM), which was used as a fluorescent reagent. The fluorescence of NAM-sulfite in micro-fluidic channel was detected. The calibration curve of sulfite ions in the range of 1.5-30 μmol/L (SO₂ 3-60 ppbv) showed a linear relation R² = 0.995, and the relative standard deviation (R.S.D.) was 1.9% for 10 μmol/L sulfite ions in five measurements. The entire measurement procedure was achieved by the integrated microchip, and the consumption of reagents was drastically reduced. It was satisfactory to apply this method to determine on-line the SO₂ level in the air.     

化学需氧量在线自动监测仪示值误差的检定

介绍化学需氧量(COD)在线自动监测仪示值误差的检定方法及注意事项。选取基准试剂邻苯二甲酸氢钾,依次配制零点溶液和质量浓度分别为50,150,500 mg/L的COD标准物质溶液,用于检定COD maxⅡ型在线监测仪的示值误差。直接配制溶液为100 mg/L的COD标准溶液,与相同浓度的标准物质溶液GBW(E)082219进行比较,结果符合检定规程JJG 1012–2006的要求。检定结果表明:以重铬酸钾为氧化剂时,邻苯二甲酸氢钾的COD氧化值呈线性关系,可直接配制100 mg/L的COD标准溶液;检定COD maxⅡ型在线监测仪,每次需要的标准溶液体积为100 m L,综合考虑,进行示值误差检定时,每种浓度至少配制500 m L。作为还原性标准物质用于检定仪器示值误差,邻苯二甲酸氢钾可能无法准确反映水体中有机物的真实还原情况,具有一定的局限性。     

Quantitative analysis of trace bulk oxygen in silicon wafers using an inert gas fusion method.

This paper describes a method for removing oxide film from the surface of silicon wafers using an inert gas fusion impulse furnace and precise determination of bulk oxygen within the wafer. A silicon wafer was cut to about 0.35 g (6 x 13 x 2 mm) and dropped into a graphite crucible. The sample was then heated for 40 s at 1300 degrees C. The wafer's oxide film was reduced by carbon and removed as carbon monoxide. The treated silicon sample was taken out of the graphite crucible and maintained again with the holder of the oxygen analyzer. The graphite crucible was then heated to 2100 degrees C. The treated silicon sample was dropped into the heated graphite crucible and the trace bulk oxygen in the wafer was measured using the inert gas fusion infrared absorption method. The relative standard deviations of the oxygen in silicon wafer samples with the removed surface oxide film were determined to be 0.8% for 9.8 x 10(17) atoms/cm3, and 2.7% for 13.0 x 10(17) atoms/cm3.