室内空气中甲醛快速检测的研究

对使用BH-1型甲醛分析仪测定室内空气中甲醛浓度的方法进行了研究.对于低、中、高甲醛浓度的测定,其相对误差<1.8%,相对标准偏差(RSD)<5.6%(n=6),平均相对标准偏差(MRSD)<4.9%(n=6).同时与国家标准方(GB/T 18204.26酚试剂分光光度法)进行了实验室和现场比对,测定结果无显著差异,该仪器测定的总不确定度为10.4%.其方法快速、灵敏,适合现场多点、大批量监测,可与酚试剂分光光度法等效使用.     

室内空气中VOC现场快速检测方法研究

对基于PID原理的VOC快速检测仪测定室内空气中总挥发性有机物进行了深入的研究,探讨了快检仪测定VOCs的特点和优势。分别采用已知组分的VOC标准气体和现场采样分析,对两种VOC测定方法的测定结果进行了比较研究,得出比值R的范围,提出VOCs表观浓度的概念,对进一步研究两种方法的可比性提供了可靠的依据。     

室内空气中总挥发性有机物(TVOC)分析方法的研究

针对室内挥发性有机物测定方法的不完善,提出了利用热脱附-气相色谱质谱联用测定空气中挥发性有机物的测试方法,测定空气中挥发性有机物的线性范围为0ng～800ng,最低检出限可达0.05μg/m3(采样体积10L计),相对标准偏差4%～10%。该方法灵敏度高、操作简便、重现性好、准确可靠,适合室内空气中挥发性有机物的测定。     

气相-动态顶空进样-气相色谱/质谱法间接测定饮用水源水中苦味酸

建立气相-动态顶空进样-气相色谱/质谱法(D-HS-GC/MS)间接测定饮用水源水中苦味酸(即2,4,6-三硝基苯酚)的方法。基于苦味酸与次氯酸钠反应生成挥发性有机物———氯化苦(硝基三氯甲烷),气相-动态顶空进样技术可对水样液上气相空间的氯化苦进行吹脱捕集,通过气相色谱/质谱法测定氯化苦含量来间接测定苦味酸的浓度。结果表明:苦味酸浓度在1.00²0.0μg/L范围内呈良好的线性关系(r=0.9993),方法检出限为0.40μg/L;1.00,2.50,10.0μg/L标准点测得结果的相对标准偏差(RSD)分别为12.5%、9.2%和10.5%(n=7)。对实际水样进行分析,加标回收率为102%20.0μg/L范围内呈良好的线性关系(r=0.9993),方法检出限为0.40μg/L;1.00,2.50,10.0μg/L标准点测得结果的相对标准偏差(RSD)分别为12.5%、9.2%和10.5%(n=7)。对实际水样进行分析,加标回收率为102%¹31%,RSD为3.5%131%,RSD为3.5%¹6.6%(n=3)。     

家装涂料中有机挥发性化合物(VOC)含量检测

采用自动顶空结合气相色谱-质谱仪(GC-MS)对家装市场产品中有机挥发性化合物(VOC)进行定性分析,收集常用常见的挥发性有机化合物(VOC)种类,建立完善的被测物体系,再对家装涂料产品分类,采用气相色谱法检测,以内标标准曲线法定量。37种目标化合物的相关系数在0.999以上;方法检测低限为0.0004%;平均回收率在89.9%~106.2%之间;相对标准偏差小于3%。     

铝及铝合金中铁、硅、铜的联合快速测定

本文建立了铝及铝合金中铁、硅、铜的联合快速测定方法。利用氢氧化钠分解试样,盐酸酸化,并用高锰酸钾作为氧化剂制备试样溶液。在适当的酸度条件下,分别采用邻二氮菲、钼酸铵、双环己酮草酰二腙(BCO)作显色剂,测定铁、硅、铜。采用本法对标准样品纯铝及铝合金中的铁、硅、铜进行测定,铁的相对误差和相对标准偏差(n=6)分别在0.40~1.15%之间和1.31~1.81%之间;硅的相对误差和相对标准偏差(n=6)分别在0.55~1.70%之间和0.90~2.44%之间;铜的相对误差和相对标准偏差(n=6)分别在0.87~4.35%之间和1.30~2.55%之间。     

氢氧化锂中铁、硫酸根的联合快速测定

本文建立了氢氧化锂中铁和硫酸根的联合快速测定方法。利用盐酸分解制备试样溶液,在适当的酸度条件下,分别采用邻二氮菲、氯化钡作显色剂,测定铁、硫酸根。采用本法对标准样品氢氧化锂中的铁、硅、铜进行测定,铁的相对误差和相对标准偏差(n=6)分别在0.40~1.15%之间和1.31~1.81%之间;硫酸根的相对误差和相对标准偏差(n=6)分别在0.55~3.33%之间和0.90~2.44%之间。     

微波消解-石墨炉原子吸收法测定食品接触用纸制品中铅的含量

采用硝酸-过氧化氢混合溶液微波消解食品接触用纸制品,石墨炉原子吸收法测定纸制品中铅的含量。标准曲线相关系数0.9991,方法检出限0.006mg/kg,测定结果相对标准偏差2.31%~3.53%(n=6),加标回收率93.1%~102.7%。结果表明方法具有简便、准确和灵敏度高的优点。     

基于纳米氧化铟表面的二硫化碳传感器研究

基于氧化铟(In2O3)纳米材料催化二硫化碳的氧化反应产生化学发光的现象,建立一种检测环境空气中痕量二硫化碳的催化发光气体传感器。研究结果表明:在检测波长460nm、反应温度371℃、载气流速600mL/min的最优条件下,考察二硫化碳浓度在0.42²1μg/mL(r=0.9993,n=6)间的响应情况,检出限为0.04μg/mL(3σ),对21μg/mL的二硫化碳连续平行测7次,其相对标准偏差为1.8%。此外,考察相同浓度的常见挥发性有机物的干扰情况,其结果表明该传感器具有很好的选择性。连续80h通过8.4μg/mL的二硫化碳,发光强度无明显降低,相对标准偏差小于5%,表明此传感器使用寿命长。     

高效液相色谱法测定口服液中低聚木糖的含量

建立了测定口服液中低聚木糖含量高效液相色谱法。样品中的大分子多糖和较高聚合度木糖用乙醇水溶液沉淀除去,然后用4.0mol/L硫酸水解,高效液相色谱测定,外标法定量。方法线性范围为0.1~4.0mg/mL(r=0.999);回收率:酸解前为100.1~103.1%,相对标准偏差RSD为1.0%(n=6)。酸解后为89.8~95.2%,相对标准偏差RSD为2.2%(n=6);检测限为10mg/mL。该方法选择性好,结果准确可靠,适用于口服液中低聚木糖含量的测定。     

Design and validation of portable SPME devices for rapid field air sampling and diffusion-based calibration

The use of SPME fibers coated with porous polymer solid phases for quantitative purposes is limited due to effects such as interanalyte displacement and competitive adsorption. For air analysis, these problems can be averted by employing short exposure times to air samples flowing around the fiber. In these conditions, a simple mathematical model allows quantification without the need of calibration curves. This work describes two portable dynamic air sampling (PDAS) devices designed for application of this approach to nonequilibrium SPME sampling and determination of airborne volatile organic compounds (VOCs). The use of a PDAS device resulted in greater adsorbed VOC mass compared to the conventional SPME extraction in static air for qualitative screening of live plant aromas and contaminants in indoor air. For all studied air samples, an increase in the number of detected compounds and sensitivity was also observed. Quantification of aromatic VOCs in indoor air was also carried out using this approach and the PDAS/SPME device. Measured VOC concentrations were in low parts-per-billion by volume range using only 30-s SPME fiber exposure and were comparable to those obtained with a standard NIOSH method 1501. The use of PDAS/SPME devices reduced the total air sampling and analysis time by several orders of magnitude compared to the NIOSH 1501 method.     

热湿地区室内挥发性有机物多源散发研究现状

分析热湿地区室内空气污染现状,对影响热湿地区室内空气污染因素的独特特征进行总结。介绍国内外热湿环境下挥发性有机物多污染源散发机制的研究现状,指出湿热条件下室内装修家具等具有多污染源的挥发性有机物散发模型及环境影响因素研究的不足,提出对室内温度场、风速场、湿度场、污染物浓度分布进行模拟仿真的研究方向。     

空气采样技术及不确定度分析

本文介绍了室内环境空气质量检测的采样技术 ,对常用的直接采样法和富集采样法的特点、使用条件进行了阐述 ,分析了富集采样法的不确定度 ,指出采样过程中应注意的一些常见问题。     

变速直膨式空调系统运行特性的稳态ANN模型

在假设系统输出显、潜冷量的相对值在不同的蒸发器入口空气状态下不发生明显变化的前提下,本文针对实验用变速直膨式空调系统建立了稳态人工神经网络(ANN)模型,预测其在不同压缩机、风机转速组合下的系统输出,利用输出显、潜冷量的相对值可以消除室内空气状态对系统输出的影响。通过稳态实验获得数据训练、检测并验证ANN模型预测变速直膨式系统运行特性的准确性,并通过非训练状态点下的稳态实验验证所提出假设与ANN模型的适用性。ANN模型的训练、检测以及验证实验结果的最大误差均小于5%,平均误差均小于3%,表明该稳态ANN模型可以在训练状态点以及非训练状态点较为准确地预测变速直膨式系统的运行特性。     

大型低温环境室竖向气压变化特点分析

为了找出大型低温环境室室内正压设计方法存在的问题,对低温环境室在不同室温下的竖向气压变化特点进行分析,提出室内竖向气压分布的计算方法,该算法的准确性得到了实测数据的验证,其平均相对误差为5.9%。分析结果表明:大型深冷低温环境室的竖向气压变化很大,且在降温过程中室内正压不断增大。对于高度为20 m、室温为-165℃的大型深冷低温环境室,其下部正压值可超过421 Pa,远高于低温环境室室内正压以往的设计值(5—10 Pa)和安全防护值(200 Pa),因此应大幅度提高其室内正压的设计值和安全防护值。为确保室内全部空间维持正压,低温环境室的室内正压控制点应设置在顶部。     

室内PM2.5浓度标准的探讨

PM 2.5在室内颗粒物中占有很大比例,由于具有比表面积大的特点,对多种有机物具有较强的吸附能力,可以直接进入肺泡,导致年总死亡率、心肺疾病死亡率以及肺癌死亡率的增加,对人体产生全方位的影响。所以将PM 2.5纳入我国室内空气质量检测范围和评价体系是加强空气污染防治、保障人体健康的必然要求。通过分析一些国家和国际组织的PM 2.5标准、我国《环境空气质量标准》及室内PM2.5的检测标准,对我国《室内空气质量标准》中PM2.5的浓度标准值进行探讨,为室内PM 2.5浓度的控制提出明确的目标与方向。     

Effect of particle size distribution on hydrodynamics of pneumatic conveying system based on CPFD simulation

The effect of particle size distribution on the hydrodynamics of dilute-phase pneumatic conveying system was analyzed using computational particle fluid dynamics (CPFD) simulation. The influence of a simulation parameter, i.e., correction factor of drag coefficient (k), on the hydrodynamics of pneumatic conveying system was determined via CPFD simulation. When results of simulation were compared with experimental data of previous studies, the average error of pressure drop per length predicted by the CPFD approach with the correction factor was below 4.4%. Saltation velocity and the pressure drop per unit length declined as the drag force coefficient increased. Simulation results also revealed that the pressure drop per length and the saltation velocity were decreased when the fine powder fraction in the particle size distribution was increased, although the width of particle size distribution was widened, and the standard deviation was increased. Finally, the Relative Standard Deviation (RSD) of pressure drop per length was measured and compared with median diameter (d₅₀), Sauter mean diameter, geometric mean diameter, and arithmetic mean diameter. The RSD of the Sauter mean diameter was 5.8%, approximately twice less than the RSD value of d₅₀ commonly used in pneumatic conveying.     

Air sampling with porous solid-phase microextraction fibers

A new, rapid air sampling/sample preparation methodology was investigated using adsorptive solid-phase microextraction (SPME) fiber coatings and nonequilibrium conditions for volatile organic compounds (VOCs). This method is the fastest extraction technique for air sampling at typical airborne VOC concentrations. A theoretical model for the extraction was formulated based on the diffusion through the interface between the sampled (bulk) air and the SPME coating. Parameters that affect the extraction process including sampling time, air velocity, air temperature, and relative humidity were investigated with the porous (solid) PDMS/DVB and Carboxen/PDMS coatings. Very short sampling times from 5 s to 1 min were used to minimize the effects of competitive adsorption and to calibrate the extraction process in the initial linear extraction region. The predicted amounts of extracted mass compared well with the measured amounts of target VOCs. Findings presented in this study extend the existing fundamental knowledge related to sampling/sample preparation with SPME, thereby enabling the development of new sampling devices for the rapid sampling of air, headspace, water, and soil.     

Guaranteed conditional design of the median chart with estimated parameters

A common assumption for most control charts is the fact that the process parameters are supposed to be known or accurately estimated from Phase I samples. But, in practice, this is not a realistic assumption and the process parameters are usually estimated from a very limited number of samples that, in addition, may contain some outliers. Recently, a median chart with estimated parameters has been proposed to overcome these issues and it has been investigated in terms of the unconditional Average Run Length (ARL). As this median chart with estimated parameters does not take the “Phase I between‐practitioners” variability into account, in this paper, we suggest to revisit it using the Standard Deviation of the ARL as a measure of performance. The results show that this Standard Deviation of the ARL–based median chart actually requires a much larger amount of Phase I data than previously recommended to sufficiently reduce the variation in the chart performance. Due to the practical limitation of the number of the Phase I data, the bootstrap method is recommended as a good alternative approach to define new dedicated control chart parameters.