关于地面水中悬浮物测定方法的改进

地面水非过滤性残渣(悬浮物)的分析测定,以前我们一直是采用总残渣减去过滤性残渣的分析方法(简称①法),该方法操作起来工作量大,分析结果相对误差大,精密度差。 今年,我们对方法进行了改进,并做了一系列的对比实验。该方法直接用滤纸将水样过滤,连同非过滤性残渣一起烘干称量,再减去原来滤纸的重量(简称②法)。在取样量都是50ml的情况下,相对误差缩小1～2倍,当取样量扩大到250 ml时,误差可达到规定的质控要     

悬浮物测定中有关问题

1最小取样量 :以所取水样中悬浮物含量5.0 mg为宜 ,低于此数则称量误差偏大。 2最大取样量 :一般样品水样中悬浮物最佳含量为 1 0～1 50 mg;粘度高、颗粒细的废水 (如造纸、酿造 )应少于 80 mg;对只含无机悬浮物水样取样中悬浮物多些则无妨。 3取样方法 :当分取水样量在50 ml以上时应使用量筒快速分取 ;当悬浮物浓度高分取量在 50 ml以下时 ,最好把移液管尖端小孔放大后分取水样。 4放冷 :以在干燥器中放冷30分钟再称量为宜 ,既达到冷至室温又不致因吸潮而使恒重困难悬浮物测定中有关问题@徐玉宏$阜阳市环境监测站!安徽阜阳236012…     

影响悬浮物测定结果的因素分析

通过对水中悬浮物的测定条件、取样量以及样品采集等方面的因素分析 ,找出了悬浮物监测结果产生误差的原因 ,提出了解决的方法和如何进行悬浮物测定的质量控制 ,进而提高监测数据的准确性和精密性     

地表水悬浮物分析中的几个问题

对地表水悬浮物分析中的样品烘干时间、次数和取样问题进行了实验,提出了减少悬的体操的烘干恒重次数、缩短分析过程呼时间的意见。同时提出悬浮物应单独采集样品,以提高悬浮物的分析质量。     

便携式分光光度法现场测定污染场地地下水中铬

在硫酸介质中,用Ce~(4+)将Cr~(3+)氧化成Cr~(6+),用便携式分光光度计现场测定铬污染地下水中的Cr~(3+)、Cr~(6+)和总铬。通过试验,对氧化还原反应的可行性、反应时间、酸度、Ce~(4+)加入量、DPC用量、稳定时间、干扰因素等条件优化,使该方法在0μg/L~1 600μg/L范围内线性良好,当取样量为25 m L时,方法检出限为12.5μg/L。用该方法测定实际样品,RSD为4.4%~8.2%。用该方法与标准方法同时测定Cr~(3+)、Cr~(6+)和总铬,2种方法的相对偏差为-4.4%~4.3%。     

滤纸法测定悬浮物的干扰及其消除

提出了滤纸法测定悬浮物时，水样的酸碱度，取样量的多少对悬浮物测定有直接的影响。通过实验验证，对于偏酸，偏碱的水样用酸碱中和后再过滤即可消除影响，取样量应根据悬浮物的不同而定。     

滤纸法测定水中悬浮物应注意的几个问题

水中悬浮物是指不能通过滤器并于 10 3～ 10 5℃烘干至恒重的固体物。目前悬浮物的测定大多采用滤纸法。该法涉及取样、过滤、洗涤、烘干、冷却、称量等分析过程 ,实际上是一种条件试验 ,测定时必须严格控制实验条件 ,每一环节都不得马虎大意 ,否则将使结果产生较大误差。现结合多年的实践 ,就悬浮物测定应注意的几个问题谈些看法。1　器具选择要适当称量瓶要选择高型的 ,高度以将滤纸折成扇形后放入称量瓶不影响盖瓶塞为宜 ,瓶塞磨口应严密 ,防止在称量、冷却过程中由于瓶塞不密而吸附水分。滤纸应选择中速定量滤纸 ,其直径大小应根据悬浮…     

污水样品中NO2-N测定时色度混浊的去除

Al( OH) 3 悬浮液 (按标准方法配制 )与Na OH( 2 5% ) Zn SO4( 1 0 % )两种方法去浊效果好 ,特别是 Na OH Zn SO4可达 1 0 0 %去浊能力。活性炭方法去色能力可达 1 0 0 %。如果采用Na OH Zn SO4 活性炭 ( 0 .2 ml 1 .0 ml 0 .5g)方法则既可脱色又可去浊 ,是测定有色混浊水样的行之有效的方法 ,回收率可达 1 0 2 %。注意事项 :1增加 Al( OH) 3 和活性炭用量 ,在絮凝过滤中 ,NO2 - N易造成滞留现象 ,测定结果偏低 ,回收率仅 85%。 2 Al( OH ) 3 加入量不宜过多 ,每1 0 0 ml水样加 2 ml为宜。污水样品中NO_2-N测定时色度混…     

无色透明样品测定氨氮时应注意的问题

1颜色 :若试液所呈黄色较浅 ,可直接取5 0 ml样品进行分析 ;若黄色较深 ,应适量少取 ;若呈现桔红色 ,则应先将样品进行适当稀释后 ,再进行测定。2混浊 :试液无混浊 ,说明样品中所含钙、镁等易于水解的金属离子较少 (酒石酸钾钠有掩蔽钙、镁的作用 ) ,不影响测定 ,可直接取样进行分析 ;若试液出现白色混浊 ,甚至出现白色沉淀 ,说明样品中所含钙、镁等金属离子较多 ,即硬度较高 ,应进行预处理。 3处理方法——絮凝沉淀法 :取 1 0 0 ml水样 ,加入 1 ml1 0 %的硫酸锌溶液 ,用2 5 %的氢氧化钠溶液调节 p H至 1 0 .5左右 ,混匀。静置 ,过滤 ,弃去…     

碘量法快速测定烟气SO2

YQ- 2型烟气采样机 ;1 2 5ml玻璃筛板吸收瓶。在吸收瓶中装适量吸收液 ,定量加碘标准使用液 ( 0 .0 0 5mol/L) ,使总体积为 50 ml,加 0 .5%淀粉溶液 1 ml,以 0 .5L/min采样。采样至吸收液由兰色变无色时关机并记录采样时间及流量计前温度、压力。按下式计算 SO2 浓度 :SO2 ( mg/Nm3 ) =( C× V1× 6 4× 1 0 0 0 ) /V0　　式中 C为 I2 标液浓度 ( mol/L) ;V1为 I2 标液用量 ( ml) ;V0 为标态下烟气采样体积 ( L) ;6 4为SO2 摩尔质量 ( g)。本法与标准方法相对偏差0 .3%～ 3.2 % ,两法结果无显著性差异。碘量法快速测定烟气SO_2@张…     

The influence of water vapour on the determination of glutaraldehyde vapour concentrations using an electrochemical fuel cell sensor

The effects of relative humidity (40-90% RH) and varying glutaraldehyde vapour concentrations (< 0.1 ppm) on the response of an electrochemical fuel cell sensor have been investigated over time (0-400 s). These studies have identified changes in the response of the fuel cell with time after sampling. In particular, it has been found that the maximum cell output for water vapour occurs ca. 10 s after sampling whilst the response to glutaraldehyde occurs much later (> 100 s). For mixtures containing different ratios of water and glutaraldehyde vapours, the time taken to reach maximum fuel cell response varies between 10 and 100 s, depending on the ratio of the two vapours. For instance, glutaraldehyde vapour containing higher % RH has been found to result in shorter times to reach maximum fuel cell response. A comparison was made between measuring glutaraldehyde vapour concentrations in the presence of water vapour at the maximum fuel cell response and also at a fixed interval (240 s) after sampling. Such a comparison resulted in a reduction in the standard error from 36% to 5% for a glutaraldehyde vapour sample (0.023 ppm) measured at different values of relative humidity (40 to 80%). Examination of the effect of the sample volume (30-60 ml) on the response of the fuel cell shows, as expected, an approximate doubling of the fuel cell response. Optimisation of the fuel cell measurement parameters to measure a 60 ml sample leads to a lowering of the limit of detection from 0.083 ppm (for data taken at the maximum cell response) to 0.017 ppm for data measured 240 s after sampling. In the light of recent reductions in the legal limits for exposure to glutaraldehyde, this has important implications for the measurement of glutaraldehyde vapour in the workplace.     

Application of portable gas chromatography-photo ionization detector combined with headspace sampling for field analysis of benzene, toluene, ethylbenzene, and xylene in soils

A method based on headspace (HS) sampling coupling with portable gas chromatography (GC) with photo ionization detector (PID) was developed for rapid determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in soils. Optimal conditions for HS gas sampling procedure were determined, and the influence of soil organic matter on the recovery of BTEX from soil was investigated using five representative Chinese soils. The results showed that the HS-portable-GC-PID method could be effectively operated at ambient temperature, and the addition of 15 ml of saturated NaCl solution in a 40-ml sampling vial and 60 s of shaking time for sample solution were optimum for the HS gas sampling procedure. The recoveries of each BTEX in soils ranged from 87.2 to 105.1 %, with relative standard deviations varying from 5.3 to 7.8 %. Good linearity was obtained for all BTEX compounds, and the detection limits were in the 0.1 to 0.8 μg kg^?1 range. Soil organic matter was identified as one of the principal elements that affect the HS gas sampling of BTEX in soils. The HS-portable-GC-PID method was successfully applied for field determination of benzene and toluene in soils of a former chemical plant in Jilin City, northeast China. Considering its satisfactory repeatability and reproducibility and particular suitability to be operated in ambient environment, HS sampling coupling with portable GC-PID is, therefore, recommended to be a suitable screening tool for rapid on-site determination of BTEX in soils.     

Development of a diffusive sampling method for determination of methyl isocyanate in air

A diffusive sampling method for determination of methyl isocyanate in air has been developed. A glass fibre filter impregnated with 1-(2-methoxyphenyl)piperazine in a commercially available diffusive sampling device was used to collect methyl isocyanate and the derivative formed was analysed with LC-MS/MS. The sampling rate was determined to be 15.6 ml min(-1), with a relative standard deviation of 7.3%. The sampler was validated for sampling periods from 15 min to 8 h, for relative humidities from 20% to 80% and for concentrations from I to 46 microg m(-3). A field validation was also made and the diffusive sampling results showed no difference compared to a pumped reference method. The impregnated filters have to be stored apart from the diffusive sampler housing and loaded into the sampler prior to each sampling.     

Impaction collection and slurry sampling for the determination of arsenic, cadmium, and lead in sidestream cigarette smoke by inductively coupled plasma-mass spectrometry

The slurry sampling technique has been applied for the determination of arsenic, cadmium and lead in sidestream cigarette smoke condensate (SS CSC) by inductively coupled plasma mass spectrometry (ICP-MS). The smoke collection system consists of a "fishtail" chimney in conjunction with an impaction trap and a mixed cellulose ester (MCE) backup filter for the SS CSC collection. The smoke condensates, collected at three different regions of the system (i.e. the inner wall of the chimney, the impaction trap and the MCE filter), were individually prepared and analyzed and showed that about 70 and 20% of Cd and Pb, respectively, were trapped by the impaction trap and the MCE filter with less than 5% trapped by the chimney. In contrast, about 60% of As was trapped by the impactor and a relatively high percentage of As, about 30%, was deposited onto the inner wall of the chimney. The uneven distribution of trace metals at each collection stage strongly suggested that the composition of smoke aerosol and the associated physical form of the analytes may be different. The yields of As, Cd and Pb for the sidestream cigarette smoke of the 1R4F reference cigarette were 29.5 +/- 2.4, 421 +/- 6.6 and 46.4 +/- 0.9 ng cigarette(-1)(n= 3) respectively, when the cigarette was smoked according to the smoking regime: 45 mL puff volume of 2-s puff duration at an interval of 30 s with 50% ventilation holes covered. The analytical results for the slurry sampling technique were also compared with other sample preparation techniques and show good agreement.     

气相色谱法同时测定地表水中的百菌清、环氧七氯和有机氯农药

用正己烷一次同时萃取地表水中的百菌清、环氧七氯和有机氯农药,萃取液脱水后进气相色谱仪进行测定。当取样体积为500ml时,方法检出限为0．01～0．02μg,／L,标准曲线相关系数大于0．999,方法精密度的相对标准偏差为1．5％-4．0％,加标回收率为81．6％～109．6％。该方法用于实际样品测定,结果令人满意。     

Validation of a diffusive sampler for NO2

A diffusive sampler for NO2, Willems badge, was validated in laboratory experiments and field tests. The collecting reagent for NO2 in the sampler is triethanolamine, and the analysis is based on a modified colorimetric method, the Saltzman method. The analysis was performed by a flow injection analysis (FIA) technique. The sampling rate for the sampler was determined to be 40.0 ml min-1. There was no effect of NO2 concentration or relative humidity on sampling rate, and the influence of sampling time was found to be small. The detection limit was 4 micrograms m-3 for a 24 h sample. The capacity is high enough to allow sampling of 150 micrograms m-3 for 7 days, which is twice the recommended Swedish short-term (24 h) guideline value as a 98-percentile over 6 months. In field tests, the sampler performed well, even at wind speeds higher than 2 m s-1, and at low temperatures. The overall uncertainty of the method was 24%. The sensitivity and capacity of the method also make it suitable for personal sampling for 2-8 h in working environments.     

Analysis of indoor gaseous formic and acetic acid, using radial diffusive samplers

A diffusive sampling method for the determination of gaseous acetic and formic acids, using a radial symmetry diffusive sampler, has been optimised for a 7-day exposure time in this study. Sampling rate determinations were performed on data obtained from a dynamic exposure chamber, simulating the indoor conditions of an empty, closed, room, at room temperature and minimal wind speed. Analysis has been performed by means of ion chromatography. The sampling rates for formic acid concentrations of 128 microg m(-3) and 1248 microg m(-3) were determined to be 91.2 +/- 3.9 ml min(-1) and 111.6 +/- 2.8 ml min(-1), respectively. The acetic acid sampling rate was independent of the concentration in the range 160 microg m(-3)-1564 microg m(-3), and amounted to 97.3 +/- 3.1 ml min(-1). Experimentally determined sampling rates showed deviations of 3% for acetic acid, and 3-21% for formic acid, in relation to theoretically derived values. The blank values were as low as 1.69 +/- 0.07 microg for formic acid and 1.21 +/- 0.14 microg for acetic acid, and detection limits lower than 0.5 microg m(-3) could be achieved, which is an improvement of 98-99% compared to previously validated diffusive sampling methods. This study describes the first step of an extended validation program in which the applicability of these types of samplers for the measurement of organic acids will be validated and optimised for the environmental conditions typical for museum showcases.     

Determination of acrylic acid in air by using diffusion denuder tubes combined with HPLC technique

A procedure for the determination of atmospheric acrylic acid in air at the microgram m-3 to mg m-3 level is described. Diffusion-based sampling, designed to discriminate gaseous analytes from their particulate counterparts, has been used. Acrylic acid is collected with an efficiency of > 98% in tubular denuders coated with sodium hydroxide-barium hydroxide-hydroquinone monomethyl ether, and analyzed by high performance liquid chromatography with UV absorbance detection. The detection limit is 2.9 micrograms m-3 at a flow rate of 0.5 L min-1 and 30 min sampling time. A precision (p = 0.95, n = 10) of 7.5% of the overall procedure was achieved at the 100 micrograms m-3 level. Results of laboratory studies concerning the effect of the coating reagent and the relative humidity on the sampling efficiency as well as possible interferences, in particular by ozone, and the elimination of these interferences are discussed. This method was developed to monitor workplace atmospheres as well as ambient air in industrial environments.     

气相色谱法测定固定污染源废气中氯甲基甲醚和二氯甲基醚的研究

氯甲基甲醚(CMME)和二氯甲基醚(BCME)属于确认人类致癌物,因此,建立精准、绿色的CMME和BCME检测分析方法十分必要。基于2,4,6-三氯苯酚+乙醇钠+乙醇衍生化体系,利用气相色谱法(电子捕获检测器)测定了固定污染源废气中的CMME和BCME,并且系统地优化了采样条件、衍生化条件,确定了衍生化产物的结构及衍生比率。结果表明：工作曲线相关系数均大于0.990;当采样量为10 L时,检出限均为0.003 mg/m³;当实际样品加标量分别为0.010、0.100、1.00 mg/m³时,测定结果的相对标准偏差分别为15%～16%、8.9%～13%、10%～11%,加标回收率分别为89.2%～90.8%、75.3%～78.6%、76.5%～77.2%。     

Evaluation of two adsorbents for diffusive sampling and thermal desorption-gas chromatographic analysis of monoterpenes in air

Tube type samplers with two different adsorbents, Chromosorb 106 and Tenax TA, were evaluated by laboratory experiments and field tests for simultaneous diffusive sampling of alpha-pinene, beta-pinene and delta 3-carene and subsequent thermal desorption-gas chromatographic analysis. No statistically significant effects of exposure time, concentrations of monoterpenes or relative humidity were found for samplers with Chromosorb 106 when running a factorial design, with the exception of the adsorption of delta 3-carene, for which some weak effects were noted. Samplers with Tenax TA were affected by the sampling time as well as the concentration for all terpenes, with a strong interaction effect between these two factors. The terpenes showed good storage stability on both adsorbents. No effect of back-diffusion was noted when using Chromosorb 106, while Tenax TA showed some back-diffusion effects. The uptake rates, in ml min-1, for the terpenes on Chromosorb 106 were 0.36 for alpha-pinene, 0.36 for beta-pinene and 0.40 for delta 3-carene. The corresponding average values on Tenax TA were 0.30 for alpha-pinene, 0.32 for beta-pinene and 0.38 for delta 3-carene. The field validation proved that diffusive sampling on Chromosorb 106 agreed well with pumped sampling on charcoal for stationary samples, while the personal samples indicated a discrepancy of 25% between Chromosorb 106 and charcoal samples. Tenax TA generally gave lower results than Chromosorb 106 in all field samples. Samplers packed with Chromosorb 106 could be used to monitor terpene levels in workplaces such as sawmills. The major advantages with this method are the sampling procedure, which is simple to perform compared to other techniques, the easily automated analysis procedure and the possibility to reuse the samplers.