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1.
气相色谱法具有较高的灵敏度和良好的线性关系。按照EPA QA/QC的要求,将该方法运用于实际样品分析。结果表明。水中汽油检出限为0.04mg/L。水中苯系物检出限为0.003-0.005mg/L,土壤中汽油检出限为0.5mg/kg,土壤中苯系物检出限为0.005-0.008mg/kg。样品加标回收率为97.1%~106.8%。变异系数为2.1%~4.6%,结果令人满意。  相似文献   

2.
气相分子吸收光谱法测定水中的氨氮   总被引:1,自引:0,他引:1  
应用气相分子吸收光谱法测定水中的氨氮,测定了该方法的检出限、精密度和准确度,并对实际样品进行了测定和加标回收实验,发现该方法的精密度及准确度均较好,在实际应用当中有一定的优越性,同时也存在一些问题有待改善。  相似文献   

3.
在沉积物样品元素分析中样品预处理即样品的消解是一个重要步骤。微波样品消解技术近十几年来受到普遍关注。本文小结了这一技术在沉积物元素分析应用中的一些重要问题,包括消解试剂体系的选择,消解程序和时间的确定等。  相似文献   

4.
在脂肪提取器中,以石油醚洗涤提取一定量土壤样品中的PCB,并以KOH溶液对提取液进行碱解处理。提取液经进一步净化、脱水、浓缩后,以GC-ECD进行分析,采用外标法根据标准样品和实测样品PCB_3特征峰高比进行定量。对20g土样进行处理分析,方法最低检出限为1.5×10~(-4)mgPCB_3/kg土样。  相似文献   

5.
1.范围和应用 1.1 本方法用于测定2,3,7,8-TCDD。 1.2 这个色谱/质谱(GC/MS)方法适合于测定城市污水和工业污水中的2,3,7,8-TCDD。用方法625可以检查样品中的2,3,7,8-TCDD。得到肯定结果后,必须使用方法613对其进行最后的定性确证和定量测定。 1.3 本方法对于2,3,7,8-TCDD的检出限(MDL,其定义在节14.1)列于表1。  相似文献   

6.
BOD5考核样品的测定过程受到诸多因素的影响,时常出现一些不理想的分析结果。通过确定考核样品的CODcr值与其BOD5值之间的关系,预测其BOD,值,以此预测值来确定恰当的稀释倍数,并对不在最佳状态的测定值进行合理的校正等,可以有效地提高BOD,考核样品的成功率,具有很高的应用价值。  相似文献   

7.
概述了欧盟生态标志计划,介绍了欧盟生态标志计划的实施程序,包括标志产品种类划分和产品标准确定程序、标志申请和审批程序、正在研究制订的标志产品种类等,介绍了英国生态标志计划,对欧盟生态标志计划中的生命周期评价进行了评述,并对欧盟生态标志计划中的问题进行了讨论。  相似文献   

8.
为了对柴油机排放PAHs在气相和颗粒相中的分配进行研究,采用了滤膜串联"PUF/XAD-2/PUF"吸附柱的方法采集柴油机排气中的气相和颗粒相PAHs,使用程序升温挥发(PTV)技术结合气相色谱-质谱联用(GC-MS)方法对PAHs进行了定性和定量分析。所用分析方法重复性的相对标准偏差(RSD)低于6.1%,检出限范围...  相似文献   

9.
固相萃取-气相色谱/质谱法测定水中多环芳烃   总被引:24,自引:2,他引:22  
建立了固相萃取-气相色谱/质谱联用测定水中多环芳烃(PAHs)的分析方法.优化了固相萃取条件。结果表明,固相萃取效率高、萃取时间短,采用MS的选择离子检测方式对实际水样中PAHs进行定性定量分析,平均回收率在80.4%~115%之间,相对标准偏差为7.03%~18.5%,方法的检出限在0.010~0.020μg/L之间。通过实际样品中PAHs的分析表明,该法快速,溶剂用量少,能满足痕量分析的要求。  相似文献   

10.
建立了热解析-固相微萃取-气相色谱法测定空气样品中挥发性有机化合物的分析方法,并对色谱分离条件、玻璃针筒保存样品的稳定性、固相微萃取萃取纤维、萃取时间、色谱进样时间等条件进行了优化,9种挥发性有机化合物的峰面积与其质量浓度在所测范围内有较好的线性关系,相对标准偏差<8.8%,检出限为0.05~0.75 μg/100 mL,满足实际空气样品测定需要。  相似文献   

11.
The aim of this study was to assess the performance of a method of analyzing pesticides in rice by using pressurized liquid extraction (PLE) and to perform a preliminary monitoring by using that method. The instrumental quantification limit, instrumental detection limit, method quantification limit, and method detection limit were determined. PLE temperature was also optimized for 6 target pesticides. Mean recoveries of spiked rice with target pesticides (4 ng/g and 40 ng/g) were 83%–109% with the repeatability of the analysis, represented as relative standard deviations, ranged from 1.3% to 11% (n = 5) for PLE at 130°C. These results were satisfactory according to the method of positive list in Japan. In a preliminary analysis of 10 target pesticides in 54 commercial rice samples, ferimzone was detected in only one unpolished rice sample.  相似文献   

12.
Huang H  Sorial GA 《Chemosphere》2006,64(7):1150-1156
Trace level perchlorate analysis in water initiated a new development in the Ion Chromatography (IC) technology. Maintenance of a low detection limit may be highly affected by the operating conditions of the IC system. In this paper the homoscedasticity of the IC system within the calibration concentration range, the effect of the system drift on the calibration curve and the effect of the self regeneration suppressor (SRS) current on the detection limit were investigated. The experimental results were evaluated by statistical methods such as the Cochran test and the lack of fit test. The detection limits were obtained by two ways. One through method detection limit (MDL) and the other through detection limit from the calibration curve (DTC). The Cochran test results revealed the homoscedasticity of the IC system. The effect of system drift on the calibration curve was noticed by the lack of fit test. MDL yielded a lower but less reliable detection limit than DTC. An acceptable detection limit can be achieved under the lower SRS current (100 mA).  相似文献   

13.
For the first time, the concepts of limit of detection and limit of quantification, commonly used in analytical chemistry, are applied to the field of active biomonitoring with terrestrial mosses, using the controls as blanks so that the limits indicate the error associated with the transplant technique. The application of these concepts to data corresponding to Hg concentrations in the surroundings of a chlor-alkali plant and a power plant, makes interpretation of the results easier by providing better spatial and temporal coherence. This procedure may allow improvement in the standardization of active biomonitoring techniques as it is applicable to all kinds of biomonitors. One disadvantage of the application of the limit of detection and limit of quantification is that they only take into account the alpha error, or risk of false positives, and do not take into account the beta error, or risk of false negatives.  相似文献   

14.
氯气校正法(HJ/T70-2001)是测定高氯废水化学需氧量的国标方法,为了减少样品测定过程带来的环境污染,研究在不改变HJ/T70-2001氧化体系及测试条件的情况下,将取样体积由20 mL减半为10 mL,试剂的使用量相应减半,对方法的检出限、相对误差、相对标准偏差等指标进行验证。结果表明,该方法的检出限符合要求,准确度较高,精密度较好,可用于高氯废水化学需氧量的测定。  相似文献   

15.
The aim of this study was to develop an analytical method for the determination of residues of organophosphorus and carbamate pesticides which are widely used in Tunisia. This method involves a liquid-liquid extraction procedure followed by liquid chromatography tandem mass spectrometry (LC/MS/MS) for the identification and quantification of compounds. Ionization of molecules was performed by the electrospray mode. Multiple reactions monitoring (MRM) was the acquisition mode used for the monitoring of two MS/MS transitions for each compound. The average recoveries obtained, at three different fortification levels, ranged between 65% and 106% for most of the pesticides studied, except for methamidophos (lower than 25%).The linearity of the method was in the range of 5 to 50 μ g/L with a correlation coefficient from 0.995 to 0.999, depending on the analyte. The estimated limit of detection and limit of quantification were 2 μ g/L and 5 μ g/L, respectively. The precision of the analytical procedure was satisfactory and the coefficients of variation, evaluated at three concentration levels were lower than 15% for most pesticides studied. The application of the method was investigated in a population of agricultural workers chronically exposed to various pesticides some of which, such as carbofuran, carbendazim, methomyl and pirimicarb, were detected in some serum samples.  相似文献   

16.
A simple method for the determination of dimethyl fumarate (DMFu) in silica gel pouches has been developed. The gas chromatographic behaviour of DMFu was investigated; the instrumental method, based on EI mass spectrometry coupled with an Ion Trap Detector operating whether in full scan mode or in MS/MS mode was also investigated. Several factors have been evaluated and optimized during the development process: solvent and temperature of extraction, type of stationary phase in capillary column. The analytical procedure consists of two steps as follows: (a) the sample preparation using 10 g of sample extracted with acetonitrile in an ultrasonic, heated bath and (b) the determination by gas chromatography-ion trap mass spectrometry. Mass spectrometry in conjunction with chromatographic separation is a very powerful combination for identification of an analyte in the extract in spite of selective detectors employed with GC, such as ECD, FPD and NPD, that offer only limited specificity. Blank samples show no interfering peaks in the areas of interest, so the specificity of the method was assured under the investigated GC/MS conditions. The method has been validated in terms of recovery, repeatability, linearity, detection limits and measurement uncertainty. The results obtained meet both the method validation criteria and requirements of the European/National legislation. The method was verified to be accurate with 97 % mean recoveries at 0.05 mg/kg and 1.00 mg/kg levels; the repeatability (expressed as RSD %) was found to be better than 15 %. Good linearity was found in the range between 0.05 μg/mL and 5.0 μg/mL and a value of R2 > 0.9998 was calculated. The procedure ensures high specificity and a good sensitivity with detection limit (ld) of 0.02 mg/kg and quantification limit (LOQ) of 0.05 mg/kg. This procedure has been successfully applied for the analysis of several hundred of real samples collected during a monitoring control plan started last year in our country. All samples exceeding the maximum allowed level of DMFu (0, 1 mg/kg) were confirmed by GC/MS/MS (ITD) for a higher degree of confidence in identification. The main advantages of this method include: rapidity, simplicity (few, simple steps), reliability, cheapness, no need for long and difficult clean-up and evaporation steps, high specificity by using GC/MS and GC/MS/MS, availability for routine monitoring.  相似文献   

17.
A sensitive and simple procedure is descrobed for the analysis of the mycotoxin patulin. The method involves extraction of patulin from the sample, silica gel column chromatographic clean-up, preparation of the aniline imine, thin-layer chromatographic separation on silica gel, hydrogen chloride hydrolysis of the imine, and fluorophore formation from the liberated aniline with fluorescamine. A linear calibration curve was obtained for the 10-100 ng range and the limit of detection was 5 ng. Recoveries of patulin from samples of apple juice spiked at 50-500 ppb were quantitative.  相似文献   

18.
GOAL, SCOPE, AND BACKGROUND: Diesel exhaust is believed to consist of thousands of organic constituents and is a major cause of urban pollution. We recently reported that a systematic separation procedure involving successive solvent extractions, followed by repeated column chromatography, resulted in the isolation of vasodilatory active nitrophenols. These findings indicated that the estimation of the amount of nitrophenols in the environment is important to evaluate their effect on human health. The isolation procedure, however, involved successive solvent extractions followed by tedious, repeated chromatography, resulting in poor fractionation and in a significant loss of accuracy and reliability. Therefore, it was crucial to develop an alternative, efficient, and reliable analytical method. Here, we describe a facile and efficient acid-base extraction procedure for the analysis of nitrophenols. MATERIALS AND METHODS: Diesel exhaust particles (DEP) were collected from the exhaust of a 4JB1-type engine (ISUZU Automobile Co., Tokyo, Japan). Gas chromatography-mass spectrometry (GC-MS) analysis was performed with a GCMS-QP2010 instrument (Shimadzu, Kyoto, Japan). RESULTS: A solution of DEP in 1-butanol was extracted with aqueous NaOH to afford a nitrophenol-rich oily extract. The resulting oil was methylated with trimethylsilyldiazomethane and subsequently subjected to GC-MS analysis, revealing that 4-nitrophenol, 3-methyl-4-nitrophenol, 2-methyl-4-nitrophenol, and 4-nitro-3-phenylphenol were present in significantly higher concentrations than those reported previously. DISCUSSION: Simple acid-base extraction followed by the direct analysis of the resulting extract by GC-MS gave only broad peaks of nitrophenols with a poor detection limit, while the GC-MS analysis of the sample pretreated with (trimethylsilyl)diazomethane gave satisfactorily clear chromatograms with sharp peaks and with a significantly lowered detection limit (0.5 ng/ml, approximately 100 times). CONCLUSION: The present method involving an acid-base extraction, in situ derivatization, and GC-MS analysis has shown to be a simple, efficient, and reliable method for the isolation and identification of the chemical substances in DEP.  相似文献   

19.
A simple but reliable procedure was developed to analyze dimethyl sulfoxide (DMSO) in wastewater. The isotope DMSO_d6 was used as the internal standard to ensure accuracy. The DMSO was reduced with stannous chloride and measured as dimethyl sulfide (DMS) with purge-and-trap gas chromatography/mass spectrometry. The method detection limit was at the sub-microgram-per-milliliter level; precision, as measured by standard deviation, was better than +/- 0.5%; and the recoveries were between 95 and 105% at the level of 2 microg/mL. The procedure could use standard analytical instrumentation used for volatile organic compound analysis. A field study was conducted to validate the method and quantify DMSO concentration range in the three water pollution control plants (WPCPs) in the city of Philadelphia, Pennsylvania. Results showed that, when a local chemical facility discharged, DMSO concentration could be as high as 12 mg/L in the influent to a WPCP. This would lead to the formation of a toxic "canned corn" DMS odor during the treatment processes.  相似文献   

20.
A method for the high resolution, high sensitivity analysis of polluted air for individual organic compounds is described. Samples collected from 50 mL of ambient air at 87 K (liquid argon) are Injected without use of a valve into a silica capillary column which Is then temperature programmed from — 30°C to 180°C. Hydrocarbons (4 to 10 carbons) as well as carbonyl compounds, chlorinated compounds and terpenes can be identified and quantified. The detection limit, not strongly dependent on carbon number, is estimated to be 0.3 ppbc in a 50 mL sample. Use of small samples eliminates the need to remove water vapor, a procedure which might jeopardize sample integrity.  相似文献   

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