固体进样元素分析技术在农业领域的应用

重金属是农产品、农田土壤、肥料、饲料等农业样品中的重要污染物,传统的实验室分析方法需繁琐的前处理,耗时费力,无法满足重金属的快速检测需求。固体进样元素分析技术具有简化样品前处理、便捷、绿色、高效等优势,在农业领域中元素的快速检测分析中具有良好的应用前景。通过对固体进样元素分析技术,包括样品导入技术和电热蒸发、电感加热、激光烧蚀、X射线荧光光谱、激光诱导击穿光谱等固体进样分析系统进行综述,并对这些技术在农业领域中的应用做了进一步的梳理。固体进样分析技术已在农业样品中元素的快速检测、现场监测、风险评估等工作中发挥着举足轻重的作用,相信随着仪器研发、材料科学、机器学习等新兴技术的快速发展,其结构小巧、使用简单、分析迅速等优势将会充分发挥,为农业领域中质量安全监管提供一种更为有效、可靠的快速检测手段。     

Field air analysis with SPME device

Solid-phase microextraction (SPME) devices were used for a wide scope of air-monitoring including field sampling and analysis of volatile organic compounds (VOCs), formaldehyde, and particulate matter (PM) in air. Grab (instantaneous) and time-weighted average (TWA) sampling were accomplished using exposed and retracted SPME fibers, respectively. Sampling time varied from 1 to 75 min, followed by analysis with a gas chromatograph (GC). A portable GC equipped with unique, in-series detectors: photoionization (PID), flame ionization (FID), and dry electrolytic conductivity (DELCD), provided almost real-time analysis and speciation for common VOCs during an indoor air quality surveys. Indoor air samples collected with SPME devices were compared with those collected using conventional National Institute for Occupational Safety and Health (NIOSH) methods. Air concentrations measured with the SPME device were as low as 700 parts-per-trillion (ppt) for semi-volatile organic compounds. SPME methodology proved to be more sensitive than conventional methods, and provided a simple approach for fast, cost-effective sampling and analysis of common VOCs in indoor air. SPME technology combined with fast portable GC reduced the sampling and analysis time to less than 15 min. The configuration offered the conveniences of immediate on-site monitoring and decision making, that are not possible with conventional methods. In addition, SPME fibers were applied to sampling of particulate matter in diesel engine exhaust. Linear uptake and particulate build-up on the fiber were observed. Preliminary research suggests that SPME fibers could also be applied to sampling of airborne particulate matter.     

Methods of multivariate data analysis applied to the investigation of fen soils

Fen soils from two sites of the Rhin-Havel-Luch, a peatland in the north-east of Germany, have been investigated. The samples have been collected in two horizons, representing different degrees of degradation and mineralisation of peat. Gravimetric measurements, energy dispersive X-ray fluorescence (EDXRF), elemental analysis, and ¹H low resolution nuclear magnetic resonance (LR-NMR) of the fen soil samples have been performed. By multivariate analysis of all the experimental data, especially by the principal component analysis (PCA) and by the cluster analysis, respectively, it was possible to classify the fen soils, to identify their characteristic properties, to detect temporal and local variations, and to prove representative field sampling. Furthermore, the correlation between variables of the applied analytical methods could be interpreted in context to the composition of fen soils and mutual influences of their properties.     

恶臭成分的仪器分析方法研究进展

对恶臭污染物质的测定内容包括恶臭物质的总体浓度、具体成分及相应的浓度水平。随着痕量气体分析技术水平的提高,增加受控恶臭污染物的种类成为可能。恶臭物质因种类繁多、性质差异大,分析方法多种多样。该文根据不同恶臭物质的物理、化学特性,结合国内外最先进的分析技术和标准,从恶臭物质样品采集、前处理以及不同分析仪器的选择方面,综述了目前恶臭成分的仪器分析方法研究进展。     

热重-流动载气液滴微吸附体系的建立及其应用于卷烟纸的热解产物分析

将液相微萃取技术用于流动载气条件下热重逸出组分的吸附,自行设计和建立了热重-流动载气液滴微吸附(TG-GFSDMA)联用装置,并结合气相色谱-质谱(GC-MS),建立了可以进行热重逸出组分分析的检测系统.使用该系统并结合划分温度段连续取样法,研究了卷烟纸在主失重区的热失重行为及其热解逸出产物,并考察了热重载气流量对液滴...     

GC analysis of gas in halogen lamps using a new sampling device

Summary A new type of gas sampling device was constructed to improve the analysis of the gas in halogen lamps. Low levels of gases such as O₂, CH₄, C₂H₄ and CH₃Br could be determined by the techniques worked out.     

A versatile set up for implementing different flow analysis approaches: Spectrophotometric determination of nickel in steel alloys

An arrangement capable of implementing the four principal types of flow analysis processes, monosegmented flow analysis (MSFA), flow injection analysis with multicommutation and binary sampling (FIA-MBS), flow injection analysis with sandwich sampling (FIA-SS) and sequential injection analysis (SIA) is described. The core of the flow manifold is a six-way solenoid valve that is assembled together with three three-way solenoid valves in order to provide a versatile flow network. Software was written in VisualBasic 3.0 to give a friendly working structure allowing the user to easily choose the flow variables and the kind of flow system. The reliability of the flow set up for implementation of the four flow analysis systems was evaluated by means of the spectrophotometric determination of nickel in steel alloys, based on the formation of a colored complex with dimethylglyoxime (DMG). The performances of the four different flow methodologies were compared. The reagent consumptions per determination were 4.0 mg of triethanolamine, 6.0 mg of potassium persulfate and 0.6 mg of DMG. When the flow set up was instructed through the software to implement MSFA, FIA-MBS, and FIA-SS approaches, a sampling frequency of 40 samples/h was obtained, while 30 samples could be processed per hour in the SIA mode. The precisions, evaluated as the relative standard deviation of ten determinations were 0.7%, 1.6%, 1.8% and 3.1% for the MFSA, FIA-MBS, FIA-SS and SIA systems, respectively. The results for determination of nickel in steel alloys presented good agreement with the reference method (ICP OES), showing no significant difference at a confidence level of 95%.     

Sampling volatile organic compounds using a modified solid phase microextraction device

Headspace solid phase microextraction (headspace SPME) has been demonstrated to be an excellent solvent-free sampling method. One of the major factors contributing to the success of headspace SPME is the concentrating effect of the fiber coating toward organic compounds. The affinity of the fiber coating toward very volatile analytes, such as chloromethane, may, however, not be large enough for detection at the parts per trillion concentration level. Static headspace analysis, on the other hand, is very effective for these very volatile compounds. As analyte volatility decreases, the sensitivity of static headspace analysis drops. The complementary nature of these two sampling methods can be exploited by combining the SPME device with a gastight syringe. The sensitivity of the new sampling device is better than that of SPME for very volatile compounds or that of static headspace analysis for less volatile compounds. This new method can sample a wide range of compounds from chloromethane (b.p. −24°C) to bromoform (b.p. 149°C) with estimated limits of detection at the low parts per trillion level.     

System for the generation of standard gas mixtures of volatile and semi-volatile organic compounds for calibrations of solid-phase microextraction and other sampling devices

Standard gases are used for quality control and quality assurance, development of analysis methods and novel air sampling devices. The use of solid-phase microextraction (SPME) and other novel technologies for research in the area of air sampling and analysis requires systems/devices for reliable standard gas generation and sampling. In this paper we describe a new gas standard generating system for volatile organic compounds (VOCs) and semi-VOCs that was designed, built, and tested to facilitate fundamental and applications research with SPME. The system provided for the generation of a wide range of VOC/semi-VOC concentrations and mixing various standard gases, estimation of detection limits, testing the effects of sampling time, air temperature and relative humidity, testing the effects of air velocity and ozone on sampling/extractions. The system can be also used for calibrations of analytical instrumentation, quality control and quality assurance checks, and cross-validations of SPME with/and other sampling techniques.     

Evaluation of a Continuous Composite Sampler for Volatile Organic Compounds in Water

Abstract

The high volatility and low water solubility of volatile organic compounds (VOCs), make the collection of representative samples difficult. The standard grab sampling method only gives information of that moment in time when the sample is taken. When the composition of VOCs is varying, continuous composite sampling will give a more representative sample. However, no thorough evaluation of its use for VOCs has been reported.

The use of an automatic continuous composite sampler for the analysis of VOCs in water was studied. The causes and magnitude of the VOCs losses during the sampling process were determined.

Adsorbent cartridges were used to trap the VOCs escaping from solution during the sampling process. Sorption phenomena occurring on the containers and/or tubings were also evaluated. Sorption losses were much more significant than volatilization losses.

The results indicate that a modified version of this sampler can be an alternative for the long term sampling of water for VOC analysis.     

“Short-end injection” rapid analysis capillary electrochromatography

Summary The analytical benefits of using “short-end injection” rapid analysis in capillary electrochromatography (CEC) have been demonstrated. These include extremely rapid analysis times, the potential for voltage gradients to be exploited, high hydrodynamic loadability and the convenience of using short detachable lengths of packed capillaries. “Short-end injection” rapid CEC has been demonstrated for the analysis of a standard neutral test mixture and three pharmaceutically active steroids. Extremely short analysis times were obtained due to the increased effective field strength experienced by the packed bed and the reduced length to the detector. In conjunction with an appropriate sampling rate, peak efficiencies in excess of 554,000 plates/metre (i.e. 41,500 plates per column) could be obtained. The repeatability of retention time and peak area compared favourably to that obtained using a conventional CEC approach.     

Real-time Event Recognition and Analysis System for Nanopore Study

To achieve fast and accurate analysis of weak current signal of nanopore-based single molecule detection, an online data process based on adaptive threshold algorithm with data buffering technique and finite impulse response filtering was designed. A software system based on the data process was developed for online recognition and analysis of nanopore events during nanopore experiment. To testify the performance of the algorithm and software system, ideal signals with different noise level (20–100 pA) were generated at bandwidth ranging from 3 kHz to 100 kHz. The result showed that this software system was stable at different bandwidths and sampling rates and could be used in analyzing the signals at high noise. The proposed software system was further applied to aerolysin nanopore experiment for detection of poly(dA)₄ molecules. The results showed that the data process system could be applied in real nanopore recording experiment with high accuracy and speed.     

悬浊液直接进样非火焰原子吸收法测定蔬菜样品中微量铬的研究

本文通过用直接悬浊液进样原子吸收法对新鲜蔬菜中铬的测定,研究了各种实验条件,并建立了实际测定新鲜蔬菜中微量元素的方法。该法将可用于食品。     

Performance and characteristics of a trace gas analyzer for the determination of volatile organic compounds in air

An instrument has been developed and tested for the continuous measurement of volatile organic compounds (VOC) in air. The system consists of a gas chromatograph equipped with a dedicated sampling device that allows the sample to be transferred to a cooled microtrap via sampling loops (10, 100, 250 ml) or via a direct pump transfer to the trap. The microtrap is placed in the chromatographic oven just below a modified split-splitless injector, allowing direct liquid injection for calibration of the system; the injector is in communication with the sampling valve equipped with the loop and the sampling pump. The system allows 24-hour sampling and analysis of a large number of VOC (up to 25 individual hydrocarbons ranging from C2 C9) and also polar volatile organic compounds PVOC. Thanks to the particular trap geometry, a minimum consumption of liquid nitrogen (between 150 300 ml) is needed for each analytical run and no water managing system is normally required for humid air samples.     

微流控进样阿达玛变换显微荧光成像单细胞分析

将微流控芯片用于单细胞进样,以自制阿达玛变换显微荧光成像分析系统进行成像检测,讨论了影响单细胞进样和荧光成像的主要因素,并对花粉细胞DNA含量进行定量分析。结果表明：微流控进样技术与HT显微成像技术相结合,可有效可靠地应用于单细胞分析中,所测定的三个玉帘花粉的DNA含量分别为124．4、123．9和62．9pg。     

水中痕量有机污染物质富集技术的发展──聚氨酯类泡沫富集回收水中的多环芳烃

用聚氨酯类泡沫（PUF）富集回收蒸馏水、自来水与河水中的多环芳烃，方法简便，回收率高，适于现场采集各种不同类型的水样．GC／MS分析中，氘化芘在IL蒸馏水中的检出限为26ng／L；而在HPLC／FLD分析中，苯并（k）荧蒽、苯并（a）芘、二苯并（a，h）蒽、苯并（ghi）在IL蒸馏水中的检出限分别为0.86、0.51、2.1和3.0ng／L.     

Precision of an automated all-glass capillary gas chromatography system with an electron capture detector for the trace analysis of estrogens

Subnanogram detection of steroids has become increasingly important today. One applicable method for gas chromatographic determination of subnanogram quantities of estrogens as halogenated derivatives is electron capture detection. HFB-derivatives of 7 different estrogens were automatically injected onto a prolonged narrow bore wall-coated glass capillary column. Normal split injection could not be used for this trace analysis because of too much loss of sample. Only small amounts of sample were available from which double analysis had to be performed. Cross-contamination of the automatic sampling system as well as precision of retention times and peak areas were determined. The type of injection described showed better quantitative results compared to the splitless injection technique. All details of the system used together with the results are this discussed in this paper.     

Automated high-capacity sorption probe for extraction of organic compounds in aqueous samples followed by gas chromatographic analysis

An automated high-capacity sorption device for GC analysis of ultra trace components has been developed. The scope of the presented technique was to combine the simplicity of solid-phase microextraction (SPME) with the high extraction efficiency of the stir bar sorptive extraction technology. Sorptive extractions of water samples were performed using polydimethylsiloxane (PDMS) rubber tubing (120 microl) mounted onto a glass rod. The sampling procedure was carried out by a robotic autoinjector. Since the setup is fully automated, unattended and precise time-controlled extraction of samples is possible and makes quantitation with non-equilibrium extractions feasible. The sorption probes are easy to exchange, which facilitates off-line/in-field sampling. The system was evaluated with a test mixture of 44 environmentally hazardous compounds. Detection limits were found to be in the sub-ppt region. The performance of the system was demonstrated with the analysis of polycyclic aromatic hydrocarbons in urban snow.     

Etude de la repartition de l'uranium dans les roches par la methode des traces de fission. Application a l'echantillonage en vue du dosage de l'uranium

The distribution of uranium in two different rock species: basalt from the Fangataufa atoll (located in Polynesia) and granit from the Hoggar mountains (located in Sahara) was studied by the fission track method. The two distributions observed appear quite different: uranium is uniformly distributed in the vitrous part of the basalt while in granit it is located on the intergranular joints. Applying the sampling model proposed by A. D. WILSON to the observed distributions of uranium, the weight of the analytical sample corresponding to a required sampling error can be estimated. Results show that representative sample weights of the bulk powdered material, as usually obtained by milling, are about some tenths of milligrams for basalt and more than the grams for granit (for uranium analysis). So, in trace element analysis, the sampling error could be more important than the analytical one. This fact could explain the relatively poor accuracy of trace determinations in rock samples (including the reference samples).      

Ultraviolet detection of amino acids based on their on-column conjugation with cupric cation using a disposable electrophoresis microdevice

A method for fast sensitive ultraviolet detection of amino acids was developed with a disposable electrophoresis microdevice. The microdevice was conveniently constructed by fixing a fused-silica capillary with a sampling fracture to a printed circuit board. During the separation process, the on-column conjugation of amino acids with cupric cation led to the ultraviolet absorption at 232 nm that could be directly used for fast analysis of amino acids. Using 20 mM boric acid (pH 5.3) containing 5 mM cupric cation and 0.015% Tween 20 as running buffer, this method could completely separate lysine, glutamine and serine at a sampling time of 2 s at +210 V and a separation voltage of +1800 V (240 V/cm). The theoretical plate numbers were from 140,000 to 205,000 plates/m. The linear ranges were from 10 to 500 μM for lysine, 20-1000 μM for glutamine and serine. The novel protocol had been successfully used to detect amino acids in beverage samples with recovery more than 85.0%, indicating its advantages and potential analytical application in different fields.