Development of an epoxy-based monolith used for the affinity capturing of Eschericha coli bacteria

An epoxy-based monolith has been developed for use as hydrophilic support in bioseparation. This monolith is produced by self-polymerization of polyglycerol-3-glycidyl ether in organic solvents as porogens at room temperature within 1 h. One receives a highly cross-linked structure that provides useful mechanical properties. The porosity and pore diameter can be controlled by varying the composition of the porogen. In this work, an epoxy-based monolith with a high porosity (79%) and large pore size (22 μm) is prepared and used in affinity capturing of bacterial cells. These features allow the passage of bacterial cells through the column. As affinity ligand polymyxin B is used, which allows the binding of gram-negative bacteria. The efficiency of the monolithic affinity column is studied with Escherichia coli spiked in water. Bacterial cells are concentrated on the column at pH 4 and eluted with a recovery of 97 ± 3% in 200 μL by changing the pH value without impairing viability of bacteria. The dynamic capacity for the monolithic column is nearly independent of the flow rate (4 × 10⁹ cells/column). Thereby, it is possible to separate and enrich gram-negative bacterial cells, such as E. coli, with high flow rates (10 mL/min) and low back pressure (<1 bar) in a volume as low as 200 μL compatible for real-time polymerase chain reaction, microarray formats, and biosensors.     

Green analytical chemistry in sample preparation for determination of trace organic pollutants

The principles of green chemistry are applied to not only chemical engineering and synthesis, but also increasingly analytical chemistry. We describe environment-friendly analytical techniques applied to isolate and to enrich trace organic pollutants from solid and aqueous samples. Amounts of organic solvents used in analytical laboratories are reduced by applying solventless extraction, extraction using other types of solvent, assisted solvent extraction and miniaturized analytical systems.     

Carbon sequestration and estimated carbon credit values as measured using <Superscript>13</Superscript>C labelling and analysis by means of an optical breath test analyser

Recent developments in optical systems (isotope-selective non-dispersive infrared spectrometry) for breath testing have provided a robust, low-cost option for undertaking ¹³C analysis. Although these systems were initially developed for breath testing for Helicobacter pylori, they have an enormous potential as a soil science research tool. The relatively low cost of the equipment, US$15,000–25,000, is within the research budgets of most institutes or universities. The simplicity of the mechanisms and optical nature mean that the equipment requires relatively low maintenance and minimal training. Thus methods were developed to prepare soil and plant materials for analysis using the breath test analyser. Results that compare conventional mass spectrometric methods with the breath test analyser will be presented. In combination with simple ¹³C-plant-labeling techniques it is possible to devise methods for estimating carbon sequestration under different agronomic management practices within a short time frame. This enables assessment of the carbon credit value of a particular agronomic practice, which can in turn be used by policy makers for decision-making purposes. For global understanding of the effect of agricultural practices on the carbon cycle, data are required from a range of cropping systems and agro-ecological zones. The method and the approach described will enable collection of hard data within a reasonable time.     

高分子多孔微球富集－HPLC法测定水体中的有机磷

本文提出应用国产高分子多孔微球－ＧＤＸ系列富集－反相高效液相色谱法测定废水中久效磷、乐果、甲基对硫磷三种有机磷农药分析方法。三种不同型号色谱固定相（ＧＤＸ－１０２，ＧＤＸ－３０１和ＧＤＸ－５０１）对水体中ｎｇ／ｍＬ级久效磷、乐果和甲基对硫磷的富集效率分别达到８５％、８２％和９３％以上。采用μ－ＢｏｎｄａｐａｋＣ１８作固定相，以６０％甲醇水溶液作流动相，对三种有机磷农药的分离度可达到１．２以上。本法用于分析水体中有机磷农药，结果令人满意。     

水中挥发性有机有害物质分析的痕量富集研究──疏水富集效果的评价

用通过容量（ＱＢ）作为疏水富集效果的评价指标，ＱＢ可根据反相液相色谱的保留体积或容量因子来求得。本文列出了若干水中典型有机有害物质在反相色谱填料上的通过容量，并与从前沿色谱得到的数据进行了比较和讨论。     

2,3-Dihydroxypyridine-loaded cellulose: a new macromolecular chelator for metal enrichment prior to their determination by atomic absorption spectrometry

New macromolecular chelators have been synthesized, by loading 2,3-dihydroxypyridine (DHP) on cellulose via linkers -NH-CH₂-CH₂-NH-SO₂-C₆H₄-N=N- and -SO₂-C₆H₄-N=N-, and characterized by elemental analysis, TGA, IR, and CPMAS ¹³C NMR spectra. The cellulose with DHP anchored by the shorter linker had better sorption capacity (between 69.7 and 431.1 mol g^–1) for Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II), and Fe(III)) than the other (51.9–378.1 mol g^–1); the former was therefore studied in detail as a solid extractant for these metal ions. The optimum pH ranges for quantitative sorption (recovery 97.6–99.8%) on this matrix were: 7.0–9.0, 6.0–9.0, 3.0–8.0, 6.0–8.0, 6.0–9.0, 6.0–7.0, and 2.0–6.0 respectively. Desorption was quantitative with 0.5 mol L^–1 HCl and 0.5 mol L^–1 HNO₃ (for Pb). Simultaneous sorption (at pH 7.0) of all metal ions other than Fe(III) was possible if their total concentration did not exceed the sorption capacity (lowest value). The recovery of seven metal ions from their mixture at pH 6.0 was nearly quantitative when the concentration level of each metal ion was 0.2 g mL^–1. The optimum flow rate of metal ion solutions for quantitative sorption of metal onto a column packed with DHP-modified cellulose was 2–7 mL min^–1, whereas for desorption the optimum flow rate for the acid solution was 2–4 mL min^–1. The time needed to reach 50% of the total loading capacity (t_1/2) was <5 min for all the metal ions except Ni and Pb. The limit of detection (blank+3s) was from 0.70 to 4.75 g L^–1 and the limit of quantification (blank+10s) was between 0.79 and 4.86 g L^–1. The tolerance limits for NaCl, NaBr, NaI, NaNO₃, Na₂SO₄, Na₃PO_4, humic acid, EDTA, Ca(II), and Mg(II) for sorption of all metal ions are reported. The column packed with DHP-anchored cellulose can be reused at least 20 times for enrichment of metal ions in water sample. It has been used to enrich all the metal ions in pharmaceutical and water samples before their determination by flame AAS. RSD for these determinations was between 1.1 and 6.9%.     

Some applications of multidimensional gas chromatography to the enrichment of minor components in essential oil analysis

The use of multidimensional gas chromatography (MDGC) for the analysis of essential oils is gaining in importance. A rarely used application consists in the enrichment of minor components through a MDGC system provided with a cold trap between trap column and analytical column. Under suitable conditions, in fact, the cold-trap can store a trapped compound (or a fraction) for a long time. Consequently, the same fraction can be heart-cut from several successive chromatographic runs on the first column and stored together in order to accumulate trace compounds; afterwards the accumulated fraction can be injected in the analytical column. The possibilities of this technique will illustrated through some examples of analysis of complex essential oils.     

复合螯合剂—活性碳柱现场富集天然水中痕量元素

本文提出了一种适于野外条件下的富集天然水中多个痕量元素的方法。研究了四种螫合剂在活性碳上的吸附特性及多种溶剂、酸、碱洗脱螯合剂的特性。研究了20多个元素在不同pH值下的螯合剂——活性碳的静态和动态吸附性能。采用直径10mm,长80mm柱可在现场富集天然水中不同形态的痕量元素。加入回收率为90～108％。天然水中大量的Na、K、Ca、Mg等元素不被吸附。可用多种分析方法测定。     

磷酸三丁酯萃淋树脂富集水中痕量酚类化合物的研究

本文对磷酸三丁酯（ＴＢＰ）萃淋树脂为柱填料，研究了富集水中酚类化合物及其洗脱条件。结果表明，以ＴＢＰ萃淋树脂为富集剂，水样ｐＨ值为１－７，以３０ｍｌ／ｍｉｎ的流速通过吸附柱，用８ｍｌ０．１ｍｏｌ／Ｌ的ＮａＯＨ洗脱，多种酚类化合物回收率在９７％－１０３％。此外还试验了地面水中常见干扰物的影响，该方法富集倍数达１２５倍，最低检测限０．５μｇ／Ｌ。对实际样品１－１００μｇ／Ｌ范围内的测定相对标准偏差４．     

Micropreparative system for enrichment of capillary GC effluents

An automated system for preparative gas chromatography with capillary columns is described. The effluet from the capillary column is switched to the FID detector or to the traps by means of a Live-T switching device. The pneumatics is controlled by a microprocessor so that repetitive sampling can be performed over a period of days in order to enrich sufficient amount of material for NMR or other spectroscopic methods. The effluent containing the compounds is collected in glass tubes filled with column packing material (e.g. Chromosorb coated with 3% OV - 101, crosslinked). The trap temperatue can be adjusted from + 20°C to ? 80°C, depending on the trapping material and volatility of trapped substances. The analysis of enriched substances or chromatographic fractions can be performed by thermal desorption of the same traps or by solven elution. The recovery of enriched substances is higher than 90%. High capacity and resolution for enrichment of trace components are obtained with the aid of a double column-double oven system. Examples of such applications are given.