Evaluation of gel permeation chromatography to Fourier transform infrared spectrometric detection using a modified thermospray for analysis of polystyrene samples

A heated gas flow modified thermospray was used to couple gel permeation chromatography (GPC) to Fourier transform infrared spectrometry (FTIR) for the analysis of the standard polystyrene samples. Effluents from the GPC column were evaporated and the solutes were deposited as a series of spots on the surface of a moving stainless steel belt (0.025 mm thickness × 13 mm width). The belt continuously transferred the spots into the diffuse reflectance (DRIFT) accessory of the FTIR spectrometer, enabling identification of the deposited solutes by measurement of the diffuse reflectance IR spectrum. The IR spectra of the separated components showed excellent agreement of the spectral features to those of standard FTIR spectra and no thermal degradation was observed. Received: 20 May 1996 / Revised: 17 October 1996 / Accepted: 28 November 1996     

高效液相色谱法测定大豆中13种三嗪类除草剂多残留量

建立了同时检测大豆中13种三嗪类除草剂多残留量的反相高效液相色谱(RP-HPLC)方法。样品经乙腈提取,凝胶渗透色谱和中性氧化铝SPE柱净化,然后采用RP-HPLC-二极管阵列检测法测定,外标法定量。对样品前处理和色谱分离条件进行了研究和优化。13种三嗪类除草剂在0.06~5.0 mg/L范围内线性良好,相关系数为0.9998~0.9999。在0.02~1.0μg/g浓度范围内,平均加标回收率在71.9%~101.9%之间,相对标准偏差为2.3%~10.7%。方法简便、快速,净化效果较好,可同时满足进、出口大豆中多种除草剂残留量的检验工作需要。     

Rhodium and palladium β-diketonate determination with on-line supercritical fluid extraction-high performance liquid chromatography via solid phase extraction

 An on-line system of supercritical fluid extraction (SFE) and high performance liquid chromatography (HPLC) via solid phase extraction (SPE) is described for the determination of palladium and rhodium 2,2,6,6-tetramethyl-3,5-heptanedione-(thd) as well as rhodium-acetylacetonate-(acac) and benzylacetonate-(bzac) chelates. The chelates were extracted with supercritical CO₂ from sand and humic acid, concentrated on SPE cartridges and analysed with HPLC. Two cartridge materials were tested and compared to off-line trapping. The percentage of the breakthrough and cartridge retained material were measured in liquid dichloromethane. The SFE conditions could be optimized to separate metal chelates during the extraction. The supercritical fluid (SF) behaviour of different ligands on rhodium were investigated. Received: 19 July 1996/Revised: 11 December 1996/Accepted: 14 December 1996     

Glass slides functionalized by 1‐carboxyethyl‐3‐methylimidazolium chloride for the determination of triazine herbicides in rice using high‐performance liquid chromatography

A novel and simple supported ionic‐liquid‐based solid‐phase extraction method for the determination of triazine herbicides in rice was developed. Glass slides were functionalized by an ionic liquid, 1‐carboxyethyl‐3‐methylimidazolium chloride, and were used for the simultaneous extraction of seven triazine herbicides in rice samples. The effects of the type of extraction solvent, the extraction time, the type and volume of loading solvent, and the type of eluting solvent on the extraction efficiency were investigated and optimized. Under the optimum operation conditions, the limits of detection for seven triazine herbicides in rice samples obtained by high‐performance liquid chromatography were 3.16–5.42 ng/g, which were lower than the maximum residue levels established by various organizations. The linear correlation coefficients were higher than 0.9975 in the concentration range of 0.015–1.08 μg/g for the seven triazine herbicides. The recoveries of the seven triazine herbicides at the two concentration levels of 0.15 and 0.45 μg/g are between 82.47 and 104.21%, with relative standard deviations of 0.69–9.19%. The intra‐ and inter‐day (n = 5) precisions for all triazine herbicides at the spiked level of 0.30 μg/g were 1.72–11.71%.     

Determination of Molecular Weight of PDPS Modified Copolymers

Molecular weight (MW) determinations of polydiphenylsiloxane‐co‐polydimethylsiloxane (PDPS/PDMS), polydiphenylsiloxane‐co‐polymethylphenylsiloxane (PDPS/PMPS) and polydiphenylsiloxane‐co‐polymethyl(3,3,3‐trifluoropropyl)siloxane (PDPS/PMFPS) statistical copolymers by gel permeation chromatography (GPC), GPC coupled differential viscometer (GPC‐DV) and light scattering (LS) techniques have been compared and discussed. The MW obtained by GPC‐DV in the PDPS/PDMS and the PDPS/PMPS series agreed with that obtained by LS very well. In PDPS/PDMS copolymers, it was found that the MW obtained by GPC was much lower than that obtained by GPC‐DV and LS, as Ph₂SiO) content is higher than 50 mol%. In PDPS/PMFPS copolymers, the MW obtained by GPC was far different from that obtained by GPC‐DV and the deviation decreased with increasing Ph₂SiO) mol%. The α values of the copolymers can be explained by the structure of the polymer in tetrahydrofuran (THF). Based on the relatively soluble copolymers, not only the differential refractive index increments (dn/dc) of PMPS, PDMS and PMFPS homopolymers but also that of the PDPS homopolymer in THF could be calculated by their corresponding copolymers.     

Selective enrichment procedures for the determination of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in environmental samples by gel permeation chromatography

An improved two-step clean up procedure involving alumina-silica column chromatography and gel permeation chromatography (GPC) of air particulate matter (NBS SRM 1648) and river sediment extracts and a GPC clean up procedure for marine biota samples are described for the determination of polycyclic aromatic hydrocarbons with two to five rings and selected polychlorinated biphenyl congeners, respectively. Bio-Beads SX-12 and SX-3 were used as packing materials. The recoveries obtained varied from 52 to 78% depending on the compound. Quantitative data for NBS SRM 1648 were comparable with those described previously for this sample.     

Systematic parallel investigation of RAFT polymerizations for eight different (meth)acrylates: A basis for the designed synthesis of block and random copolymers

Poly(acrylate)s as well as poly(methacrylate)s were successfully synthesized via reversible addition‐fragmentation chain‐transfer (RAFT) polymerizations using 2‐cyano‐2‐butyl dithiobenzoate (CBDB) as RAFT‐agent. Four different ratios of RAFT to initiator were screened for four acrylates and four methacrylates using automated parallel synthesizer robots. The reactions were monitored by gel permeation chromatography (GPC) and gas chromatography (GC). The knowledge obtained during this screening was used for the designed synthesis of block and random copolymers containing a water‐ and a non water‐soluble monomer. The results obtained from GPC analysis together with ¹H NMR spectroscopy demonstrate the possibility to design and prepare well‐defined block and random copolymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3831–3839, 2005     

Gel Permeation for the On Line Removal of Proteins from Plasma Samples Prior to HPLC

Abstract

Gel permeation chromatography (GPC) has been investigated for the on line removal of proteins from plasma samples prior to their analysis by HPLC. The results show that GPC is a mild and effective way to remove proteins from plasma samples. It can very well be coupled on line to HPLC, providing the solutes are suitable for preconcentration on the analytical column itself or on a small pre-column, after the GPC. Under these conditions excellent reproducibility and accuracy can be obtained.     

Phenylurea and Triazine Herbicides in the Garonne River (France) During High Flood and Low Water Periods

Abstract

Phenylureas and triazines were analysed by reversed-phase liquid chromatography using UV detection at 254 nm after an on-line preconcentration step on a PRP-1 copolymer in order to determine pesticides in river water at μg/1 level or lower. Running water was sampled in the Garonne from a station located at La Réole, upstream from Bordeaux and from a small tributary, the Dropt. Water samples were collected mainly at several periods between December 1989 and September 1990 at a low water time (December 1989) and during two high flood periods (February 1990 and May 1990). Atrazine, simazine, de-ethylatiazine, diuron, chlortoluron and isoproturon were detected and quantified. In the Garonne river, atrazine, simazine, de-ethylatrazine and diuron were usually present at the sampling time, whereas chlortoluron and isoproturon maximised during the winter flood (February). In the Dropt river, triazine concentrations were normally between 1.0 and 0.1 μg/1 and maximised at 2.2 μg/1 during the spring flood (June 1990). De-ethylatrazine/(Atrazine + Simazine) ratio seems to be significantly higher than in the Mississippi river and may be in relation to the use of simazine in the drainage basin. These data are in agreement with seasonal applications of phenylurea and triazine herbicides and hydrologic and pluviometric conditions.     

Derivatization of aromatic amines for analysis in ammunition wastewater II: Derivatization of methyl anilines by iodination with a Sandmeyer-like reaction

An analytical method for the determination of aromatic amines in water is introduced that uses iodination with a Sandmeyer-like reaction to replace the amino group by iodine in aqueous solution. The non-polar derivatives are extracted with pentane or toluene, separated with gas chromatography and sensitively detected with an ECD. Thirteen major metabolites of nitroaromatic explosives were investigated. The method was used to analyze these metabolites in water samples from the site of a former ammunition plant. The results are compared with the derivatization of aromatic amines via bromination of the aromatic ring. Received: 23 December 1996 / Revised: 31 January 1997 / Accepted: 8 February 1997     

Sequential flow-injection spectrophotometric determination of iron(II) and iron(III) by copper(II)-catalyzed reaction with Tiron

A flow injection method for the sequential determination of iron(II) and iron(III) was developed. It is based on the differential reaction kinetics of iron(II) and iron(III) with Tiron in a double-injection FI system. The proposed method employs the accelerating action of copper(II) for the oxidation of iron(II) in the presence of Tiron. A linear calibration graph is obtained for iron (II) and iron(III) in the concentration range 1.8 × 10^–5– 1.8 × 10^–4 mol/L; the throughput of samples is 30 injections/h. Received: 22 October 1996 / Revised: 4 December 1996 / Accepted: 10 December 1996     

A new non-enzymatic tracer for time-resolved fluoroimmunoassay of triazine herbicides

Summary The synthesis, characterization and application of a new kind of conjugate as tracer for use in time-resolved fluoroimmunoassay of triazine herbicides is described. Bovine serum albumin (BSA) served as carrier molecule, to which a triazine herbicide derivative and the Eu(III)-chelate W8044-Eu were subsequently coupled. The conjugate was characterized after each synthesis step by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The total composition was 1 BSA : 5.2 (±0.7) haptens : 5.1 (±0.4) fluorophores as calculated from the MALDI-MS data. The conjugate was successfully applied in competitive fluoroimmunoassays with sequential or simultaneous incubation of herbicide and tracer. With the sequential assay, the lowest detection limit was 0.1 g/l for terbutryn. Results of assays performed with microtiter strips were compared with those obtained with commercial micro affinity columns.     

Isothermal pressure dependence of the solubility of some triazines in supercritical CO2

 The solubility of two related series of each three triazine compounds has been determined in supercritical CO₂, at 40 °C and pressures between 80 and 220⋅10⁵ Pa. A high pressure small volume cell with adjustable optical path and built-in circulation pump has been constructed to be used with quartz windows in a Perkin Elmer UV-VIS spectral photometer. At 220 bar solubilities are between 0.3 and 25 g/L, dependent on the specific triazine structure. The isothermal pressure dependence of the solubility could be modelled using the pressure dependent dielectric constant of CO₂ as the only variable. Received: 30 October 1996/Revised: 3 April 1997/Accepted: 13 April 1997     

液体色谱,凝胶色谱分析低聚芳砜及其双烯大分子单体

本文用液相色谱和凝胶色谱对双酚A、双酚S型低聚芳砜及α,ω-双甲基丙烯酸聚芳砜酯大分子单体进行了组分分析,通过改合成条件、测定数均分子量等辅助手段确定液相色谱各峰的归属,计算其分子量及分子量分布指数,并对两种方法测定的结果进行了比较。用液相色谱观察低聚体每个组分的含量及其反应过程中的消长情况比凝胶色谱清晰。     

Comparison of Three Techniques for Lipid Removal from Seal Blubber: Gel Permeation,Acid Treatment,and Dialysis with Semipermeable Membrane

Abstract

Harbor seal blubber samples were analyzed for PCDD/Fs and PCBs by splitting the initial extract into three aliquots and applying three different techniques for lipid removal (the first step of sample cleanup methodology for GC-HRMS analysis): gel permeation chromatography (GPC), sulfuric acid treatment, and dialysis through semipermeable membrane. Correlation coefficients of analyte concentrations obtained from three sets of replicate samples ranged from 0.965 to 0.994. In addition, a number of seal blubber samples were processed without pre-extraction using only the dialysis technique. The analyte concentrations in these samples correlated well with the analyte concentrations obtained from dialyzed blubber extracts (correlation higher than 0.998). For all analyses (PCDD/Fs, NO- and MO-PCBs) the average surrogate standard recoveries for the GPC and dialysis techniques varied from 68 to 111%. The recoveries for PCDD/Fs and MO-PCBs standards ranged from 61 to 89% and 36 to 43% for the NO-PCBs when the acid treatment technique was used. Dialysis was proven to be an efficient technique for lipid removal of biological samples in comparison with the GPC and acid treatment techniques.     

s‐Triazine‐based hyperbranched polyethers: Synthesis,characterization, and properties

A series of s‐triazine‐based hyperbranched polyethers (HBPE) have been synthesized to obtain thermostability but flexible polymers by an interfacial polycondensation of different diols as A₂ and cyanuric chloride as B₃ monomers using A₂ + B₃ approach in the presence of a phase transfer catalyst. The polymerization reaction parameters are optimized, and the results indicate that the optimum conditions for the interfacial polycondensation are a 2:3 mole ratio of cyanuric chloride to diol using butanediol, benzyldimethylhexadecyl ammonium chloride as the catalyst, dichloromethane as the organic solvent, and a three‐step procedure with keeping the reaction mixture at different low temperatures for 2h/2h/5h. Other techniques such as high‐temperature solution, one‐step polycondensation, and transesterification were also carried out to synthesize the HBPE but proved to be not suitable due to large number of side reactions. The synthesized polymers were characterized by FTIR, ¹H NMR, and ¹³C NMR spectroscopy, hydroxyl number determination, solution viscosity measurements, and GPC analysis. The thermal behavior of the hyperbranched polymer was investigated by thermogravimetric analysis and differential scanning calorimetry. All the results were compared with those from an analogous linear polyether, obtained from 2‐methoxy‐4,6‐dichloro‐s‐triazine and butanediol by using the same polymerization technique. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3994–4004, 2010     

Gel permeation for the on line removal of proteins from plasma samples prior to HPLC

Gel permeation chromatography (GPC) has been investigated for the on line removal of proteins from plasma samples prior to their analysis by HPLC. The results show that GPC is a mild and effective way to remove proteins from plasma samples. It can very well be coupled on line to HPLC, providing the solutes are suitable for preconcentration on the analytical column itself or on a small pre-column, after the GPC. Under these conditions excellent reproducibility and accuracy can be obtained.     

Quantitative determination of specified chlorobiphenyls in fish with capillary gas chromatography and its use for monitoring and tolerance purposes

A gel permeation (GPC) clean-up procedure of fish samples in combination with capillary gas chromatography is used for the determination of individual chlorobiphenyls. The described method is compared with a more universal method based on saponification. Starting from a tolerance for PCB's expressed as a technical Aroclor, tolerance for some specified individual chlorobiphenyls are derived. It is shown that these tolerances for specified individual chlorobiphenyls can be used for monitoring and tolerance purposes. Rejection obtained with the Dutch PCB tolerance agree with rejections obtained with individual tolerances.     

Simple solution for a complex problem: proanthocyanidins, galloyl glucoses and ellagitannins fit on a single calibration curve in high performance-gel permeation chromatography

This study was undertaken to explore gel permeation chromatography (GPC) for estimating molecular weights of proanthocyanidin fractions isolated from sainfoin (Onobrychis viciifolia). The results were compared with data obtained by thiolytic degradation of the same fractions. Polystyrene, polyethylene glycol and polymethyl methacrylate standards were not suitable for estimating the molecular weights of underivatized proanthocyanidins. Therefore, a novel HPLC-GPC method was developed based on two serially connected PolarGel-L columns using DMF that contained 5% water, 1% acetic acid and 0.15 M LiBr at 0.7 ml/min and 50 °C. This yielded a single calibration curve for galloyl glucoses (trigalloyl glucose, pentagalloyl glucose), ellagitannins (pedunculagin, vescalagin, punicalagin, oenothein B, gemin A), proanthocyanidins (procyanidin B2, cinnamtannin B1), and several other polyphenols (catechin, epicatechin gallate, epicallocatechin gallate, amentoflavone). These GPC predicted molecular weights represented a considerable advance over previously reported HPLC-GPC methods for underivatized proanthocyanidins.     

Designed chimaeric galactosyl-mimodye ligands for the purification of Pseudomonas fluorescens beta-galactose dehydrogenase

Two chimaeric galactosyl-mimodye ligands were designed and applied to the purification of Pseudomonas fluorescens galactose dehydrogenase (GaDH). The chimaeric affinity ligands comprised a triazine ring on which were anchored: (i) an anthraquinone moiety that pseudomimics the adenine part of NAD+, (ii) a galactosyl-mimetic moiety (D-galactosamine for ligand BM1 or shikimate for ligand BM2), bearing an aliphatic 'linker', that mimics the natural substrate galactose, and (iii) a long hydrophilic 'spacer'. The mimodye-ligands were immobilised to 1,1-carbonyldiimidazole-activated agarose chromatography support, via the spacer's terminal amino-group, to produce the respective mimodye adsorbents. Both immobilized mimodyes successfully bound P. fluorescens GaDH but failed to bind the enzyme from rabbit muscle. Adsorbent BM1 bound GaDH from green peas and Baker's yeast, but adsorbent BM2 failed to do so. The mimodye-ligand comprising D(+)-galactosamine (BM1), compared to BM2, exhibited higher purifying ability and enzyme recovery for P. fluorescens GaDH. The dissociation constants (KD) of BM1 and BM2 for P. fluorescens GaDH were determined by analytical affinity chromatography to be 5.9 microM and 15.4 microM, respectively. The binding capacities of adsorbents BM1 and BM2 were 18 U/mg adsorbent and 6 U/mg adsorbent, respectively. Adsorbents BM1 and BM2 were integrated in two different protocols for the purification P. fluorescens GaDH. Both protocols comprised as a common first step DEAE anion-exchange chromatography, with a second step of affinity chromatography on BM1 or BM2, respectively. The purified GaDH obtained from the protocols using BM1 and BM2 showed specific activities equal to 1077 and 854 U/mg, respectively. The former is the highest reported so far and the enzyme appeared as a single band after sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis.