Some ion-exchange resins for anion-chromatography

The quaternary ammonium salts, n-butyltrimethylammonium iodide, 1,1,3,3-tetramethylbutyltrimethylammonium iodide, n-octadecyltrimethylammonium iodide and tri-n-dodecylmethylammonium iodide were synthesized from commercially available amines and together with n-hexadecyltrimethylammonium bromide tested for retention by a series of macroreticular resins (XAD-2, XAD-4, XAD-7, XAD-8 and XAD-11) for use as "surface" ion-exchangers in the chromatography of anions. Exchange-capacity studies of the coated resins showed that the non-polar XAD-2 and XAD-4 resins had retention characteristics superior to those of the polar resins and that pore size in the resin was more important than surface area per unit weight of resin. Tri-n-dodecylmethylammonium salts in XAD-2 gave the highest exchange capacity, with best retention under elution conditions. Columns prepared from this anion-exchanger were used to separate and analyse simple mixtures of anions (chloride, nitrate and sulphate) each within the 1-30 ppm range, by single-column operation with indirect photometric detection and also by conductivity detection with background-ion suppression. Though of use for the determination of anions in simple mixtures, the resolution and performance were generally poorer than those displayed by a commercial (Dionex) column. This is at least partly attributable to the inferior column-packing properties of the granular XAD-resin.     

用不同方法收集端红玉兰(Magnolia Rufidula Law et Zhou)鲜花香气的研究

利用XAD-4树脂吸附、微波加热后XAD-4树脂吸附、减压水蒸汽蒸馏加尾气吸附．乙醚浸提等方法收集端红玉兰(Magnolia rufidula Law et zhou)鲜花香气，并用色-质联用法分析。乙醚浸提方法获得的香成分最丰富，与其它方法收集的香成分基本一致。微波加热法所需样品少，收集时间短，效果良好。     

Determination of Trace Amounts of Cobalt in Natural Water Samples as 4-(2-Thiazolylazo) Recorcinol Complex After Adsorptive Preconcentration

ABSTRACT

A chromatographic method has been established for the determination of trace amounts of cobalt by preconcentration on Amberlite XAD-16 resin as cobalt/4-(2-Thiazolylazo) resorcinol (TAR) complexes. The conditions (e.g. pH, resin amounts, matrix ions) affecting the recovery of cobalt from aqueous solution were studied. The method has been employed for the determination of cobalt in natural water samples.     

Neutron irradiation in activation analysis: A new rabbit for the NBSR

Two radiochemical separation methods were developed for the separation of ⁸⁸Y from a SrS target (3.2 g, pressed into a 19 mm disc) and Al (2.5 g, the capsule contained the target). The first method was based on solvent extraction technique using undiluted TBP/HNO₃ system and the second was an extraction chromatography using a column packed with TBP-impregnated Amberlite XAD-4 resin. A simple procedure was used for the impregnation of the XAD-4 resin with TBP. For both methods concentrated nitric acid was used for extraction/adsorption and 2M HCl for back extraction/elution of ⁸⁸Y. In terms of recovery of ⁸⁸Y, the solvent (TBP)-impregnated resin showed better results (average 91.2% compared to 88.9% with extraction).     

Synthesis and Application of a New Acrylic Ester Resin for Recycling SIPA from its Water Solution

A new acrylic ester polymer YWB-7 resin was prepared and characterized. The properties of YWB-7 resin were compared with those of the commercial Amberlite XAD-7, Diaion HP2MG and hypercrosslinked macroporous polymer NDA-150 resins. Both surface area and micropore area of YWB-7 resin were bigger than those of XAD-7 resin and HP2MG resin. The YWB-7 resin was successfully employed to recycle 5-sodiosulfoisophthalic acids （SIPA） from its solutions with and without methanol.     

Derivatization-Gas Chromatographic Analysis of Nalidixic Acid in Tablets

A simple and improved gas chromatographic method has been developed for the quantitative analysis of nalidixic acid. The method is based on the derivatization of nalidixic acid with pentafluorobenzyl bromide in acetone, using potassium carbonate as a base-catalyst. The derivative obtained was chromatographed on an OV-101 column and the pentafluorobenzyl ester of cinoxacin was used as an internal standard. The method was satisfactorily applied to the analysis of nalidixic acid in tablets, and the results agree well with those obtained using the UV absorption spectrophotometric method.     

2-噻吩乙酸在三种不同树脂上的吸附热力学和动力学研究

通过静态吸附实验,研究了XAD-4,NDA-100和ND-90吸附树脂对水溶液中2-噻吩乙酸的吸附热力学及动力学特性,结果表明,2-噻吩乙酸在XAD-4树脂上是单层吸附,符合Langmuir等温吸附方程,吸附过程符合准一级动力学吸附方程.2-噻吩乙酸在NDA-100和ND-90树脂上的吸附也能用Langmuir等温吸附方程表示,但并不只是单层吸附,而主要是由毛细管凝聚和微孔填充作用造成的吸附,吸附过程可分为大孔和中孔区的吸附以及微孔区的吸附两个阶段,两个阶段都符合准一级动力学吸附方程.     

Comparisons of sorption of aquatic humic matter by DAX-8 and XAD-8 resins from solid-state (13)C NMR spectroscopy's point of view

Aquatic humic solutes were separated in parallel by the non-ionic macroporous DAX-8 and XAD-8 resins from four different fresh water sources. On average, the sorptive power of the DAX-8 resin does not differ systematically from that of the XAD-8 resin. The DAX-8 resin seems to have more precise column characteristics compared with the XAD-8 resin. There was no significant difference between the major elemental compositions of the parallel humic-solute bulks obtained by these two resins. According to the (13)C NMR spectroscopy the content and quality of aliphatic carbons, especially those representing terminal methyl groups or methylene carbons, were the most systematic and powerful discriminating factors between the humic extracts obtained by these two resins. Generally speaking the DAX-8 and XAD-8 resins seem to isolate humic-solute bulks almost equally, although the content of aliphatics is slightly greater for the former, producing mixtures with similar structural compositions for general purposes. The structural composition and quantity of the humic-solute mixture isolable with a weakly basic DEAE-cellulose anion exchange resin differs partially from any humic fraction obtained by non-ionic sorbing solids. The environmental impact was also visible on the quality of the structural fine-chemistry of the different humic isolates obtained both by the DAX-8 and XAD-8 resins.     

4-(4'-Methyltetrafluorophenyl)-2,3,5,6-tetrafluorobenzyl bromide: a new electrophoric derivatizing reagent

Commercially-available 4,4'-dimethyloctafluorobiphenyl was converted in a single step to 4-(4'-methyltetrafluorophenyl)-2,3,5,6-tetrafluorobenzyl bromide (MTFP-TFBBr) for the purpose of providing a new electrophoric derivatizing reagent. When reacted with this reagent, 2-fluoro-O6-(2'-hydroxyethyl)hypoxanthine, a model analyte, gave a mixture of isomeric products (apparently substituted at N7 and N9, analogous to its known reaction with pentafluorobenzyl bromide), and 53 femtograms of the mixture was detected at S/N = 10 by gas chromatography electron capture mass spectrometry (GC-EC-MS). As intended, the volatility of the MTFB-TFBBr derivative was much less (two-fold) than that of the corresponding pentafluorobenzyl derivative. It is anticipated that MTFB-TFBBr sometimes will be useful in providing an electrophoric derivative that encounters less background noise in analysis by electrophore derivatization/GC-EC-MS.     

Application of tryptamine as a derivatizing agent for the determination of airborne isocyanates. Part 5. Investigation of tryptamine-coated XAD-2 personal sampler for airborne isocyanates in workplaces.

The development of an efficient solid sorbent personal sampler with increased convenience for sample collection in workplaces is described. Several solid sorbents were coated with tryptamine, and sampling tubes were prepared with the coated sorbents. These tubes were evaluated for the collection of phenyl isocyanate vapour generated in a commercial test atmosphere generation system that permits the simultaneous collection of up to 12 uniformly loaded samples. Tryptamine-coated XAD-2 resin was shown to be the most efficient solid sorbent for the collection of airborne phenyl isocyanate. The optimum amount of tryptamine needed for coating XAD-2 resin was investigated.     

Derivatization-Gas Chromatographic Determination Of Mercaptans

Abstract

After being precipitated as silver mercaptides, mercaptans were converted into their pentafluorobenzyl derivatives in high yields by reaction with sodium sulfide and then with pentafluorobenzyl bromide. The derivatives were analyzed down to sub-ppm levels by gas chromatography with a flame ionization detector. It is possible that the above method is developed for the trace analysis of mercaptans in environmental matrices.     

High-volume sampling of airborne polychlorobiphenyls with amberlite xad-2 resin

Polyurethane foam, polyurethane foam coated with DC-200, Florisil, and Amberlite XAD-2 resin have been evaluated in a small-scale comparative study of their ability to sample airborne polychlorobiphenyls. XAD-2 resin has an excellent collection efficiency for tetrachlorobiphenyl at 1 l min^-1 flow rates and is also suitable for high-volume air sampling. A high-volume air sampler was modified to sample both particulate and vapor-phase polychlorobiphenyls by incorporating the XAD-2 resin behind a glass fiber filter. When the sampling system was operated at a flow rate of 0.7 m³ min^-1 for 24 h, the collection efficiencies for tetrachlorobiphenyl and Aroclor 1221 were 96.5% and 83.0%, respectively.     

A new method of plutonium speciation in sea water

A new method of plutonium speciation in large volume of sea water was developed by using adsorption of Pu(IV)-Xylenol Orange chelate and Pu-Arsenazo chelate on XAD-2 resin, respectively. The tetravalent plutonium ion reacts selectively with Xylenol Orange in acid solution and that adsorbed on XAD-2 resin. Total plutonium can be collected onto the resin in the form of its Arsenazo-III complex. The determination of plutonium then was carried out by alpha-ray spectrometric method after decomposition of organic complexes and ion exchange separation. The present method is confirmed for convenient and rapid preconcentration procedure for plutonium shipboard chemistry.     

Nickel determination in saline matrices by ICP-AES after sorption on Amberlite XAD-2 loaded with PAN

In the present paper, a solid phase extraction system for separation and preconcentration of nickel (ng g⁻¹) in saline matrices is proposed. It is based on the adsorption of nickel(II) ions onto an Amberlite XAD-2 resin loaded with 1-(2-pyridylazo)-2-naphthol (PAN) reagent. Parameters such as the pH effect on the nickel extraction, the effect of flow rate and sample volume on the extraction, the sorption capacity of the loaded resin, the nickel desorption from the resin and the analytical characteristics of the procedure were studied. The results demonstrate that nickel(II) ions, in the concentration range 0.10–275 μg l⁻¹, and pH 6.0–11.5, contained in a sample volume of 25–250 ml, can be extracted by using 1 g Amberlite XAD-2 resin loaded with PAN reagent. The adsorbed nickel was eluted from the resin by using 5 ml 1 M hydrochloric acid solution. The extractor system has a sorption capacity of 1.87 μmol nickel per g of Amberlite XAD-2 resin loaded with PAN. The precision of the method, evaluated as the R.S.D. obtained after analyzing a series of seven replicates, was 3.9% for nickel in a concentration of 0.20 μg ml⁻¹. The proposed procedure was used for nickel determination in alkaline salts of analytical grade and table salt, using an inductively coupled plasma atomic emission spectroscopy technique (ICP-AES). The standard addition technique was used and the recoveries obtained revealed that the proposed procedure shows good accuracy.     

预衍生化-气相色谱-质谱法测定水中酸性除草剂

向水样中逐滴加硫酸(1+2)调节至pH<2,用二氯甲烷先后提取3次。合并的提取液用无水酸性硫酸钠脱水,并蒸缩至约1 mL后用吹氮法蒸干。加入丙酮溶解残渣后,在催化剂碳酸钾存在下用五氟苄基溴进行衍生化,溶于正己烷中的衍生产物用极性硅胶柱进行纯化。先用甲苯-正己烷(1+6)混合溶剂淋洗净化柱以除去衍生产物中的干扰副产物,然后用甲苯-正己烷(9+1)从净化柱上将目标化合物洗脱,所得洗脱液经浓缩并加入八氟联苯作内标后供气相色谱-质谱分析。气相色谱中用HP-5MS毛细管色谱柱进行分离,质谱分析中用负化学离子源及选择离子扫描(SIM)。此方法对测定的14种酸性除草剂的检出限(3S/N)均小于10 ng.L-1。对所述14种除草剂做了回收试验,结果在66.0%~117.0%之间,测定7次的相对标准偏差均小于9%。     

New anion-exchange solid-phase extraction support used for preconcentration and determination of lead in water samples by flame atomic absorption spectrometry

A new chelating resin was prepared by coupling Amberlite XAD-2 with Brilliant Green through an azo spacer. The resulting resin has been characterized by FTIR spectrometry, elemental analysis, and thermogravimetric analysis and studied for the preconcentration and determination of trace Pb(II) ions from solution samples. The anionic complex of Pb(II) and iodide was retained on the resin by the formation of an ion associate with Brilliant Green on Amberlite XAD-2 in weak acidic medium. The optimum pH value for sorption of the metal ion was 5.5. The sorption capacity of the functionalized resin is 53.8 mg/g. The chelating resin can be reused for 20 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 103% was obtained for the metal ion with 0.1 M EDTA as the eluting agent. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The resin was subjected to evaluation through batch binding and column chromatography of Pb(II). The equilibrium adsorption data of Pb(II) on modified resin were analyzed by Langmuir, Freundlich, and Temkin models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined to be 0.192, 13.189, and 3.418 at pH 5.5 and 25 degrees C. The method was applied for lead ion determination in tap water samples.     

Azocalix[4]pyrrole Amberlite XAD-2: New polymeric chelating resins for the extraction, preconcentration and sequential separation of Cu(II), Zn(II) and Cd(II) in natural water samples

Two novel azocalix[4]pyrrole Amberlite XAD-2 polymeric chelating resins were synthesized by covalently linking diazotized Amberlite XAD-2 with calix[4]pyrrole macrocycles. The chelating resins were used for extraction, preconcentration and sequential separation of metal ions such as Cu(II), Zn(II) and Cd(II) by column chromatography prior to their determination by UV/vis spectrophotometry or flame atomic absorption spectrophotometry (FAAS) or inductively coupled plasma atomic emission spectroscopy (ICP-AES). Various parameters such as effect of pH on absorption, concentration of eluting agents, flow rate, total sorption capacity, exchange kinetics, preconcentration factor, distribution coefficient, breakthrough capacity and resin stability, were optimized for effective separation and preconcentration. The resin showed good ability for the separation of metal ions from binary and ternary mixture on the basis of pH of absorption and concentration of eluting agents. The newly synthesized resins showed good potential for trace enrichment of Cu(II), Zn(II) and Cd(II) metal ions, especially for Cu(II), as compared to the earlier reported resins. The synthesized resins were recycled at least 8-10 times without much affecting column sorption capacity. The presented method was successfully applied for determination of Cu(II), Zn(II) and Cd(II) in natural and ground water samples.     

Preconcentration of trace metals on Amberlite XAD-4 resin coated with dithiocarbamates and determination by inductively coupled plasma-atomic emission spectrometry in saline matrices

Preconcentration of Cd(II), Cu(II), Mn(II), Ni(II), Pb(II) and Zn(II) in saline matrices on Amberlite XAD-4 resins coated with ammonium pyrrolidine dithiocarbamate (APDC) and piperidine dithiocarbamate (pipDTC) and subsequent determination by inductively coupled plasma atomic emission spectrometry were studied. Parameters such as effect of pH, effect of HNO(3) concentration on elution of metals from resin were studied. The results show that Amberlite XAD-4 coated with APDC was more efficient in the recovery of metal ions compared with Amberlite XAD-4 coated with pipDTC, in the concentration range of 0.1-200 mug l(-1), for 1 g of Amberlite XAD-4 coated resin. The detection limits for Cd(II), Cu(II), Mn(II), Ni(II), Pb(II), Zn(II) are 0.1, 0.4, 0.3, 0.4, 0.6, 0.5 mug l(-1), respectively, for resin coated with APDC and 0.7, 1.0, 0.8, 0.9, 1.7 and 1.2 mug l(-1) for resin coated with pipDTC. The effect of diverse ions on the determination of aforesaid metals was studied. The method was applied for the determination of trace metal ions in artificial sea water and natural water samples. The results were compared with extraction AAS method.     

Determination of lovastatin acid in serum by gas chromatography/mass spectrometry

The acid form of lovastatin, an HMG-CoA reductase inhibitor, was analyzed by gas chromatography/negative-ion chemical ionization mass spectrometry after derivatization with pentafluorobenzyl bromide and bis-(trimethylsilyl)trifluoroacetamide (BSTFA). Mass spectrometry of this derivative produced a dominant [M-181]- ion under chemical ionization conditions using ammonia as the reagent gas. The limit of detection was approximately 2 pg injected on column.     

Isolation of organic water pollutants by xad resins and carbon

The recovery efficiencies of XAD resins −2, −4, −7, and −8 and of resin mixtures were measured using distilled water samples containing 13 organic pollutants. An equal-weight mixture of XAD-4 and XAD-8 was most efficient. XAD-2 and XAD-4/8 were further terted and found effective using tapwater. Carbon was tested as a sorbent for materials not well retained by the resins. In-column solvent washing before sample sorption was found to be as effective as Soxhlet extraction for removing background impurities. Some compounds can be desorbed from carbon by in-column solvent elution; others require Soxhlet extraction. An XAD-4/8 column in series with a carbon column was used to sample 1000 1 of tapwater. Halomethanes, n-hydrocarbons, polynuclear aromatic compounds and dibenzofuran in the order of ng/l were identified using a gas chromatograph-mass spectrometer-computer system.