Multisyringe Flow Injection Potentialities for Hyphenation with Different Types of Separation Techniques

The advantages of combining flow techniques with separation techniques are noteworthy. Flow-based methods are excellent tools for automating analytical procedures owing to their speed of analysis, reagent and sample saving ability, versatility, and inexpensive equipment. However, flow-based methods alone do not allow the separation of several analytes in a mixture. On the other hand, separation techniques (viz., chromatographic separations, capillary electrophoresis), widely used in analytical research due to high selectivity, require more expensive instrumentation. Thus, the combination of both techniques achieved the required selectivity with a more versatile, automated and, in some cases, low-cost methodology.

Multisyringe flow injection evidences interesting features with the utilization of the aforementioned combination of methods. Its potential for hyphenation with different separation techniques have been recently explored and are depicted in the present paper.     

Multisyringe chromatography (MSC) using a monolithic column for the determination of sulphonated azo dyes

A methodology based on multisyringe chromatography with a monolithic column was developed to determine three sulphonated azo textile dyes: Acid Yellow 23, Acid Yellow 9 and Acid Red 97. An ion pair reagent was needed because of the low affinity between the monolithic column and the anionic dyes. The proposed analytical system is simple, versatile and low-cost and has great flexibility in manifold configuration.The method was optimized through experimentation based on experimental design methodology. For this purpose two blocks of full factorial 2³ were done sequentially. In the first experimental plan, the factors studied were: the % of acetonitrile in organic phase, the % of H₂O in the mobile phase and the kind of ion pair reagent. In this stage, a simple configuration was used which has only one syringe for the mobile phase.After the first experimentation, we added a second syringe with a second mobile phase to the multisyringe module and performed a second full factorial 2³. The factors studied in this case were: the % of acetonitrile in the second mobile phase, the pH and the concentration of ion pair reagent in both mobile phases. After this design, the optimal conditions were selected for obtaining a good resolution between the peaks of yellow dyes (1.47) and the elution of red dye in less than 8 min.The methodology was validated by spiking different amounts of each dye in real water samples, specifically, tap water, well water and water from a biological wastewater lagoon.     

Simultaneous determination of hydrochlorothiazide and losartan potassium in tablets by high-performance low-pressure chromatography using a multi-syringe burette coupled to a monolithic column

This contribution describes use of a separation method based on on-line coupling of a multisyringe flow system with a chromatographic monolithic column for simultaneous determination of hydrochlorothiazide and losartan potassium in tablets. The system comprised a multisyringe module, three low-pressure solenoid valves, a monolithic C₁₈ column (25 mm × 4.6 mm i.d.), and a diode-array detector. The mobile phase was 10 mmol L⁻¹ potassium dihydrogen phosphate (pH 3.1)-acetonitrile-methanol (65:33:2 v/v/v) at a flow rate 0.8 mL min⁻¹. UV detection was carried out at 226 nm. The multi-syringe chromatographic (MSC) method with UV spectrophotometric detection was optimized and validated. Results from validation were very good. The analysis time was about 400 s. The method was found to be applicable to routine analysis of both compounds in tablets. The coupling of the monolithic columns with a multi-syringe flow-injection analysis manifold provides an excellent and inexpensive tool to solve the separation problems without use of HPLC instrumentation.     

Interfacing on-line solid phase extraction with monolithic column multisyringe chromatography and chemiluminescence detection: An effective tool for fast, sensitive and selective determination of thiazide diuretics

A new, multisyringe flow injection set-up has been developed for the completely automated determination of trace thiazide compounds with diuretic action in different types of samples. The proposed instrumental set-up exploits for the first time, a low pressure on-line solid phase extraction-liquid chromatography-chemiluminescence detection method. This novel combination of sample treatments in flow systems expands the current applicability of low pressure liquid chromatography due to the isolation/preconcentration of the target compounds, besides high selectivity and sensitivity.For the determination of three thiazide compounds named hydroflumethiazide, furosemide and bendroflumethiazide, the proposed set-up provided with the preconcentration of only 1 mL of sample, limits of detection of 3, 60 and 40 μg L⁻¹, respectively. Furthermore wide linear dynamic ranges of 6-4000, 140-20,000 and 90-40,000 μg L⁻¹, respectively, were obtained. Besides of this, a high injection throughput of 12 h⁻¹ was also achieved. As in sports, thiazide diuretics are prohibited substances, the proposed method has been applied to their determination in urine samples. Furthermore the potential of the proposed method as a fast-screening approach for emerging contaminants in waters has been also tested by applying it to well water and leachates from a solid waste landfill.     

高效液相色谱法测定盐地碱蓬汁中7种水溶性维生素和18种氨基酸

采用Ｓｈｉｍ－ｐａｃｋＣＬＣ－ＯＤＳＣ_（１８）色谱柱和ＡＡ０３反相键合相柱,对盐地碱蓬（以下称碱蓬）汁中７种水溶性维生素和１８种氨基酸进行了分离测定,结果令人满意。     

一种新的分离三硝基甲苯及其代谢产物的高效液相色谱方法

An HPLC method is described for separation of TNT and its main reduction metabolites. Two columns(LC-C(18) and LC-CN)are connected in series and operated isocratically at 1.0mL/min with water-methanol-tetrahydrofuran(60+ 35+ 5 ). The baseline separation of 4-amino-2,6-dinitrotoluene(4A) and 2-amino-4,6-dinitrotoluene(2A) ,which are main metabolites of TNT,is obtained(Rs=2.1).     

Chromophoric Water-Soluble Tetrakis(4-Carboxyphenylazo)-calix[4]arene: Binding of Arylammonium Ions and Benzene

The interaction of water-solubletetrakis(4-carboxyphenylazo)calix[4]arene with N,N,N trimethylarylammoniumiodides and benzene was investigated in order to correlate the effect ofanilinium salts on the binding properties of the cup-shaped hydrophobiccavity with the monolayer spreading behavior of a series of amphiphilicanalogs. Whereas multiple binding is observed for N,N,N-trimethylaniliniumiodide and benzene, NMR titration oftetrakis(4-carboxyphenylazo)calix[4]arene withN,N,N-trimethyl-N-(2-naphthyl)ammonium iodide indicates 2 : 1 complexationwithin the cavity of the calixarene with binding constants of K₁ = 8024 M^-1and K₂ = 3134 M^-1.     

Analytical Separation of Copper(II), Cobalt(II) and Nickel(II) Using Polymer Bound Anthrantic Acid

Abstract

The preferential complexing tendency of different nietal ions towards chelating agents anchored on a polymer has been used for separation of transition metals. the anthranilic acid group was anchored on the polymeric cellulose back-bone by successive coupling with trifunctional reagent cyanuric chloride, in diozane medium, at pH 7 and 9–10, respectively. This polymer bound chelating agent was used to separate copper(II), nickel(II) and cobalt(II) in the concentration range 1.0–0.1 mmol/L. the separation of a mixture of two components was quantitative using column chromatography.     

P350微孔快速色谱柱分离富集铀的性能研究

以铀为例研究了P₃₅₀萃淋树脂微孔色谱柱的性能。结果表明,柱径和树脂粒度是影响柱效的主要因素,当柱径为2～3mm,树脂粒度为120～140目时,上柱流速可为1～8mL/min,洗脱体积仅为1mL.理论塔板高度比内径为7mm的常现柱下降2个数量级以上,并可节省大量试剂。提出抽空洗脱方式,解决了空床体积影响柱效的难题。     

聚(St-DVB)型整体柱的制备及其对蛋白质的色谱分离性能

苯乙烯(St)为单体,二乙烯基苯(DVB)为交联剂,在致孔剂甲苯和十二醇存在下,直接以Ф4.6×50mm色谱柱管为模具,同时在整个反应过程中通过氩气对反应混合物施加一个恒定的压力,通过原位聚合制备了聚(苯乙烯-二乙烯基苯)(PSD)型整体柱。在聚合过程中对反应混合物施加一定的压力,使制备的整体柱表面光滑无凹痕现象,并且使柱子的两头平整不凹陷,有利于提高柱效。本文对整体柱的孔结构及其对蛋白质的分离性能进行了研究。实验结果表明,整体柱内部含有大量类似渠道的大孔,孔径为2μm~3μm,在流速为5ml/min时,背压为7MPa。而且流速对色谱分离效率的影响小,流速从1ml/min增大到3ml/min时,牛血清白蛋白和溶菌酶这两种蛋白质的总分离效能指标K1的值基本保持不变,保持在3.35左右,说明可以通过提高流速实现蛋白质的快速分离。     

高效液相色谱法分析谷氨酸棒杆菌细胞内尿苷二磷酸葡萄糖和尿苷二磷酸半乳糖

建立了利用高效液相色谱分离分析谷氨酸棒杆菌细胞内尿苷二磷酸(UDP)葡萄糖与UDP半乳糖的新方法,考察了不同色谱柱、不同分离模式及不同流动相组成对UDP葡萄糖和UDP半乳糖的保留特性及分离度的影响。结果表明,在Zorbax NH2柱(250 mm×4.6 mm i.d.,5 μm)上以0.125 mol/L KH2PO4缓冲液(pH 3.6)-乙腈(体积比为40∶60)溶液为流动相,可使谷氨酸棒杆菌细胞内的两种中间代谢产物UDP葡萄糖与UDP半乳糖在22 min内达到基线分离。该方法对UDP葡萄糖和UDP     

Particle Loaded Monolithic Sol‐Gel Columns for Capillary Electrochromatography: A New Dimension for High Performance Liquid Chromatography

Particle‐loaded (3 μm, octadecylsilica) monolithic sol‐gel columns have been prepared and selected characteristics measured. Several electrical properties may be calculated from simple current measurements in the column as a whole. Resistivity in the packed segment is approximately three times that in open segments, resulting in a 60% increase in field strength in the packed regions compared to the capillary with no packing. The surprisingly high specific permeability of these sol‐gel columns is characteristic of 8‐μm particles, which allows their operation in the microLC mode at pressures as low as 69 kPa where their efficiency is about 50,000 plates per meter and in the CEC mode where efficiency is about 106,000 plates per meter at 5 kV. There is a relatively rapid loss of efficiency with increasing linear velocity beyond 0.2 mm/s in microLC mode, which may be due to additional diffusion processes in the inter‐particulate voids. A rapid loss of efficiency above 0.5 mm/s is also observed in the CEC mode, for the same reasons. Chromatographic retention behavior in either separation mode is characteristic of conventional octadecylsilica particles, indicating that analytes have significant access to the surface within the pores of the immobilized bonded phase.     

分子印迹整体柱在高效液相色谱和电色谱手性分离中的应用

在常规不锈钢色谱管中以甲基丙烯酸为功能单体,采用原位聚合法制备了(5S,11S)-特罗格尔碱(S-TB)的印迹整体柱。考察了流动相中添加不同量的醋酸和水对分离的影响,结合台阶梯度洗脱模式在S-TB整体柱上实现了对TB消旋体的快速分离。另外,以碱性单体2-二甲基乙基胺甲基丙烯酸酯(DAMA)为功能单体,在毛细管中采用原位聚合法制备了毛细管分子印迹整体柱,用于在毛细管电色谱（CEC）中对消旋体1,1′-联-2-萘酚(BNL)进行手性分离。结果表明,以AMA为功能单体可以制备其他酸性模板的分子印迹聚合物,从而扩大了分子印迹聚合物MIP）在CEC分离中的应用范围。     

甲基膦酸二甲庚酯萃取色谱法分离金、铂的研究

本文研究了以4.0mol/L H_2SO_4-0.50mol/L MgSO_4 为流动相,以硅烷化硅球负载的甲基膦酸二甲庚酯(P350)作固定相。萃取色谱法使微量铂、金与常见贱金属分离,富集在色谱柱上的铂和金分别用0.10mol/L HCl和1.0％Na_2SO_2溶液洗脱进行连续分离与测定。经实际样品的试用考核,结果令人满意。     

Poly (methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary for in-tube solid phase microextraction coupled to high performance liquid chromatography and its application to determination of basic drugs in human serum

A poly (methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column was prepared for in-tube solid-phase microextraction. Comparing with the commonly used open tubular extraction capillary, which cannot provide sufficient extraction efficiency since the ratio of its coating volume to that of the capillary void volume is relatively small, the monolithic column with greater phase ratio combined with convective mass transfer provides the possibility to improve the extraction efficiency with shorter capillary. As to poly (methacrylic acid-ethylene glycol dimethacrylate), its hydrophobic main chains and acidic pendant groups make it a superior material for extraction of basic analytes from aqueous matrix.An on-line monolithic capillary column solid phase microextraction (SPME) method was developed for determination of theobromine, theophylline and caffeine in serum samples. The high extraction efficiency was obtained for all the three analytes, yielding the detection limits of 12, 8 and 6.5 ng/mL by UV detection, respectively. Excellent method reproducibility (R.S.D. < 2.9%) was found over a linear dynamic range of 0.05-2 μg/mL in serum sample. The monolithic capillary column was proved to be reusable in coping with serum samples, which would facilitate practical determination of basic drugs.     

Separation and Identification of Oligomeric-Hindered Amine Light Stabilizer Uvasorb HA 88 by High-performance Liquid Chromatography (HPLC) Coupled With Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALSI-TOF-MS)

Abstract

Uvasorb HA 88 is widely used as a light stabilizer to prevent plastic polymer degradation. Its high molecular weight and oligomeric characters provide challenge for quality control. In this study, high-performance liquid chromatography (HPLC) coupled with electrospray ionization time of flight mass spectrometry (ESI-TOF MS) was applied for separation and detection of Uvasorb HA 88. The synthesis scheme was deduced and confirmed by the characterization of Uvasorb HA 88 products from different batches. Direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was employed for the detailed characterization of chemical composition of Uvasorb HA 88. Furthermore, a reliable reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with MALDI-TOF MS method was established and the weight-average and number-average molecular masses were calculated. The results revealed that six oligomers with repeat unit numbers from 1 to 4 were present in Uvasorb HA 88. A molecular weight of up to 6808?g mol^?1 was detected and two new series of oligomers were reported for the first time. Different series of oligomers and positional isomers were observed in Uvasorb HA 88. This work provides a suitable method to evaluate the technical grade of Uvasorb HA 88 as well as comprehensive characterization of complex oligomeric hindered amine light stabilizers.     

正相高效液相色谱法分离和测定2—（4—羟基苯氧基）丙酸

采用在硅胶柱（ＺＯＲＢＡＸ ＳＩＬ）上，以正己烷：乙酸＝７０：３０：２．５为流动相及ＵＶ检测器（２５４ｎｍ）的高效液相色谱法分离和测定２－（４－羟基苯氧基）丙酸。在选定的色谱操作条例上，２－（４－羟基苯氧基）丙酸与杂质对苯二酚等之间具有良好的分离效果。该方法具有较好的重现性和准确性。     

高效液相色谱光度法测定痕量铜、锌、铁、锰的磺化四苯基卟啉配合物

本文用磺化四苯基卟啉作柱前衍生试剂,研究了试剂与铜(Ⅱ)、锌(Ⅱ)、铁(Ⅲ)及锰(Ⅱ)的络合反应。在ODS柱上,用乙腈-水(40:60,V/V)作流动相,溴化四丁基铵作离子对试剂,在420nm波长处进行光度检测。提出了离子对反相高效液相色谱快速分离及测定痕量铜、锌、铁及锰的新方法。检测下限为(×10^-3ppm):Mn 3.6、Fe 1.8 、Zn 0.93、Cu 0.70。应用于植物样品中痕量铜、锌、铁及锰的测定,分析结果与标准参考值相符。     

Soluble manganese(IV) as a chemiluminescence reagent for the determination of opiate alkaloids, indoles and analytes of forensic interest

We present the results of our investigations into the use of soluble manganese(IV) as a chemiluminescence reagent, which include a significantly faster method of preparation and a study on the effect of formaldehyde and orthophosphoric acid concentration on signal intensity. Chemiluminescence detection was applied to the determination of 16 analytes, including opiate alkaloids, indoles and analytes of forensic interest, using flow injection analysis methodology. The soluble manganese(IV) reagent was less selective than either acidic potassium permanganate or tris(2,2′-bipyridyl)ruthenium(III) and therefore provided a more universal chemiluminescence detection system for HPLC. A broad spectral distribution with a maximum at 730 ± 5 nm was observed for the reaction between the soluble manganese(IV) and a range of analytes, as well as the background emission from the reaction with the formaldehyde enhancer. This spectral distribution matches that reported for chemiluminescence reactions with acidic potassium permanganate, where a manganese(II) emitting species was elucidated. This provides further evidence that the emission evoked in reactions with soluble manganese(IV) also emanates from a manganese(II) species, and not bimolecular singlet oxygen as suggested by previous authors.