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1.
Summary A miniaturized flow cell for an electrical conductivity detector has been made and applied to the ion chromatography of inorganic anions. It consisted of stainless steel tubes (0.13 mm ID×0.31 mm OD) and PTFE tubes (0.25 mm ID×2 mm OD). The detection limit for chloride at S/N=3 was 36 pg or 0.33 ppm for a 0.11 l injection.  相似文献   

2.
This paper discusses the newest advancement in chemical suppression preceding conductivity detection. The new suppressor uses electrolysis of deionized water to generate the required acid or base for the suppression neutralization reaction and utilizes the electrical field to enhance, through electrodialysis, the suppressor's capacity for neutralization. The suppressor is able to accommodate eluents as high as 150 mM NaOH, without the need for a separate regenerant solution, by recycling the conductivity detector cell waste to the regenerant and electrolysing the water in the waste stream to the required acid or base. The device is able to use deionized water as regenerant and neutralize the eluent stream to deionized water without the expected increase in resistance by employing ion exchange material in intimate contact with the electrodes and the membranes. The current is carried with low resistance through the ion-exchange material via ion transport from one ion-exchange site to another.  相似文献   

3.
Weak-acid anions such as borate and cyanide, present problems in chemically suppressed ion chromatography, since the acids are weakly ionised, giving low conductivity and therefore decreased sensitivity. For borate this problem was overcome by converting the weak acid to its sodium salt, by the use of a second anion micromembrane suppressor (AMMS) as an ion exchange reactor (IER), flushed by EDTA reagent, to supply sodium ions for the conversion. This paper will discuss the use of this IER system to determine cyanide, which is also a very weak acid, with a similar pKa to borate. The detection limit for cyanide of 50 microM compare favourably with indirect conductivity detection.  相似文献   

4.
张丽媛  费旭东  邱丰  林苗 《色谱》2015,33(2):164-168
建立了离子色谱-抑制型电导检测同时测定食品级润滑油中Cl-、NO3-、SO42- 3种代表性无机阴离子的方法。样品经50%(v/v)甲醇水溶液超声提取,离心后所得下层水相用0.22 μm混合纤维过滤膜净化,以15 mmol/L KOH溶液为淋洗液,采用抑制型电导检测器进行检测,外标法定量。在上述条件下,Cl-、NO3-、SO42- 3种无机阴离子在0.10~20.00 mg/L范围内具有良好的线性关系(R2>0.999);检出限(S/N=3)为0.01~0.03 mg/kg;在1.00、5.00、10.00 mg/kg添加水平下,实际样品中3种阴离子的加标回收率为90.0%~103.6%,相对标准偏差为2.8%~5.7%。结果表明,该方法无需燃烧、灰化油相基质等繁琐耗时的前处理过程,可以快速、准确定量测定食品级润滑油中Cl-、NO3-、SO42- 3种无机阴离子的含量,适用于润滑油等油品中痕量无机阴离子的同时分离与测定。  相似文献   

5.
A novel method for the determination of carbocisteine (S-CMC), a mucolytic and expectorant drug with an acidic amino acid structure, was developed and validated, using non-suppressed ion-chromatographic system with conductimetric detection, and anion or cation exchange columns. Among the various combinations of column type and eluent composition tested, a cation exchange column with a 0.25 mM tri-fluoroacetic acid (TFA) as eluent in isocratic mode at 1.2 ml/min gave the best results. S-CMC was very well separated from all common amino acids (resolution > 2.6). The retention time was 3.5 min and the asymmetry factor 1.1. A linear calibration curve from 17 to 400 microg/ml (r = 0.99994), with a detection limit of 0.14 microg (5.6 microg/ml-25 microl injection volume) and a precision of 1.5% R.S.D. (100 microg/ml, n = 3) was achieved. The proposed method was applied for the determination of S-CMC content in intensely colored commercial formulations (syrups). No interference from excipients was found and the only pretreatment step was the appropriate dilution with the mobile phase. Recovery from standard additions was ranged from 96.0 to 104.9% and precision (R.S.D., n = 3) 1.8-3.6%.  相似文献   

6.
The linearity of calibration curves in ion chromatography with suppressed conductivity detection using hydroxide eluents was investigated. Theoretical calibration curves were derived for strong electrolytes and weak monobasic acids and the results compared with experimental data. At low concentrations up to 1 micromol l(-1) the autoprotolysis of water induces left-curved calibration functions even for strong electrolytes like nitrate. The experimental data are best described by a quadratic function, the differences between linear and quadratic regression being up to 10%. At higher concentrations the calibration curves for strong electrolytes are linear. Due to incomplete dissociation, the calibration curves for weak mono- and dibasic acids show a right curvature. Thus, depending on the analyte and the concentration range of interest, analysts should carefully choose between a linear and a quadratic regression function.  相似文献   

7.
Indirect conductimetric detection of cyclodextrins (CDs) was investigated in liquid chromatography (LC). The mobile phase contained an electrolytic substance which maintained high background, and CDs were indirectly detected owing to a depression of the background signal due to dilution of the mobile phase by the analyte molecules. The dynamic reserve, defined as the ratio of the background to its noise level, was (1–2) × 105, and the detection limits at S/N = 3 were 23–40 ng for CDs when a microcolumn LC system was employed.  相似文献   

8.
A rapid and sensitive method for the determination of domperidone in plasma was developed, using high-performance liquid chromatographic separation with tandem mass spectrometry detection. The samples were rendered basic with 1 M Na2CO3 and the domperidone extracted using tert.-butyl methyl ether, followed by back-extraction into formic acid (2% in water). Chromatography was performed on a Phenomenex Luna C8 (2), 5 microm, 150x2 mm column with a mobile phase consisting of acetonitrile-0.02% formic acid (300:700, v/v), delivered at 0.2 ml/min. Detection was performed using an Applied Biosystems Sciex API 2000 mass spectrometer set at unit resolution in the multiple reaction monitoring mode. TurbolonSpray ionisation was used for ion production. The mean recovery of domperidone was +/- 100%, with a lower limit of quantification set at 0.189 ng/ml. This assay method makes use of the increased sensitivity and selectivity of tandem mass spectrometric detection resulting in a rapid (extraction and chromatography) and sensitive method for the determination of domperidone in human plasma, which is more sensitive than previously described methods.  相似文献   

9.
宋卫得  袁晓鹰  吕宁  陈太法  惠希东  苏征  金伟  刘冰 《色谱》2016,34(11):1084-1090
通过对色谱柱类型、流速、柱温、pH值、淋洗液浓度等影响因素的研究,建立了多级梯度淋洗-电导抑制离子色谱同时测定果汁中26种有机酸和阴离子的分析方法。结果表明,当流速为1.00 mL/min、柱温为30℃、pH值为5.5~6.8时,26种组分的测定结果更准确。26种组分在0.02~10.0 mg/L范围内具有良好的线性关系(r均大于0.995),检出限(S/N=3)为0.17~52.0 μg/L;在0.20~2.00 mg/L添加水平下的回收率为85.58%~108.86%,相对标准偏差为0.15%~7.65%(n=6)。该方法简便快速、灵敏度好、准确度高,适于果汁中26种组分的痕量分析。  相似文献   

10.
Suppressed conductimetric detection ion chromatography (IC) was investigated for the separation and detection of common inorganic anions, calcium and magnesium by anion-exchange chromatography using a sodium carbonate-EDTA mobile phase. The formation of anionic Ca2+ -EDTA and Mg2+ -EDTA complexes allowed its separation from other inorganic anions opening the way for their simultaneous determination in a single chromatographic run. The effect of the pH, carbonate and EDTA concentrations in the eluent and the previous addition of EDTA to the samples has been studied. The optimised experimental conditions were applied to the determination of Ca2+ and Mg2+ in mineral waters with results in agreement with alternative ICP-MS methodologies.  相似文献   

11.
T. Takeuchi  T. Miwa 《Chromatographia》1993,37(5-6):281-283
Summary Indirect conductimetric detection of nonelectrolytes was investigated in microcolumn liquid chromatography. The mobile phase contained an electrolytic substance which maintained a high background and analytes were indirectly detected owing to a depression of the background signal. The dynamic reserve, defined as the ratio of the background to its noise level, was 9.3×104, and the detection limits at S/N=3 were 10–32 ng for alcohols examined.  相似文献   

12.
Rapid methods for etidronate, clodronate, pamidronate, and alendronate assays are presented. The methods are based on ion chromatography with indirect UV detection, which avoids the need for chemical derivatization procedures. Each compound is analyzed on an individual basis. There is no need for having separation among these analytes because the aim of the proposed methods is to analyze each compound separately either in bulk material or pharmaceuticals. Phenosphere (150 x 2.0-mm, 5 microm) and Sphereclone (250 x 2.0-mm, 5 microm) anion exchange columns were employed with sodium citrate (20mM) as the mobile phase. The methods are simple, rapid (analysis time of 5 min for etidronate and clodronate and 7 min for alendronate and pamidronate), and demonstrate precision (relative standard deviation was lower than 2.0% in all concentrations), accuracy, and specificity. Calibration curves are linear with r(2) > 0.99 over the concentration range of 50 to 400 microg/mL for etidronate and clodronate, and of 100 to 500 microg/mL for pamidronate and alendronate. Furthermore, they employed silica-based columns, which are cheaper than polymeric columns frequently used in previous reported methods.  相似文献   

13.
Guan CL  Ouyang J  Li QL  Liu BH  Baeyens WR 《Talanta》2000,50(6):1197-1203
A simple method for simultaneous determination of three catecholamines using ion chromatography (IC) with direct conductivity detection (CD) based on the ionization of catecholamines in acidic medium without chemical suppression is developed in the present paper. The method could be used for the determination of these catecholamines in pharmaceutical preparations for the purpose of drug quality control. The recovery of catecholamines was more than 97% (n=3) and the relative standard deviation (R.S.D.) (n=11) was less than 2.1%. In a single chromatographic run, norepinephrine (NE), epinephrine (E) and dopamine (DA) can be determined in less than 10 min. The detection limits were found to be 0.001 μg/ml for NE, 0.01 μg/ml for E and DA respectively. Linear ranges were 0.01–50 μg/ml for NE (r2=0.9998), 0.1–50 μg/ml for E (r2=0.9995) and DA (r2=0.9999), respectively.  相似文献   

14.
林立  李仁勇  王琳琳  邱云 《色谱》2018,36(11):1189-1193
建立离子色谱-抑制型电导检测牛肝菌中胆碱、腐胺和尸胺的方法。牛肝菌干片样品经7 mmol/L甲烷磺酸溶液提取,过滤膜,经反相固相萃取柱净化后进样分析。胆碱、腐胺、尸胺与样品中共存离子在IonPac CS17(250 mm×4 mm)阳离子交换色谱柱上可实现较好分离。以7 mmol/L甲烷磺酸为淋洗液等度淋洗,25 min可完成一次样品测定。胆碱、腐胺和尸胺的检出限(S/N=3)分别为0.002、0.002和0.003 mg/L,具有较宽的线性范围(0.01~10 mg/L),样品加标回收率为91.6%~100.2%。该方法简便、选择性好、灵敏度高,适用于牛肝菌中胆碱、腐胺和尸胺的检测分析。  相似文献   

15.
A direct approach utilizing ion pairing reversed-phase chromatography coupled with suppressed conductivity detection was developed to monitor biodegradation of anionic surfactants during wastewater recycling through hydroponic plant growth systems and fixed-film bioreactors. Samples of hydroponic nutrient solution and bioreactor effluent with high concentrations (up to 120 mS electrical conductance) of inorganic ions can be analyzed without pretreatment or interference. The presence of non-ionic surfactants did not significantly affect the analysis. Dynamic linear ranges for tested surfactants [Igepon TC-42, ammonium lauryl sulfate, sodium laureth sulfate and sodium alkyl (C10-C16) ether sulfate] were 2 to approximately 500, 1 to approximately 500, 2.5 to approximately 550 and 3.0 to approximately 630 microg/ml, respectively.  相似文献   

16.
A new ion chromatographic (IC) system has been established by using micelles of 3-(N,N-dimethylmyristylammonio)propanesulfonate (Zwittergent 3-14) loaded onto a reversed-phase packed column as the separation column with an electronic rotary switching valve packed-bed suppressor for conductometric detection of inorganic anions. An aqueous H3BO3-Na2B4O7 solution has been demonstrated to be the most desirable eluent for this IC system. The relationship between retention time and the concentration of the borate eluent was determined for a series of model anionic analytes and this relationship was found to be opposite to that exhibited in a conventional anion-exchange IC system. The rapid elution and complete separation of monovalent inorganic anions were obtained by initially using a high-concentration borate solution as the eluent for a short-period, and then switching to a lower-concentration borate eluent to complete the separation. Detection limits for nitrite, bromide, nitrate, and chlorate were 0.85, 0.88, 0.95 and 4.8 microM, respectively, when a 7.0 mM Na2B4O7 eluent was used. Moreover, the ability to directly detect these monovalent anions in samples containing high concentrations of sulfate and/or chloride ions provided a major advantage of this approach.  相似文献   

17.
With the aid of a central composite face-centered design, an ion chromatographic method was developed and optimized for analyzing organic acids in tobacco. A Dionex-100 ion chromatograph with an ion suppressor and a conductivity detector, and a Bio-Rad Aminex HPX-87H column were employed. Only 13 analyses were required to optimize two factors: column temperature and eluent strength. Two sets of optimal conditions for separating nine acids were found: 1.8 mM HFBA eluent and 42 °C column temperature, and 0.8 mM HFBA eluent and 50 °C column temperature. The flow-rate was 0.6 ml min−1 and the analysis time was 18 min or less. A sample preparation procedure included extraction of 2 g ground tobacco with 100 ml of 5 mM sulfuric acid solution for 3 h, filtration of the extract, and dilution of the filtrate 10-fold with deionized water.  相似文献   

18.
The determination of biogenic amines in alcoholic beverages is important to assess the potential risks associated with the consumption of high concentrations of these compounds. In addition, product storage conditions and the length of storage can cause the formation of biogenic amines that reduce product quality. We report a new method using cation-exchange chromatography with either suppressed conductivity, integrated pulsed amperometry, UV, or a combination of these detection techniques to determine biogenic amines in alcoholic beverages. The main objective was to provide a direct comparison between IPAD and suppressed conductivity detection for determining biogenic amines in alcoholic beverages. Suppressed conductivity is the simplest detection approach for determining putrescine, cadaverine, histamine, agmatine, phenylethylamine, spermidine, and spermine with good sensitivity (0.004-0.08 mg/l) and was used to evaluate the influence of storage time and conditions on the evolution of biogenic amines in alcoholic beverages. Integrated pulsed amperometric detection (IPAD) detects more biogenic amines than suppressed conductivity detection, enabling the detection of dopamine, tyramine, and serotonin. Tyramine was simultaneously determined by UV detection and IPAD to provide confirmation and ensure the accuracy of the analytical results. The linearity of biogenic amine responses was within 0.1-20 mg/l and peak area precisions were 0.24-4.97% for IPAD, suppressed conductivity-IPAD, and UV detection. The sensitivity for the 10 biogenic amines using the 3 detection techniques varied considerably from 0.004-1.1 mg/l and recoveries were within 85-122%.  相似文献   

19.
As part of the formulation of a cell-based pharmaceutical product, cells were harvested from mice and incubated in a cocktail containing cell culture media and high levels of trifluoroacetic acid (TFA). The cells were washed with a phosphate-buffered saline solution to remove residual cell culture media and other reagents before the cells were infused back into the mice from which they originated. Because of the potentially toxic nature of the TFA, the cells were washed multiple times and the final wash was monitored for residual TFA in order to demonstrate the efficient removal of the reagent before the cell product could be reintroduced into the test animal. This report describes the method that was developed incorporating anion-exchange chromatography with suppressed conductivity detection for the analysis of residual TFA (down to 50 ng/ml) in the presence of high concentrations of phosphate and chloride interferences. The ultimate sensitivity of the method was improved by selectively removing halide anions using a silver cartridge before sample analysis. The method proved to be rugged and reproducible enough to be validated and used to monitor residual TFA levels in cell washes in support of an acute toxicological study. Results demonstrating the method’s sensitivity, selectivity, precision and linearity were reported.  相似文献   

20.
Gilchrist E  Smith N  Barron L 《The Analyst》2012,137(7):1576-1583
An investigation into capillary-scale ion chromatography with suppressed conductivity detection is presented for the identification of low molecular weight anions in samples of limited size. Both particle-packed and polymer monolith capillary ion exchange resins were compared with respect to their chromatographic efficiencies, operating back-pressures and thermal selectivities. Using a multistep hydroxide gradient, it was possible to separate a large selection of inorganic and organic anions in <23 mins using both phases with an injection volume of only 0.4 μL. Method performance was tested with respect to linearity, range, reproducibility and sensitivity and compared to a micro-bore (2 mm) IC method. Limits of mass sensitivity improved by factors up to 1,800-fold using the capillary IC system and lay in the range 0.3-26.2 pg. The finalised analytical method was applied to the determination of both endogenous and exogenous species in sweat and fingermark deposits. It was possible to determine presence of elevated levels of thiocyanate and benzoate in the sweat of three moderate smokers (5-10 cigarettes/day) in comparison to non-smokers. A controlled firing experiment was also conducted to assess the transfer of gunshot residue into fingerprints of a firer. Similarly, identification of direct contact with a black powder substitute is presented via analysis of latent fingermarks. To the best of our knowledge, this represents the first study of sweat and fingerprints using capillary-scale suppressed ion chromatography.  相似文献   

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