Quantitative determination of toxic mono- and non-ortho polychlorinated biphenyls in cod liver oil after selective liquid chromatographic separation

Summary By application of chromatographic column filled with Supelclean ENVI-Carb/Celite and elution with three solvents of different polarity three PCB fractions were obtained. Fraction A contained poly-ortho PCBs, Fraction B mono-ortho PCBs, and Fraction C non-ortho PCBs. The Supelclean ENVI-Carb/Celite column was used in combination with a sample preparation procedure for pre-cleaning of acid-stable chlorinated hydrocarbons such as DDT and its metabolites, HCH isomers, and regulation-relevant PCB congeners. The method was optimized using standard solutions of 55 PCB congeners, 8 chlorinated pesticides and contaminated cod liver oil samples. The influence of traces of remaining matrix on the elution profile of the organochlorine compounds on Supelclean ENVI-Carb/Celite was observed. Quantitation was carried out by GC-ECD with fused silica capillary columns of different polarity.     

Liquid chromatographic isolation of coplanar PCB congeners on an activated carbon stationary phase

A rapid and uncomplicated method for the fractionation of PCBs leading to an isolation of the highly toxic non-ortho substituted PCBs is described. The liquid chromatographic separation was achieved on a stationary phase consisting of activated carbon and Celite 545. Using eluents with different polarity, isolation of the non-ortho substituted PCBs in a single fraction was achieved. The fractions were analysed by GC/MS. The method was tested by the determination of non-ortho substituted PCBs in technical mixtures (Aroclor 1254 and Aroclor 1242). The results were compared with those obtained by using an HPLC fractionation on a porous graphitic carbon column. Finally, the micro-column fractionation was used for the determination of non-ortho substituted PCBs in native soil samples.     

Liquid chromatographic isolation of coplanar PCB congeners on an activated carbon stationary phase

A rapid and uncomplicated method for the fractionation of PCBs leading to an isolation of the highly toxic non-ortho substituted PCBs is described. The liquid chromatographic separation was achieved on a stationary phase consisting of activated carbon and Celite 545. Using eluents with different polarity, isolation of the non-ortho substituted PCBs in a single fraction was achieved. The fractions were analysed by GC/MS. The method was tested by the determination of non-ortho substituted PCBs in technical mixtures (Aroclor 1254 and Aroclor 1242). The results were compared with those obtained by using an HPLC fractionation on a porous graphitic carbon column. Finally, the micro-column fractionation was used for the determination of non-ortho substituted PCBs in native soil samples. Received: 5 March 1997 / Revised: 4 June 1997 / Accepted: 6 June 1997     

Isolation and determination of toxic congeners of polychlorinated biphenyls in environmental samples

A Method has been developed for the separation and enrichemen of there non-ortho, eight mono-ortho, and di-ortho substituted polychlorinated biphenyls (PCBs) from Aroclor formulations and environmental samples. The fractionation is accomplished using high performance liquid chromatography (HPLC) with a 2-(1-pyrenyl)ethyldimethylsilysily silca column. GC-MSD with an optimized temperature program was used for quantitation, Hexane, pentane, cyclohexane, iso-octane, and 2-propanol were tested as a mobile phase for the isolation of the thirteen target PCBs in a Aroclor 1242, 1254, and 1260 (1:1:1) misture, Pentane at room temperature with a slow rate of 0.7 ml/min is the condition of choice. The average recovery of thirteen target PCBs spiked in the Aroclor mixture is 99.5% with an average relative standard deviation of 4.5%. The average method detection limit is 8pg/μl. Targer PCBs in the reference solis, incinarator ash, and sediment samples were measured.     

Determination of polychlorinated biphenyls in human blood plasma by on-line and off-line liquid chromatography–gas chromatography

A method for the determination of non-, mono- and di-ortho substituted polychlorinated biphenyls in human blood plasma is presented. The non-ortho CBs are isolated from the bulk of PCBs by HPLC on a dinitroanilino-propyl silica column and collected as a heart-cut fraction that is transferred on-line to GC-MS utilizing concurrent solvent evaporation technique. The on-line coupling serves to lower the limit of determination and to partly automate the sample clean-up. The di- and mono-ortho CBs are analyzed by off-line GC-ECD using two different columns. Sample pre-treatment is performed by extraction with organic solvents and fractionation on silica gel. A high reproducibility and an absolute over-all recovery of approximately 70 % is demonstrated. The method is applied to samples of blood from 5 individuals. All the samples demonstrated a similar relative concentration profile. It was also shown that three CB congeners (CB 126, CB 156 and CB 170) contributed to the major part of the toxic equivalent quantity of the PCB content in the blood.     

Carbon column HPLC and carborane-phase capillary GLC for the separation of polychlorinated biphenyl congeners

Summary With the HPLC carbon column Shandon Hypercarb, the polychlorinated biphenyl congeners are separated by a gradient mixture of acetonitrile and toluene in such a way that the congeners with two (or more) orthochlorine substituents are eluted first, followed by those with one ortho-chlorine and at last the coplanar congeners. Within each group, subfractionation is observed according to the total number of chlorines. For GLC, the SGE HT 5 capillary column exhibits a much more efficient separation of 65 congeners found in Clophen A 40 than the usual DB-5 column, especially for the higher chlorinated congeners. Therefore, the HPLC fractionation on Shandon Hypercarb combined with the GLC on HT 5 offers new possibilities for the analysis of the toxicologically relevant coplanar and mono-ortho substituted PCB congeners.     

Fractionation of chlorinated and brominated persistent organic pollutants in several food samples by pyrenyl-silica liquid chromatography prior to GC-MS determination

A high-performance liquid chromatography (HPLC) method using a column of 2-(1-pyrenyl) ethyldimethylsilylated silica was developed in this work in order to achieve satisfactory and reproducible fractionation of polychlorinated biphenyls (PCBs) from brominated flame retardants (BFRs) (polybrominated diphenylethers, PBDEs; and polybrominated biphenyls, PBBs). After the study of different chromatographic parameters (mobile phase composition and separation temperature were the most important) an isocratic elution with isooctane:toluene (98:2, v/v) at a flow-rate of 1 mL/min, a temperature of 45 °C, and UV-detection at 225 nm was selected for fractionation of PCBs (time region, 4.0-5.8 min) from PBDEs (5.8-9.0 min) and from PBBs (5.8-11.0 min). The applicability of this method to food samples was demonstrated by fractionating PCBs from PBDEs in three food samples (cheese, milk, and fish). Interferences from PCBs (present in real samples at much higher concentrations than PBDEs) were removed in this way. In addition, by analysing these samples by gas chromatography-mass spectrometry (GC-MS) with and without previous fractionation we were able to observe an improvement in detection sensitivity for PBDEs after HPLC fractionation.     

High-resolution separation of polychlorinated biphenyls by comprehensive two-dimensional gas chromatography

Comprehensive two-dimensional gas chromatography (GC x GC) with micro electron-capture detection (microECD) has been optimised for the separation of polychlorinated biphenyl congeners with emphasis on the separation of 12 toxic non- and mono-ortho chlorinated biphenyls (CBs), viz. CBs 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169 and 189. The selection of the first- and second-dimension columns and the temperature programme optimisation were carried out with a mixture of 90 CBs and the results are compared with those of one-dimensional GC. A complete separation of all 12 priority CBs was obtained with two column combinations, HP-1-HT-8 and HP-1-SupelcoWax-10. With the HP-1-HT-8 column set, ordered structures show up in the two-dimensional plane, with the number of chlorine substituents and their position (ortho vs. non-ortho) being the main parameters of interest. This can help with congener identification. Estimated detection limits are excellent, i.e. about 10 fg. To illustrate the potential and the versatility of GC x GC-microECD, a cod liver extract and a standard mixture of the 17 most toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans together with 90 CBs were analysed as an application.     

Application of a novel large-volume injection method using a stomach-shaped inlet liner in capillary gas chromatographic trace analysis of dioxins in human milk and plasma.

A newly developed large-volume injection (LVI) technique that employs a unique stomach-shaped inlet liner (SSIL) inside of a programmable temperature vaporizer was used for the determination of trace amounts of dioxins in human milk and plasma. The initial temperature and the initial dwelling time of the inlet and the kind of solvent used were found to be critical in determining the analytical sensitivity of dioxins due to the loss of these relatively volatile compounds during solvent vaporization. Human milk and plasma were purified and fractionated by pre-packed multi-layered silica-gel chromatography and activated carbon silica-gel column chromatography. A 20-microL aliquot of the fraction collected from the chromatography with toluene was directly applied to the LVI system in high-resolution gas chromatography/high-resolution mass spectrometry. Excellent correlation (r > 0.97) between the values obtained by the LVI method using the SSIL device and those by the conventional regular-volume splitless injection method was obtained for PCDDs, PCDFs and non-ortho PCBs in human milk and plasma samples.     

Separation of polychlorinated dibenzo-p-dioxins/furans,non-ortho/mono/di/tri/tetra-ortho-polychlorinated biphenyls,and polybrominated diphenyl ethers groups of compounds prior to their determination with large volume injection gas chromatography—Quadrupole ion storage tandem mass spectrometry

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are important environmental contaminants. Their maximum legally allowable levels in food and environment are in the low pg g⁻¹ range. Therefore some highly selective and sensitive analytical methods must be used to determine them. Prior to final determination by GC/MS the cleaned-up samples have to be split into some fractions in view of large differences in concentrations of various analytes and existence of numerous chromatographic co-elutions (which in any case cannot be fully avoided). The aim of this study was to: (i) develop a robust, time-saving analytical method to isolate, clean-up and fractionate PCBs, PBDEs and PCDD/Fs prior to their determination with gas chromatography/ion trap mass spectrometry; (ii) assess method performance using laboratory validation data and some certified reference materials; (iii) use the developed method to assess PCB/PBDE/PCDD/F levels in samples of commercially available food. A combination of alumina, florisil, modified silica gel and two carbon columns were used for sample cleanup and fractionation. Separate fractions containing dioxins/furans, PBDE, non-ortho, mono-ortho and di-/tri-/tetra-ortho PCBs were obtained. The method statistical parameters were compatible with 1883/2006 EC Regulation (80–120%, RSD below 15%). The method performance was successfully used to evaluation of some real life food samples.     

Interpreting the difference between conventional and bi-directional plate-height measurements in liquid chromatography

An experimental and theoretical study was conducted of the column characterization technique in which plate heights determined using the conventional pulse-response method are compared with those determined using a bi-directional method where an eluite sample is introduced into one end of a chromatographic column and elution occurs at the same end after the flow direction is reversed inside the column. Experiments are presented for a micropellicular HPLC column before and after its performance has been degraded by repeated sample injections, for a low-pressure column containing nonporous glass particles, and for an HPLC column containing particles with 300 Å pores. The results obtained are interpreted in terms of several different theories which apply in various Fourier number ranges. It was shown that the transcolumn contribution to convective dispersion in a chromatographic column is largely responsible for the difference observed between conventional and bi-directional plate-height measurements and that a collocation method can be employed to develop a useful analytical expression for this contribution.     

高效液相色谱-电感耦合等离子体质谱联用同时测定鸡肉与鸡肝中的7种砷形态

建立了一种同时测定阿散酸、亚砷酸根、砷酸根、砷胆碱、砷甜菜碱、一甲基砷和二甲基砷等7种砷形态的高效液相色谱-电感耦合等离子体质谱分析方法。样品采用人工胃液作为提取液进行超声处理,再以碳酸铵溶液和水作为流动相,采用阴离子分析柱将样品提取液进行分离,最后进入电感耦合等离子体质谱测定。各砷形态在1～50 μg/kg范围内线性关系良好,相关系数r2均在0.999以上;在1、2、10 μg/kg 3个添加水平进行了方法学验证,平均回收率为84.3%～106.6%,相对标准偏差为1.4%～4.2%; 7种砷形态的定量限均为1 μg/kg。方法重现性好、灵敏度高、前处理简单,适用于鸡肉和鸡肝中主要有机砷和无机砷残留的分析检测。     

Separation of Methylated Purines by High Pressure Liquid Chromatography

Abstract

This paper reports a method for the separation and measurement of methylated purines of interest to carcinogenesis studies by high-pressure liquid chromatography (HPLC) following their column chromatographic isolation from collected urine samples. HPLC was evaluated on three different cation-exchange columns, with optimum conditions obtained on a Partisil 10-SCX column employing isocratic elution with 0.25M (NH₄)H₂PO₄ at pH 4.0. This column was also found to be useful for the separation of mono-methylguanine isomers. Application is shown to the analysis of rat urine following animal treatment with methyl methanesulfonate.     

Enantiomeric reversed-phase high-performance liquid chromatography resolution of D-/L-penicillamine after spirocyclization with ninhydrin and by using copper(II)-L-proline complex as a chiral selector in the mobile phase

A new HPLC method by fluorescence or UV/vis absorbance detection has been developed for the separation and quantification of penicillamine stereoisomers after their spirocyclization with ninhydrin. The separation was performed on an achiral C18 column by isocratic elution with a copper(II)-l-proline complex as a chiral selector in the mobile phase. The method was able to detect traces of l-penicillamine in samples of d-penicillamine below 0.1% in fairly short times (about 16min) with a good resolution (R(s)=1.31). On the whole, the method was found to be stable and useful in the quality control of the bulk material and formulations.     

Direct determination of Benzo[a]pyrene in oil distillates by on-line two-dimensional HPLC with column switching

Summary A selective and sensitive HPLC method for the determination of Benzo[a]pyrene (B[a]p) in oil fractions by means of column switching is described. The diluted oil samples were injected directly onto a silica column with isooctane as eluent. After fast elution of the main part of the sample matrix, the B[a]p containing fraction was transferred on-line to a dinitro-aryl-modified silica column for final separation with isooctane/tetrahydrofuran. A detection limit of 50 ppt B[a]p was found when using fluorescence detection.Dedicated to Professor Leslie S. Ettre on the occasion of his 70th birthday.     

High-performance-liquid chromatographic separation of 1,3,5-trizine herbicides

Summary A number of 11 triazine herbicides and 7 of their corresponding metabolites were separated in a single HPLC run. The separation was achieved on a reversed-phase column using gradient elution with acetonitrile/buffer. Detection was by UV absorption at a wave-length of 220 nm.     

高效液相色谱梯度法测定雷公藤制剂中雷公藤甲素的含量

采用高效液相色谱梯度法分离测定雷公藤制剂中雷公藤甲素的含量,用国产YWG色谱柱分离,二极管阵列检测器检测,所得三维光谱与空白光谱进行差减,取波长218nm处色谱图积分,定量。与等度法比较,梯度法具有更高的分离度、灵敏度,测定雷公藤口服液中雷公藤甲素的质量浓度为202．0μg／L,每片雷公藤片剂含甲素11．74μg,结果显著低于等度法和标示量（P<0．05）。     

A fully automated catecholamines analyzer based on cartridge extraction and HPLC separation

Summary A fully automated analyzer is described for the HPLC analysis of catecholamines. Firstly urinary and plasma catecholamines are reacted with diphenylboronic acid giving a complex without requiring a pH-meter step. This complex is strongly retained on a C 18 cartridge and elution with acetic acid solutions shows recoveries higher than 90 %. The catecholamines are eluted also by the mobile phase employed for the HPLC’ analysis. An intelligent autosampler makes the complex and fills a loop with all the solvents necessary for the sample cleanup. It then inverts the flow and pumps the sample and the solvents throught the cartridge. In the elution step the disposable extraction cartridge is positioned on stream with the HPLC analytical column by an automatic sampler. The separation is performed by ion-pair reversed-phase high-performance liquid chromatography, with sodium dodecyl sulphate as pairing ion, a short analytical column and electrochemical detection. The HPLC analysis time is 3 min and the total sample turnover time is 8 min. The recoveries and the precision of the analyzer are given together with correlation with manual HPLC.     

Determination of alkylphenols and alkylphenol polyethoxylates by reversed-phase high-performance liquid chromatography and solid-phase extraction

A simple, accurate and reproducible reversed-phase high-performance liquid chromatography (HPLC) method was developed for the separation and characterisation of alkylphenols (APs) and alkylphenol polyethoxylates (APEOs), using a C18 octadecyl silica (ODS) column. APs and each APEO oligomer were separated successfully within a reasonable time without gradient elution. An excellent resolution was obtained, even for mixtures of APs and low EO number APEOs, which are otherwise difficult to separate using conventional normal-phase HPLC methods. This method, combined with solid-phase extraction, was highly applicable for the simultaneous determination of alkylphenols and alkylphenol ethoxylates in real samples.     

Group separation of organohalogenated compounds by means of comprehensive two-dimensional gas chromatography

Separations of 12 compound classes, polychlorinated biphenyls (PCBs), diphenyl ethers (PCDEs), naphthalenes (PCNs), dibenzothiophenes (PCDTs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), terphenyls (PCTs) and alkanes (PCAs), toxaphene, organohalogenated pesticides (OCPs), and polybrominated biphenyls (PBBs) and diphenyl ethers (PBDEs) by comprehensive two-dimensional gas chromatography were evaluated. Five column combinations, DB-1 x 007-210, DB-1 x HT-8, DB-1 x LC-50, DB-1 x 007-65HT and DB-1 x VF-23ms were used to study, primarily, group-type separations, but attention was devoted also to within-class separation, especially for those classes which were not addressed in much detail before, the PCNs, OCPs, PBBs and PCTs. The DB-1 x 007-210 column set did not offer any extra separation compared to one-dimensional GC. For the DB-1 x HT-8 column combination, the useful principle of congener separation on the basis of number of halogen substituents in a molecule was confirmed (PCBs, toxaphene) and extended (PCTs, PBDEs). No practically useful group-type separation was observed for this column combination. The DB-1 x LC-50 set provides group separation based on planarity: planar compounds such as PCDDs, PCDFs, PCDTs and PCNs are much more retained than, and therefore separated from, non-planar analytes. Within the classes of PCBs, PBBs and PCTs highly useful separation of planar from non-planar compounds was also observed. The DB-1 x 007-65HT column set effectively separates PCAs and PBDEs from all other compound classes, and provides a good separation of brominated and chlorinated analogue classes from each other. This column set was the most efficient one for within-class separation of OCPs and PCNs. Finally, DB-1 x VF-23ms yields excellent within-class separations, especially of non-aromatic compounds, viz. OCPs, toxaphene and PCAs. No group separation was observed here. The applicability of the approach was demonstrated for a sediment extract and a dust extract. In the sediment extract, PCDDs, PCDFs, PCAs and PCNs were identified and their efficient separation was achieved. In the dust sample, separation of PCAs and PBDEs was achieved and several new PBDE congeners were identified.