Determination of priority pollutant phenols by isocratic HPLC

Summary An isocratic high performance liquid chromatographic method, able to determine ng/l of Priority Pollutant Phenols (PPP) in water, is proposed. A Nucleosil 5 C 18 column and an 30 mM ammonium acetate (pH 5.0): acetonitrile: methanol (56:34:10) eluent are used. Linearity ranges from 5–50 ppm of phenols; variation coefficients are about 4% (n=7) at the 30 ppm level with a 5μl injection. Dual UV detection helps to identify different phenols. The use of an anionic exchanger column and of methanol: hydrochloric acid (9:1) as eluent allows selective preconcentration of priority phenols and recoveries in the range 79–105%.     

Determination of tetraiodothyronine in serum by HPLC and electrochemical detection

Tetraiodo-L -thyronine (T4) in human serum was determined by HPLC using a nonphysiological internal standard. For sample preparation, a cation exchange resin, RP-chromatography on C-18 or phenylphase, and electrochemical detection (Metrohm 656 or BAS-LC 4 A) were employed. The mobile phase (0.8 ml/min) was 10 mM H₃PO₄/CH₃OH (40/60 v/v) or 10 mM H₃PO₄/CH₃CN (70/30 v/v, 1.5 ml/min), the voltage applied 800 mV. The coefficient of variation (day to day) was 6.8% (N = 40); concentrations of T4 found were 11 to 20% lower than those obtained by two different commercially available immunoassays.     

反相高效液相色谱法测定竹红菌中竹红菌甲素的含量

建立了高效液相色谱法测定竹红菌提取物中竹红菌甲素含量的方法.样品用c18柱为分离柱,甲醇-水（体积比83：17）为流动相,检测波长为300nm进行分析.竹红菌甲素在进样量0.252～2.52μg范围内峰面积线性关系良好（r=0.999 9）,回收率为98%～103%,方法的RSD为0.20%～0.36%（n=5）.该分析方法简便快速,适合作为常规分析方法.     

Determination of glibenclamide in human serum by HPLC

The antidiabetic drug glibenclamide can be reliably quantitated in human serum with high performance liquid chromatography. The serum is buffered and extracted with toluene. The organic solvent is evaporated, the residue dissolved in the mobile phase and an aliquot sampled automatically and chromatographed. UV-detection at 229 m allows a lower limit of quantitation of 5 ng/ml. Precise handling of exact volumes facilitates external calibration. Statistical data for imprecision and inaccuracy are given and illustrate reliable quantification. Application of the method to experimental and clinical pharmacokinetic studies with specific problems is illustrated.     

Determination of column selectivity toward polycyclic aromatic hydrocarbons

An empirical test is described for the evaluation of column selectivity in reversed-phase liquid chromatography. Using a test mixture of three polycyclic aromatic hydrocarbons (PAH), overall column selectivity toward PAH was assessed for over 20 different commercial C₁₈ columns. Retention behavior was correlated to phase type (i.e., monomeric and polymeric surface modification chemistry) for custom synthesized phases. A classification scheme is proposed in which commercial C₁₈ columns are grouped into three classes based on retention behavior: monomeric-like, polymeric-like, and intermediate phase selectivity toward PAH. Correlation of retention behavior of the test mixture with the separation of PAH mixtures and with more general column properties (e.g., phase thickness) is discussed.     

Simultaneous Determination of Isoniazid and Acetylisoniazid in Human Plasma by Hydrophilic Interaction Liquid Chromatography Tandem Mass Spectrometry and Its Application to a Pharmacokinetics Related to N-Acetyltransferase2 Genetic Polymorphism

A rapid, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with hydrophilic interaction chromatography has been developed and validated for the simultaneous determination of isoniazid and acetylisoniazidin human plasma. Following precipitation of the protein, the analytes were extracted from human plasma, with high extraction recovery (>70%) for both Isoniazid and acetylisoniazid. The analytes were then separated using a hydrophilic interaction chromatography (HILIC) column and detected by electrospray ionization (ESI) mass spectrometry performed with a triple-quadrupole mass spectrometry. The quantification of the analytes was realized by low-energy collision dissociation tandem mass spectrometry (CID-MS/MS) using the multiple reaction monitoring (MRM) mode at m/z of 138.1→121.1 for isoniazid and m/z 180.1 → 138.1 for acetylisoniazid, respectively. The method was linear over the concentration range of 5–50,000 ng/mL for both. The intra-day and inter-day relative standard deviations (RSD) were less than 15% and the relative errors (RE) were all within 15%. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic studies of isoniazid related to NAT2 genetic polymorphism in healthy Chinese subjects. The results showed that there were significant differences in the pharmacokinetic parameters of isoniazid and acetylisoniazid between subjects with and without mutations in the NAT2 gene.     

Separation and analysis of nitroarenes from airborne particulate organic matter by HPLC and capillary GC-MS methods

Normal-phase HPLC has been applied to the separation of nitroarenes from dichloromethane extracts from airborne particulate matter samples collected in urban regions of Upper Silesia. GC-MS and capillary gas chromatography with NP detector analysis of the nitroarene fraction made it possible to identify and determine quantitatively those compounds which dominate in the organic matter emitted to the atmosphere in highly industrialized regions (2-nitrofluorene, isomeric nitroarenes of MW = 247, i.e. nitropyrene/nitrofluoranthene/nitroacephenanthrylene).     

防晒类化妆品中2种帕地马酯的高效液相色谱检测及质谱确证

建立了同时测定防晒类化妆品中帕地马酯A和帕地马酯O的高效液相色谱分析方法及质谱确证方法。化妆品样品以甲醇为提取溶剂进行超声提取,提取液离心处理,取上清液经微孔滤膜过滤后测定。采用XTerra MS C18柱(250×4.6mm,5μm)分离,外标法定量。结果表明防晒类化妆品中帕地马酯A和帕地马酯O的方法定量限均为0.5mg/kg,在低、中、高3个添加水平范围内平均回收率为89.1%~112.5%,相对标准偏差为2.0%~7.7%。对于疑似阳性样品,进一步采用液相色谱-串联质谱法进行确证分析。该方法准确、快速、灵敏度高,适用于防晒类化妆品的实际检验工作。     

Determination of cholesterol in fat and muscle of pig by HPLC and capillary gas chromatography with solvent venting injection

Two methods for determination of cholesterol in fat and muscle of pig were evaluated: extraction with chloroform:methanol (2:1, v/v) followed by saponification (method 1) and direct saponification (method 2). HPLC and GC were used to determine cholesterol concentrations. GC analysis was performed with a capillary column of 100 μm using a PTV injector in the modes of cold split and solvent venting. Cholesterol was analyzed without derivatization. Both methods of extraction did not present significant differences (p > 0.01). Sample analysis by GC with solvent venting injection and HPLC showed the lowest % r.s.d. but GC in the cold split mode allowed to obtain a shorter analysis time. Cholesterol concentrations obtained by HPLC were not statistically different from the results obtained by GC with solvent venting injection and were slightly lower than those previously reported. Cholesterol concentrations in fat and muscle tissues respectively ranged from 52 to 77 mg/100 g and from 55 to 65 mg/100 g.     

Determination of Amino Acidsas Their N-Hydroxy-succinimidyl-3-indolylacetate Derivatives by Reversed-phase HPLC

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Quantitative in silico analysis of the selectivity of graphitic carbon synthesized by different methods

Molecular interaction energy (MI) values calculated by molecular mechanics (MM2) using a model graphitic carbon phase were used for studying the selectivity of different types of graphitic carbon columns. The MI values well correlated with logk values measured on a graphitic carbon synthesized from 100% organic materials (r = 0.961, n = 13) but not with logk values measured on a graphitic carbon synthesized using silica matrix (r = 0.558, n = 17). The latter logk values correlated well with the hydrogen bonding energy values calculated using a model silica phase (r = 0.856, n = 17). The reason for the poor correlation of the logk values measured on the latter graphitic carbon is that the silica matrix might not be completely eliminated in the production process.     

Selectivity optimization in green chromatography by gradient stationary phase optimized selectivity liquid chromatography

Stationary phase optimized selectivity liquid chromatography (SOSLC) is a promising technique to optimize the selectivity of a given separation by using a combination of different stationary phases. Previous work has shown that SOSLC offers excellent possibilities for method development, especially after the recent modification towards linear gradient SOSLC. The present work is aimed at developing and extending the SOSLC approach towards selectivity optimization and method development for green chromatography. Contrary to current LC practices, a green mobile phase (water/ethanol/formic acid) is hereby preselected and the composition of the stationary phase is optimized under a given gradient profile to obtain baseline resolution of all target solutes in the shortest possible analysis time. With the algorithm adapted to the high viscosity property of ethanol, the principle is illustrated with a fast, full baseline resolution for a randomly selected mixture composed of sulphonamides, xanthine alkaloids and steroids.     

Separation of nonionic surfactants according to functionality by hydrophilic interaction chromatography and comprehensive two-dimensional liquid chromatography

It is shown, that amphiphilic polymers--such as polysorbates and fatty esters of polyethylene glycol can be separated by comprehensive two-dimensional liquid chromatography using a reversed phase column (under critical conditions for the polyoxyethylene chain) and a HILIC column, which may arranged in different order. The mobile phases in both dimensions can be 93-97 wt% acetone water. As the retention of higher esters on the reversed phase column is very strong, this column should be used as the first dimension. On the HILIC column all fractions elute within a reasonably short time (at a flow rate of 2.5 ml/min within 2 min). With a flow rate of 0.1 ml/min in the first dimension, a full separation can be achieved in 90 min.     

离子色谱分离-(二极管阵列)紫外检测法测定AMPS的含量和纯度

建立了用高效液相色谱法测定AMPS含量和纯度的方法.样品用Zorbax SAX阴离子交换柱为分离柱,0.1 mol/L KH2PO4溶液为流动相,检测波长为220 nm进行分析.AMPS在进样量0.5～50 μg范围内峰面积线性关系良好,回收率为96.0%～103.2%,方法的平均RSD为0.49% (n=6).该方法可作为常规分析方法.     

HPLC analysis of organic acids using a novel stationary phase

In the present work, a high performance liquid chromatographic method with UV detection for the separation of six organic acids including, tartaric, malic, acetic, lactic, citric and succinic is described.The separation was performed on a novel stationary phase TEKNOKROMA, Tr-010065 Mediterranea sea₁₈ (15 cm × 0.4 cm, i.d. 3 μm) and using water with a 0.1% (v/v) of formic acid as mobile phase. The advantages of this packing over a conventional octadecylsilane (ODS2) column are reported.The method was validated with respect to linearity, limits of detection and repeatabilities within day and between days and satisfactory results were obtained.The proposed method was applied for the determination of these compounds in commercially available white wines. The samples were injected directly without previous treatment. LC-MS was used as a confirmatory technique.