Enhanced Detection of Sulphur and Phospho-rous Containing Compounds in HPLC-Induc-tively Coupled Plasma Mass Spectrometry Using Chemical Resolution via Hexapole-Based Reaction with Oxygen

The sensitive detection of sulphur and phosphorous-containing compounds using HPLC-ICPMS is difficult due to the high background caused by polyatomic interferences. One potential solution to the problem of polyatomic interferences for S and P is to react the latter with oxygen in the collision hexapole to separate them from interferences eg; (O₂ on S and NOH on P). This has the effect of moving the detection mass from 31 and 32 to 47 and 48 m/z for P and S respectively. This region is clear from interferences thereby providing an increase in the sensitivity of detection for the analytes of approximately 50–100 fold. For omeprazole, a model S containing compound, a limit of detection (LOD) of 800 pg on column was achieved, an increase of ca. 100 fold in sensitivity. Similarly in the case of ZD6126 a phosphorous-containing pro-drug, an increase in sensitivity of 50 times was observed with an LOD of 1 ng on column.     

Pheumatoamperometric determination of cyanide,sulfide and their mixtures

A rapid pneumatoamperometric method for quantifying cyanide in the presence or absence of sulfide is described. The gaseous mixture of hydrogen cyanide and hydrogen sulfide is separated by inserting a short chromatographic column packed with silica gel between the reaction vessel used to generate the volatile acids and the porous gold electrode that the detects them. The detection limit is ca. 5 ng cyanide in 2 ml of solution regardless of sulfide content. The detection limit for sulfide is ca. 1.0 ng in 2 ml of solution when cyanide is present and ca. 0.7 ng in absence of cyanide. Both sulfite and nitrite interfere.     

高效液相色谱-质谱法测定特定用途保健药品中的褪黑激素

采用ＨＰＬＣ－ＭＳ联用法测定了具有改善睡眠等特定功能的保健药品中的褪黑激素。利用质谱谱库检索和二极管阵列检测光谱图鉴定“松果体素”药品中的褪黑激素,以甲醇－水（７０∶３０）为流动相,检测波长为２７５ｎｍ。用外标法进行定量分析,方法最低检测限为０．２ｎｇ。     

Analysis of vinca alkaloids in plasma and urine using high-performance liquid chromatography with electrochemical detection

The reversed-phase high-performance liquid chromatography with electrochemical detection was used to quantify plasma and urine levels of vinblastine, vincristine, vindesine and a metabolite of vinblastine, desacetylvinblastine. Sample clean-up consisted of solid-phase extraction with a Bond Elut CN column. The extracts were separated on a Hypersil ODS column. The mobile phase consisted of a mixture of methanol and 10 mM phosphate buffer (pH 7.0). The limit of sensitivity using electrochemical detection was 100 pg on-column for all compounds with a signal-to-noise ratio of 3. Quantification of the compounds in human plasma and urine was possible down to 1 ng/ml (ca. 1 pmol). Pharmacokinetic results show that the sensitivity of the method is adequate for drug monitoring in clinical research.     

Assay of hydroxyfarrerol in biological fluids

A high-performance liquid chromatographic method for the determination of hydroxyfarrerol (IdB 1031) in biological samples was developed. IdB 1031 was first extracted by liquid-solid partition and the extracts were evaporated and analysed on a reversed-phase column under isocratic conditions, using either an electrochemical or a UV detector. The detection limit was ca. 5 ng/ml. Preliminary pharmacokinetic data showed that rats treated orally with 500 mg/kg had an average peak plasma concentration (Cmax) of 497 ng/ml after 2 h.     

Assay of nicergoline and three metabolites in human plasma and urine by high-performance liquid chromatography-atmospheric pressure ionization mass spectrometry.

A method for the simultaneous determination of nicergoline and three of its metabolites in human plasma and urine has been developed using high-performance liquid chromatography-atmospheric pressure ionization mass spectrometry. Nicergoline and its metabolites were extracted from the plasma and urine samples with chloroform and separated on a reversed-phase ODS column. The eluents were led to the atmospheric pressure ionization interface and then analysed in the selected-ion monitoring mode. The detection limits of nicergoline and three of its metabolites were ca. 2 ng/ml in plasma and ca. 10 ng/ml in urine, at a signal-to-noise ratio of 4.     

Development of chiral HPLC for selenoamino acids with ICP-MS detection:application to selenium nutritional supplements

The enantiomeric separation of three underivatized seleno-amino acids, D,L-selenocystine, and D,L-selenomethionine, and D,L-selenomethionine, with UV and ICP-MS detection is described. An HPLC column with a chiral crown ether stationary phase and a mobile phase of 0.10 M HCIO4 was used. Absolute detection limits obtained with UV detection ranged from 34.5 to 47.1 ng whereas those obtained with the plasma detector were ca. 40-400 times better. The separations with either detector were good, with the little detector effect on the resolution. Ten commercially available dietary selenium supplements were analyzed using the chiral column to identify and quantify the selenium species present with both detection modes. Selenium species were easily identified using ICP-MS detection, whereas UV detection was not viable because of interferences from the sample matrix and inadequate sensitivity. Selenium species that were unretained using the chiral column were identified using anion exchange chromatography. Total amounts in the samples were also measured using a conventional digestion and enzymatic digestion with ICP-MS detection.     

Determination of lidocaine in human serum by capillary gas chromatography with surface ionization detection

A novel analytical method has been developed for the determination of lidocaine (2-(diethylamino)-N-(2,6-dimethyl)phenylacetamide) in human serum. After solvent extraction from serum the extract was analyzed by gas chromatography employing a van den Berg type solventless injector, a new sensitive and selective detector, the surface ionization detector, and a bonded phase flexible fused silica capillary column. The detection limit was ca. 30–50 ng/ml.     

Solid phase extraction and HPLC determination of spiramycin in plasma and vitreous concentrations

A method for extracting spiramycin by an octadecylsilica cartridge is described for plasma or vitreous samples. The macrolide antibiotic is then measured by reversed-phase HPLC with UV detection. The limit of detection is estimated to be 50 ng/mL. The coefficient of variation for the procedure is 6.1% and 5.2% for the range of concentrations 0.2 micrograms/mL and 10 micrograms/mL respectively. By this method, pharmacokinetic profiles were performed for five adult patients. Spiramycin could be accurately measured in the vitreous humour, allowing the determination of antibiotic at its site of action.     

Simultaneous determination of a new dihydropyridine calcium antagonist (MPC-1304) and its metabolite in dog plasma by high-performance liquid chromatography with electrochemical detection.

A rapid and sensitive high-performance liquid chromatographic analysis, with electrochemical detection, has been developed for the simultaneous determination of a new calcium-channel antagonist, (+/-)-methyl 2-oxopropyl-1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedi carboxylate (I, MPC-1304), and its active metabolite in dog plasma. The plasma extract with toluene was chromatographed on a reversed-phase column and detected by an electrochemical detector at + 0.92 V. Calibration curves were linear from 2.0 to 100.0 ng/ml, and the detection limit was ca. 0.25 ng/ml. This method is applicable to the simultaneous determination of I and its metabolite in dog plasma following the oral administration of I.     

An optimized gas chromatographic determination of priority pollutant phenols

Priority pollutant phenols are determined by gas chromatography on an SE-30 WCOT column using hydrogen carrier and flame ionization detection with dual internal standards. Linear responses over ranges ca. 12–125 ng per component are achieved and detection limits at or below 1 ng are obtained. Carrier flow and temperature program are optimized to maintain baseline resolution while affording an analysis time of less than 15 minutes.     

High-performance liquid chromatographic determination of N-(2-methyl-2-propyl)-3-oxo-4-aza-5 alpha-androst-1-ene-17 beta-carboxamide, a 4-azasteroid, in human plasma from a phase I study

A sensitive and selective high-performance liquid chromatographic method has been developed for the quantitative determination of N-(2-methyl-2-propyl)-3-oxo-4-aza-5 alpha-androst-1-ene-17 beta-carboxamide (I) in human plasma. I, a 5 alpha-reductase inhibitor and a potential therapeutic agent for benign prostatic hyperplasia, is a member of the family of compounds referred to as the 4-azasteroids. The 4-N-methyl analogue of the drug was used as the internal standard and calibration curves were developed at two levels of sensitivity to cover a large dynamic range of plasma concentrations. Drug was isolated from biological fluids with a solid-phase C18 extraction column; the analyte was further purified by adsorption and desorption from a second extraction column (CN cartridge). Evaluation of the isolation method revealed that it was reproducible and drug recoveries equalled ca. 90%. Chromatography was carried out on a C8 column (5 micron) with ultraviolet detection at 210 nm. The detection limit was ca. 10 ng/ml for I. Human plasma levels are reported for I following single-dose oral administration of 50,200 and 400 mg of drug; urinary excretion data are reported for a single volunteer given 400 mg of I.     

Flow-injection hydride generation atomic absorption spectrometric study of the automated on-line pre-reduction of arsenate, methylarsonate and dimethylarsinate and high-performance liquid chromatographic separation of their l-cysteine complexes

An automated on-line pre-reduction of arsenate, monomethylarsonate (MMA) and dimethylarsinate (DMA) using flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) is feasible. The kinetics of pre-reduction and complexation depend strongly on the concentration of l-cysteine and on the temperature in the following increasing order: inorganic As(V)相似文献   

Determination of (-)-bunolol and its metabolite, dihydro-(-)-bunolol, in human aqueous humour by gas chromatography-negative ion chemical ionisation mass spectrometry.

(-)-Bunolol (LB) was applied to the human eye in a commercially available eye drop formulation. LB and its metabolite, dihydro-(-)-bunolol (DHLB) were identified and quantified in human aqueous humour. The compounds were analysed as their trimethylsilyl-pentafluorobenzamide derivatives using gas chromatography-negative ion chemical ionisation mass spectrometry. In the case of DHLB the corresponding 2H3-labelled isotopomers were used as internal standards and LB was quantified against its methoxime derivative. Calibration curves for LB and DHLB against internal standards were linear with correlation coefficients 0.994 and 0.996, respectively. Replicate analyses of a pooled sample of aqueous humour containing LB and DHLB gave standard errors of the mean of +/- 9.8 and +/- 2.4% for the concentrations of LB and DHLB, respectively. The practical limit of detection of the method was ca. 30 pg for LB and ca. 100 pg for DHLB. The derivatization procedure was also satisfactory for the analysis of a number of other beta-blockers which are used in ophthalmological practice.     

Pulsed amperometric detection of sulfur-containing pesticides in reversed-phase liquid chromatography

Pulsed amperometric detection at a gold electrode is demonstrated for the separation of eight sulphur-containing pesticides on a C-18 reversed-phase column with 50% (v/v) acetonitrile in acetate buffer (pH 5.0) as the mobile phase. Detection was based on a two-step potential waveform with adsorption of the analyte during cathodic polarization and subsequent amperometric detection catalyzed by oxide formation following anodic polarization. The mechanism of the anodic detection involves prior adsorption of the sulfur compounds. Hence, the shape of the calibration curve is strongly influenced by the adsorption isotherm of the analyte and, therefore, deviates from linearity at high concentrations. Detection limits below 100 ng ml^?1 in 20-μl samples (e.g., 0.8 ng of dimethoate) were obtained by using preconcentration from a larger sample onto a C-18 fore column prior to injection into the separation column.     

Fully automated column-switching HPLC determination of aflatoxin M1 in milk using dialysis as sample preparation

A procedure has been developed for the automated determination of aflatoxin M1 in decreamed milk, by using on-line dialysis and subsequent trace enrichment on a reverse phase column. After foreflush to the analytical column the determination is performed with fluorescence detection. Fully automated analysis within 10 min is thus possible with reproducible dialysis recoveries above 50% (CV is 3.3%, n = 20) and detection levels of 50 ng/kg.     

高效液相色谱法同时测定牛肉及其制品中敌草隆、绿麦隆的残留量

介绍了用高效液相色谱同时测定牛肉及其制品中脲类除草剂——敌草隆、绿麦隆残留量的方法。色谱柱为ＳｅｌｅｃｔｏｓｉｌＣ１８柱,流动相为甲醇－水（６０∶４０,Ｖ／Ｖ）,ＵＶ－２４５ｎｍ检测。最小检测量：敌草隆为０．４ｎｇ,绿麦隆为０．５ｎｇ。线性范围均为０．０５～１０ｍｇ／Ｌ。回收率：敌草隆为８７．３４％～８７．６４％,绿麦隆为８８．７８％～９１．９４％。     

气相法分析化妆品中的防腐剂

 采用大口径中极性毛细管柱HP 170 1(15m× 0 5 3mmi d × 1 0 μm)对苯甲醇、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯和对羟基苯甲酸丁酯等化妆品中常用的 5种防腐剂进行了气相分析方法研究。结果表明 ,该毛细管柱能够很好地分离这 5种化合物 ,抗干扰性良好 ,其检出限分别是 13ng ,70ng ,70ng ,10 0ng和 10 0ng ,线性范围为 5 0ng～ 5 0 0ng。     

顶空气相色谱-质谱法测定婴幼儿食品中的呋喃

通过顶空装置将样品中的呋喃提取出来,以D4-呋喃作为内标物,HP-PLOT Q石英毛细管柱作为分析柱,采用气相色谱分离,质谱定性定量,建立了婴幼儿食品中呋喃的顶空气相色谱-质谱联用分析方法。方法的低浓度工作曲线的线性范围为10～70 ng,高浓度工作曲线的线性范围为50.0～400.0 ng,两条曲线的相关系数均为0.997。方法的定性检出限（S/N≥3）为3.8 ng/g,定量检出限（S/N≥10）为10.0 ng/g。不同基底样品中高低添加浓度的加标回收率为90.0%～98.4%,相对标准偏差均小于10%。     

Sensitive method for the determination of the antiarrhythmic drug detajmium in serum by solid-phase extraction and high-performance liquid chromatography with fluorimetric detection.

The objective of this study was to develop a very sensitive and selective method for the determination of detajmium (4-3-diethylamino-2-hydroxypropyl-ajmaline), a sodium-channel-blocking drug with antiarrhythmic properties, in serum. A high-performance liquid chromatography (HPLC) method with solid-phase extraction and fluorimetric detection has been applied. Serum samples were diluted with phosphate buffer (pH 3.5) and the extraction of detajmium and ajmaline, which was used as an internal standard, was carried out with Oasis cartridges (Waters). The chromatographic separation was performed on a RP18 column. The limit of quantification for serum samples of detajmium was 1 ng/ml with good reproducibility (R.S.D. < 15%) and a linear response from 1 to 200 ng/ml. The described method is highly sensitive and specific for the determination of detajmium in serum of patients and volunteers.