Simultaneous Determination of Tramadol and Acetaminophen in Human Plasma by LC–ESI–MS

This study presents a high-performance liquid chromatography–electrospray ionization–mass spectrometric (LC–ESI–MS) method for the simultaneous determination of tramadol and acetaminophen in human plasma using phenacetinum as the internal standard. After alkalization with saturated sodium bicarbonate, both compounds were extracted from human plasma with ethyl acetate and were separated by HPLC on a Hanbon LiChrospher CN column with a mobile phase of 10 mM ammonium acetate buffer containing 0.5% formic acid–methanol (40:60, v/v) at a flow rate of 1 mL min⁻¹. Analytes were determined using electrospray ionization in a single quadrupole mass spectrometer. LC–ESI–MS was performed in the positive selected-ion monitoring (SIM) mode using target ions at [M+H]⁺ m/z 264.3 for tramadol, [M+H]⁺ m/z 152.2 for acetaminophen and [M+H]⁺ m/z 180.2 for phenacetinum. Calibration curves were linear over the range of 5–600 ng mL⁻¹ for tramadol and 0.03–16 μg mL⁻¹ for acetaminophen. The inter-run relative standard deviations were less than 14.4% for tramadol and 12.3% for acetaminophen. The intra-run relative standard deviations were less than 9.3% for tramadol and 7.9% for acetaminophen. The mean plasma extraction recovery for tramadol and acetaminophen were in the ranges of 82.7–85.9 and 83.6–85.3%. The method was applied to study the pharmacokinetics of a new formulation of tramadol/acetaminophen tablet in healthy Chinese volunteers.     

Analysis of thiamine in dried yeast by high-performance liquid chromatography and high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry

Summary High-performance liquid chromatography (HPLC) and high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS) have been applied to the analysis of thiamine in dried yeast. Thiamine was extracted from dried yeast with isobutanol containing sodium 1-octanesulfonate as an ion-pairing agent and determined by HPLC on a reversed phase ODS column with UV detection at 254 nm. Response was linear in the range 25–300 μg/g of thiamine in dried yeast with a coefficient of variation in the reproducibility of 8.0%. Thiamine was recovered in good yield (109.2%, n=5). Identification of the thiamine peak was obtained by the mass spectrum using the HPLC/APCI-MS system. The utility of the selected ion monitoring technique using the HPLC/APCI-MS was also investigated. The results obtained by this method are in good agreement with those obtained by the thiochrome method [1].     

Can food quality be enhanced by chromatography?

Summary Quality of food is the utmost goal of all food producers. It is determined by chemical, physical, microbiological, and even psychological aspects. The chemical and microbiological quality aspects are especially responsible for health and welfare of the consumer. Quality of food, therefore, at all times has to be ensured and be enhanced as far as possible. From the chemical point of view, foods contain a great number of major and minor components. That determine the nutritional value of a food product. Furthermore, taste and flavour are the result of many food minor components. Foods also may contain unwanted compounds like residues and contaminants. Which represent undesirable aspects of food quality. With chromatography as a powrful analytical tool in food chemistry, the quality of food products cannot only be characterized but also be enhanced. Examples of enhancing quality of food by applying chromatography to cheese, margarine, meat, and other products is reported. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

高效液相色谱/大气压化学电离质谱分析新型复合抗氧剂

 应用高效液相色谱 /大气压化学电离质谱技术 ,其中包括直接进样技术、同时正负离子扫描方式、可编程的源内碰撞诱导解离 (CID)技术 ,以及红外光谱分析技术 ,对一种用于润滑油的新型复合抗氧剂进行了分离分析 ,并对其中的有效组分进行了定性鉴定。该方法简便、快速、可靠。     

Simultaneous Determination of Carbamate and Organophosphorus Pesticides in Honeybees by Liquid Chromatography-Mass Spectrometry

Summary The potential of liquid chromatography-mass spectrometry (LC-MS) has been studied for the simultaneous determination of sixteen carbamate and organophosphorus pesticides in honeybees using a traditional sample preparation protocol based on acetone extraction and dichloromethane partitioning. The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ES) interfaces were compared. APCI offered better sensitivity and specificity for a higher range of pesticides. Limits of quantification were from 0.01 to 0.17 mg kg^–1, at which recoveries obtained were between 64 and 93%, except for pirimicarb that was at 13%, with relative standard deviations ranging from 7 to 20%. Fenitrothion, fenoxycarb, methiocarb and phoxim were found in bees from Valencian Community beehives at concentrations between 0.03 and 3.75 mg kg^–1.     

Analysis of priority pesticides and phenols in Portuguese river water by liquid chromatography-mass spectrometry

Summary The determination of selected pesticides and phenols in Portuguese river water samples was carried out from April to September, 1999. The method involved 200 mL samples taken by offline, solid phase extraction by OASIS polymeric cartridges followed by liquid chromatography-atmospheric pressure, chemical ionization-mass spectrometry (LC-APCI-MS). Recoveries of pesticides were 50–96% and 72–120% for the Platform and HP 1100 instruments, respectively. Chlorophenols gave recoveries of 60–91%. Triazines and transformation products like desethylatrazine (DEA) and desisopropylatrazine (DIA) and compounds such as diuron and chlorophenols were positively identified by LC-APCI-MS. The levels detected of the different compounds varied from 0.01–2.61 μg L⁻¹, the most frequently detected compounds being, atrazine, simazine, terbuthylazine, alachlor, metolachlor, Irgarol, diuron, 2,4,6-trichlorophenol, desisopropylatrazine and desethylatrazine.     

Rapid isocratic HPLC analysis of beta-carotene in red peppers (Capsicum annuum L.) and food preparations

Summary A simple, rapid high-performance liquid chromatography method has been devised in order to separate and quantify β-carotene present in red pepper (Capsicum annuum L.) fruits and food preparations. A reversed-phase isocratic non-aqueous system enables the separation of β-carotene within a few minutes, with detection at 450 nm. The selection of extraction solvents, mild saponification conditions, and chromatographic features, is evaluated and discussed. The method is proposed for rapid screening of large plant populations, plant selection, as well as for food products, and also for nutrition and quality control studies.     

Separation and quantitation of nicergoline and related substances by high-performance liquid chromatography/atmospheric pressure ionization mass spectrometry

Summary This study demonstrated the utility of high-performance liquid chromatography/atmospheric pressure ionization mass spectrometry (HPLC/API-MS) in the investigation of 10-methoxy-1,6-dimethylergoline-8-methanol 5-bromonicotinic acid ester (Nicergoline) and its related substances. The analysis was performed by using an ODS column with ammonium acetate and methanol mixture as the mobile phase. Nicergoline and its related compounds could be characterized by HPLC/API-MS in terms of their molecular weight. The use of multiple ion detection techniques for the quantitation of these compounds was also investigated. The detection limits of nicergoline and its related substances were 5 to 10 ng each at a signal-to-noise ratio of 4. The method was also applied to the study of the decomposition products of nicergoline in simulated gastric and intestinal fluids.     

Analysis of functionalized polyisobutylenes by capillary SFC, SEC, HPLC, and CGC-MS after fraction collection

Summary An analytical strategy has been developed for analysis of polyisobutylenes partially functionalized with isothiocyanate groups ( ) by capillary supercritical-fluid chromatography (CSFC), size- exclusion chromatography (SEC), and reversed-phase liquid chromatography (RPLC). Fractions collected from semi-preparative RPLC and SEC were further characterized by capillary GC-MS (gas chromatography coupled with mass spectrometry). Complete characterization of the polymer was achieved by comparing the results obtained from the different techniques. The degree of polymerization and the relative quantity of the different series of macromolecular chains of polyisobutylene were estimated.     

Analysis of oligonucleotides using coupled high performance liquid chromatography-electrospray mass spectrometry

Summary Improved HPLC and ESMS conditions have been established, allowing the separation and analysis of oligodesoxyribonucleotides by coupled HPLC-ESMS.     

On line trace enrichment for isolation of vitamin B2 in food samples

Summary Vitamin B₂ was enriched by liquid-solid extraction from large volumes of aqueous samples on a short precolumn. The enriched compounds were transferred onto an analytical reversed-phase column and separated by ion-pair chromatography. The equipment used provides the possibility of automation for routine analysis.Dedicated to Professor J. F. K. Huber on the occasion of the 60th birthday.     

天然维生素E制品中杂质的分离与鉴定

利用高效液相色谱、气相色谱-质谱联用与高分辨质谱对天然维生素E制品中的杂质进行了分离分析与结构鉴定。采用正相高效液相色谱法分离天然维生素E的4种异构体及2种杂质,并对杂质馏分进行富集纯化。将气相色谱-质谱联用与高分辨质谱检测相结合,用于获得杂质的结构信息。通过比较杂质精确相对分子质量和解析质谱碎片离子,推断杂质为芝麻素及其同分异构体表芝麻素。经与芝麻素对照品保留时间及碎片离子数据比对,确证了对杂质结构的推断。所建立的杂质鉴定方法快捷、有效,可应用于天然维生素E制品的食品安全控制。     

Optimization of HPLC-APCI-MS conditions for the qualitative and quantitative determination of total solanesol in tobacco leaves

HPLC coupled online with atmospheric pressure chemical ionization MS (APCI-MS) technique was evaluated for the qualitative and quantitative determination of solanesol in extracts of tobacco leaves. The solanesol and other compounds in the extract were separated on an Alltima C(8) (4.6 mm x 250 mm) column with methanol and water (98:2 v/v) as mobile phase, with flow rate of 0.8 mL/min and UV detection wavelength of 211 nm. In the APCI(+) mode, abundant stable [M-H(2)O + H](+) ion (m/z at 613.5) was observed, with low abundance of other fragmentation ions. A comparison of APCI-MS and ESI-MS techniques showed that APCI mode is more sensitive than ESI mode, and thus better suited for solanesol analysis. When comparing UV 211 nm and APCI-MS in SIM for solanesol quantification, the former offered better precision and reproducibility, but the latter was more than 200 times sensitive in detection. The developed method has been successfully applied to the analysis and comparison of solanesol concentration in different tobacco leaf samples.     

Determination of vitamin A in pharmaceutical preparations by high-performance liquid chromatography with diode-array detection

Summary A very simple high-performance liquid chromatographic method for determination of Vitamin A in pharmaceutical preparations without the need for saponification was developed. A reversed-phase (Nova-Pack C₁₈, 4 m) column was used with a mobile phase of acetonitrile-tetrahydrofuran-water (55378) and a flowrate of 1.5 ml/min. Sample treatment only consisted of the extraction of retinol acetate content from capsules or tablets with methanol. Total extraction was achieved by shaking vigorously with the aid of magnetic stirring for three hours at room temperature. No change of solvent is necessary to introduce the sample in the chromatographic system. This method is suitable for routine quantification of Vitamin A.     

Characterization and quantification of triacylglycerols in peanut oil by off‐line comprehensive two‐dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry

The complexity of natural triacylglycerols (TAGs) in various edible oils is prodigious due to the hundreds of set is of TAG compositions, which makes the identification of TAGs quite difficult. In this investigation, the off‐line 2D system coupling of nonaqueous RP and silver‐ion HPLC with atmospheric pressure chemical ionization MS detection has been applied to the identification and quantification of TAGs in peanut oil. The method was successful in the separation of a high number of TAG solutes, and the TAG structures were evaluated by analyzing their atmospheric pressure chemical ionization mass spectra information. HPLC and MS conditions have been optimized and the fragmentation mechanisms of isomers have been validated. In addition, an internal standard approach has been developed for TAG quantification. Then this system was applied in peanut oil samples and there was a total of 48 TAGs including regioisomers that have been determined and quantified.     

Determination of vitamins D2 and D3 in pharmaceuticals by supercritical-fluid extraction and HPLC separation with UV detection

Summary The supercritical-fluid extraction of vitamins D₂ and D₃ with carbon dioxide is reported for the first time. The extraction recovery was enhanced by direct addition of diethyl ether to sample contained in the extraction cell. Separation and detection of the analytes was performed off-line by reversed-phase liquid chromatography with UV-detection. The quantification limit of the method is 4.1 μg for both analytes, with precision, expressed as relative standard deviation, of 3.8 and 6.3% for vitamins D₂ and D₃, respectively (η=7). The proposed method has been applied to the determination of vitamin D in different pharmaceutical products; recoveries were between 85 and 105%.     

Systematic screening and characterization of glycosides in tobacco leaves by liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry using neutral loss scan and product ion scan

Glycosides in tobacco leaves are highly important aromatic precursors. It is necessary to reveal glycosides in tobacco leaves to improve tobacco planting and processing. This study describes a method for the systematic screening of glycosides in tobacco leaves by liquid chromatography with tandem mass spectrometry. Although glycosides contain numerous aglycones, the number of glycans is limited. Based on a screening table of glycans designed for neutral loss scan, glycosides with different aglycones were systematically screened out. Then, the MS² fragment spectra of scanned glycosides were further obtained using product ion scan. By comparison with the spectra in online tandem mass spectral databases, reported references, and verification by commercial standards, 64 glycosides were detected, including 39 glycosides linked with monosaccharides, 18 glycosides linked with disaccharides and 7 glycosides linked with trisaccharides. It is noteworthy that glycosides linked with trisaccharides have previously been rarely reported in tobacco. This method appears to be a useful tool for the systematic screening and characterization of glycosides in tobacco and can potentially be applied to other plants.     

Comparison of sonic spray lonization with atmospheric pressure chemical lonization as an interface of liquid chromatography-mass spectrometry for the analysis of some local anesthetics

Summary Sonic spray ionization (SSI) was compared with atmospheric pressure chemical ionization (APCI) as an interface for liquid chromatography (LC)-mass spectrometry (MS) for the analysis of some local anesthetics. Peaks at [M+H]⁺ constituted the base peaks for all compounds by both SSI and APCI, except for prilocaine. The sensitivities by SSI for tetracaine, benzoxinate, dibucaine, bupivacaine and mepivacaine were 4–16 times higher than those by APCI; those by SSI for procaine and lidocaine were equivalent to those by APCI. Only for prilocaine was the sensitivity by SSI two times lower than that by APCI. In view of the higher sensitivities obtained for many local anesthetics by SSI, we established a detailed procedure for the assay of these drugs in human plasma and urine by LC-MS with SSI in combination with a diol-bonded silica gel HPLC column that enabled direct injection of crude biological samples without complicated pretreatment. The recoveries, sensitivities, accuracies and precisions were found satisfactory to quantitate them at their therapeutic levels.     

Monitoring of biologically active amines in cereals and cereal based food products by HPLC

Summary Biologically active amines (putreanine sulphate, N-acetyl putrescine, putrescine, cadaverine, histamine, agmatine, N-acetyl spermidine, spermidine, spermine) were separated and quantified in cereal flour and cereal products by a liquid chromatographic method. The method consists of the separation of ion pairs formed between biologically active amines and octanesulphonic acid on a reversed-phase column, postcolumn derivatization with o-phtalaldehyde-2-mercapthoethanol and spectrofluorometric detection. Results of the reliability study were satisfactory. The method was linear for each amine at 1–10 mg L⁻¹. Putrescine and spermidine were the only amines always detected in cereal flour and cereal products, ranging from 2.45 to 47.83 mg kg⁻¹ for putrescine and 3.27 to 37.14 mg kg⁻¹ for spermidine. The most important differences among types of samples were found in polyamine derivatives. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.