Cerebrospinal fluid transmitter metabolites and atmospheric pressure.
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Adult↗
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Results for “ATMOSPHERIC PRESSURE”
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Detection of non-prescription heroin markers in urine with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.
The planned introduction of a prescription heroin program in Germany created a need for differentiation between non-prescription and prescribed diamorphine use. The following substances were chosen as markers of non-prescription heroin: acetylcodeine (AC); its metabolites codeine (C) and codeine 6-glucuronide (C6G); papaverine (P); and noscapine (N). Typical heroin markers diamorphine (DAM) and its metabolites monoacetylmorphine (MAM) and morphine (M) were also determined. The drugs were extracted from urine samples with solid-phase extraction (C18) using standard 200-mg columns and 96-well microplates (100 mg). The extracts were examined with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (positive ionization) in two isocratic systems. Selected ion monitoring procedures were applied for protonated molecular masses and characteristic fragments of drugs involved. The limits of detection were in the range of 0.5-1 ng/mL urine. The occurrence of selected heroin markers was investigated in 25 urine samples collected from heroin abusers (road traffic offenders and overdosed patients). C6G was found in all samples, C in 24 samples, N in 22 samples, MAM in 16 samples, P in 14 samples, DAM in 12 samples, and AC in 4 samples. The appearance of these compounds in urine reflects their pharmacokinetic properties and the composition of non-prescription heroin.
Adult↗
Validated assay for quantification of oxcarbazepine and its active dihydro metabolite 10-hydroxycarbazepine in plasma by atmospheric pressure chemical ionization liquid chromatography/mass spectrometry.
Oxcarbazepine (OX), a new antiepileptic, may lead to unwanted side-effects or even life-threatening intoxications after overdose. Therefore, a validated liquid chromatographic/mass spectrometric (LC/MS) assay was developed for the quantification of OX and its pharmacologically active dihydro metabolite (dihydrooxcarbazepine, DOX, often named 10-hydroxycarbazepine). OX and DOX were extracted from plasma by the authors' standard liquid/liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. The compounds were quantified in the selected-ion monitoring mode using atmospheric pressure chemical ionization electrospray LC/MS. The assay was fully validated. It was found to be selective. The calibration curves were linear from 0.1 to 50 mg l(-1) for OX and DOX. Limits of quantification were 0.1 mg l(-1) for OX and DOX. The absolute recoveries were between 60 and 86%. The accuracy and precision data were within the required limits. The analytes in frozen plasma samples were stable for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with OX. The measured therapeutic plasma levels ranged from 1 to 2 mg l(-1) for OX and from 10 to 40 mg l(-1) for DOX. The validated LC/MS assay proved to be appropriate for quantification of OX and DOX in plasma for clinical toxicology and therapeutic drug monitoring purposes. The assay is part of a general analysis procedure for the isolation, separation and quantification of various drugs and for their full-scan screening and identification.
Anticonvulsants↗
Study of different atmospheric-pressure interfaces for LC-MS/MS determination of acrylamide in water at sub-ppb levels.
A rapid, sensitive and selective method based on LC-MS/MS has been developed for the direct determination of acrylamide residues in water in compliance with the current European Union (EU) 98/83 Drinking Water Directive. Given the high polarity of acrylamide, the application of a rapid on-line solid phase extraction step, commonly used for preconcentrating low analyte levels, was not found to be completely satisfactory. Therefore, an alternative approach based on the use of direct large-volume injection into the LC-MS/MS system has been used. Three atmospheric-pressure interfaces (ESI, APCI and Ion Sabre APCI) were checked to reach the required sensitivity (0.1 microg/l). All three interfaces were tested by analysis of six different water samples (surface water, groundwater, drinking water and three treated water samples) spiked at three concentration levels each (0.1, 1 and 10 microg/l). When using ESI, poor sensitivity and high matrix effects were observed. This situation improved when APCI was used as the interface because no matrix effect was found, although sensitivity was not completely satisfactory. The best results were obtained by interfacing the Ion Sabre APCI; its higher sensitivity for acrylamide (LOD 0.03 microg/l) and the absence of matrix effects recommended its selection. Using this approach, satisfactory recoveries (90-97%) and precision (<12%) were obtained for all water samples studied. Besides, the acquisition of two different MS/MS transitions allowed not only the quantification but also the confirmation of acrylamide in water at concentration levels around 0.1 microg/l.
Acrylamides↗
Survival of mammals breathing organic liquids equilibrated with oxygen at atmospheric pressure.
Because oxygen and carbon dioxide are very soluble in certain silicone oils and fluorocarbon liquids, these liquids will support respiration of mammals. Mice and cats respiring silicone oil die shortly after return to air breathing, while those breathing fluorocarbon survive for weeks. The respiration of mice is optimally supported by these organic liquids at about 20 degrees C. In cats, arterial oxygenation is excellent, but there is some impairment of carbon dioxide elimination. All animals have suffered some pulmonary damage from breathing fluorocarbon liquids. Continued investigation of organic fluid respiration may lead to development of a safe method to support the respiration of man by liquids equilibrated with gases at atmospheric pressure.
Animals↗
EFFECTS OF PERFUSION OF OXYGENATED MICROMOLECULAR SOLUTIONS AT NORMAL ATMOSPHERIC PRESSURE INTO THE ISCHEMIC LEFT VENTRICULAR MYOCARDIUM.
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Animals↗
Trace determination of 1-aminopropanone, a potential marker for wastewater contamination by liquid chromatography and atmospheric pressure chemical ionization-mass spectrometry.
1-Aminopropanone (APR) is a volatile aminoketone of human origin that has been identified in raw sewage and surface waters. However, the traditional methodology for the determination of APR is extremely complicated and requires a skilled chemist to achieve consistent results. This investigation presents a novel and simple method for the analysis of APR by direct derivatization in aqueous media. APR is synthesized as its hydrochloride and derivatized using mercaptoethanol and o-phthalaldehyde. The product of reaction is separated on a 15 cm x 4.6 mm Luna C-18 column (1 mL/min, 45:55 acetonitrile: Water) and detected using a single quadrupole mass spectrometer detector operated in atmospheric pressure chemical ionization (APCI) mode. Method detection limits as low as 100 nM were routinely obtained with a precision of 1.7%. Recoveries of APR were always found to be greater then 88% in surface and wastewater samples fortified at three different levels. However, despite the robustness of the method and the fact that APR was consistently detected in urine it was not present in a variety surface or wastewaters analyzed during the course of the study. These results pose a critical question on the use of APR as a tracer for human derived wastewaters.
Acetone↗
Rapid evaluation of phenolic component profile and analysis of oleuropein aglycon in olive oil by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS).
Epidemiological studies have linked the Mediterranean diet with a low incidence of cardiovascular diseases. Olive oil, the major fat component of this diet, is characterized by antioxidant properties related to their content in catecholic components, particularly oleuropein aglycon. Therefore quantification of these components in edible oils may be important in determining the quality, and consequently its commercial value. The present method allows us to obtain the profile of the phenolic components of the oil from the methanolic extracts of the crude olive oil. In particular tyrosol, hydroxytyrosol, elenolic acid, deacetoxyligstroside and deacetoxyoleuropein aglycons, ligstroside and oleuropein aglycons, and 10-hydroxy-oleuropein are clearly identified by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). Moreover, oleuropein and its isomers present in the oil are quantified by APCI-MS/MS analysis of the extracts without preliminary separation from other phenolic compounds.
Dietary Fats, Unsaturated↗
Quantitation of the 5HT1D agonists MK-462 and sumatriptan in plasma by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.
The 5HT1D agonist sumatriptan is efficacious in the treatment of migraines. MK-462 is a drug of the same class which is under development in our laboratories. Bioanalytical methods of high efficiency, specificity and sensitivity were required to support the preclinical and clinical programs. These assays were based on HPLC with tandem MS-MS detection. MK-462 and sumatriptan were extracted using an automated solid-phase extraction technique on a C2 Varian Bond-Elut cartridge. The n-diethyl analogues of MK-462 and sumatriptan were used as internal standards. The analytes were chromatographed using reversed-phase (nitrile) columns coupled via a heated nebulizer interface to an atmospheric pressure chemical ionization source. The chromatographic run times were less than 7 min. Both methods were precise, accurate and selective down to plasma concentrations of 0.5 ng/ml. The assay for MK-462 was adapted to separately monitor the unlabeled and 14C-labeled species of the drug following intravenous administration of radiolabeled material to man.
Chromatography, High Pressure Liquid↗
Pharmacokinetic screening for the selection of new drug discovery candidates is greatly enhanced through the use of liquid chromatography-atmospheric pressure ionization tandem mass spectrometry.
Selection of a new drug discovery candidate from a series of compounds requires a means of performing rapid analytical method development and sensitive quantitation of each drug in serum, plasma or other biological matrices. Information on serum/plasma concentration, bioavailability and half-life can often aid the discovery process by selecting those candidates with the desired pharmacokinetic parameters. In one series of farnesyl protein transferase (FPT) inhibitors, gas chromatography with nitrogen-phosphorus detection (NPD) was initially used to analyze samples from pharmacokinetic studies in mice and monkeys. Typical turnaround times using this technique approached 2-4 weeks for method development, quantitation of study samples and calculation of pharmacokinetic parameters. Once LC-atmospheric pressure ionization (API) MS-MS analysis was implemented in these same studies, they could be completed in less than one week. The advantages of using LC-API-MS-MS to aid in the drug candidate selection process is demonstrated for one compound (SCH 44342) in this series of FPT inhibitors.
Administration, Oral↗
Detection of flunixin in equine urine using high-performance liquid chromatography with particle beam and atmospheric pressure ionization mass spectrometry after solid-phase extraction.
A normal-phase HPLC method combined with particle-beam mass spectrometry (PB-MS) was developed for the analysis of non-steroidal anti-inflammatory drugs (NSAIDs). The forty one NSAIDs analysed responded in one or more (electron impact, positive and negative chemical ionisation) modes and highly characteristic spectra were produced. A mixed-mode solid-phase extraction (SPE) method for isolating acidic NSAIDs was developed using the Bond Elut Certify II cartridge. The average recovery was 88.5%. Flunixin, extracted by SPE from urine of a mare to which the meglumine salt had been administered was positively identified by HPLC-PB-MS and HPLC-atmospheric pressure ionization (API) MS methods.
Animals↗
Determination of nicotine and cotinine in human plasma by liquid chromatography-tandem mass spectrometry with atmospheric-pressure chemical ionization interface.
Here we report a sensitive liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method capable of quantifying nicotine down to 1 ng/ml and cotinine to 10 ng/ml from 1.0 ml of human plasma. The method was validated over linear ranges of 1.0-50.0 ng/ml for nicotine and 10.0-500.0 ng/ml for cotinine, using deuterated internal standards. Compounds were simply extracted from alkalinized human heparinized plasma with methylene chloride, reconstituted into a solution of acetonitrile, methanol and 10 mM ammonium acetate (53:32:15, v/v) after the organic phase was dried down, and analyzed on the LC-MS-MS, which is a PE Sciex API III system equipped with a Keystone BDS Hypersil CI8 column and atmospheric pressure chemical ionization (APCI) interface. The between-run precision and accuracy of the calibration standards were < or = 6.42% relative standard deviation (R.S.D.) and < or = 11.8% relative error (R.E.) for both nicotine and cotinine. The between-run and within-run precision and accuracy of quality controls, (2.5, 15.0, 37.5 ng/ml for nicotine and 25.0, 150.0, 375.0 ng/ml for cotinine), were < or = 6.34% R.S.D. and < or = 7.62% R.E. for both analytes. Sample stabilities in chromatography, in processing and in biological matrix were also investigated. This method has been applied to pharmacokinetic analysis of nicotine and cotinine in human plasma.
Chromatography, Liquid↗
[Influence of high atmospheric pressure on the vitamin C content of various organs].
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Adrenal Glands↗
Analysis of toxic norditerpenoid alkaloids in Delphinium species by electrospray, atmospheric pressure chemical ionization, and sequential tandem mass spectrometry.
A rapid electrospray mass spectrometry method was developed for screening larkspur (Delphinium spp.) plant material for toxic norditerpenoid alkaloids. The method was calibrated using two standard alkaloids, methyllycaconitine (1) and deltaline (2), with a recovery of 92% from spiked samples and relative standard deviations of 6.0% and 8.1% for the two alkaloids, respectively. Thirty-three samples of plains larkspur, Delphinium geyeri, were analyzed. Methyllycaconitine (1) concentration was 0.27% +/- 0.08% during a 1-month period in 1997 establishing the relative risk of poisoning from the plant to be low. The method was also applied to the trace analysis (<1 ppm) of 1 in serum samples from sheep dosed different levels of the alkaloid. Electrospray ionization combined with sequential tandem mass spectrometry and HPLC coupled to atmospheric pressure chemical ionization (APCI) mass spectrometry were used to detect and tentatively identify three new norditerpenoid alkaloids from Delphinium nuttallianum [bearline (6), 14-acetylbearline (7), 16-deacetylgeyerline (8)]. The tentative structure of the new alkaloids was predicted from the tandem mass spectra fragmentation patterns and assigning the substitution pattern for methoxy and acetyl groups at the C-14 and C-16 carbons.
Alkaloids↗
The analysis of alkyl-capped alcohol ethoxylates and alcohol ethoxycarboxylates from alcohol ethoxylates by atmospheric pressure chemical ionization mass spectrometry.
Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd.
Journal Article↗
Quantitation of spectinomycin residues in bovine tissues by ion-exchange high-performance liquid chromatography with post-column derivatization and confirmation by reversed-phase high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry.
Determinative and confirmatory methods of analysis for spectinomycin residue in bovine kidney, liver, muscle and fat have been developed. The determinative method is a single-column HPLC ion-exchange procedure that incorporates a two-step post-column oxidation of the secondary amines to primary amines followed by derivatization with o-phthalaldehyde. The method was validated in all tissues to a low-end concentration of 0.10 micrograms/g (limit of quantitation) and to a high-end of 10 micrograms/g for kidney, which is the rate-limiting tissue for residues of spectinomycin. The recovery of spectinomycin from all tissues was > 80% and the variability (R.S.D.) was generally < 10%. For liver, an alternative reversed-phase HPLC separation was required for incurred-residue samples. The confirmatory method employed an atmospheric pressure chemical ionization-MS-MS approach utilizing a rapid reversed-phase HPLC system with a mobile phase of methanol and 1% acetic acid. The protonated molecular ion for spectinomycin at m/z 333 produced four diagnostic reaction-product ions at 98, 116, 158 and 189 for confirmation. The method was validated to a lower limit of confirmation of 0.10 micrograms/g.
Animals↗
On-line determination of carboxylic acids, aldehydes and ketones by high-performance liquid chromatography-diode array detection-atmospheric pressure chemical ionisation mass spectrometry after derivatization with 2-nitrophenylhydrazine.
2-Nitrophenylhydrazine (2-NPH) is widely used for the derivatization of carboxylic acids, aldehydes and ketones, in industrial and biological samples. These compounds react with 2-NPH to form derivatives, which are separated by high-performance liquid chromatography (HPLC) and detected with diode array detection (DAD). The UV spectra give information about the functionality of the compounds: carboxylic acid or ketone/aldehyde. Most of the eluting compounds in "known" samples are well characterised by the retention time (comparison with those of standards) of the 2-NPH derivative and their UV spectrum. The identification of different unknown 2-NPH derivatives of carboxylic acids, ketones and/or aldehydes, in industrial or biological samples, based on retention time and/or UV spectrum is not sufficient. These unknown 2-NPH compounds can be identified with on-line atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) based on the molecular mass or/and the fragmentation of the derivative. A novel and specific on-line HPLC-DAD-APCI(-)-MS method is described for the determination of carboxylic acids, ketones and aldehydes, after on-line pre-column derivatization with 2-NHP. The fragmentation of different 2-NPH derivatives were investigated and the possibilities of APCI(-)-MS detection were demonstrated by the on-line identification of an unknown derivative, which turned out to be a side product between 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 2-NPH in the presence of high concentrations of a cyclic amide in the sample solution.
Aldehydes↗
Determination of organonitrogen pesticides in large volumes of surface water by liquid-liquid and solid-phase extraction using gas chromatography with nitrogen-phosphorus detection and liquid chromatography with atmospheric pressure chemical ionization mass spectrometry.
During a recent study to determine the fluxes and fates of contaminants in the St. Lawrence River, the majority of organonitrogen pesticides analysed in samples of surface water were found in the dissolved phase. This paper compares two extraction techniques and two analytical techniques for 10 chemicals (metolachlor, seven triazines and two degradation products of atrazine-cyanazine-propazine and simazine) in the dissolved phase in large volumes of surface water, using a fibre glass filter with 0.7 micron porosity. Samples of filtered surface water (1-20 l) were extracted by means of a liquid-liquid technique using the Goulden large-sample extractor, and by means of a solid-phase extraction technique, using cartridges filled with 500 mg of a large particle-size graphitized carbon black as adsorbent: Carbopack B (500-666 microns). The pesticides were analysed by gas chromatography on two DB-5 and DB-210 capillary columns with nitrogen-phosphorus detection (GC-NPD) and by liquid chromatography coupled with mass spectrometry equipped with an atmospheric pressure chemical ionization interface (LC-APCI-MS). The recoveries were high (67-100%) for the majority of the target pesticides in a volume of 17.85 l of Milli-Q water, compared to recoveries in the same volume of filtered surface water (51-102%). The detection limits ranged from 0.4 to 4 ng/l and from 0.6 to 3 ng/l for GC-NPD and LC-ACPI-MS techniques, respectively.
Chromatography, Gas↗