Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Analytic Sample Preparation Methods”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed2006

Electrospray ionization LC-MS/MS validated method to quantify griseofulvin in human plasma and its application to bioequivalence study.

A simple, sensitive and rapid liquid chromatography/tandem mass spectrometry (LC-MS/MS) method has been developed and validated to quantify griseofulvin in human plasma using propranolol hydrochloride as internal standard (IS). Samples were prepared using solid phase extraction and analysed without drying and reconstitution. The analytes were chromatographed on Hypersil, hypurity C18 reverse phase column under isocratic conditions using 0.05% formic acid in water:acetonitrile (30:70, v/v) as the mobile phase. Total chromatographic run time was 3.0 min. Quantitation was done on a triple quadrupole mass analyzer API-3000, equipped with turbo ion spray interface and operating in multiple reaction monitoring (MRM) mode to detect parent-->product ion transition for analyte and IS. The method was validated for sensitivity, matrix effect, accuracy and precision, linearity, recovery and stability studies. Linearity in plasma was observed over the concentration range 20-3000 ng/mL for griseofulvin. Lower limit of quantification (LLOQ) achieved was 20 ng/mL with precision (CV) less than 10% using 5 microL injection volume. The absolute recovery of analyte (87.36%) and IS (98.91%) from spiked plasma samples was consistent and reproducible. Inter-batch and intra-batch coefficients of variation across four validation runs (LLOQ, LQC, MQC and HQC) was less than 7.5%. The accuracy determined at these levels was within +/-4.2% in terms of relative error. The method was applied to a pilot bioequivalence study of 500 mg griseofulvin tablet in six healthy human subjects under fed condition.

Antifungal Agents↗
PubMed1986

Simplified methods for preparation of microbial fatty acids for analysis by gas chromatography with electron-capture detection.

Analysis of bacterial metabolites and constituents by gas chromatography (GC) with frequency-pulsed electron-capture detection (FPECD) has been suggested as an approach to rapid identification of infection in man. In such methods conversion of analytes to electrophoric derivatives is obligatory. Present methods for analysis of microbial carboxylic acids by GC-FPECD use trichloroethylation. In order to simplify and possibly automate such sample preparation procedures, we investigated pentafluorobenzylation via extractive alkylation and via solid-supported reagents. The sensitivity in terms of minimum amounts of bacteria detectable were determined for the trichloroethyl and pentafluorobenzyl derivatives and results from solid-supported reagents were compared to extractive alkylation.

Alkylation↗
PubMed1997

A coupled PCR and restriction digest method for the detection and analysis of the SV40 regulatory region in infected-cell lysates and clinical samples.

The polymerase chain reaction (PCR) is an increasingly popular analytical tool for the detection of virus sequences in laboratory preparations as well as in human clinical samples. In studies involving papovaviruses SV40, BK virus (BKV), and JC virus (JCV), one of the primary targets for analysis is the viral regulatory region, as that section of the papovavirus genome is distinct. A primary concern with PCR-based studies is whether amplified DNA sequences may be derived from laboratory contaminants. Recognizing that common sources of PCR contamination are the positive control templates, we devised a facile method to distinguish between real and false-positive PCR-amplified SV40 regulatory region DNAs. SV40 constructs that had been engineered to contain different combinations of 72-basepair (bp) enhancer elements and 21-bp repeats, as well as two introduced unique restriction enzyme sites, were used as positive control templates for PCR amplification. Cleavage of PCR-amplified DNA identifies products from the engineered control plasmids. The procedure is rapid, simple and cost-effective. We also report that primer sets predicted to be specific for the SV40 regulatory region can be used to amplify BKV and JCV regulatory region sequences under conditions of reduced stringency.

BK Virus↗
PubMed1982

Serum ASAT, ALAT, ALP, LD, GT, and CK determined in the Cobas-Bio centrifugal analyser by the methods of the Scandinavian Committee on Enzymes.

The recommended methods of the Scandinavian Committee on Enzymes [4, 5, 6, 7, 8] have been applied to the Cobas-Bio centrifugal analyser. Reagents and serum volumes were scaled down and final molarities were kept equal. Serum volumes in microliters were as follows: ASAT 30, ALAT 30, ALP 3, LD 5, GT 20, and CK 10. Including the dead space of the sample cup, the volume needed to perform all six tests was 113 microliter. Within-run and between-run precision (CV%) were as follows: ASAT 1.32 and 1.95, ALAT 1.68 and 2.93, ALP 1.56 and 3.10, LD 1.63 and 4.44, GT 0.81 and 2.23, and CK 1.02 and 1.94. Mean deviations (%) from target values of two commercial sera were as follows: ASAT -0.3 and -0.4, ALAT -0.4 and -2.2, ALP -1.8 and -7.3, LD 0.4 and -6.2, GT 13.9 and -10.7, and CK -4.9 and -1.3. Results of all the methods correlated well with those obtained with their respective manual methods. Analytical time for 28 samples of each analyte was 10 min, apart from CK which was 14 min. Reagent cost per sample was 0.6, 0.9, 0.1, 0.3, 0.9, and 26 US cents respectively. All reagents were prepared in the laboratory, except those for CK which were bought from J.T. Baker (Phillipsburgh, NJ, USA). In conclusion, the methods keep the features of the manual methods but they are more precise and practicable, much faster and cheaper, and use minimal amounts of sera more convenient for paediatric work.

Alanine Transaminase↗
PubMed2005

Development of a quantitative method for determination of acrylamide in infant powdered milk and baby foods in jars using isotope dilution liquid chromatography/electrospray ionization tandem mass spectrometry.

An improved method has been developed for the determination of acrylamide in infant powdered milk and baby foods in jars, a particular class of foodstuffs which represent an important source of nutrition for young infants and babies. This method uses isotope dilution liquid chromatography coupled to a tandem mass spectrometer with electrospray ionization and is significantly more sensitive than previous published methods with a limit of quantification estimated at 1 microg kg(-1). The new method offers effective sample preparation procedures including defatting with petroleum ether, extraction with aqueous solution of sodium chloride, further liquid-liquid extraction with ethyl acetate and clean-up by solid-phase extraction (SPE) with HLB 200 mg cartridges. The analytical method was well validated and good results were obtained with respect to repeatability (RSD < 5%) and recovery (86-97%) which fulfilled the requirements defined by European Union (EU) legislation. The acrylamide level in infant powdered milk and baby foods in jars were 3.01-9.06 microg kg(-1) and 6.80-124.93 microg kg(-1), respectively. Especially, this new method is successfully applied to the trace quantification of acrylamide in infant/baby foods, the content of which is less than 10 microg kg(-1).

Acrylamide↗
PubMed2003

Determination of epirubicin and its metabolite epirubicinol in saliva and plasma by HPLC.

We present a high-performance liquid chromatography (HPLC) method suitable for the analysis of epirubicin and its metabolite epirubicinol in saliva and plasma. Preparation of saliva and plasma samples was performed by extraction of analytes with a chloroform:2-propanol mixture (6:1, vol/vol) and evaporation of the organic phase to dryness under vacuum at a temperature of approximately 45 degrees C. The chromatographic analysis was carried out by reversed-phase isocratic elution of the anthracyclines with a Chromsep stainless steel HPLC column (150 x 4.6 mm I.D.) filled with Nucleosil 100 S C(18) material, particle size 5 micro m. The detection was accomplished by spectrofluorimetry at excitation and emission wavelengths of 474 and 551 nm, respectively. The anthracyclines eluted within 10 min of injection, and the method appeared to be specific. The method is linear over a concentration range of 5 to 1000 micro g/L for epirubicin and 2 to 400 micro g/L for epirubicinol (r > 0.99) in both saliva and plasma. The recoveries from saliva and plasma of epirubicin, epirubicinol, and the internal standard doxorubicin were 88.9 and 69.0%, 87.6 and 77.3%, and 80 and 67.9%, respectively. The lower limit of quantification was 5 micro g/L for epirubicin and 2 micro g/L for epirubicinol. The method proved to be precise and accurate, as the within-day and between-day coefficients of variation were less than 10%. Overall results indicate that our method is suitable for the bioanalysis of epirubicin and epirubicinol in saliva as well as plasma.

Antibiotics, Antineoplastic↗
PubMed2005

Rapid analysis of 14C and 3H in graphite and concrete for decommissioning of nuclear reactor.

A rapid oxidizing combustion method using a commercial Sample Oxidizer has been investigated to determine separately the 14C and 3H activities in graphite and concrete. By this method the sample preparation time can be reduced to 2-3 min. The detection limits for 3H and 14C are 0.96 and 0.58 Bq/g graphite and 0.11 and 0.06 Bq/g concrete, respectively. The cross contamination of 14C and tritium in the preparation of samples is less than 0.2%. The interference of other radionuclides in the determination of 14C and tritium in graphite is insignificant. The analytical accuracy, investigated by the standard addition method, is better than 95%. In addition, an acid digestion method has also been used to examine the graphite and concrete activities, to allow comparison with the method developed herein. The two methods show good agreement for graphite samples. Graphite samples were collected from the Danish Reactors DR-2 and DR-3, in addition to two concrete cores drilled in the Danish reactor DR-2; these were analysed for 3H and 14C using the method that has been developed.

Journal Article↗
PubMed2000

An improved anion-exchange HPLC method for the detection and purification of adenoviral particles.

We have developed an anion-exchange high-performance liquid chromatography (HPLC) method using Q Sepharose XL (Amersham Pharmacia Biotech) as adsorbent to analyze samples containing adenovirus. This method has several major advantages over the HPLC method previously described for quantitating particles, namely (1) a >10-fold improvement in the detection limit of adenovirus in crude preparations; (2) absence of interferences originating from nucleic acids and proteins which usually contaminate crude samples; (3) unprecedented sharpness and symmetry of adenovirus peak, rendering the identification of the viral peak unambiguous, even in extremely crude and dilute preparations; and (4) no enzymatic treatment required even for crude samples. This assay was used to quantitate particles in samples taken at the transfection and amplification stages of production of various recombinant adenovirus, and in cultures of wild-type adenovirus of different serotypes. A modification of this analytical method was also developed for the purification of infectious adenovirus particles, including fiber-modified and third-generation recombinant viruses, giving highly purified preparations from low-titer crude lysates with an excellent overall recovery (50-74%).

Adenoviridae↗
PubMed2005

Analysis of crystalline phases in airborne particulates by grazing incidence X-ray diffractometry.

Amounts of crystalline phases of airborne particulates collected on a silicon wafer (10 x 10 mm) using a high-volume air sampler were analyzed by grazing incidence X-ray diffractometry (GIXD). Airborne particulates were classified into five size ranges (1.09-10.5 microm) with a cascade impactor attached on the sampling ports of the high-volume air sampler. GIXD was used throughout this analysis to obtain better sensitivity for small amounts of airborne particulates on the silicon wafer. Calibration standards on the silicon wafer for the diffractometric determination were prepared by the suspension droplet method of the crystalline standards dispersed in cyclohexane. Analytical lines were (020) for gypsum, (101) for quartz, (104) for calcite, (200) for halite, and (110) for sal ammoniac. The sample and the calibrating standards were heated at 350 degrees C for 2 h to avoid mutual interference with gypsum (041 and 221) when calcite and halite were determined. The GIXD method enables us to determine 0.23-13.2 microg of gypsum, quartz, calcite, halite and sal ammoniac in 0.110-0.233 mg of airborne particulates on the silicon wafer.

Air Pollutants↗
PubMed1991

Electrochromatographic solid-phase extraction for determination of cimetidine in serum by micellar electrokinetic capillary chromatography.

A highly effective electrochromatographic solid-phase extraction and preconcentration method is reported for the determination of cimetidine in serum in the concentration range 0.233-11.4 micrograms/ml. Preconcentrated samples were determined by micellar electrokinetic capillary chromatography while ranitidine was used as an internal standard. Sample preparation included retention of the analyte on a C18 solid-phase cartridge, followed by elution assisted by an applied voltage of 150 V. From 0.5-ml serum samples, 20-50-microliters aliquots were collected for electrophoretic analysis. Within the studied concentration range, the method was linear and provided adequate precision.

Chromatography↗
PubMed2005

Carbon isotope analyses of cellulose using two different on-line techniques (elemental analysis and high-temperature pyrolysis)--a comparison.

Even though the recent development in on-line methods for the stable isotope determination in cellulose has led to a significant increase in sample throughput and decrease in sample preparation expenditure, there still is a large potential for optimizing the analytical procedures by simultaneously measuring the isotope ratios of two or even more elements. Therefore, the main objective of this study was to answer the question whether high-temperature pyrolysis (HTP) is a suitable and reliable technique for the determination of the carbon isotopic composition of cellulose simultaneously during the well-known conventional oxygen isotope analysis. This study shows that HTP of cellulose is a technique that can produce reasonable delta(13)C values, matching the requirements of most research problems related to paleoclimatology. The reproducibility of the delta values for (13)C/(12)C is better than 0.2 per thousand. Some deficiencies of the method are related to the incomplete conversion of the organic carbon in the sample to carbon monoxide. A clear isotope effect seems to be related to the non-statistical conversion of the carbon in the cellulose to CO. The extent of this effect appears to be controlled by the relative proportion of crystallized and amorphous matter in the cellulose structure. Those deficiencies can be eliminated by using an appropriate normalization and by applying the principles of identical treatment for reference materials and samples. In general, a very good agreement is achieved for carbon isotope values determined by HTP and elemental analysis (EA).

Carbon↗
PubMed1990

Simultaneous high-performance liquid chromatographic analysis of carbidopa, levodopa and 3-O-methyldopa in plasma and carbidopa, levodopa and dopamine in urine using electrochemical detection.

Two assay procedures are described for the analysis of levodopa, carbidopa and 3-O-methyldopa in plasma and levodopa, carbidopa and dopamine in urine. The methods are suitable for quantifying the analytes following therapeutic administration of levodopa and carbidopa. Both were based on reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection and with methyldopa as the internal standard. Plasma samples were prepared by perchloric acid precipitation followed by the direct injection of the supernatant. Urine was prepared by alumina adsorption, and the analytes were desorbed with perchloric acid solution containing disodium EDTA and sodium metabisulfite prior to injection into the HPLC system. The methods have been utilized to evaluate the pharmacokinetics and bioavailability of oral dosage forms containing levodopa and carbidopa.

Carbidopa↗
PubMed2002

Determination of taltirelin, a new stable thyrotropin-releasing hormone analogue, in human plasma by high-performance liquid chromatography turbo-ionspray ionization tandem mass spectrometry.

A rapid, selective and sensitive assay of taltirelin, a novel thyrotropin-releasing hormone analogue, in human plasma has been developed. This method is based on a rapid sample preparation and high-performance liquid chromatography (HPLC) turbo-ionspray ionization tandem mass spectrometry (MS-MS). Analytes were purified from human plasma by SPE cartridge and separated by gradient HPLC. Turbo-ionspray ionization and MS-MS analyses were carried out by PE-Sciex API 3000 tandem mass spectrometer. Taltirelin was separated from its metabolite (acid form) on a semi-micro ODS column in methanol - 0.1% (v/v) formic acid. The selected reaction monitoring by precursor-->product ion combination of m/z 406-->264, was used for determination of taltirelin. The linearity was confirmed in the concentration range of 17-4137 pg/ml in human plasma, and the precision of this assay, expressed as a relative deviation, was less than 9.8% over the entire concentration range with adequate assay accuracy. The results obtained by the HPLC-MS-MS method correlated well with those of the radioimmunoassay method reported previously. Therefore, the HPLC-MS-MS method is useful for the determination of taltirelin with sufficient selectivity and sensitivity on pharmacokinetic studies in human.

Chromatography, High Pressure Liquid↗
PubMed1986

Automatic preparation of human serum samples for analysis of the drug enoximone and its sulphoxide metabolite using high-performance liquid chromatography.

A method for the estimation of the cardiotonic drug enoximone and its major sulphoxide metabolite, in serum, is described. The method uses a new technique for the preparation of biological material prior to the separation of analytes using high-performance liquid chromatography. This technique has been described as the automated sequential trace enrichment of dialysates (ASTED). The sample preparation process operates concurrently with the chromatographic separation. Aliquots of 500 microliters of serum are required for the analysis of serum from patients who have received a single 75-mg dose of enoximone. Within- and between-run coefficients of variation were found to be 2.8 and 3.9% for enoximone and 2.5 and 3.7% for enoximone sulphoxide. These values were obtained from estimating serum supplemented with enoximone and its metabolite, at concentrations of 0.5 and 1.0 mg/l, respectively.

Autoanalysis↗
PubMed2004

Determination of neomycin by LC-tandem mass spectrometry using hydrophilic interaction chromatography.

A specific, and automated method was developed to quantitate neomycin in human serum. Samples were prepared with an automated solid phase extraction (SPE). The hydrophilic interaction chromatography (HILIC) was used for additional sample cleanup and baseline separation. The analyte neomycin was detected with electrospray ionisation tandem mass spectrometry (ESI-MS-MS). Using a volume of 500 microl biological sample the lower limit of quantification was 100 ng/ml. The described HILIC-MS-MS method is suitable for clinical and pharmcokinetical investigations of neomycin.

Chromatography, Liquid↗
PubMed2000

Evaluation of ursodeoxycholic acid bioavailability from immediate- and sustained-release preparations using gas chromatography-mass spectrometry and high-performance liquid chromatography.

An improved procedure is presented for the determination of ursodeoxycholic acid (CAS 128-13-2, UDCA) in human plasma and bile after oral administration of UDCA-containing dosage forms. The plasma samples after solid-phase extraction with silica-based C18- and strong anion exchange cartridges were assayed by gas chromatography-mass spectrometry (GC-MS) using selected-ion monitoring. The hexafluoroisopropyl trifluoroacetate ester derivative of UDCA was selected for GC analysis since it is easily and rapidly prepared by a one-step reaction. Biliary UDCA levels were determined by a rapid and simple high-performance liquid chromatographic (HPLC) method with on-line sample purification. This analytical protocol was used to investigate the pharmacokinetic of a new sustained-release capsule of UDCA in comparison with a reference immediate-release preparation after single oral administration. Statistical evaluation of the area under the plasma concentration-time curves indicated that two formulations are equivalent with regard to the amount of drug absorbed. However, pharmacokinetic data showed that with the sustained-release preparation a significantly delayed mean peak plasma level was reached compared with the reference preparation. Moreover, the immediate- and extended-release capsules were found to achieve a comparable degree of biliary enrichment with UDCA.

Adult↗
PubMed2000

Laboratory database to manage electrophoresis and chromatography separations and the associated samples.

A database was developed to store, organize, and retrieve the data associated with electrophoresis and chromatography separations. It allows laboratories to store extensive data on separation techniques (analytical and preparative). The data for gel electrophoresis includes gel composition, staining methods, electric fields, analysis, and samples loaded. The database stores data on chromatography conditions, the samples used, and the fractions collected. The data structure of this database was designed to maintain the link between samples (including fractions) from chromatography separations and their analysis by gel electrophoresis. The database will allow laboratories to organize and maintain a large amount of separation and sample data in a uniform data environment. It will facilitate the retrieval of the separation history of important samples and the separation conditions used.

Chromatography↗
PubMed2000

A RIA combined with SPE for the determination of a dual D2-receptor and beta2-adrenoceptor agonist, AR-C68397XX, in human plasma.

A radioimmunoassay has been developed for the determination of AR-C68397XX, a dual D2-receptor and beta2-adrenoceptor agonist, in human plasma. The method incorporates solid phase sample extraction and is suitable for the determination of the analyte at pg ml(-1) concentrations. The antiserum was raised in Suffolk cross sheep following primary and booster immunisations with an immunogen prepared by conjugating a carboxyphenylmethyl derivative of AR-C68397XX, to bovine serum albumin. The radioligand was prepared by the 125I-labelled iodination of a derivative of AR-C68397XX. The solid phase extraction procedure, using octadecyl sorbent, was introduced to remove matrix interferences in the plasma and to enhance method sensitivity. The calibration range is 20-500 pg ml(-1), using 0.5 ml of undiluted human plasma sample.

Adrenergic beta-2 Receptor Agonists↗