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Analytical Procedures (analytical + procedure)

Distribution by Scientific Domains

Chemistry	51%
Business, Economics, Finance and Accounting	14%
Earth and Environmental Science	12%
Life Sciences	8%
Medical Sciences	5%
Engineering	5%

Distribution within Chemistry

Analytical Chemistry	19%
General & Introductory Food Science & Technology	13%
Crystallography	5%

Selected Abstracts

The World Has Changed,Have Analytical Procedure Practices?

CONTEMPORARY ACCOUNTING RESEARCH, Issue 2 2010
GREG TROMPETER
M1; M42 Analytical Procedures (APs) provide a means for auditors to evaluate the "reasonableness" of financial disclosures by comparing a client's reported performance to expectations gained through knowledge of the client based on past experience and developments within the company and its industry. Thus, APs are fundamentally different than other audit tests in taking a broader perspective of an entity's performance vis-à-vis its environment. As such, APs have been found to be a cost-effective means to detect misstatements, and many have argued that a number of prior financial frauds would have been detected had auditors employed effective APs. With several dramatic and far-reaching developments over the past decade, the current study examines whether and how APs have changed during this period. In particular, we focus on the impact of significant "enablers" and "drivers" of change such as technological advancements and the enactment of the Sarbanes-Oxley Act. We also compare our findings to an influential study of the practices of APs by Hirst and Koonce (1996) that was conducted over 10 years ago. We interview 36 auditors (11 seniors, 13 managers, and 12 partners) from all of the Big 4 firms using a structured questionnaire. The data reveal some similarities in findings when compared to prior research (e.g., auditors continue to use fairly simple analytical procedures). However, there are a number of significant differences reflecting changes in AP practices. For instance, as a result of technology auditors now rely more extensively on industry and analyst data than previously. Further, auditors report that they develop more precise quantitative expectations and use more non-financial information. They also appear to rely more on lower level audit staff to perform APs, conduct greater inquiry of non-accounting personnel, and are willing to reduce substantive testing to a greater extent as a result of APs conducted in the planning phase. Finally, the Sarbanes-Oxley Act has had an impact in greater consideration and knowledge of internal controls, which is seen as the most important factor driving the use and reliance on APs. [source]

A Note on the Interdependence between Hypothesis Generation and Information Search in Conducting Analytical Procedures,

CONTEMPORARY ACCOUNTING RESEARCH, Issue 2 2003
Stephen K. Asare
Abstract This study examines the linkage among the initial hypothesis set, the information search, and decision performance in performing analytical procedures. We manipulated the quality of the initial hypothesis set and the quality of the information search to investigate the extent to which deficiencies (or benefits) in either process can be remedied (or negated) by the other phase. The hypothesis set manipulation entailed inheriting a correct hypothesis set, inheriting an incorrect hypothesis set, or generating a hypothesis set. The information search was manipulated by providing a balanced evidence set to auditors (i.e., evidence on a range of likely causes including the actual cause - analogous to a standard audit program) or asking them to conduct their own search. One hundred and two auditors participated in the study. The results show that auditors who inherit a correct hypothesis set and receive balanced evidence performed better than those who inherit a correct hypothesis set and did their own search, as well as those who inherited an incorrect hypothesis set and were provided a balanced evidence set. The former performance difference arose because auditors who conducted their own search were found to do repeated testing of non-errors and truncated their search. This suggests that having a correct hypothesis set does not ensure that a balanced testing strategy is employed, which, in turn, diminishes part of the presumed benefits of a correct hypothesis set. The latter performance difference was attributable to auditors' failure to generate new hypotheses when they received evidence about a hypothesis that was not in the current hypothesis set. This demonstrates that balanced evidence does not fully compensate for having an initial incorrect hypothesis set. These findings suggest the need for firm training and/or decision aids to facilitate both a balanced information search and an iterative hypothesis generation process. [source]

Design Considerations for Research on Analytical Procedures

INTERNATIONAL JOURNAL OF AUDITING, Issue 3 2001
Stephen K. Asare
This article discusses research design considerations for conducting behavioral research on auditors' performance of analytical procedures (APs). With the trend in practice towards increasing reliance on APs, it is essential that auditors are proficient in completing such tests. Therefore, research to understand and improve auditors' performance of APs is important. Once an unexpected fluctuation is identified, APs involve three phases: generation of plausible hypotheses (likely causes); gathering evidence to examine plausible hypotheses; and identification of the most likely cause followed by appropriate follow-up actions. Although prior research has focused on these phases in isolation, they are, in fact, interrelated. Important research design issues and trade-offs for each of the phases of APs are discussed. For instance, in examining hypothesis generation there are choices as to the amount and nature of case background information, number of ratios or accounts to explain; ex-post evaluation of the quality of the hypothesis set; and instructions on number of causes that account for the fluctuation. Significant considerations are identified for making informed decisions among design choices. [source]

Acute toxicity and bioaccumulation of pesticide Diazinon in red tilapia (Oreochromis niloticus x Mossambicus albina)

ENVIRONMENTAL TOXICOLOGY, Issue 4 2002
Jaime A. Palacio
Abstract Young red tilapias were exposed for 96 h to each one of 6 concentrations of the pesticide Diazinon in order to determine the pesticide's acute toxicity level. After the ascertaining the lethal concentration (LC50) at 96 h, a level 10 times lower was selected for the bioaccumulation study of the pesticide in male and female specimens exposed for 9 days. The elimination process was carried out for 10 days beginning right after the conclusion of the accumulation process. Analytical procedures were developed and used for the studies of acute toxicity and bioaccumulation of Diazinon in red tilapia. A lethal concentration [LC50 (96 h)] of 3.85 mg/L was found, and steady-state accumulation, at a concentration of 28.45 mg/kg, was reached at 7.72 days. In the elimination process a concentration of 0.29 mg/kg was found in tilapia tissue by the sixth day after the fish were moved to clean water, and it continued to decrease quickly toward nondetectable levels. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 334,340, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10063 [source]

Quantitation of valproic acid in pharmaceutical preparations using dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection without prior derivatization

DRUG TESTING AND ANALYSIS, Issue 7 2010
Hamid Reza Sobhi
Abstract Dispersive liquid-liquid microextraction (DLLME), coupled with gas chromatography-flame ionization detection (GC-FID), has been successfully used for the extraction and determination of valproic acid (VPA) in pharmaceutical preparations. In the developed method, an appropriate mixture of extracting and disperser solvents was rapidly injected into an aqueous sample. Having formed a cloudy solution, the mixture was centrifuged and then the extracting solvent was sedimented at the bottom of a conical test tube. The extract was then injected into a GC system directly, without any further pretreatment. Initially, microextraction efficiency factors were optimized and the optimum experimental conditions found were as follows: tetrachloroethylene (9.0 µL) as extracting solvent; acetone (1.0 mL) as disperser solvent; 5 mL acidic aqueous sample (pH 1) without salt addition. Under the selected conditions, the calibration curve showed linearity in the range of 0.1,5.0 mg/L with regression coefficient corresponding to 0.9998. The limit of detection was found to be 0.05 mg/L. Finally, the method was applied for the determination of VPA in two different pharmaceutical preparations. A reasonable intra-assay (3.9,10.8%, n = 3) and inter-assay (5.6,11.4%, n = 3) precision illustrated the good performance of the analytical procedure. The protocol proved to be rapid and cost-effective for screening purposes. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Direct Simultaneous Determination of Cu, Ni and V in Seawater Using Adsorptive Cathodic Stripping Voltammetry with Mixed Ligands

ELECTROANALYSIS, Issue 10 2005
A. Cobelo-García
Abstract An analytical procedure is proposed for the direct simultaneous determination in a single scan of Cu, Ni and V in seawater by means of adsorptive cathodic stripping voltammetry (ACSV) with mixed ligands (DMG and catechol). Optimum conditions for the determination of these three elements were studied. Detection limits of the technique depended upon the reproducibility of the procedura blank, and were found to be 0.5,nM for Cu, 0.4,nM for Ni and 0.3,nM for V. The method is suitable for the analysis of estuarine, coastal and open-ocean waters, and especially to study the metal contamination in areas subject to oil spill events. [source]

Heavy Metals in Matrices of Food Interest: Sequential Voltammetric Determination at Trace and Ultratrace Level of Copper, Lead, Cadmium, Zinc, Arsenic, Selenium, Manganese and Iron in Meals

ELECTROANALYSIS, Issue 18 2004
Clinio Locatelli
Abstract The voltammetric methods are very suitable and versatile techniques for the simultaneous metal determination in complex matrices. The present work, regarding the sequential determination of Cu(II), Pb(II), Cd(II), Zn(II) by square-wave anodic stripping voltammetry (SWASV), As(III), Se(IV) by square-wave cathodic stripping voltammetry (SWCSV) and Mn(II), Fe(III) by square-wave voltammetry (SWV) in matrices involved in foods and food chain as wholemeal, wheat and maize meal, are an interesting example of the possibility to sequentially determine each single element in real samples. Besides the set up of the analytical method, particular attention is aimed either at the problem of possible signal interference or to show that, using the peak area Ap as instrumental datum, it is possible to achieve lower limits of detection. The analytical procedure was verified by the analysis of the standard reference materials: Wholemeal BCR-CRM 189, Wheat Flour NIST-SRM 1567a and Rice Flour NIST-SRM 1568a. Precision, as repeatability, and accuracy, expressed as relative standard deviation and relative error, respectively, were lower than 6% in all cases. In the presence of reciprocal interference, the standard addition method considerably improved the resolution of the voltammetric technique. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meals sampled on market for sale. A critical comparison with spectroscopic measurements is also discussed. [source]

Determination of uranium, iron, copper, and nickel from ore samples by MEKC using N,N,-ethylene bis(salicylaldimine) as complexing reagent

ELECTROPHORESIS, Issue 3 2008
Muhammed Aslam Mirza
Abstract An analytical procedure has been developed for the separation of dioxouranium(VI), iron(III), copper(II), nickel(II), cobalt(II), cobalt(III), palladium(II), and thorium(IV) by MEKC using N,N,-ethylene bis(salicylaldimine) (H2SA2en) as a complexing reagent with total runtime <4.5,min. SDS was used as micellar medium at pH,8 with sodium tetraborate buffer (0.1,M). An uncoated fused-silica capillary with an effective length of 50,cm×75,,m id was used with an applied voltage of 30,kV with photodiode array detection at 231,nm. Linear calibrations were obtained within 0.111,1000,,g/mL of each element with LODs within 37,325,ng/mL. The developed method was tested for analysis of uranium ore samples indicating its presence within 103,1789,,g/g with RSD within 0.79,1.87%. Likewise copper, nickel, and iron in their combined matrix were also simultaneously determined with RSD 0.4,1.6% (n,=,6). [source]

The construct validity of three entry level personality inventories used in the UK: cautionary findings from a multiple-inventory investigation,

EUROPEAN JOURNAL OF PERSONALITY, Issue S1 2003
Neil Anderson
This paper reports psychometric analyses into the convergent and divergent validity of three popular entry-level measures of occupational personality in the UK and Continental Europe. A sample of 504 individuals completed all three measures: the British version of the Hogan Personality Inventory (HPI), the Occupational Personality Questionnaire (OPQ Version FS5.2), and the Business Personality Indicator (BPI). In addition, independent ratings of the conceptual loading of primary source scales onto the Five Factor Model (FFM) were obtained (n,=,66). Data were used in a three-stage analytical procedure directed at examining psychometric and construct validity. Results are reported for descriptive statistics (means, standard deviations, Cohen's d), internal consistency reliability (Cronbach's alphas), and exploratory factor analyses. Findings into the construct validity of first-order scales (i.e. primary source scales) and second-order scales (i.e. FFM loadings) are presented in detail, including multitrait,multimethod (MTMM) analyses of convergent and divergent validity. For some scales, the observed variability in our sample suggested significant range restriction/enhancement. It was found that scale reliabilities were generally lower than those typically reported by the test publishers, and that published factor structures for these measures could not be replicated by the authors for this sample of individuals. Further independent construct validity research into occupational personality inventories is encouraged based upon our proposed model of single-, dual-, and multiple-inventory construct validation studies. Practically, our findings suggest that when IWO psychologists or personnel professionals aim to select/screen job applicants for a particular personality trait those who are selected may vary depending on (i) which personality inventory is used, (ii) the actual variability in the applicant sample tested, and (iii) reliability of the scales under consideration. As such, this study sounds a note of caution. Future research is called for to replicate these findings. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Recognition of resonance in long radial transmission lines with static VAR compensation using travelling waves

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 1 2005
Ljubivoje M. Popovi
Abstract This paper presents an analytical procedure for estimation of resonance frequencies in long-distance radial transmission lines with static VAR compensation. The development of the procedure is based on a new approach in solving this problem. It employs the fact that the phenomenon is characterized by an algebraic sum of travelling current waves at the beginning of the line. Relatively simple analytical expressions are obtained by considering the phase angles of only one direct and only one corresponding reflected wave. Besides enabling a simpler and faster solution of the problem under various realistic conditions, the obtained analytical expressions also offer more direct analytical insight into the interplay of basic parameters. Copyright © 2005 John Wiley & Sons, Ltd. [source]

An assessment of hydraulic design of trickle laterals considering effect of minor losses,

IRRIGATION AND DRAINAGE, Issue 4 2007
Gürol Y
canalisations d'eau; canalisations tertiaires; conception hydraulique; analyse; perte de charge Abstract The accurate design of trickle irrigation laterals needs to determine the total energy losses that includes the pipe friction losses along the lateral line and the local pressure losses, sometimes called minor losses, due to the protrusion of emitter barbs into the flow. Evaluation of energy losses is usually carried out by assuming the hypothesis that minor losses can be neglected, even if previous experimental studies indicated that minor losses can become a significant percentage of total energy losses as a consequence of the high number of emitters installed along the lateral line. In this study, a simple analytical procedure is presented to evaluate the effect of minor losses which is characterized by a coefficient ,i, expressing the amount of minor head losses as a fraction of the kinetic head, on trickle lateral design. According to both the design cases of without and including minor losses, the dimensionless design curves were developed for both the various lateral diameters and lengths. The results of two practical examples for designing either the diameter or the length indicated that, in some design cases, neglecting minor losses may lead to erroneous designs of the lateral diameter and length. This method is simple and easily adaptable to solve lateral hydraulic problems but sufficiently precise in comparison with the alternative procedures. The proposed equations are useful when applied for design and evaluation purposes and offer a practical field solution for laterals used in irrigation systems. Copyright © 2007 John Wiley & Sons, Ltd. La conception précise des canalisations tertiaires dans un système d'irrigation au goutte à goutte doit déterminer le total des pertes de charge qui viennent du frottement dans la canalisation elle-même mais aussi des pertes locales, parfois appelées pertes mineures, dues à la protubérance de barbes au niveau des goutteurs. Cette évaluation est normalement réalisée en considérant comme négligeables les pertes mineures, même si des études expérimentales ont montré que ces pertes mineures pouvaient constituer un pourcentage significatif de la perte de charge totale du fait du grand nombre de goutteurs installés le long de la canalisation tertiaire. Dans cette étude, une procédure analytique simple est proposée pour évaluer l'effet des pertes mineures sur la conception des canalisations tertiaires grâce à un coefficient ,i, exprimant le montant de ces pertes en une fraction de la charge cinétique. En fonction des diverses options de conception prenant ou non en compte les pertes mineures, des courbes de conception non dimensionnelles ont été tracées pour les diamètres et les longueurs des canalisations. Les résultats de deux exemples concrets montrent que, dans certains cas de conception, le fait de négliger les pertes mineures peut conduire à des conceptions de diamètre et de longueur erronées. Cette méthode est simple et facilement adaptable à la résolution de problèmes hydrauliques au niveau des tertiaires mais suffisamment précise par rapport des méthodes alternatives. Les équations proposées sont utiles pour la conception et l'évaluation et offrent une solution de terrain concrète pour les canalisations tertiaires utilisées dans des systèmes d'irrigation (au goutte à goutte). Copyright © 2007 John Wiley & Sons, Ltd. [source]

Predicting % of crystallinity in FCC catalysts by FT-MIR and PLS

JOURNAL OF CHEMOMETRICS, Issue 11-12 2008
Angel Dago
Abstract This paper describes an analytical procedure for prediction of percent of crystallinity of fluidized catalytic cracking catalysts (FCC) using Fourier transform mid infrared spectroscopy (FT-MIR) and partial least-squares (PLS) multivariate calibration technique. In order to make a robust regression model, multiplicative scatter correction (MSC) and smoothed second derivative pre-processing methods were tested. Root mean squared error of prediction (RMSEP) of an independent test set was used to measure the performance of the models. The comparison shows that reasonable values of RMSEP and RMSECV were obtained for PLS-MSC model (RMSEP,=,0.8% and RMSECV,=,1.3%). The accuracy of the results obtained by the PLS-MSC regression model is in accordance with the uncertainty of the XRPD reference method. The developed method can be implemented in a refinery laboratory environment with ease. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Analysis of Volatile Compounds in Beef Fat by Dynamic-Headspace Solid-Phase Microextraction Combined with Gas Chromatography,Mass Spectrometry

JOURNAL OF FOOD SCIENCE, Issue 5 2008
A. Watanabe
ABSTRACT:, A solid-phase microextraction (SPME) technique has been applied to the determination of the volatile compounds, including diterpenoids and lactones, in cooked beef fat. The ability of static-headspace SPME to extract lactones was disappointing, regardless of the type of SPME fiber or the temperature used. Dynamic-headspace SPME extraction with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C, by contrast, enabled the analysis of volatiles, including delta-lactones, gamma-lactones, and diterpenoids, with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C. Fifty-three compounds were identified from only 0.20 g of rendered beef fat, and 76% of these showed reliable peak size repeatability: the coefficient of variation was less than 10% on the total ion chromatograms obtained from gas chromatography,mass spectrometry (GC,MS) analysis. Some lactones showed higher CV values (>10%), but single-ion mode GC,MS analysis reduced them to 10% or less. In a study of beef samples available to the Japanese market, our analytical procedure revealed significantly higher levels of 1-hexanol, octadecane, ethyl tetradecanoate, gamma-nonalactone, but lower levels of delta-decalactone, delta-dodecalactone, and neophytadiene, in Japanese Black cattle than in beef imported from Australia. [source]

Detection of explosives on human nail using confocal Raman microscopy

JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2009
Esam M. A. Ali
Abstract Trace amounts of explosives were detected on human nail using confocal Raman microscopy. Contamination of the nail can result from the manual handling, packaging or transportation of explosive substances. Raman spectra were obtained from pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT), ammonium nitrate and hexamethylenetetramine (HMTA) particles on the surface of the nail with dimensions in the range 5,10 µm. An added difficulty in an analytical procedure is the presence of a nail varnish coating that has been applied, which traps the particulate matter between the coating and nail. Using confocal Raman microscopy, interference-free spectra could be acquired from particles of explosives visually masked by the nail varnish. Spectra of the explosives could be readily obtained in situ within 90 s without alteration of the evidential material. Acquisition of a Raman point map of a PETN particle under the nail varnish coating is also reported. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Confirmation and determination of carboxylic acids in root exudates using LC,ESI-MS

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2007
Zuliang Chen
Abstract Reversed-phase liquid chromatography with UV detection is of limited applicability in the separation and identification of carboxylic acids because of the column's poor separation efficiency and the non-selective nature of the UV detector. To address this issue, RP-LC with electrospray ionization mass spectrometry has been explored for the confirmation and determination of carboxylic acids in plant root exudates, with ESI-MS providing structural information, high selectivity, and high sensitivity. The separation of 10 carboxylic acids (pyruvic, lactic, malonic, maleic, fumaric, succinic, malic, tartaric, trans -aconitic, and citric acid) was performed on a C18 column using an eluent containing 0.1% (v/v) acetic acid within 10 min, where the acidic eluent not only suppressed the ionization of the carboxylic acids to be retained on the column, but was also compatible with ESI-MS detection. In addition, an additional standard was used to overcome the matrix effect. The results showed that peak areas correlated linearly with the concentration of carboxylic acids over the range 0.05,10 mg/L. The detection limits of target acids (signal-to-noise S/N ratio of 3) ranged from 20 to 30 ,g/L. Finally, the proposed method was used for the confirmation and determination of low-molecular-weight carboxylic acids in plant root exudates, and provided a simple analytical procedure, including sample processing, fast separation, and high specificity and sensitivity. [source]

Near-critical carbon dioxide extraction and liquid chromatography determination of UV filters in solid cosmetic samples: A green analytical procedure

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2005
Amparo Salvador
Abstract Near-critical carbon dioxide extraction of four UV filters used as sunscreens in lipsticks and makeup formulations is reported. Extraction parameters were optimized. Efficient recoveries were obtained after 15 min of dynamic extraction with a 80:20 CO2/ethanol mixture at 300 atm and 54°C, using a 1.8 mL/min flow rate. Extracts were collected in ethanol, and appropriately diluted with ethanol and 1% acetic acid to obtain a 70:30 v/v ethanol/1% acetic acid solution. The four UV filters were determined by LC with gradient elution using ethanol/1% acetic acid as mobile phase. The accuracy of the analytical procedure was estimated by comparing the results with those obtained by methods based on classical extraction. The proposed method only requires the use of CO2, ethanol and acetic acid avoiding the use of more toxic organic solvents, thus it could be considered as both operator and environment friendly. [source]

Validation of a quantitative assay using GC/MS for trace determination of free and conjugated estrogens in environmental water samples

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2003
Asmaa Mouatassim-Souali
Abstract It has been shown that sewage effluent can discharge human hormones and pharmaceuticals, particularly estrogens and synthetic chemicals, which are able to disrupt animal and human endocrine systems into surface waters. Since many surface waters receive sewage effluent and are subsequently used to produce drinking water, it is of principal interest to assess their contamination level and thereby their possible public health and environmental impact. To date, no data concerning the occurrence of estrogens present in the French aquatic environment are available. We therefore developed and validated an analytical procedure, which allows simultaneous quantitative determination of three natural estrogens, 17,-estradiol, estriol, and estrone and one of the synthetic estrogens most widely used in contraception, ethinylestradiol, in water. Water samples are extracted using solid-phase extraction (SPE) and then separated by gas-chromatography coupled with mass spectrometric detection. Under our conditions, detection limits of estrogens reached the pg range of injected sample, i. e. less than 0.1 ng L,1. Conjugated estrogens were also investigated using the same procedure as described above but with a enzymatic hydrolysis preliminary step before extraction. The analysis of samples collected from four wastewater treatment plants and from surface water showed significant concentrations of estrogens ranging from 2 to 18 ng L,1 and from 0.5 to 3 ng L,1, respectively. Furthermore, no estrogen conjugated forms were detected in the water samples. [source]

An easy non-invasive X-ray diffraction method to determine the composition of Na-pyroxenes from high-density `greenstone' implements

ACTA CRYSTALLOGRAPHICA SECTION A, Issue 1 2008
Roberto Giustetto
A large number of polished stone implements from Palaeolithic to Bronze Age sites of Northern Italy and Southern France are made of high-pressure (HP) metamorphic rocks (eclogite and related rocks), mainly consisting of Na-pyroxene (jadeite to omphacite) from the metamorphic belt of the Western Alps. The standard archaeometric study of prehistoric stone implements follows a procedure that is invasive, expensive and time-consuming. Since Na-pyroxenes may show a large compositional range, a thorough study of the variations affecting the dhkl values, obtained by X-ray diffraction, of three selected reflections as a function of different chemical composition was carried out, in order to determine the chemistry of Na-pyroxene isomorphic mixtures and roughly evaluate their relative amounts. These reflections (21, 310, 002) are sharp, intense and sensitive to the variation of pyroxene chemical composition. Using such dhkl values measured on pyroxenes of known chemistry, a Ca-pyroxene(Di),jadeite(Jd),aegirine(Ae) compositional diagram was constructed, from which the composition of an unknown pyroxene can be estimated within an error of about 5%. When the size of the object is relatively small and a flat polished surface is present, the proposed analytical procedure becomes totally non-invasive. The data obtained shed light on the provenance sources of such implements and the prehistoric trade routes. [source]

Multi-residue analysis of eight thioamphetamine designer drugs in human urine by liquid chromatography/tandem mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2009
Maria Nieddu
An analytical procedure for the simultaneous determination in human urine of several thioamphetamine designer drugs (2C-T and ALEPH series) is reported. The quantitative analysis was performed by liquid chromatography/tandem mass spectrometry and has been fully validated. The mass spectrometer was operated in positive-ion, selected reaction monitoring (SRM) mode. In order to minimize interferences with matrix components and to preconcentrate target analytes, solid-phase extraction was introduced in the method as a clean-up step. The entire method was validated for selectivity, linearity, precision and accuracy. The method turned out to be specific, sensitive, and reliable for the analysis of amphetamine derivatives in urine samples. The calibration curves were linear over the concentration range of 1 to 100,ng,mL,1 for all drugs with correlation coefficients that exceeded 0.996. The lower limits of detection (LODs) and quantification (LOQs) ranged from 1.2 to 4.9,ng,mL,1 and from 3.2 to 9.6,ng,mL,1, respectively. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Development of a method for the direct analysis of peptide AM336 in monkey cerebrospinal fluid using liquid chromatography/electrospray ionization mass spectrometry with a mixed-function column

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2003
Wei Bu
A liquid chromatography/mass spectrometry (LC/MS) analytical procedure, using a single column for sample clean-up, enrichment and separation, has been developed for the determination of the peptide AM336 in monkey cerebrospinal fluid (CSF). CSF samples were injected and analyzed using a polymer-coated mixed-function high-performance liquid chromatography (HPLC) column with gradient elution and application of a timed valve-switching event. The mass spectrometer was operated in the positive electrospray ionization (ESI+) mode with single ion recording (SIR) at m/z 920. The method was validated, yielding calibration curves with correlation coefficients greater than 0.9892. Assay precision and accuracy were evaluated by direct injection of AM336-fortified CSF samples at three concentration levels. Analyzed concentrations ranged from 99.93 to 113.1% of their respective theoretical concentrations with coefficients of variation below 9.0%. An evaluation of the signal-to-noise (S/N) ratio for a 200 ng/mL calibration standard, considered to be the lower limit of quantitation (LLOQ), resulted in an estimated limit of detection (LOD) of 31.2,ng/mL. Preliminary data suggest the possibility of using this method to analyze AM336 also in plasma samples, pending the successful outcome of additional investigations. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Development of a method based on accelerated solvent extraction and liquid chromatography/mass spectrometry for determination of arylphenoxypropionic herbicides in soil

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2001
Stefano Marchese
A sensitive and specific analytical procedure for determining arylphenoxypropionic herbicides in soil samples, using Ionspray ionization (ISI) liquid chromatography/mass spectrometry (LC/MS), is presented. Arylphenoxypropionic acids are a new class of herbicides used for selective removal of most grass species from any non-grass crop, commercialized as herbicide esters. Previous studies have shown that the esters undergo fast hydrolysis in the presence of vegetable tissues and soil bacteria, yelding the corresponding free acid. The feasibility of rapidly extracting arylphenoxypropionic herbicides from soil by accelerated solvent extraction (ASE) techniques was evaluated. Four different soil samples were fortified with target compounds at levels of 5 and 20,ng/g by following a procedure able to mimic weathered soils. Herbicides were extracted by a methanol/water (80:20 v/v) solution (0.12,M) of NaCl at 90,°C. After clean-up using graphitized carbon black (GCB) as absorbent, the extract was analyzed by HPLC/ISI-MS. The effect of concentration of acid in the mobile phase on the response of ISI-MS was investigated. The effects of varying the orifice plate voltage on the production of diagnostic fragment ions, and on the response of the MS detector, were also investigated. The ISI-MS response was linearly related to the amounts of analytes injected between 1 and 200,ng. The limit of detection (signal-to-noise ratio,=,3) of the method for the pesticides in soil samples was estimated to be less than 1,ng/g. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Albedo, atmospheric solar absorption and heating rate measurements with stacked UAVs

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 629 2007
M. V. Ramana
Abstract This paper reports unique measurements of albedo, atmospheric solar absorption, and heating rates in the visible (0.4 to 0.7 µm) and broadband (0.3 to 2.8 µm) spectral regions using vertically stacked multiple lightweight autonomous unmanned aerial vehicles (UAVs). The most significant finding of this study is that when absorbing aerosols and water vapour concentrations are measured accurately and accounted for in models, and when heating rates are measured directly with stacked aircraft, the simulated clear sky heating rates are consistent with the observed broadband heating rates within experimental errors (about 15%). We conclude that there is no need to invoke anomalous or excess absorption or unknown physics in clear skies. Aerosol,radiation,cloud measurements were made over the tropical Indian Ocean within the lowest 3 km of the atmosphere during the Maldives Autonomous UAV Campaign (MAC). The UAVs and ground-based remote sensing instruments determined most of the parameters required for calculating the albedo and vertical distribution of solar fluxes. The paper provides a refined analytical procedure to reduce errors and biases due to the offset errors arising from mounting of the radiometers on the aircraft and due to the aircraft attitude. Measured fluxes have been compared with those derived from a Monte-Carlo radiative transfer algorithm which can incorporate both gaseous and aerosol components. Under cloud-free conditions the calculated and measured incoming fluxes agree within 2,10 W m,2 (<1%) depending upon the altitudes. Similarly, the measured and calculated reflected fluxes agreed within 2,5 W m,2 (<5%). The analysis focuses on a cloud-free day when the air was polluted due to long-range transport from India, and the mean aerosol optical depth (AOD) was 0.31 and mean single scattering albedo was 0.92. The UAV-measured absorption AOD was 0.019 which agreed within 20% of the value of 0.024 reported by a ground-based instrument. The observed and simulated solar absorption agreed within 5% above 1.0 km and aerosol absorption accounted for 30% to 50% of the absorption depending upon the altitude and solar zenith angle. Thus there was no need to invoke spurious or anomalous absorption, provided we accounted for aerosol black carbon. The diurnal mean absorption values for altitudes between 0.5 and 3.0 km above mean sea level were observed to be 41 ± 3 W m,2 (1.5 K/day) in the broadband region and 8 ± 2 W m,2 (0.3 K/day) in the visible region. The contribution of absorbing aerosols to the heating rate was an order of magnitude larger than the contribution of CO2 and one-third that of the water vapour. In the lowest 3 km of the tropical atmosphere, aerosols accounted for more than 80% of the atmospheric absorption in the visible region. Copyright © 2007 Royal Meteorological Society [source]

Application of column-switching HPLC method in evaluating pharmacokinetic parameters of zaltoprofen and its salt

BIOMEDICAL CHROMATOGRAPHY, Issue 5 2009
Hyun Kyoung Yang
Abstract The objective of this study was to compare the pharmacokinetic parameters of zaltoprofen and those of its sodium salt in rats. Zaltoprofen, a potent non-steroidal anti-inflammatory agent, was virtually insoluble in water, but its sodium salt had excellent water solubility. To investigate the effect of aqueous solubility differences upon their pharmacokinetic parameters, minicapsules containing the drug powders were administrated orally to rats, and blood samples were taken via the common carotid artery. A column-switching high-performance liquid chromatographic analytical procedure was developed and validated for the quantitation of zaltoprofen in rat plasma samples. Our study demonstrated that the time required to reach maximum plasma concentration (Tmax) of zaltoprofen sodium was significantly reduced and its maximum plasma concentration (Cmax) was increased 1.5-fold, relative to the values for zaltoprofen. It is anticipated that the sodium salt of zaltoprofen will allow the rapid onset of the drug's action in the treatment of inflammatory diseases. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Electronic Properties of 3,3,-Dimethyl-5,5,-bis(1,2,4-triazine): Towards Design of Supramolecular Arrangements of N-Heterocyclic CuI Complexes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2007
Blandine Courcot Dr.
Abstract A new efficient and safe synthesis of 3,3,-dimethyl-5,5,-bis-(1,2,4-triazine) is presented. The electron-density distribution and electrostatic properties (charge, electrostatic potential) of this molecule were analyzed. These properties were derived from a high-resolution single-crystal X-ray diffraction experiment at 100,K and compared to the results obtained from ab initio DFT quantum-mechanical calculations. Comparisons of its electrostatic potential features and integrated atomic charges (quantum theory of atoms in molecules, QTAIM) have been made with those of related molecules such as bipyrimidine ligands. Two methods were used to derive integrated charges: one is based on the conventional analytical procedure and the second uses a steepest-ascent numerical algorithm. Excellent agreement was obtained between these two methods. Charges and electrostatic potential were used as predictive indices of metal chelation and discussed in the light of complexation abilities of the title compound and related molecules. The crystal structure of a CuI complex of 3,3,-dimethyl-5,5,-bis(1,2,4-triazine) is reported here. In the solid state, this complex forms a three-dimensional multibranch network with open channels in which counterions and solvent molecules are located. This architecture involves both cis and trans isomers of the title compound. [source]

Underpotential Deposition Study and Determination of Bismuth on Gold Electrode by Using Voltammetry

CHINESE JOURNAL OF CHEMISTRY, Issue 6 2002
Yong-Ling Du
Abstract The cyclic voltammetry (CV) and the semidifferential anodic stripping voltammetry (SdASV) were used for investigation of bismuth(III) underpotential deposition (UPD) on gold electrode. Based on the excellent electrochemical properties of Au/ Bi UPD system, a new method for determining bismuth (III) was established. A solution of 0.1 mol/L HNO3 was selected as the supporting electrolyte. Factors affecting the Bi(III) UPD and stripping steps were investigated and an optimized analytical procedure was developed. The calibration plots for Bi(III) concentration in the range 1.25 × 10,8 -1.0 × 10,7 mol/L were obtained. The detection limit, calculated as three times the standard deviation of the analytical signal of 8.3 × 10,8 mol/L for a 90 s electrodeposition at 0.00 V (while the solution magnetically stirred at a speed of 300 rpm), was 7.5 × 10,9 mol/ L. For 8 successive determinations of 1.25 × 10,7 mol/L Bi(III), the obtained RSD (relative standard deviation) was 0.4%. The developed method was applied to bismuth determining in medicine and urine samples. The analytical results were compared with that of atomic emission spectrometry (AES) method. [source]

The World Has Changed,Have Analytical Procedure Practices?

A Note on the Interdependence between Hypothesis Generation and Information Search in Conducting Analytical Procedures,

Ricin poisoning and forensic toxicology,

DRUG TESTING AND ANALYSIS, Issue 4 2009
Frank Musshoff
Abstract Ricin is one of the most fascinating poisons due to its high toxicity: as little as 500 µg can kill an adult. It gained fame by its use in the so-called ,umbrella murder' to kill the Bulgarian dissident Georgi Markov in 1978. Ricin also became known as a potential bio-terror agent to which people could be exposed through the air, food, or water. The origin, biochemistry, toxicity, and analytical procedures for the determination of ricin are summarized. The homicide of Markov is described as well as recent cases of criminal ricin use. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Voltammetric Analysis of Trace Levels of Platinum Group Metals , Principles and Applications

ELECTROANALYSIS, Issue 21 2007
2Article first published online: 4 OCT 200, Clinio Locatelli
Abstract The compelling use of autocatalytic converters, containing platinum group metals (PGMs), has been the cause, in the environmental and biological matrices, of an increasing concentration of such metals. For this reason, in the last decade, the literature has reported several papers regarding analytical procedures for the determination of Pt(II), Pd(II) and Rh(III) in real samples, generally employing spectroscopic methods. The present review intends to highlight the contribution of the voltammetric techniques for the determination of these metals, including also those less investigated, i.e. Iridium, Osmium and Ruthenium. [source]

Probing Biomolecular Interactions at Conductive and Semiconductive Surfaces by Impedance Spectroscopy: Routes to Impedimetric Immunosensors, DNA-Sensors, and Enzyme Biosensors

ELECTROANALYSIS, Issue 11 2003
Eugenii Katz
Abstract Impedance spectroscopy is a rapidly developing electrochemical technique for the characterization of biomaterial-functionalized electrodes and biocatalytic transformations at electrode surfaces, and specifically for the transduction of biosensing events at electrodes or field-effect transistor devices. The immobilization of biomaterials, e.g., enzymes, antigens/antibodies or DNA on electrodes or semiconductor surfaces alters the capacitance and interfacial electron transfer resistance of the conductive or semiconductive electrodes. Impedance spectroscopy allows analysis of interfacial changes originating from biorecognition events at electrode surfaces. Kinetics and mechanisms of electron transfer processes corresponding to biocatalytic reactions occurring at modified electrodes can be also derived from Faradaic impedance spectroscopy. Different immunosensors that use impedance measurements for the transduction of antigen-antibody complex formation on electronic transducers were developed. Similarly, DNA biosensors using impedance measurements as readout signals were developed. Amplified detection of the analyte DNA using Faradaic impedance spectroscopy was accomplished by the coupling of functionalized liposomes or by the association of biocatalytic conjugates to the sensing interface providing biocatalyzed precipitation of an insoluble product on the electrodes. The amplified detections of viral DNA and single-base mismatches in DNA were accomplished by similar methods. The changes of interfacial features of gate surfaces of field-effect transistors (FET) upon the formation of antigen-antibody complexes or assembly of protein arrays were probed by impedance measurements and specifically by transconductance measurements. Impedance spectroscopy was also applied to characterize enzyme-based biosensors. The reconstitution of apo-enzymes on cofactor-functionalized electrodes and the formation of cofactor-enzyme affinity complexes on electrodes were probed by Faradaic impedance spectroscopy. Also biocatalyzed reactions occurring on electrode surfaces were analyzed by impedance spectroscopy. The theoretical background of the different methods and their practical applications in analytical procedures were outlined in this article. [source]