The role of analytical chemists in the research on the cultural heritage.

Professionals belonging to very different areas of expertise are usually involved in research on the cultural heritage. Among the names given to the person in charge of analyses are conservator or material scientist, as the most usual, but never "analytical chemist", despite analytical equipment, obtainment of analytical data and application of chemometrics approaches to obtain analytical results are always involved in their tasks. This article tries to be a call of attention to analytical chemists by showing the different areas within the research on cultural heritage in which they should be involved to provide the necessary analytical information. Examples of the analytical equipment involved in these studies, the research on pigments, dyes, binders and coatings, dating and cleaning of artworks are given, thus showing that analytical information on chemical aspects related to research on the cultural heritage should be, evidently, conducted in cooperation with analytical chemists.

Qualitative/quantitative strategy for the determination of glufosinate and metabolites in plants.

A simple method for the simultaneous determination of glufosinate and itsmetabolites in plants based on liquid chromatography­ultraviolet (LC­UV) absorption detection after derivatization with fluorenylmethoxycarbonyl chloride (FMOC-Cl) of some analytes to facilitate separation is reported here. Nonavailable standard metabolites were identified by LC­TOF/mass spectrometry (MS), which also confirmed all target analytes. Ultrasound-assisted extraction was used for sample preparation (power of 70 Wand duty cycle of 0.7 s/s for 10 min) with subsequent evaporation of the extractant, reconstitution and filtration as the cleanup/concentration step prior to derivatization, and chromatographic separation and detection at 270 nm for underivatized analytes and 340 nm for those that were derivatized. The chromatographic analysis was completed in 40 min using a Luna® column (C18 phase). The analytical characteristics of the method were linear dynamic range of the calibration curves within 0.047­700 µg/mL with a regression coefficient (rc) of 0.999 for glufosinate, 0.077­700 µg/mL with a rc of 0.998 for N-acetyl-glufosinate, and 0.116­600 µg/mL with a rc of 0.998 for 3-(methylphosphinico)propanoic acid. The precision for the determination of glufosinate (studied at two levels, 0.1 and 5 µg/mL) was 2.7 and 6.0 % for repeatability and 4.7 and 7.2%for within-laboratory reproducibility, respectively. Identification and confirmatory analysis of the presence of glufosinate and metabolites in the extracts from treated plants was carried out by LC­TOF/MS in high-resolution mode for the precursor ion. The method was validated by analyzing wheat (Triticum aestivum) samples (resistant and susceptible biotypes) treated with 300 g of glufosinate/ha following conventional agronomical practices.

Automated method for targeting analysis of prostanoids in human serum by on-line solid-phase extraction and liquid chromatography-mass spectrometry in selected reaction monitoring.

Prostanoids are potent biologically active lipid molecules demanding for analysis methods combining precision, sensitivity and high-throughput for pharmacological and clinical applications. The present research describes the development and validation of an on-line automated method based on solid-phase extraction liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) for the quantification of prostanoids in human serum. This approach overcomes the main limitation of previous methods involving manual protocols, such as analyte losses, metabolites degradation and time-consuming protocols, are minimized. Human serum (100 µL) was directly injected into an automatic solid-phase extraction workstation for cleanup and preconcentration of the target metabolites. The eluate was on-line transferred to a reversed-phase analytical column for chromatographic separation prior to mass spectrometry detection in selected reaction monitoring mode. The detection limits for the target analytes ranged from 2.3 to 63.3 pg on column. The precision (expressed as relative standard deviation) was within 3.30 and 6.15% for repeatability and from 4.16 to 11.11% for within-laboratory reproducibility. Accuracy was evaluated with spiked and non-spiked serum samples to estimate concentration differences that could be affected by matrix effects or inefficient SPE performance. Accuracy, estimated as recovery factor, was from 87.7 to 100% for the target compounds. The proposed method is reliable and has an excellent potential for high-throughput use in both clinical and research laboratories by minimizing analyst intervention.

Fast ultrasound-assisted extraction of polar (phenols) and nonpolar (lipids) fractions in Heterotheca inuloides Cass.

INTRODUCTION: Heterotheca inuloides Cass., also known as "arnica", is used in traditional medicine in Mexico. OBJECTIVE: Development of fast methods for the extraction of lipidic and phenolic fractions from arnica plants and their subsequent characterization. METHODOLOGY: Ultrasound was applied to accelerate extraction of the target compounds from this plant and reduce the use of organic solvents as compared with conventional methods. Gas chromatography-ion trap mass spectrometry and liquid chromatography with diode-array detection were used for the characterization of the lipidic and phenolic fractions, respectively. RESULTS: Under optimal extraction conditions, 9 and 55 min were necessary to complete extraction of the lipidic and phenolic fractions, respectively. The fatty acids present at the highest concentrations in H. inuloides were eicosatetraenoic n3 (24.6 µg/g), cis-9-hexadecenoic n7 (23.1 µg/g), exacosanoic (22.7 µg/g) and cis-9-octadecenoic acid (21.3 µg/g), while the rest were in the range 7.6-1.3 µg/g. The most concentrated phenols were guaiacol (41.5 µg/g), catechin (38.7 µg/g), ellagic acid (35.9 µg/g), carbolic acid (24.2 µg/g) and p-coumaric acid (19.5 µg/g), while the rest were in the range 5.1-0.4 µg/g. CONCLUSION: Ultrasound reduces the time necessary to complete the extraction 160 and 26 times, the extraction volume 2.5 and 4 times, and increases the extraction efficiency 5 and 3 times for lipidic and phenolic fractions, respectively, in comparison with conventional extraction methods. In addition, the characterization of the lipidic and phenolic fractions constitutes a first approach to the H. inuloides metabolome.

Fast and selective determination of triterpenic compounds in olive leaves by liquid chromatography-tandem mass spectrometry with multiple reaction monitoring after microwave-assisted extraction.

A method for fast and selective determination of the main triterpenic compounds present in olive leaves - oleanolic, ursolic and maslinic acids as triterpenic acids and, uvaol and erythrodiol as triterpenic dialcohols - is reported here. Quantitative isolation of the analytes has been accomplished in 5min by microwave assistance using ethanol as extractant. Due to the medium polarity of triterpenic acids and dialcohols, different ethanol-water ratios were tested in order to select the optimum extractant composition for their solubilisation. Microwave assistance provided a significant shortening of the leaching time as compared to conventional procedures by maceration, which usually requires at least 5h. After extraction, determination was carried out by liquid chromatography-tandem mass spectrometry (LC-MS-MS) with a triple quadrupole (qQq) mass detector without any clean-up step prior to chromatographic analysis. Highly selective identification of triterpenes was confirmed by multiple reaction monitoring (MRM) using the most representative transitions from the precursor ion to the different product ions, while the most sensitive transitions were used for MS-MS quantitation. Total analysis performed in 25 min enables the characterization of a fraction with particular interest in the pharmacological area.

Role of lees in wine production: A review.

The sometimes contradictory role attributed by scientists to lees in wine production is discussed in this review. Studies dealing with the importance of lees in the natural removal of undesirable compounds from wine, the effect of lees-wine contact on the volatile fraction of wines, the key influence of lees on biogenic amine contents in wines, the interactions between lees and phenolic compounds, and the importance of mannoproteins and lipids released by lees have been critically reviewed. Finally, the present exploitation of lees is also outlined.

Sequential (step-by-step) detection, identification and quantitation of extra virgin olive oil adulteration by chemometric treatment of chromatographic profiles.

An analytical method for the sequential detection, identification and quantitation of extra virgin olive oil adulteration with four edible vegetable oils--sunflower, corn, peanut and coconut oils--is proposed. The only data required for this method are the results obtained from an analysis of the lipid fraction by gas chromatography-mass spectrometry. A total number of 566 samples (pure oils and samples of adulterated olive oil) were used to develop the chemometric models, which were designed to accomplish, step-by-step, the three aims of the method: to detect whether an olive oil sample is adulterated, to identify the type of adulterant used in the fraud, and to determine how much aldulterant is in the sample. Qualitative analysis was carried out via two chemometric approaches--soft independent modelling of class analogy (SIMCA) and K nearest neighbours (KNN)--both approaches exhibited prediction abilities that were always higher than 91% for adulterant detection and 88% for type of adulterant identification. Quantitative analysis was based on partial least squares regression (PLSR), which yielded R2 values of >0.90 for calibration and validation sets and thus made it possible to determine adulteration with excellent precision according to the Shenk criteria.

Focused microwave-assisted Soxhlet extraction of acorn oil for determination of the fatty acid profile by GC-MS. Comparison with conventional and standard methods.

A study of the feasibility of focused microwave-assisted Soxhlet extraction of acorn oil and comparison of results from analysis of trans fatty acids in the oil thus obtained with those for oils obtained by use of other methods commonly used for oil extraction are reported here. The proposed method was optimized by means of a 21-experiment screening design to determine, by means of a reduced number of experiments, which factors affect both extraction efficiency and the degree of unsaturation of the fatty acids in the oil. The proposed method enables total extraction of the fatty acids in 30 min, which is much less than the time required by the Folch (4.5 h), Soxhlet (16 h), and ISO (8 h) reference methods and the stirring-extraction method (56 h). The efficiency of extraction achieved by use of the proposed method is statistically equivalent to that achieved by use of the other methods; the composition of the extracts obtained by use of the proposed method and the Folch and stirring reference methods are also statistically similar. No trans fatty acids were present in the extracts obtained by use of the Folch, stirring, and proposed methods but they were detected in the extracts obtained by use of both the Soxhlet and ISO methods.

Discrimination and classification of olive tree varieties and cultivation zones by biophenol contents.

The peak areas from a high-performance liquid chromatography-diode array (HPLC-DAD) analysis of biophenols extracted from olive leaves have been used as chemotaxonomic markers to construct chemometric models in order to discriminate and classify (1) 13 varieties of Olea europaea olive trees, namely, Alameño, Arbequina, Azulillo, Chorna, Hojiblanca, Lechín, Manzanillo, Negrillo, Nevadillo, Ocal, Pierra, Sevillano, and Tempranillo, from the same cultivation zone and (2) Arbequina samples from six different geoghaphical origins, namely, Córdoba, Mallorca (north and south), Ciudad Real, Lleida, and Navarra. Models based on principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used for discrimination between samples as a function of the tree varieties and cultivation zone, whereas K nearest neighbors (KNN) and soft independent modeling of class analogy (SIMCA) models were generated to classify the samples used to validate the models into one of the groups previously established by PCA and HCA. KNN classified correctly 93 and 92% of the samples into the variety and cultivation zone, respectively; meanwhile, the SIMCA models predicted 85 and 92%, respectively.

Ultrasound-assisted extraction of phenolic compounds from strawberries prior to liquid chromatographic separation and photodiode array ultraviolet detection.

Ultrasound-assisted extraction was used for the determination of phenolic compounds present in strawberries. The optimization study of the extraction was carried out using spiked samples (100 mg/kg). The sample immersed in an aqueous solution containing hydrochloric acid (0.4 M) was sonicated for 2 min (duty cycle 0.2 s, output amplitude 20% of the nominal amplitude of the converter, applied power 100 W with the probe placed 1cm from the bottom of the water bath and 5 cm from the walls of the precipitate glass). Subsequent separation was carried out by liquid chromatography (LC) with photodiode array UV detection. Calibration curves using the standard addition in green strawberries typically gave linear dynamic ranges of 2-300 mg/l for all analytes; R(2) values exceeded 0.996 in all cases. The method was applied to two types of strawberries to demonstrate the applicability of the proposed method, which is much faster and produces less analyte degradation than methods as solid-liquid, subcritical water and microwave-assisted extraction.

Dynamic ultrasound-assisted extraction of colistin from feeds with on-line pre-column derivatization and liquid chromatography-fluorimetric detection.

A dynamic ultrasound-assisted extraction (UAE) method with on-line pre-column derivatization/high performance liquid chromatography (HPLC) and fluorimetric detection is proposed for the analysis of colistin in feed. A flow injection manifold is used for the development of the extraction and derivatization steps and for interfacing them with the separation/detection step, thus providing an on-line approach with the advantage of minimum sample handling. The derivatization was performed with ortho-phthaldialdehyde and 2-mercaptoethanol. The optimum conditions for colistin extraction and formation of the fluorescent derivative have been obtained by experimental design methodology. The use of a high-intensity probe sonication makes UAE an expeditious (7 min versus > 1 h) and efficient (93.1-98.2% versus 87.5-94% of recovery) alternative as compared with extraction using an ultrasonic bath. The within-laboratory reproducibility and repeatability, expressed as percentage of relative standard deviation, were 5.2 and 5.8, respectively.

Identification and quantification of trans fatty acids in bakery products by gas chromatography-mass spectrometry after dynamic ultrasound-assisted extraction.

trans Fatty acids have been determined in 14 bakery products using derivatisation by ester formation, gas chromatography-mass spectrometry (GC-MS) for individual separation, identification and quantification following total fat isolation by dynamic ultrasound-assisted extraction (DUAE). The detection and quantification limits between 0.98 and 3.93 microg g(-1) and 3.23 and 12.98 microg g(-1), respectively, and the linear dynamic ranges between LOQs values and 12,000 microg g(-1) thus obtained, demonstrated the utility of the approach for this type of analysis thanks to the wide determination range and high information level it provides. The proposed extraction method--validated by comparison with the Folch reference method--drastically reduces the extraction time as compared with the reference method without degradation of the target analytes by ultrasound irradiation, as demonstrated in the subsequent quantification step. The overall method thus developed could be a valid alternative to the reference method as the present and foreseeable increased demand for the analysis of these analytes makes mandatory faster methods. The number of samples used support the validation process.

Fast separation and determination of phenolic compounds by capillary electrophoresis-diode array detection. Application to the characterisation of alperujo after ultrasound-assisted extraction.

A dynamic approach has been proposed for the ultrasound-assisted extraction of twenty phenolic compounds from alperujo, a semisolid waste from the olive oil industry, that is a representative example of samples with a complex matrix. Multivariate methodology was used to carry out a detailed optimisation study of both the separation-determination and extraction steps in terms of resolution-analysis time and extraction efficiency, respectively. Consequently, the proposed method was able to extract the target analytes in 13 min; then, after dilution and centrifugation, the extract was injected into the capillary electrophoresis-diode array detection system for individual separation determination in 11 min. No cleanup of the extract was required. This method is less time-consuming, more selective and provides a larger information level than the Folin-Ciocalteau spectrophotometric method. Alperujo was demonstrated to be a powerful source of phenolic compounds, particularly as compared with olive oil--8680 versus 50-1200 microg/g.

Superheated liquids for extraction of solid residues from winemaking processes.

Solid residues from winemaking processes have been subjected to extraction with superheated water-ethanol mixtures. Identification and characterization of the extracted compounds were achieved by spectrophotometry, gas chromatography with either flame-ionization or mass detectors, and-high performance liquid chromatography with UV detection. Extraction was performed statically with single or repeated cycles. All variables affecting the extraction process have been studied and optimised. The extraction time and temperature were 65 min and 210 degrees C, respectively. Extracts comprised two phases--an aqueous phase, rich in phenolic compounds, and an oily phase, comprising mainly fatty acids. The method allows manipulation of extract composition by changing the applied pressure, temperature, water-to-ethanol ratio, and pH. The method is faster than traditional extraction procedures for obtaining valuable compounds from these residues.

Flow-injection spectrophotometric determination of cyanate in bioremediation processes by use of immobilised inducible cyanase.

A new flow injection (FI) method for photometric monitoring of cyanate in bioremediation processes using immobilised native cyanase is described. The method is based on the catalytic reaction between cyanate and bicarbonate to produce ammonia and carbon dioxide in the presence of an inducible native cyanase, immobilised in a reactor packed with glass beads. Two degrees of purification of the biocatalyst were used-heated cell-free extract and purified extract of cyanase from Pseudomonas pseudoalcaligenes CECT 5344. The ammonia produced by the enzymatic reaction is finally monitored photometrically at 700 nm using a modification of the conventional Berthelot method. The method furnishes different calibration curves depending on the degree of purification of the cyanase, with linear ranges between 1.23 and 616.50 micromol L(-1) ( r(2)=0.9979, n=7) and between 1.07 and 308.25 micro mol L(-1) ( r(2)= 0.9992, n=7) for the heated cell-free extract and the purified cyanase extract, respectively. No statistically significant differences between the samples were found in the precision study evaluated at two cyanate concentration levels using one-way analysis of variance. A sampling frequency of 15 h(-1) was achieved. The method was used to monitor cyanate consumption in a cyanate bioremediation tank inoculated with Pseudomonas pseudoalcaligenes CECT 5344 strain. The correlation between cyanate degradation and ammonia production was tested using a conventional method. Finally, the method was applied to different samples collected from the bioremediation tank using the standard addition method; recoveries between 85.9 and 97.4% were obtained.

New methods for acceleration of meat sample preparation prior to determination of the metal content by atomic absorption spectrometry.

Focused microwave-assisted digestion and ultrasound leaching have been applied for the extraction of Pb, Cd, Cr, Cu, Fe, Zn, Ca, and Mg from raw meat. Semimembranous muscle (SM) of raw pig ham was used for optimizing both the digestion and extraction steps by multivariate approaches. The detection and quantification limits were 0.5 and 0.9 microg kg(-1) for Pb, 0.06 and 0.1 microg kg(-1) for Cd, 0.2 and 1.2 microg kg(-1) for Cr, 0.4 and 3 microg kg(-1) for Cu, 0.04 and 0.1 mg kg(-1) for Fe, 0.012 and 0.017 mg kg(-1) for Zn, 0.3 and 0.4 mg kg(-1) for Ca, and 0.01 and 0.03 mg kg(-1) for Mg. The precision, expressed as relative standard deviation (RSD), ranged between 2.5 and 9.6% for focused microwave-assisted digestion and between 3.5 and 10.6% for ultrasound leaching. The methods were then compared with a reference method and applied to a certified reference material (bovine muscle 184, from the BCR). The t-test, applied to the results obtained from focused microwave-assisted digestion, revealed that they are in agreement (p>0.01) with the certified and estimated values in the case of Pb, Cd, Cr, Cu, Fe, Ca, Mg, and Zn but not in that of Fe. In the case of ultrasound leaching, only the extraction of Pb, Cu, and Ca was quantitative. The method based on microwave digestion provides more accurate and precise results than ultrasound leaching. These new procedures have many advantages with regards to conventional methods, namely, reduction of the extraction time, simplification of the process, avoidance of chemical emissions to the atmosphere, and no losses of metals by volatilization.

Superheated water extraction of cholesterol from solid food.

A method based on superheated water extraction has been developed for the removal of cholesterol from solid food thus providing a clean approach by avoiding the use of organic solvents. A preconcentration step was also studied with the aim of solving the problem derived from low-cholesterol-content samples and dilution effect. The research also involved the optimisation of the parameters affecting the extraction process by a central composite experimental design as well as a univariate study of the optimisation of the preconcentration step. The time required for total removal of the target compound was 60 min. The method was validated using a certified reference material (NIST-CRM 1845) and was used to analyse food samples within a wide range of cholesterol concentrations. The efficiency for the CRM was 105%. The precision of the method yielded values less than 6.5% (expressed as relative standard deviation) in all instances.