Determination of suspected fragrance allergens in cosmetics by matrix solid-phase dispersion gas chromatography-mass spectrometry analysis

An effective low cost sample preparation methodology for the determination of regulated fragrance allergens in leave-on and rinse-off cosmetics has been developed applying, for the first time, matrix solid-phase dispersion (MSPD) to this kind of analytes and samples. The selection of the most suitable extraction conditions was made using statistical tools such as ANOVA, as well as a factorial multifactor experimental design. These studies were carried out using real cosmetic samples. In the final conditions, 0.5 of sample, previously mixed with 1g of anhydrous Na(2)SO(4), were blended with 2g of dispersive sorbent (Florisil), and the MSPD column was eluted with 5 mL of hexane/acetone (1:1). The extract was then analyzed by GC-MS without any further clean-up or concentration step. Accuracy, precision, linearity and detection limits (LODs) were evaluated to assess the performance of the proposed method. Quantitative recoveries (>75%) were obtained and RSD values were lower than 10% in all cases. The quantification limits were well below those set by the international cosmetic regulations, making this multi-component analytical method suitable for routine control. In addition, the MSPD method can be implemented in any laboratory at low cost since it does not require special equipment. Finally, a wide variety of cosmetic products were analyzed. All the samples contained several of the target cosmetic ingredients, with and average number of seven. The total fragrance allergen content was in general quite high, even in baby care products, with values close to or up to 1%, for several samples, although the actual European Cosmetic Regulation was fulfilled.     

Development and application of chemometric-assisted dispersive liquid-liquid microextraction for the determination of suspected fragrance allergens in water samples

A simple and green method based on dispersive liquid-liquid microextraction, mated to chemometrics and followed by mass spectrometric detection for the determination of suspected fragrance allergens in water samples is developed and assessed in this work. Volume of extraction and disperser solvent, pH, ionic strength, extraction time, sample volume, as well as centrifugation time were initially optimized in a fractional factorial design. The obtained significant factors were optimized by using a central composite design and the quadratic model between the dependent and the independent variables was built. The obtained optimal conditions were: aqueous sample of 3.8 mL, 100 μL chloroform, 1.40 mL acetone, 4 min centrifugation time, natural pH containing 5% (w/v) NaCl, and centrifugation speed 4000 rpm. Method proved to be linear over a wide range of concentration for all analytes with R(2) between 0.9807 and 0.9959. The repeatability and reproducibility of the proposed method, expressed as relative standard deviation, varied between 3-13% and 4-16%, respectively. The limits of detection ranged from 0.007 to 1.0 μg L(-1) . The recommended method was applied to water samples including baby bath as well as swimming pool water samples and was compared with a previously reported method.     

Comparison of two systems for sample preparation and injection by dynamic headspace GC analysis

The performance of two commercially available systems employing dynamic headspace techniques for collection, enrichment, and injection of volatile compounds has been compared by GC analysis of test mixtures and dairy products. For technical reasons, it has not been possible to crate identical sorbent materials for both kinds of trap were not available, the most similar adsorbent available were chosen. The total quantity of volatile compounds from a test mixture at the column head was calculated using a theoretical model which enables comparable working conditions to be obtained. Under these circumstances special attention was paid to the repeatability of the data obtained from a test mixture in order to ensure reliable results in quantitative analysis. Significant differences in repeatability between the two systems seemed to originate from their distinctly different technical designs. A qualitative comparison of the systems has been performed using a sample of Swiss cheese. On the basis of the results obtained the systems have been dedicated to different applications in the laboratory of the FAM.     

Static and dynamic headspace analysis of instant coffee blends by proton‐transfer‐reaction mass spectrometry

Instant coffee is a widespread product, generally related to a high consumer acceptability, also because of its ease of preparation. The present work addresses the characterization of the headspace of freshly brewed instant coffees resulting from different blends, during and immediately after preparation. The sample set consisted of 10 coffees, obtained by mixing three different blends in different proportions. The employment of Proton Transfer Reaction‐Mass Spectrometry (PTR‐MS) allowed for direct and real‐time sampling from the headspace, under conditions that mimic those that are encountered above the cup during and right after brewing. Different coffee brews were separated on the basis of the respective volatile profiles, and data showed good consistency with the respective blend compositions. When the headspace evolution was monitored during preparation, similar results were obtained in terms of blend separation; moreover, different blends displayed different and reproducible ‘signatures’ in terms of time evolution. A straightforward method for the prediction of headspace composition is proposed, allowing to predict the volatile profiles of two‐component and three‐component blends on the basis of the respective parent components. Overall, the results constitute a successful example of the applicability of PTR‐MS as a tool for product development in food science. Copyright © 2015 John Wiley & Sons, Ltd.     

Optimization, validation and application of a method for the determination of trichloroethylene in rat plasma by headspace solid-phase microextraction gas chromatography mass spectrometry

Trichloroethylene (TCE) is a small halogenated compound that has been used extensively as a metal degreaser and a solvent for the past 100 years. As a result of its widespread use, TCE can be found in the groundwater of about one-third of the hazardous waste sites on the United States Environmental Protection Agency's National Priorities List. Human exposure to TCE in the environmental media is of concern because TCE has been found to be carcinogenic in laboratory animals. This paper describes the development and validation of a HS-SPME-GC/MS method for determination of TCE in rat plasma. The effects of different parameters such as sample volume, extraction and desorption conditions, fiber positions and salt addition were investigated and optimized. The method is rapid, simple, sensitive and requires a very small sample volume. The lower limit of quantitation was 0.25 ng/mL and correlation coefficient (r(2)) values for the linear range of 0.25-100 ng/mL were 0.996 or greater. The precision and accuracy for intra-day and inter-day were better than 8.0%. This validated method was successfully applied to study the toxicokinetic behavior of TCE following low levels of oral administration. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Differentiation of the volatile profile of microbiologically contaminated canned tomatoes by dynamic headspace extraction followed by gas chromatography-mass spectrometry analysis

The aromatic profile of microbiologically contaminated canned tomatoes was analyzed by the dynamic headspace extraction technique coupled with gas chromatography-mass spectrometry. Canned tomatoes contaminated with Escherichia coli, Saccharomyces cerevisiae and Aspergillus carbonarius were analyzed after 2 and 7 days. About 100 volatiles were detected, among which alcohols, aldehydes and ketones were the most abundant compounds. Gas chromatographic peak areas were used for statistical purposes. First, principal component analysis was carried out in order to visualize data trends and clusters. Then, linear discriminant analysis was performed in order to detect the set of volatile compounds ables to differentiate groups of analyzed samples. Five volatile compounds, i.e. ethanol, β-myrcene, o-methyl styrene, 6-methyl-5-hepten-2-ol and 1-octanol, were found to be able to better discriminate between uncontaminated and contaminated samples. Prediction ability of the calculated model was estimated to be 100% by the “leave-one-out” cross-validation. An electronic nose device was then used to analyze the same contaminated and not contaminated canned tomato samples. Preliminary results were compared with those obtained by dynamic headspace gas chromatography-mass spectrometry, showing a good agreement.     

Simultaneous distillation-extraction and dynamic headspace methods in the gas chromatographic analysis of Parmesan cheese volatiles

Summary Dynamic headspace and simultaneous steam distillation-extraction techniques were used to isolate volatile components of Parmesan cheese. Identification of the substances was carried out by GC and GC-MS; 110 compounds were identified in the samples obtained using the headspace technique, 105 in the extracts; among them, about 50 compounds were isolated with both procedures. Mass spectral data showed evidence for a number of newly reported compounds such as 3-(methylthio)propanal, -tetradecalactone, 9-tetra-decenoic and 9-hexadecenoic acids. Mass spectra of some compounds are discussed and a comparison between the results obtained with the two sampling methods is given.     

Evaluation of solid-phase micro-extraction coupled to gas chromatography-mass spectrometry for the headspace analysis of volatile compounds in cocoa products

The aroma profile of cocoa products was investigated by headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC–MS). SPME fibers coated with 100 μm polydimethylsiloxane coating (PDMS), 65 μm polydimethylsiloxane/divinylbenzene coating (PDMS-DVB), 75 μm carboxen/polydimethylsiloxane coating (CAR-PDMS) and 50/30 μm divinylbenzene/carboxen on polydimethylsiloxane on a StableFlex fiber (DVB/CAR-PDMS) were evaluated. Several extraction times and temperature conditions were also tested to achieve optimum recovery. Suspensions of the samples in distilled water or in brine (25% NaCl in distilled water) were investigated to examine their effect on the composition of the headspace. The SPME fiber coated with 50/30 μm DVB/CAR-PDMS afforded the highest extraction efficiency, particularly when the samples were extracted at 60 °C for 15 min under dry conditions with toluene as an internal standard. Forty-five compounds were extracted and tentatively identified, most of which have previously been reported as odor-active compounds. The method developed allows sensitive and representative analysis of cocoa products with high reproducibility. Further research is ongoing to study chocolate making processes using this method for the quantitative analysis of volatile compounds contributing to the flavor/odor profile.     

The performance of various capillary columns for the analysis of volatile flavor compounds in dairy products by dynamic headspace gas chromatography

The aim of this study was to test the suitability and performance of various stationary phases and column dimensions for dynamic headspace gas chromatography of food aromas. The trials were performed using an aqueous test mixture containing thirty seven volatile flavor components of intense aroma, and a sample of ripe Swiss Emmental cheese. The best performance with both samples was obtained with a capillary column coated with a thick film of polydimethylsiloxane. This column resolved the greatest number of compounds in the cheese sample and resulted in the overlapping of one pair of peaks only from the test mixture. Because of its other advantages, i. e. high capacity owing to its film thickness, and insensitivity to the high moisture content of some samples or traces of oxygen in the carrier gas, the polydimethylsiloxane column appears suitable for the analysis of the volatile and highly polar compounds present in complex mixtures such as food aroma.     

Optimization of dynamic headspace sampling for the analysis of trace volatile components of grape juice: Use of a PTV injector for intermediate trapping

The use of a programmed temperature vaporizing (PTV) injector has been evaluated for the on-line concentration and injection of trace organic compounds either sampled from the head-space above grape juices or purged from solution. The Simplex method was used to improve the sensitivity of the method by optimization of the experimental conditions.     

Multivariate analysis for the classification and differentiation of Madeira wines according to main grape varieties

In order to differentiate and characterize Madeira wines according to main grape varieties, the volatile composition (higher alcohols, fatty acids, ethyl esters and carbonyl compounds) was determined for 36 monovarietal Madeira wine samples elaborated from Boal, Malvazia, Sercial and Verdelho white grape varieties. The study was carried out by headspace solid-phase microextraction technique (HS-SPME), in dynamic mode, coupled with gas chromatography–mass spectrometry (GC–MS). Corrected peak area data for 42 analytes from the above mentioned chemical groups was used for statistical purposes. Principal component analysis (PCA) was applied in order to determine the main sources of variability present in the data sets and to establish the relation between samples (objects) and volatile compounds (variables). The data obtained by GC–MS shows that the most important contributions to the differentiation of Boal wines are benzyl alcohol and (E)-hex-3-en-1-ol. Ethyl octadecanoate, (Z)-hex-3-en-1-ol and benzoic acid are the major contributions in Malvazia wines and 2-methylpropan-1-ol is associated to Sercial wines. Verdelho wines are most correlated with 5-(ethoxymethyl)-furfural, nonanone and cis-9-ethyldecenoate. A 96.4% of prediction ability was obtained by the application of stepwise linear discriminant analysis (SLDA) using the 19 variables that maximise the variance of the initial data set.     

Identification of halocarbons in the Tiber and Marta rivers by static headspace and liquid–liquid extraction analysis

Volatile organochlorine compounds in the Tiber and Marta rivers have been analyzed by liquid–liquid extraction and headspace gas chromatography. Several different halogenated compounds were identified, in particular chloroform, bromoform, trichloroethane, trichloroethene, and tetrachloroethene. The concentrations of the halocarbons varied between 0.05 and 4.5 μg L^–1 with a relative standard deviation ≤4.0%. The highest concentrations were observed for chloroform, bromoform, and tetrachloroethene in the Marta and Tiber rivers. The results obtained by use of the two analytical methods were similar.     

Application of headspace solid‐phase microextraction followed by gas chromatography coupled with mass spectrometry to determine esters of carboxylic acids and other volatile compounds in Dermestes maculatus and Dermestes ater lipids

A constant problem in veterinary medicine, human healthcare, agriculture, forestry and horticulture is the large number of pests, and the lack of effective methods to combat them which cause no harm to the rest of the environment. It is recommended and desired to reduce the use of chemicals and increase the use of agents based on knowledge acquired in the fields of biology, chemistry and agrochemicals. To learn the defense mechanisms of insects we should consider not only the site of their physiological ability to protect against external factors (cuticle), but also the possibility of chemical protection, formed by all compounds on the surface and in the body of insects. In this study, a procedure was developed to determine the esters of carboxylic acids in insect lipids. Headspace solid‐phase microextraction was followed by gas chromatography coupled with gas spectrometry. First, the best conditions were selected for the analysis to obtain the best chromatographic separation. An RTx‐5 column was used for this purpose. Polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polyacrylate fibers were used to isolate acid esters. PDMS/DVB fiber achieved the best conditions for the extraction; the extraction time was 50 min, the extraction temperature was 105°C and the desorption time was 10 min at 230°C. These solid‐phase microextraction conditions were used to analyze volatile compounds extracted from insects belonging to the Dermestidae family.     

Simultaneous quantitative analysis of phosphocreatine,creatine and creatinine in plasma of children by HPLC–MS/MS method: Application to a pharmacokinetic study in children with viral myocarditis

A simple and rapid HPLC–MS/MS method was developed and validated for simultaneous measurement of phosphocreatine and its metabolites creatine and creatinine in children's plasma. A 50 μL aliquot of plasma was prepared by protein precipitation with acetonitrile–water (1000 μL, 1:1, v/v) followed by separation on a Hypersil Gold C₁₈ column (35°C) with gradient mobile phase consisting of 2 mm ammonium acetate aqueous solution (pH 10) and methanol at a flow rate of 0.3 mL/min and analyzed by mass spectrometry in both positive (phosphocreatine) and negative (creatine and creatinine) ion multiple reaction monitoring mode. Good linearity (r > 0.99) was obtained for the three analytes. The intra‐day and inter‐day values of CV were <5.46% (?13.09% ≤ RE ≤ 2.57%). The average recoveries of the three analytes were 70.9–97.5%. No obvious impact was found for the quantitation of three analytes in normal, hemolyzed and hyperlipemic plasma. In the end, this method was successfully applied to a pharmacokinetic study of phosphocreatine in children (six cases) with viral myocarditis of children after intravenous infusion of 2 g of the test drug. The pharmacokinetc parameters of phosphocreatine/creatine were as follows: t_1/2 0.24/0.83 h, T_max 0.49/0.55 h, C_max 47.34/59.29 μg/mL, AUC_last 17.07/59.63 h μg/mL, AUC_inf 17.16/79.01 h μg/mL and MRT 0.29/0.67 h.     

Toxicokinetics of strychnine and brucine after the oral administration of Biqi capsule to rats by RRLC–MS/MS

Biqi capsule is a well‐known traditional Chinese medicine formula that has been widely applied for the clinical treatment of such diseases as rheumatoid arthritis, scapulohumeral periarthritis and cervical spondylopathy. However, there is concern regarding the toxicity of Biqi capsule owing to its active ingredients, strychnine and brucine. To investigate the toxicokinetics of strychnine and brucine after oral administration of Biqi capsule to rats, a sensitive and simple rapid‐resolution liquid chromatography/tandem mass spectrometry method was developed to determine the levels of strychnine and brucine in rat plasma. Chromatographic separation was performed on a Capcell Pak C₁₈ MG II (3.0 μm, 2.0 × 35 mm) column by gradient elution with acetonitrile and 0.2% formic acid as the mobile phase. The method was validated over the range of 0.25–250 ng/mL for strychnine and 0.025–25 ng/mL for brucine. The intra‐ and inter‐day accuracies of strychnine and brucine in rat plasma were 100.3–106.6 and 90.75–106.1% respectively, and the precisions were within 14.2%. The established method was successfully applied to the toxicokinetic study of strychnine and brucine after single and multiple oral administration of Biqi capsule to male and female rats at 0.4, 0.8 and 1.6 g/kg doses. The results showed different toxicokinetic characteristics in the different groups.     

Comparison of headspace solid‐phase microextraction and solvent extraction method for the simultaneous analysis of various soil fumigants in soil or water by gas chromatography–mass spectrometry

The quantity of soil fumigants has increased globally that has focused attention on their environmental behavior. However, simultaneous analysis of traces of fumigant residues is often unreported because analysis methods are not readily available to measure them at low concentrations. In this study, typical solvent extraction methods were compared with headspace solid‐phase microextraction methods. Both methods can be used for simultaneously measuring the concentrations of five commonly used soil fumigants in soil or water. The solvent extraction method showed acceptable recovery (76–103%) and intraday relative standard deviations (0.8–11%) for the five soil fumigants. The headspace solid‐phase microextraction method also showed acceptable recovery (72–104%) and precision rates (1.3–17%) for the five soil fumigants. The solvent extraction method was more precise and more suitable for analyzing relatively high fumigant residue levels (0.05–5 μg/g) contained in multiple soil samples. The headspace solid‐phase microextraction method, however, had a much lower limits of detection (0.09–2.52 μg/kg or μg/L) than the solvent extraction method (5.8–29.2 μg/kg), making headspace solid‐phase microextraction most suitable for trace analysis of these fumigants. The results confirmed that the headspace solid‐phase microextraction method was more convenient and sensitive for the determination of fumigants to real soil samples.     

Simultaneous determination of three flavonoids and one coumarin by LC–MS/MS: Application to a comparative pharmacokinetic study in normal and arthritic rats after oral administration of Daphne genkwa extract

A selective and sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for investigating the pharmacokinetics of umbelliferone, apigenin, genkwanin and hydroxygenkwanin after oral administration of Daphne genkwa extract. Plasma samples were treated by protein precipitation with acetonitrile. Analytes were detected by triple‐quadrupole MS/MS with an ESI source in negative selection reaction monitoring mode. The transitions of m/z 161 → 133 for umbelliferone, m/z 269 → 117 for apigenin, m/z 283 → 268 for genkwanin and m/z 299 → 284 for hydroxygenkwanin were confirmed for quantification. Chromatographic separation was conducted using an Eclipse XDB‐C₁₈ column, and the applied isocratic elution program allowed for simultaneous determination of the four analytes for a total run time of 2.5 min. The linearity was validated over the plasma concentration ranges of 1.421–1421 ng/mL for umbelliferone, 0.845–845 ng/mL for apigenin, 1.025–1025 ng/mL for genkwanin and 0.845–845 ng/mL for hydroxygenkwanin. The extraction recovery rate was >82.7% for each analyte. No apparent matrix effect was observed during the bioanalysis. After full validation, the proposed method was successfully applied to compare the pharmacokinetics of these analytes between normal and arthritic rats.     

Use of experimental design to optimize the analysis of volatile compounds by dynamic headspace extraction followed by cold trapping and capillary GC

A central composite design has been used to improve the extraction performance of a dynamic headspace method; extraction yield was evaluated on a homogeneous sample of cheese powder. The volatile compounds were stripped from the sample with nitrogen and adsorbed on a Tenax trap, analysis being performed with a thermal cold trapping injector connected directly to a capillary GC. Three variables (sample temperature, extraction time, and nitrogen flow rate) were investigated, and a quadratic model with interactions was postulated. Twenty experiments was performed, each producing five responses. It was shown that the best conditions for the extraction procedure were those characterized by the highest values of the three variables investigated.     

Combination of dynamic time warping and multivariate analysis for the comparison of comprehensive two-dimensional gas chromatograms: application to plant extracts

Comprehensive two-dimensional gas chromatography (GC x GC) is now recognized as the preferred technique for the detailed analysis and characterization of complex mixtures of volatile compounds. However, for comparison purposes, taking into account all the information contained in the chromatogram is far from trivial. In this paper, it is shown that the combination of peak alignment by dynamic time warping and multivariate analysis facilitated the comparison of complex chromatograms of tobacco extracts. The comparison is shown to be efficient enough to provide a clear discrimination among three types of tobacco. A tentative interpretation of loadings is presented in order to give access to the compounds which differ from one sample to another. Once located, mass spectrometry was used to identify markers of tobacco type.     

Development and application of a UPLC‐MS/MS method for simultaneous determination of fenofibric acid and berberine in rat plasma: application to the drug–drug pharmacokinetic interaction study of fenofibrate combined with berberine after oral administration in rats

With the purpose of carrying out pharmacokinetic interaction studies ofnberberine (BBR) and fenofibrate (FBT), an UPLC‐MS/MS method has been developed and validated. The analytes, BBR and fenofibric acid (FBA, metabolite of FBT) and the internal standard, tetrahydropalmatine, were extracted with dichloromethane–diethyl ether (3:2, v/v) and separated on an Agilent Eclipse XDB C₁₈ column using a mobile phase composed of acetonitrile and water. With positive ion electrospray ionization, the analytes were monitored on a triple quadrupole mass spectrometer in multiple reaction monitoring mode. Linear calibration curves were obtained over the concentration ranges of 0.1–100.0 ng/mL for BBR and 10.0–50,000.0 ng/mL for FBA. For BBR and FBA, the intra‐ and inter‐day precisions were <11.5 and 11.9%, respectively. The accuracy was within 11.7% and 11.3%. The mean recoveries of BBR at three concentrations of 0.2, 20.0, 80.0 ng/mL were >85.6%, and those of FBA at three concentrations of 20.0, 2500.0, 40,000.0 ng/mL were >87.9%. Consequently, the proposed method was applied to the pharmacokinetic interaction study of FBT combined with BBR after oral administration in rats and was proved to be sensitive, specific and reliable to analyze BBR and FBA in biological samples simultaneously. Copyright © 2016 John Wiley & Sons, Ltd.