High-performance Liquid Chromatography With A Diode-array Detector Research Articles

Antioxidant and Anticholinesterase Potential of Two Nigerian Bitter Yams Using a Simulated Gastrointestinal Digestion Model and Conventional Extraction.

The purpose of this study was to evaluate the antioxidant and anticholinesterase activities of yellow and white bitter yams from South Western Nigeria using methanolic extraction and simulated gastrointestinal digestion models. The phenolic compounds in the bitter yam varieties were evaluated by high performance liquid chromatography with a diode array detector (HPLC-DAD). The total phenolic content of the bitter yams was measured by the Folin-Ciocalteu method, reductive potential by assessing the ability of the bitter yam to reduce FeCl3 solution, and the antioxidant activities were determined by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·) scavenging activity, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS·+) scavenging activity, nitric oxide radical (NO·) scavenging ability, hydroxyl radical scavenging ability, and ability to inhibit Fe2+-induced lipid oxidation. The HPLC-DAD analysis revealed the presence of some phenolic compounds in the studied bitter yam varieties, with varying degree of quantitative changes after cooking. The antioxidant indices (total phenolic content, total flavonoid content, reducing power, DPPH· scavenging activity, ABTS·+ scavenging activity, and NO· scavenging activity) were higher in the simulated gastrointestinal digestion model compared to the methanolic extract, with the in vitro digested cooked white bitter yam ranking higher. Similarly, the in vitro digested yams had a higher inhibitory action against lipid oxidation compared to the methanolic extracts, with the cooked white bitter yam ranking high. The methanolic extracts and in vitro enzyme digests showed no acetylcholinesterase inhibitory abilities, while methanolic extracts and the in vitro enzyme digest displayed some level of butyrylcholinesterase inhibitory activities. Therefore the studied bitter yams could be considered as possible health supplements.

The influence of light quality on phenolic acid and biflavonoid production in Anacardium othonianum Rizz. seedlings grown in vitro

Anacardium othonianum Rizz., popularly known as the Cerrado cashew tree, is widely used in medicine due to its therapeutic properties, including its antioxidant, anti-inflammatory, and antidiarrheal activities. Light is an important regulator of the growth, development of plants differentiation, and metabolism. Considering the influence of light on the production of phytochemicals, the aim of the present study was to evaluate production of gallic and 3,4-dihydroxybenzoic acids and amentoflavone in A. othonianum seedlings grown in vitro exposure to white, blue, green, red, and yellow light. The seedlings were evaluated with respect to the length of the aerial parts and the number of leaves, at 0, 20, and 40 days of treatment. The fresh and dry weights of the aerial parts and the levels of phenolic acid and biflavonoid were evaluated at 40 days via high-performance liquid chromatography with a diode array detector (HPLC-DAD). Regardless of the light wavelength used for the growth, the largest length of the aerial parts (5.54 cm) and an increase in the number of leaves (2.86-fold) were observed at 40 days. The largest accumulations of fresh weight (325.5 mg and 335.1 mg per seedling) and dry weight (83.3 mg and 84.5 mg per seedling) were observed in seedlings grown under red and yellow light, respectively. Relatively higher levels of gallic acid (0.66 mg.g-1dry weight) and amentoflavone (1.41 mg.g-1dry weight) were found in seedlings grown under blue light. In contrast, the 3,4-dihydroxybenzoic acid levels of the seedlings under red light increased (8.22 mg.g-1 dry weight).

Validación de una metodología analítica por HPLC-DAD para la cuantificación de cafeína en un ensayo de permeación in vitro empleando mucosa oral porcina

En este artículo se presentan los resultados del desarrollo y validación de una metodologíaanalítica por cromatografía líquida de alta eficiencia con detector de arreglode diodos (HPLC-DAD) para la cuantificación de cafeína; se utilizó una columnaC18 con detección UV a 273 nm y una fase móvil compuesta por agua/acetonitrilo(80:20 v/v) de modo isocrático. Las características de desempeño evaluadas permitieroncomprobar que existe una adecuada selectividad, una linealidad entre 0,5 y 50ug/mL, con una precisión expresada como RSD menor a 2%, un porcentaje de recuperacióndel 99,9% y unos límites de detección y cuantificación para el método de2,99 y 2,69 ng/mL, respectivamente. El método propuesto es útil para determinar elperfil de permeación bucal de la cafeína mediante un estudio in vitro con celdas deFranz empleando membrana bucal porcina.

Promotion effect of sulfite on deoxyosones and 4-methylimidazole in caramel model system.

In this study, hydrogen-deuterium (H/D) exchange experiment was carried out to reveal the promotion effect of sulfite on the formation of deoxyosones and 4-methylimidazole (4-MeI) in the Maillard reaction. Glucose-ammonium (40mmol/L, pH 7.4 in PBS) model systems with different levels of sulfite were incubated at 110°C for 2h. Alpha-dicarbonyls were detected after derivatization by a high-performance liquid chromatography with a diode array detector (HPLC-DAD). 4-MeI in the Maillard reaction was tested using a high-performance anion exchange chromatography with an electrochemical detector (HPAEC-ED). The H/D exchange ratios of hexose (fructose, glucose and mannose) were tested by HPAEC-MS. Results showed that the aldo-enol transition of enediol was promoted by sulfite, which promoted the formation of deoxyosones and 4-MeI. In addition, the oxidation reaction of enediols was inhibited by the antioxidant sulfite, which caused the inhibition of osones formation in the Maillard reaction.

Benzoquinone from Fusarium pigment inhibits the proliferation of estrogen receptor-positive MCF-7 cells through the NF-κB pathway via estrogen receptor signaling

Natural pigments are known for possessing a wide range of pharmacological and health-promoting properties. The pigments, produced by a new strain Fusarium (Fusarium sp. JN158) previously identified in our laboratory, were found to have 6 peaks (representing 6 compounds) by high-performance liquid chromatography with a diode-array detector (HPLC-DAD) separation. The 6th peak compound (compound VI) is a benzoquinone compound. In this study, we examined the effects of compound VI on the proliferation of breast cancer cells and aimed to elucidate the underlying mechamisms. Compound VI exerted anti-proliferative effects on MCF-7 estrogen receptor (ER)+ cells in a dose-dependent manner (IC25, 7 µM; IC50, 11 µM), whereas it had no effect on MDA-MB-231 ER− cells and normal cells. The cell index (CI) began to decrease at 24 h following treatment with benzoquinone. Mechanistically, the results from molecular analysis revealed that compound VI inhibited the expression of ERα, progesterone receptor (PR), vascular endothelial growth factor (VEGF), Bcl-2, cyclin D1 and nuclear factor-κB (NF-κB) p65, while it increased the expression of cleaved caspase-3 and Bax in the MCF-7 cells. Taken together, our findings indicate that compound VI exerts anti-proliferative effects on MCF-7 cells through the NF-κB pathway via the regulation of ER signaling. Our data may indicate that benzoquinone from Fusarium pigment may have potential for use as an anti-proliferative agent in the treatment of breast cancer.

Handling time misalignment and rank deficiency in liquid chromatography by multivariate curve resolution: Quantitation of five biogenic amines in fish

Biogenic amines (BAs) are used for identifying spoilage in food. The most common are tryptamine (TRY), 2-phenylethylamine (PHE), putrescine (PUT), cadaverine (CAD) and histamine (HIS). Due to lack of chromophores, chemical derivatization with dansyl was employed to analyze these BAs using high performance liquid chromatography with a diode array detector (HPLC-DAD). However, the derivatization reaction occurs with any primary or secondary amine, leading to co-elution of analytes and interferents with identical spectral profiles, and thus causing rank deficiency. When the spectral profile is the same and peak misalignment is present on the chromatographic runs, it is not possible to handle the data only with Multivariate Curve Resolution and Alternative Least Square (MCR-ALS), by augmenting the time, or the spectral mode. A way to circumvent this drawback is to receive information from another detector that leads to a selective profile for the analyte. To overcome both problems, (tri-linearity break in time, and spectral mode), this paper proposes a new analytical methodology for fast quantitation of these BAs in fish with HPLC-DAD by using the icoshift algorithm for temporal misalignment correction before MCR-ALS spectral mode augmented treatment. Limits of detection, relative errors of prediction (REP) and average recoveries, ranging from 0.14 to 0.50 µg mL−1, 3.5–8.8% and 88.08%–99.68%, respectively. These are outstanding results obtained, reaching quantification limits for the five BAs much lower than those established by the Food and Agriculture Organization of the United Nations and World Health Organization (FAO/WHO), and the European Food Safety Authority (EFSA), all without any pre-concentration steps. The concentrations of BAs in fish samples ranged from 7.82 to 29.41 µg g−1, 8.68–25.95 µg g−1, 4.76–28.54 µg g−1, 5.18–39.95 µg g−1 and 1.45–52.62 µg g−1 for TRY, PHE, PUT, CAD, and HIS, respectively. In addition, the proposed method spends less than 4 min in an isocratic run, consuming less solvent in accordance with the principles of green analytical chemistry.

Extraction, Separation, and Identification of Phenolic Compounds in Virgin Olive Oil by HPLC-DAD and HPLC-MS

The aim of this study was to evaluate the recovery of individual phenolic compounds extracted from virgin olive oil (VOO), from different Greek olive varieties. Sufficient recoveries (90%) of all individual phenolic compounds were obtained using methanol as an extraction solvent, acetonitrile for residue solubilization, and two washing steps with hexane. Moreover, in order to elucidate structural characteristics of phenolic compounds in VOO, high performance liquid chromatography with a diode array detector (HPLC-DAD) at 280 and 340 nm and HPLC coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS) in the negative-ion mode were performed. The most abundant phenolic compounds were oleuropein derivatives with m/z 319 and 377 and ligstroside derivatives with m/z 303, 361. Lignans, such as 1-acetoxypinoresinol and pinoresinol were also present in substantial quantities in the phenolic fraction. However, pinoresinol was co-eluted with dialdehydic form of ligstroside aglycone (DAFLA) and it was not possible to be quantified separately. The phenolic extracts, obtained from different VOO samples, yielded similar HPLC profiles. Differences, however, were observed in the last part of the chromatogram, corresponding to isomers of the aldehydic form of ligstroside aglycone. Oxidized phenolic products, originating from secoiridoids, were also detected.

Acrylamide in Romanian food using HPLC-UV and a health risk assessment

The aim of this study was to investigate the level of acrylamide from coffee, potato chips and French fries in Romanian food. According to the European Food Safety Authority, coffee beans, potato chips and French fries have the highest levels of acrylamide. For this survey, 50 samples of coffee beans, 50 samples of potato chips and 25 samples of French fries were purchased from different producers from the Romanian market. Acrylamide levels have been quantified using high-performance liquid chromatography with a diode array detector (HPLC-DAD) method, using water as mobile phase. Health risk assessment was achieved by computing the average daily intake, hazard quotient, cumulative risk, carcinogenic risk and cancer risk. For coffee, potato chips and French fries, acrylamide was not shown to pose a health risk in Romanian food.

Dyes used in pre-Hispanic textiles from the Middle and Late Intermediate periods of San Pedro de Atacama (northern Chile): new insights into patterns of exchange and mobility

Pre-Hispanic Andean textiles constitute the longest continuous textile record in the world, their structure and design being one of the most significant markers of group identity in Andean populations. Since the Late Formative Period (ca. 100–400 AD), the region around San Pedro de Atacama (SPA) in the Atacama desert of northern Chile has been part of a complex and extensive network of interacting polities through which raw materials, agricultural products, goods, people and ideas circulated in the South-Central Andes. The archaeological record in SPA abounds with textiles from various cultures that participated in such network. A study of these textiles would allow intercultural as well as diachronical comparisons. Numerous studies on textiles found in SPA have focused on their technological and iconographic features. This work addresses the identification of the organic dyes employed in the manufacture of 38 textiles found in funerary contexts in SPA from the Middle (ca. 400–1000 A.D.) and the Late Intermediate periods (ca. 1000–1450 A.D.), using high performance liquid chromatography with a diode array detector (HPLC-DAD). Purpurin and not alizarin was found in all red dyed fibers and indigotin (IND) and indirubin (INR) in all blue dyed fibers. Natural sources of these dyes are exogenous to SPA; their importation into SPA lasted for nearly a millennium. A positive correlation was found between [IND]/[INR] concentration ratio and the altitude of the place where the fiber was presumably dyed. Overall, the results indicate that finished garments and also raw dyes and ready-to-use dyed fibers were imported into SPA from neighboring regions and that foreign weavers were possibly active at SPA.

Microwave-assisted extraction of lycopene in tomato peels: Effect of extraction conditions on all-trans and cis-isomer yields

Lycopene is the primary carotenoid in tomato peels, a processing byproduct, and can be used as a natural color or bioactive ingredient. Unfortunately, extractions are inefficient as lycopene is extremely nonpolar and susceptible to degradation. As a rapid technique, microwave-assisted extraction (MAE) potentially offers efficient lycopene recovery. Thus, the objectives of this research were to: 1) optimize MAE of lycopene from tomato peels and 2) evaluate the effect of treatment on all-trans and isomer yields. Response surface methodology (RSM) was employed to optimize lycopene extraction with solvent ratio solid–liquid ratios, microwave power, and delivered energy equivalents as factors. High performance liquid chromatography with a diode array detector (HPLC-DAD) was used for isomer separation and quantification. Optimum MAE conditions were determined as: 0:10 solvent ratio at 400 W with a yield of 13.592 mg/100 g of extracted all-trans-lycopene. RSM suggested that ethyl acetate was a better MAE solvent for lycopene recovery as compared to hexane, which overall extracted less lycopene. HPLC-DAD indicated that MAE significantly improved all-trans and total lycopene yields, while conventional extraction demonstrated higher proportions of cis-isomer yields. Additionally, electron micrographs showed that significant structural disruption occurred in MAE-treated samples, possibly allowing for the improved lycopene extraction.

Influence of Serum Levels of Vitamins A, D, and E as well as Vitamin D Receptor Polymorphisms on Micronucleus Frequencies and Other Biomarkers of Genotoxicity in Workers Exposed to Formaldehyde

Background/Aim: Formaldehyde is classified as carcinogenic to humans, making it a major concern, particularly in occupational settings. Fat-soluble vitamins, such as vitamins A, D, and E, are documented as antigenotoxic and antimutagenic and also correlate with the cell antioxidant potential. This study investigates the influence of these vitamins on genotoxicity biomarkers of formaldehyde-exposed hospital workers. Methods: The target population were hospital workers exposed to formaldehyde (n = 55). Controls were nonexposed individuals (n = 80). The most used genotoxicity biomarkers were the cytokinesis-block micronucleus assay for lymphocytes and the micronucleus test for exfoliated buccal cells. Vitamins A and E were determined by high-performance liquid chromatography with a diode array detector (HPLC-DAD) and vitamin D receptor (VDR) polymorphisms by real-time PCR. Results: Significant correlations were found between genotoxicity biomarkers and between vitamins A and E in controls. Multiple regression showed that vitamin A was significantly associated with a higher mean of nucleoplasmic bridges (p < 0.001), and vitamin E was significantly associated with a decreased frequency of nuclear buds (p = 0.045) in the exposed group. No effect of vitamin D was observed. The VDRBsmI TT genotype carriers presented higher means of all the genotoxicity biomarkers; however, we found no significant associations. Conclusions: The study suggests that vitamin levels may modulate direct signs of genotoxicity.

Essential oil chemotypification and secretory structures of the neglected vegetable Smyrnium olusatrum L. (Apiaceae) growing in central Italy

AbstractAs part of our research on local plants, including neglected horticultural crops to be rediscovered as culinary vegetables, we focused on Smyrnium olusatrum, a biennal herb used in cuisine for many centuries by Romans that has now been replaced by celery. We investigated the essential oil compositions of different plant organs collected in 18 populations of central Italy (Marche, Umbria, Abruzzo, Tuscany and Latium) by gas chromatography (GC) with a flame ionization detector and GC with mass spectrometry (MS) to identify the main chemotypes that occur. Owing to the presence of thermosensitive molecules such as isofuranodiene, curzerene and germacrone undergoing Cope‐rearrangement during the GC run, a truthful quantitative determination of these constituents was accomplished by high‐performance liquid chromatography with a diode‐array detector (HPLC‐DAD). Chemical data were supported by a chemometric technique in the form of principal component analysis, which allowed identification of chemical differences among organs. Furanosesquiterpenoids were the main fraction of the oils, with isofuranodiene as the most abundant in flowers and roots, furanoeremophil‐1‐one in leaves and roots and 1‐β‐acetoxyfuranoeudesm‐4(15)‐ene in fruits. To complete the phytochemical analysis, polar compounds such as chlorogenic acid, isoquercitin, 3‐indoleacetic acid and saccharose were isolated from the ethanolic extracts of the plant by column chromatography and structurally elucidated by nuclear magnetic resonance. Moreover, a morphological and histochemical survey on the secretory structures was performed, with the special aim to localize the sites of terpenes biosynthesis in both above‐ and belowground organs. Overall, the results can be considered important in the light of the recent interest in neglected edible plants for botanical food supplements and functional foods market. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Composition and antioxidant activity of the anthocyanins of the fruit of Berberis heteropoda Schrenk.

In present study, the anthocyanin composition and content of the fruit of B. heteropoda Schrenk were determined for the first time. The total anthocyanins were extracted from the fruit of B. heteropoda Schrenk using 0.5% HCl in 80% methanol and were then purified using an AB-8 macroporous resin column. The purified anthocyanin extract (PAE) was evaluated by high-performance liquid chromatography with a diode array detector (HPLC-DAD) and HPLC-high resolution-electrospray ionization-mass spectrometry (HPLC-HR-ESI-MS) under the same experimental conditions. The results revealed the presence of seven different anthocyanins. The major anthocyanins purified by preparative HPLC were confirmed to be delphinidin-3-O-glucopyranoside (30.3%), cyanidin-3-O-glucopyranoside (33.5%), petunidin-3-Ο-glucopyranoside (10.5%), peonidin-3-O-glucopyranoside (8.5%) and malvidin-3-O-glucopyranoside (13.8%) using HPLC-HR-ESI-MS and NMR spectroscopy. The total anthocyanin content was 2036.6 ± 2.2 mg/100 g of the fresh weight of B. heteropoda Schrenk fruit. In terms of its total reducing capacity assay, DPPH radical-scavenging activity assay, ferric-reducing antioxidant power (FRAP) assay and ABTS radical cation-scavenging activity assay, the PAE also showed potent antioxidant activity. The results are valuable for illuminating anthocyanins composition of B. heteropoda Schrenk and for further utilising them as a promising anthocyanin pigment source. This research enriched the chemical information of B. heteropoda Schrenk.

Analysis of Local Anesthetics in Biological Samples via Kinetically Calibrated Liquid-Phase Solvent Bar Micro-Extraction Combined with HPLC

In this study, a liquid-phase solvent bar micro-extraction technique was used to investigate both the extraction and back-extraction processes of the target analyte. A novel concentration curve method and a classic time curve method, used under the same experimental conditions, verified the symmetry between the extraction process (target analyte moves from sample matrix to the organic solvent-based extraction phase) and the back-extraction process (target analyte moves from organic solvent to the sample matrix), providing the basis to use the target analyte in the back-extraction process to calibrate its extraction process. A quantitative calibration can be achieved using back extraction on the target analyte from the blank sample matrix in the organic solvent. Information from the process of back extraction of the target analyte, such as the time constant a, can be directly used to calculate the initial concentration of the target analyte in the sample matrix. This new kinetic calibration method employs a liquid-phase solvent bar micro-extraction technique combined with high-performance liquid chromatography with a diode array detector (HPLC-DAD) and was successfully used to analyze three local anesthetics in biological samples; it extends the application of the kinetic calibration to HPLC-DAD and establishes a novel, simple and accurate method to determine the concentration of the free drug in biological samples and its protein-binding ratio.

Microextraction of non-steroidal anti-inflammatory drugs from waste water samples by rotating-disk sorptive extraction

In this study, six non-steroidal anti-inflammatory drugs (NSAIDs) were extracted from water samples using the rotating-disk sorptive extraction (RDSE) technique. The extraction disk device contains a central cavity that allows for the incorporation of a powdered sorbent phase (Oasis™ HLB). The analytes were extracted from water and pre-concentrated on the sorbent to reach the extraction equilibrium, and then they were desorbed with solvent, derivatized and determined by gas chromatography–mass spectrometry (GC–MS). The variables for the extraction were studied using high performance liquid chromatography with a diode array detector (HPLC-DAD) to avoid the derivatization step, and the optimum values were as follows: 60mg of Oasis™ HLB, a rotation velocity of 3000rpm, a pH of 2, a sample volume of 50mL, and an extraction time of approximately 90–100min. The recoveries ranged from 71 to 104%, with relative standard deviations (RSD) between 2 and 8%. The detection limits ranged from 0.001 to 0.033µgL−1.The described method was applied to the analysis of influents and effluents from wastewater treatment plants (WWTP) in Santiago, Chile. The concentrations of the detected drugs ranged from 1.5 to 13.4µgL−1 and from 1.0 to 3.2µgL−1 in the influents and effluents, respectively. The samples were extracted by solid phase extraction (SPE). No significant differences were observed in the determined concentrations for most of the NSAIDs, indicating that RDSE is an alternative method for the preparation of water samples.

Validation of a method for the simultaneous quantification of chloroquine, desethylchloroquine and primaquine in plasma by HPLC-DAD

One of the most important aspects regarding the therapeutic efficacy of antimalarials is its quantification in biologic fluids. The detection and measurement of antimalarial drug levels is important for demonstrating (1) adequate absorption of the drug being given, (2) compliance in taking the full regimen required for treatment and (3) the level of drug in the blood at any time during the test period that parasites reappear. There is a lack of validated methods that simultaneously quantify different antimalarials administered at the same time, such as the use of chloroquine (CQ) and primaquine (PQ) in infections caused by Plasmodium vivax. In this study, a bioanalytical method was validated for the simultaneous quantification of primaquine (PQ), chloroquine (CQ) and desethylchloroquine (DSCQ) in human plasma using liquid–liquid extraction and high performance liquid chromatography with a diode array detector (HPLC-DAD). The PQ was evaluated over a concentration range of 100–3000nM and the CQ and DSCQ was evaluated over a concentration range of 20–2000nM. The selectivity of the method was verified by checking for interference by commonly used antimalarials and plasma samples. The accuracy and precision of the method was assessed for drugs spiked into human plasma and recoveries of 83.7%, 92.3%, and 76.5% were obtained for CQ, DSCQ, and PQ, respectively. The applicability of this method was also demonstrated with blood samples from patients with vivax malaria that received combination CQ plus PQ treatment. The simultaneous detection and accurate measurement of CQ, DSCQ, and PQ levels in human plasma provides an important and economical method for validating and monitoring sensitivity/resistance of P. vivax to more common treatment regimen.

Detection of nitrofurans and their metabolites in pond water and sediments by liquid chromatography (LC)-photodiode array detection and LC-ion spray tandem mass spectrometry

This study focuses on the detection of four nitrofurans (NFs) and their metabolites (NFMs) correspondingly by high-performance liquid chromatography with a diode-array detector (HPLC-DAD) and liquid chromatography-tandem mass spectrometry (LC–MS/MS) in samples of water and sediment slurries of aquaculture ponds. Results indicated that both the NFs and NFMs could be simultaneously detected in the water and sediment. The limits of detection (LODs) of the NFs were 0.05–0.1mgL−1 in the waters and 0.2–0.6mgL−1 in the sediment slurries. The sorption extents of NFs in the sediment slurries were 66.1–75.1%. The recoveries of NFs were 100.1–102.1% and 72.9–82.7% in the waters and the sediment slurries, respectively. Furthermore, the LODs of NFMs were 0.2–0.4 and 0.2–0.6μgL−1 in the waters and the sediment slurries, respectively. The sorption extents of NFMs in sediment slurries were 8.7–54.5%. The recoveries of NFMs were 92.3–102.3% and 90.4–100.2% in the waters and the sediment slurries, respectively. Adding NaCl significantly increased the extraction efficiencies of the NFM derivatives. The methods can potentially screen numerous aquatic environment samples with various salinities.

Identification of Dactylopius cochineal species with high-performance liquid chromatography and multivariate data analysis

Identification of American cochineal species (Dactylopius genus) can provide important information for the study of historical works of art, entomology, cosmetics, pharmaceuticals and foods. In this study, validated species of Dactylopius, including the domesticated cochineal D. coccus, were analysed by high-performance liquid chromatography with a diode array detector (HPLC-DAD) and submitted to multivariate data analysis, in order to discriminate the species and hence construct a reference library for a wide range of applications. Principal components analysis (PCA) and partial least squares discriminant analysis (PLSDA) models successfully provided accurate species classifications. This library was then applied to the identification of 72 historical insect specimens of unidentified species, mostly dating from the 19th century, and belonging to the Economic Botany Collection, Royal Botanic Gardens, Kew, England. With this approach it was possible to identify anomalies in how insects were labelled historically, as several of them were revealed not to be cochineal. Nevertheless, more than 85% of the collection was determined to be species of Dactylopius and the majority of the specimens were identified as D. coccus. These results have shown that HPLC-DAD, in combination with suitable chemometric methods, is a powerful approach for discriminating related cochineal species.

Simultaneous determination of 3 benzalkonium chloride homologsin cosmetics by high performance liquid chromatography

An analytical method based on high performance liquid chromatography with a diode array detector (HPLC-DAD) has been established for the simultaneous determination of 3 benzalkonium chloride homologs (n-C12H25-C9H13NCl, n-C14H29-C9H13NCl, n-C16,H33-C9H13NCl) in cosmetics. The sample was extracted with methanol (including 0.5% formic acid) under ultrasonic operation, the HPLC separation was carried out on a CAPCELL PAK SCX column (250 mm x 4.6 mm, 5 microm), the mobile phases were 40 mmol/L ammonium acetate solution (including 0.1% triethylamine) and acetonitrile with gradient elution, the flow rate was 1.0 mL/min, the detection wavelength was 260 nm, the column temperature was 25 degrees C, and the injection volume was 20 microL. The limit of detection was 50.0 mg/kg and the quantitation limit was 200.0 mg/kg for 3 benzalkonium chloride homologs in cosmetics. The linear plots were obtained between 5.0 mg/L and 3000.0 mg/L. Overall recoveries were between 92.5% and 102.1% with the relative standard deviations (RSDs) between 3.81% and 6.66%. The method is simple, rapid, accurate and suitable for the determination of 3 benzalkonium chloride homologs in cosmetics.

Evolution of the concentration of phenolic compounds in cachaça during aging in an oak (Quercus sp.) barrel

Cachaça is a traditional and popular Brazilian drink obtained by distilling fermented sugar cane juice. Among the steps involved in its production, natural aging in wood containers for a certain period of time can lead to alterations in the chemical composition, aroma, flavor and color of the beverage. The present work sought to determine the concentration of phenolic compounds after different periods of aging of the cachaça in an oak (Quercus sp.) barrel. Periodic collections during the aging period were performed, and thirteen selected phenolic compounds were determined by high performance liquid chromatography with a diode-array detector (HPLC-DAD). A progressive increase in the concentration of the compounds analyzed was observed, with syringaldehyde and gallic acid as the compounds encountered in the highest concentration.