Liliana A. Fernández

On-line micellar-enhanced spectrofluorimetric determination of rhodamine dye in cosmetics

A simple FI-fluorimetric analytical methodology for the continuous and sequential determination of rhodamine B (RhB) in cosmetic products has been developed and evaluated in terms of sensibility and selectivity. The influence of several surfactant solutions on RhB fluorescence signal has been studied; particular attention was paid in the aggregation behavior of RhB-SDS system. Linear response has been obtained in the range of 1.6 x 10(-9) and 1 x 10(-6) mol L(-1), with a detection limit of 5 x 10(-10) mol L(-1). The novel technique provides a simple dissolution of sample, on-line filtration with sampling rate higher than 100 samples h(-1) and has been satisfactorily applied to the RhB determination in commercial lipsticks.

Determination of terazosin by cloud point extraction-fluorimetric combined methodology

A new sensitive and selective preconcentration-fluorimetric method for determination of terazosin based on its native fluorescence was developed. The analyte, initially present in aqueous matrix, was treated with an extractive non-ionic surfactant solution and separated by the clouding phenomenon. The optimum analytical conditions for terazosin assay were established. Under these conditions, linear calibration curves were obtained over the range of 1x10(-5) to 7.0 microg mL(-1) with detection and quantification limits of 1.11x10(-5) and 3.7x10(-5)microg mL(-1), respectively. Additionally, the binding constant (K(B)) for the terazosin-PONPE 7.5 system was determined given a value of 1028 L mol(-1). The developed coupled methodology, which thoroughly satisfies the typical requirements for pharmaceutical control processes, was proved to be appropriate for monitoring terazosin in actual pharmaceutical formulations and biological fluid sample. The results were validated by recovery test and by comparison with other reported methods, being highly satisfactory.

Aquatic Coleoptera in the Subtropical-Pampasic Ecotone (Argentina, Buenos Aires): Species Composition and Temporal Changes

Abstract Aquatic Coleoptera assemblages present in floating vegetation in the ecotone between subtropical forest and pampasic grassland in Punta Lara (Buenos Aires, Argentina) were characterized and compared. Four pools, one located in the forest, two in the grassland and one in the forest/grassland ecotone, were sampled during a two years period (July 1996–June 1998). For each sampling station species richness and diversity were calculated, and they were compared through two similarity coefficients (Jaccard and Winer). Aquatic species of Dryopidae, Hydrochidae, Hydrophilidae, Hydraenidae, Limnichidae, Scirtidae, Haliplidae, Gyrinidae, Dytiscidae and Noteridae were identified. Highest species richness was registered in the grasslands, and lowest in the forest/grassland ecotone. Cluster analysis showed highest similarity between grassland areas, and between these and the intermediate pool, and lowest between the forest and the other areas. Biogeographical remarks are discussed. Publication funded by the Patricia Vaurie bequest.

Sensitive surfactant-mediated spectrofluorimetric determination of sildenafil.

Two simple and sensitive surfactant-mediated spectrofluorimetric methods for the determination of sildenafil are proposed in this paper. These methods are based on the interaction of sildenafil with normal micelles of HTAB (hexadecyltrimethylammonium bromide, method A) and the formation of ion-association complexes of sildenafil with SDS (sodium dodecyl sulfate, method B). In both methods, the formed species produce considerable fluorescence enhancement, which allows sildenafil to be quantitatively determined. Linearity was obtained for sildenafil in the concentration range 0.004 to 25 μg mL−1 with a detection limit of 0.0012 μg mL−1 by method A; and a linearity range of 0.005 to 50.0 μg mL−1 with a detection limit of 0.0016 μg mL−1 by method B. The proposed methods have been applied to the analysis of bulk drug, tablets, herbal medicine and beverages. Validation processes were performed by recovery studies and statistical analysis with satisfactory results.

Description of New Neotropical Berosini Larvae: Derallus paranensis and Hemiosus dejeanii (Coleoptera: Hydrophilidae)

Abstract The larval stages of the Neotropical species Derallus paranensis Oliva, 1981 and Hemiosus dejeanii (Solier, 1849) are described and figured for the first time. Notes on the bionomics of these two species are included. Larvae of D. paranensis and H. dejeanii are compared to those of other Derallus Sharp and Hemiosus Sharp species. Comparative notes to differentiate larvae of two genera related to Derallus, Allocotocerus Kraatz and Regimbartia Zaitzev are provided.

Description of the preimaginal stages and biology of Phaenonotum (Hydroglobus) puncticolle bruch (Coleoptera: Hydrophilidae)

The larvae and egg case of Phaenonotum (Hydroglobus) puncticolle Bruch, 1915 are described, based on material collected in the field and reared in the laboratory. Behavioral and populational data are included and discussed. The larvae and egg cases are compared to those of Phaenonotum (Phaenonotum) exstriatum (Say, 1835).

Description of immatures of the genus Tropisternus Solier, subgenus Pristoternus Orchymont (Coleoptera: Hydrophilidae), with emphasis on the chaetotaxy and morphometry of larval forms

The egg cases, larvae, and pupae of Tropisternus (Pristoternus) latus (Brullé, 1837), T. (P.) ovalis Castelnau, 1840, and T. (P.) laevis (Sturm, 1826) are illustrated and described for the first time. The egg cases are built with or without a mast, which can be ribbon-like or globular; all larval instars have seven anterior denticles in the anterior margin of nasale, and the antennal seta AN8 is present; the pupae bear 6 or 8 styli on the abdominal segments II-VI, the pleural styli can be either short or very long, and horn-like projections may be present on the abdominal segments II-VI. A comparison of the morphology of the egg cases, pupae and larval chaetotaxic and morphometric characters within the genus Tropisternus is presented.

Automated flow system for sildenafil enrichment using surfactant coated solid-phase with fluorescence detection.

In this work, Amberlite XAD-1180 resin is used for on-line surfactant-mediated pre-concentration of sildenafil as a prior step for its fluorescent detection. In order to activate the column for sildenafil pre-concentration, the cationic surfactant (hexadecyltrimethylammoniunm bromide, HTAB) is adsorbed onto the resin. In these conditions, sildenafil is retained by HTAB-resin and then it is eluted with ethanol and analyzed by spectrofluorimetry. Drug-surfactant association produces a considerable fluorescence enhancement, increasing considerably the sensitivity of detection. Therefore, sildenafil can be pre-concentrated and quantitatively determined, with a detection limit of 0.2 ng mL(-1). The proposed method was successfully applied to the analysis of bulk drug, human urine, tablets, and local herbal medicine. Validation processes were performed by recovering studies and statistical analysis with satisfactory results.

Catalog of the Types of Tenebrionidae and Perimylopidae (Insecta, Coleoptera) Deposited at Museo de La Plata (Argentina)

ABSTRACT The 224 types of species of Tenebrionidae and Perimylopidae (Coleoptera) housed in the collection of the Entomology Department of Museo de La Plata up until December 2008 were examined and listed; 96 names are recorded, 39 of them (41 percent) are represented by name bearing types (“primary” types). These 224 types belong to 85 species and 9 subespecies of Tenebrionidae assigned to the following subfamilies: Diaperinae (3 species, 3 types), Lagriinae (4 species, 9 types), Pimeliinae (53 species, 1 subspecies, 128 types), Stenochiinae (7 species, 10 types) and Tenebrioninae (18 species, 8 subspecies, 72 types), and 2 types belonging to 2 species of Perimylopidae. Species and subespecies herein treated were described by Berg (23), Burmeister (1), Bruch (1), Fairmaire (8), Flores & Carrara (1), Flores & Roig-Juñent (1), Flores & Vidal (2), Freude (2), Kulzer (27), Molinari (7), Müller (2), Peña (14), Peña & Barría (2), Pic (3), Steinheil (1) and Viana (1). Complete information is given for each type, including reference to original description, and label data. Two lists were added in order to support future research: one for specimens labelled as types but not found in the bibliography and seemingly not published and another for specimens labelled as types but not included in the original series.

Redescription and Taxonomic Status of Pleurhomus sahlbergi Sharp, 1883 (Coleoptera, Hydrophilidae)

The genus Pleurhomus and its sole species P. sahlbergi have been only poorly characterized, both in the original description and in subsequent treatments. A full redescription of the adults of both sexes is given; the larvae remain unknown. On the basis of the emargination in the last apparent urosternite, the untoothed claws in all pairs of legs, in both sexes, the short but evident series of punctures on the elytra, the minute notch at the distal end of the elytral commisure, and the depressed apical segment in the antenna, Pleurhomus clearly differs from Tropisternus. However, until the species of this genus, and especially those of the subgenus Homostethus, are better known, the subgeneric status of Pleurhomus within Tropisternus is here maintained, along with Homostethus, Strepitornus, Pristoternus and Tropisternus.