Influência da geometria da plataforma na determinação de chumbo em zidovudina (AZT) por ET AAS

The aim of this work was to compare the performances of the L'vov and integrated platforms in order to overcome the interferences found on lead determination in zidovudine by ET AAS. Pyrolysis and atomization temperatures found with integrated platform were 700 and 1400°C, respectively. The characteristic masses were 12.7 ± 1.2 pg with integrated platform and 11.1 ± 1.3 pg with grooved platform. The ratio between the slopes of zidovudine and aqueous curves shows a decrease in the interferences when the L'vov platform is used (bAZT/b aq = 0.97 ± 0.10) and the detection limit found was 0.03 µg.g-1. That ratio was 0.85 ± 0.07 with the integrated platform.

Aplicações eletroanalíticas com eletrodos de prata confeccionados a partir de CDs graváveis

This paper presents a new way for the construction of silver electrodes utilizing recordable CDs. The new electrodes were explored for the quantification of chloride (by potentiometry/FIA), cyanide (by amperometry/FIA) and for lead analysis (by square wave voltammetry). For the flowing measurements, a digital multimeter, connected to a microcomputer (via RS 232 interface) was used to collect directly the potential signal (for Cl- measurements) or to take the output signal from a potentiostat (for CN- measurements). The square wave voltammetry analysis was performed in a commercial instrument. The results shown good performance of the new electrodes and the detection limit (s/n = 3) attained for these three analytes were: 0.2, 50, and 200 µg L-1 for Pb2+, Cl-, and CN- respectively.

Desenvolvimento de um micro-aquecedor para sistemas de análise química em fluxo: determinação espectrofotométrica de manganês em plantas

In this work a micro-heater device to be used as an integral part of the flow analysis manifold is described. The usefulness of the device was demonstrated using it in the development of a multicommutated flow analysis procedure for the spectrophotometric determination of manganese in plant digest. The method was based on the manganese oxidation by periodate in phosphoric acid medium to form the permanganate anion. The reaction development is dependent on the temperature and it was observed that at 25 °C a time interval of ca. 15 min was necessary for the reaction to attain equilibrium. Setting the temperature to 70 ºC, this time interval could be decreased to ca. 30 s. This condition was easily attained employing the proposed micro-heater device coupled to the manifold. The procedure was applied to manganese determination in soybean digests and results compared with those obtained by inductively coupled argon plasma optical emission spectrometry (ICP-OES). No significant difference at 90% confidence level was observed. A linear response for sample concentrations ranging from 5.0 to 30.00 mg L-1 Mn2+; a relative standard deviation of 1.3% (n = 6) for a typical sample containing 6.3 mg L-1 Mn2+; a sampling rate of 22 determinations per hour; a low reagent consumption, of 12.0 mg NaIO4 per determination; and a detection limit of 1.2 mg L-1 were achieved.

Vitaminas lipossolúveis em alimentos: uma abordagem analítica

This study concerns certain problems inherent to the determination of fat-soluble vitamins in food, from extraction methods to identification and quantification. The discussion involves the main official and unofficial extraction methods coupled with spectrophotometric and HPLC techniques in which vitamins samples are obtained through liquid-liquid-solid and liquid-liquid-solid-solid extraction, indispensable to the analytical separation of different chemical compounds with vitamin functions. A saponification stage, possibly coupled with supercritical fluid extraction appears to be mandatory in the determination of vitamins A and E in their alcoholic forms. Alternative identification and quantification procedures are outlined: biological and chemical assays, analytical separations by HPLC (normal and reversed-phase), UV detection (all fat-soluble vitamins) and fluorescence detection (retinoids and tocopherols). Automation from sample preparation to quantification stages increases the data acquisition rate.

Determinação de arsênio em águas contaminadas usando fluorescência de raios-X por energia dispersiva

This work proposes a simple, fast and inexpensive method to determine As in natural waters, using X-ray fluorescence. 50 µL of each sample containing 100 mg L-1 of yttrium as internal standard were deposited over a 2.5 µm thickness MylarTM film. The samples were dried at 50 °C for 2 h. X-ray spectra were obtained using an EDXRF apparatus. The accuracy was determined by analyte addition/recovery and by comparison with Hydride Generation Atomic Absorption Spectrometry (HG AAS). A recovery of about 100% was obtained and the results were in good agreement with HG AAS. The method showed a relative standard deviation of 6.8% and a detection limit of 10.5 µg L-1 of As.

Alendronato de sódio: metodologias para análise quantitativa

This paper presents a review of some published proposals for the analysis of sodium alendronate. The drug is an aminobisphosphonate compound used to inhibit the osteoclastic resorption of bone, and different methods were developed for its quantitative determination. These methodologies employed reversed-phase or ion-exchange HPLC analysis, both associated with different detectors: UV and fluorescence detection after derivatization of the drug, conductivity and refractive index detectors, as well as the indirect UV detection. Titrimetry and spectrophotometry (with previous complexation of the drug), which are simpler procedures, were also described, but they showed poor specificity when compared to liquid chromatography.

Determinação das formas de nitrogênio e nitrogênio total em rochas-reservatório de petróleo por destilação com arraste de vapor e método do indofenol

Several extraction procedures are described for the determination of exchangeable and fixed ammonium, nitrate + nitrite, total exchangeable nitrogen and total nitrogen in certified reference soils and petroleum reservoir rock samples by steam distillation and indophenol method. After improvement of the original distillation system, an increase in worker safety, a reduction in time consumption, a decrease of 73% in blank value and an analysis without ammonia loss, which could possibly occur, were achieved. The precision (RSD < 8%, n = 3) and the detection limit (9 mg kg-1 NH4+-N) are better than those of published procedures.

Determinação de lamivudina, estavudina e nevirapina, em comprimidos, por cromatografia líquida de alta eficiência

A high performance liquid chromatography method was developed to quantify lamivudine, stavudine and nevirapine combined in tablets. The separation was carried out in less than 10 min using a phosphate buffer of pH 3.0 and acetonitrile (75:25, v/v) as mobile phase, a LiChrospher ODS column and UV detection at 266 nm. The method was linear over the range of 15-135 µg/mL (lamivudine), 4-36 µg/mL (stavudine) and 20-180 µg/mL (nevirapine). The accuracy ranged from 98.56 to 102.04% and intra-day and inter-day precision was less than 1% for the three drugs. The method showed robustness, remaining unaffected by deliberate variations in relevant parameters.

Community-acquired pneumonia in adult patients with special reference to rapid methods for etiological diagnosis

Aikuispotilaan kotisyntyisen keuhkokuumeen etiologinen diagnostiikka mikrobiologisilla pikamenetelmillä Tausta. Keuhkokuume on vakava sairaus, johon sairastuu Suomessa vuosittain n. 60 000 aikuista. Huolimatta siitä, että taudin hoito on kehittynyt, siihen liittyy yhä merkittävä, 6-15%:n kuolleisuus. Alahengitystieinfektion aiheuttajamikrobien tunnistaminen on myös edelleen haasteellista. Tavoitteet. Tämän työn tavoitteena oli tutkia Turun yliopistollisessa keskussairaalassa hoidettujen aikuispotilaiden keuhkokuumeen etiologiaa sekä selvittää uusien mikrobiologisten pikamenetelmi¬en hyödyllisyyttä taudinaiheuttajan toteamisessa. Aineisto. Osatöiden I ja III aineisto koostui 384 Turun yliopistollisen keskussairaalaan infektio-osastolla hoidetusta keuhkokuumepotilaasta. Osatyössä I tutkittiin keuhkokuumeen aiheuttaja¬mikrobeja käyttämällä perinteisten menetelmien lisäksi antigeeniosoitukseen ja PCR-tekniikkaan perustuvia pikamenetelmiä. Osatyö II käsitti 231 potilaasta koostuvan alaryhmän, jossa tutkittiin potilaiden nielun limanäytteestä rinovirusten ja enterovirusten esiintyvyyttä. Osatyössä III potilailta tutkittiin plasman C-reaktiivisen proteiinin (CRP) pitoisuus ensimmäisten viiden sairaalahoitopäi¬vän aikana. Laajoja tilastotieteellisiä analyysejä käyttämällä selvitettiin CRP:n käyttökelpoisuutta sairauden vaikeusasteen arvioinnissa ja komplikaatioiden kehittymisen ennustamisessa. Osatyössä IV 68 keuhkokuumepotilaan sairaalaan tulovaiheessa otetuista näytteistä määritettiin neutrofiilien pintareseptorien ekspressio. Osatyössä V analysoitiin sisätautien vuodeosastoilla vuosina 1996-2000 keuhkokuumepotilaille tehtyjen keuhkohuuhtelunäytteiden laboratoriotutkimustulokset. Tulokset. Keuhkokuumeen aiheuttaja löytyi 209 potilaalta, aiheuttajamikrobeja löydettiin kaikkiaan 230. Näistä aiheuttajista 135 (58.7%) löydettiin antigeenin osoituksella tai PCR-menetelmillä. Suu¬rin osa, 95 (70.4%), todettiin pelkästään kyseisillä pikamenetelmillä. Respiratorinen virus todettiin antigeeniosoituksella 11.1% keuhkokuumepotilaalla. Eniten respiratorisia viruksia löytyi vakavaa keuhkokuumetta sairastavilta potilailta (20.3%). 231 keuhkokuumepotilaan alaryhmässä todettiin PCR-menetelmällä picornavirus 19 (8.2%) potilaalla. Respiratorinen virus löytyi tässä potilasryh¬mässä kaiken kaikkiaan 47 (20%) potilaalta. Näistä 17:llä (36%) löytyi samanaikaisesti bakteerin aiheuttama infektio. CRP-tasot olivat sairaalaan tulovaiheessa merkitsevästi korkeammat vakavaa keuhkokuumetta (PSI-luokat III-V) sairastavilla potilailla kuin lievää keuhkokuumetta (PSI-luokat I-II) sairastavilla potilailla (p <0.001). Yli 100 mg/l oleva CRP-taso neljän päivän kuluttua sairaa¬laan tulosta ennusti keuhkokuumeen komplikaatiota tai huonoa hoitovastetta. Neutrofiilien komple¬menttireseptorin ekspressio oli pneumokokin aiheuttamaa keuhkokuumetta sairastavilla merkitse¬västi korkeampi kuin influenssan aiheuttamaa keuhkokuumetta sairastavilla. BAL-näytteistä vain yhdessä 71:stä (1.3%) todettiin diagnostinen bakteerikasvu kvantitatiivisessa viljelyssä. Uusilla menetelmilläkin keuhkokuumeen aiheuttaja löytyi vain 9.8% BAL-näytteistä. Päätelmät. Uusilla antigeeniosoitus- ja PCR-menetelmillä keuhkokuumeen etiologia voidaan saada selvitettyä nopeasti. Lisäksi näitä menetelmiä käyttämällä taudin aiheuttajamikrobi löytyi huomattavasti suuremmalta osalta potilaista kuin pelkästään tavanomaisia menetelmiä käyttämällä. Pikamenetelmien hyödyllisyys vaihteli taudin vaikeusasteen mukaan. Respiratorinen virus löytyi huomattavan usein keuhkokuumetta sairastavilta potilailta, ja näiden potilaiden taudinkuva oli usein vaikea. Tulovaiheen korkeaa CRP-tasoa voidaan käyttää lisäkeinona arvioitaessa keuhkokuumeen vaikeutta. CRP on erityisen hyödyllinen arvioitaessa hoitovastetta ja riskiä komplikaatioiden ke¬hittymiseen. Neutrofiilien komplementtireseptorin ekspression tutkiminen näyttää lupaavalta pi¬kamenetelmältä erottamaan bakteerien ja virusten aiheuttamat taudit toisistaan. Antimikrobihoitoa saavilla potilailla BAL-tutkimuksen löydökset olivat vähäiset ja vaikuttivat hoitoon vain harvoin.

Validação de metodologia analítica para o doseamento simultâneo de mebendazol e tiabendazol por cromatografia líquida de alta eficiência

The aim of this work was to develop and validate an analytical methodology for simultaneous determination of mebendazole and thiabendazole, two benzimidazoles used as anthelmintics. The method was based on high performance liquid chromatography, using a C18 column, a mobile phase composed of KH2PO4 0.05 mol L-1 and methanol 40:60 (v/v) and UV detection at 312 nm. The results showed that the method presented linearity from 60.0 to 140.0 µg mL-1 for mebendazole and from 99.6 to 232.4 g µL-1 for thiabendazole and it was considered selective, accurate, precise and robust according to the specific resolution from ANVISA, the Brazilian regulatory agency.

Uso da pressão gerada por uma coluna de água para controle da vazão em sistemas de análises em fluxo

This work presents a new approach to control the flow rate in hydrodynamic flow experiments. The combination of air pressure generated by an aquarium air pump and the pressure generated by a water column were used for this purpose. This device supports a stable flow rate without pulsation for a long period of time. Furthermore, the flow rate can be easily controlled at various values in one or more streams. The performance of this approach was investigated using Fe(CN)6(4-) solutions in flowing systems using amperometric and voltammetric detection in wall-jet configuration. The results showed that the performance of the proposed device was better than a commercial peristaltic pump. It suggests that this approach can be used successfully in flow analysis systems.

Simultaneous determination of B-Group vitamins in enriched cookies

The objective of this research was to determine the levels of enrichment of vitamins B1, B2, B6 and B3 in different types and brands of enriched cookies. The chromatographic separation was performed in a C18 column with gradient elution and UV detection at 254 and 287 nm. The results show that only 5 of the 24 brands evaluated are in accordance with the Brazilian legislation with respect to the vitamin content declared on the labels. However, consumption of approximately 100-150 g of most of the brands supplies the recommended dietary intake for children and adults of the vitamins evaluated.

Determinação simultânea dos ácidos orgânicos tartárico, málico, ascórbico e cítrico em polpas de acerola, açaí e caju e avaliação da estabilidade em sucos de caju

The aim of the present study was determining the main organic acids in pulp and juices, as well as evaluating their stability, after opening the package, by liquid chromatography in a C18 column with isocratic elution and UV detection. In açaí pulp tartaric, malic and citric acids were found. Cashew samples presented all of the organic acids evaluated, besides high concentrations of ascorbic and malic acids. Acerola pulp had the highest ascorbic acid concentration. A small decrease in organic acid content during storage was observed. Malic and citric acids seem to be more stable than tartaric and ascorbic acids.

Desenvolvimento e validação de método por cromatografia líquida de alta eficiência para determinação simultânea das impurezas timina e timidina na matéria-prima estavudina

A HPLC method was developed to quantify thymine and thymidine impurities in stavudine bulk drug. The separation was carried out in isocratic mode using methanol/water (20:80) as mobile phase, a C18 column and UV detection at 266 nm. The method provided selectivity based on peak purities and resolution among peaks. It was linear over the range of 0.5-5.0 µg/mL. The quantitation limits were 0.021 µg/mL for thymine and 0.134 µg/mL for thymidine. The average accuracies of three concentrations ranged from 97.06 to 102.61% and precision was close to 1%. The method showed robustness, remaining unaffected by deliberate variations in relevant parameters.

Un sistema para la deteccion de antioxidantes volatiles comunmente emitidos desde especias y hierbas medicinales

An apparatus which allows the direct measurement of the antioxidant capacity of volatiles compounds emitted from some herbs and culinary spices is described. The device comprises: a sample chamber, a mixing chamber, a pump and, a detection system. Volatiles from Clove (Syzygium aromaticum (L.) Merr. & L.M. Perry) were purged and captured into a DPPH-containing solution and changes in the absorbance were recorded on-line. Linear response was observed when temperature was set between 30-53 ºC; nitrogen flow was 15 mL min-1 during 60 min; DPPH concentration was 20 µmol L-1 and a sample size (powdered Clove) ranged between 200-1000 mg.