O estado da arte da cromatografia líquida de ultra eficiência

Ultra Performance Liquid Chromatography (UPLC) retains the same principles as High Performance Liquid Chromatography (HPLC), but uses 1-2.1 mm i.d. columns with sub-2 µm particles. It is considered the newest advance in analytical separation science. The use of these small particles with mobile phases at high linear velocities increases resolution and detectability and decreases analysis time. Thus, the analyses are faster, the solvent volume is smaller, the efficiency is higher and the detectability is 2-3 times higher when compared with HPLC analysis.

Separação cromatográfica quiral de anestésicos a partir de soluções diluídas e concentradas em escala preparativa

In this work the separation of the chiral anesthetic compounds ketamine and bupivacaine was development using two chiral stationary phases (CSP). Ketamine enantiomers were well separate in the polysaccharide-based CSP (microcrystalline cellulose triacetate - MCTA) while bupivacaine in the tartardiamide-based CSP (Kromasil CHI-TBB). In both cases, the effect of temperature was investigated under analytical conditions. An improvement in the separation performance with temperature was observed. Thermodynamic parameters were evaluated by the van't Hoff plot. We concluded that enthalpic effects controlled the retention in these chiral columns. The enantiomers of ketamine and bupivacaine were separated under overloaded conditions with a good performance.

Eletrocromatografia capilar: contextualização, estado da arte e perspectivas

Capillary electrochromatography (CEC) is a separation technique in which the mobile phase flow is based on the application of a voltage across a packed capillary, which generates an electroosmotic flow that transports the analytes along the capillary toward the detector. As it combines the separation mechanisms of high-performance liquid chromatography (HPLC) and of capillary electrophoresis (CE), CEC can be considered a hybrid of HPLC and CE. This review presents some fundamental aspects of CEC and is focused on the instrumental advances of the technique, such as column technology, operation modes and detection systems, presenting recent papers on these topics and some applications and perspectives about CEC.

Desenvolvimento e validação de metodologia analítica por CLAE-IR para determinação de artemisinina em Artemisia annua L

The aim of this work was to develop and validate an analytical methodology for determination of artemisinin used as antimalaric. The method was based on high performace liquid chromatography, using a CN column with mobile phase composed of methanol : H2O 50:50 (V/V). The results showed that the method presented linearity from 50 to 1500 µg/mL. It was considered selective, accurate, precise according to the specific resolution from ANVISA, the Brazilian regulatory agency.

Determinação de 3,4-metilenodioximetanfetamina (MDMA) em comprimidos de Ecstasy por cromatografia líquida de alta eficiência com detecção por fluorescência (CLAE-DF)

This paper describes the development and validation of simple and selective analytical method for determination of 3.4-methylenedioxymethamphetamine (MDMA) in Ecstasy tablets, using high performance liquid chromatography with fluorescence detection. Analysis was performed in a reversed phase column (LiChrospher 100 C18, 150 x 4.6 mm, 5 µm), isocratic elution with phosphate buffer 25 mmol/L pH 3.0 and acetonitrile (95:5, v/v). The method presents adequate linearity, selectivity, precision and accuracy. MDMA concentration in analyzed tablets showed a remarkable variability (from 8.5 to 59.5 mg/tablet) although the tablet weights were uniform, indicating poor manufacturing control thus imposing additional health risks to the users.

Fotodegradación heterogénea de bisfenol A en agua con dióxido de titanio

Bisphenol A (BPA) is a monomer used in epoxy resin and polycarbonate manufacture. This molecule is considered as an endocrine disruptor that causes different diseases. The human exposition to this non biodegrable substance is increasing in the time; in particular, water is contaminated by industrial remainder flow. In this article heterogeneous photo degradation of a solution of BPA in water solution using a catalytic photo reactor with UV light and titanium dioxide (TiO2) was evaluated. High performance liquid chromatography (HPLC) was used to analyze the photo degradation of BPA solutions. The influence of titanium dioxide amount, BPA concentration, reaction temperature and the catalyst state like suspension and immobilized were also determinated. The highest elimination of BPA was 83.2%, in 240 min, beginning with 0.05 mM of BPA and 100 mg/L of TiO2 in suspension.

Determinação de ácido valpróico em soro por cromatografia líquida de alta eficiência com detector de arranjo de diodos (CLAE-DAD), após derivatização com brometo de fenacila

Valproic acid (VA) is a drug used to control seizures in several epileptic conditions. In VA pharmacotherapy, therapeutic drug monitoring is recommended to obtain adequate seizure control and avoid toxicity. The aim of this study was to validate a method for the determination of valproic acid in serum, employing high performance liquid chromatography with diode array detection (HPLC-DAD), after derivatization with phenacyl bromide. The calibration curve (y=0.0133x-0.0025) presented good linearity with r²=0.9999. Accuracy (101-115%), intra-assay precision (4.53-8.15%) and inter-assay precision (3.15-6.77%) were acceptable. The quantification limit was 2.0 µg/mL. The method presented similar results to enzyme immunoassay.

Rapid and accurate hplc-dad method for the determination of the herbicide bispyribac-sodium in surface water, and its validation

A new method is described for the determination of the herbicide bispyribac-sodium in surface water, especially from river and irrigated rice water samples. The method involves extraction in solid phase and quantification by high performance liquid chromatography with diode array detection (HPLC-DAD). After optimization of the extraction and separation parameters, the method was validated. The method presented average recoveries of 101.3 and 97.7%, under repeatability and intermediate precision conditions, respectively, with adequate precision (RSD from 0.9 to 7.5%). The method was applied for the determination of bispyribac-sodium in surface water samples with a limit of detection of 0.1 μg L-1.

Method validation and stability study of quercetin in topical emulsions

This study validated a high performance liquid chromatography (HPLC) method for the quantitative evaluation of quercetin in topical emulsions. The method was linear within 0.05 - 200 μg/mL range with a correlation coefficient of 0.9997, and without interference in the quercetin peak. The detection and quantitation limits were 18 and 29 ng/mL, respectively. The intra- and inter-assay precisions presented R.S.D. values lower than 2%. An average of 93% and 94% of quercetin was recovered for non-ionic and anionic emulsions, respectively. The raw material and anionic emulsion, but not non-ionic emulsion, were stable in all storage conditions for one year. The method reported is a fast and reliable HPLC technique useful for quercetin determination in topical emulsions.

Avaliação de solventes de extração por ultrassom usando-se cromatografia líquida de alta eficiência para a determinação de hidrocarbonetos policíclicos aromáticos em solos contaminados

A method using ultrasonication extraction for the determination of 17 polycyclic aromatic hydrocarbons (PAHs), selected by the USEPA and NIOSH as "consent decree" priority pollutants, in soil by High Performance Liquid Chromatography (HPLC) was studied. Separation and detection were completed in 20 min with a C18 columm, acetonitrile-water gradient elution and ultraviolet absorption and fluorescence detections. The detection limits, for a 10 µL of solution injection, were less than 9,917 ng/g in UV detection and less than 1,866 ng/g in fluorescence detection. Several organic solvents were tested for extraction of the 17 PAHs from soils. Acetone was the best solvent among the three solvents tested, and the order of the extraction efficiencies was: acetone>methanol>acetonitrile. Ultrasonication using acetone as solvent extraction was used to evaluate the biodegradation of those compounds in contaminated soil during a vermicomposting process.

Tocoferois e tocotrienois em óleos vegetais e ovos

The distribution and content of vitamin E isomers was investigated in vegetable oils and raw and cooked egg yolk in commercial restaurants. The analysis of the eight vitamin E isomers was carried out by High Performance Liquid Chromatography (HPLC) with fluorescence detection. The tocopherol and tocotrienol composition of foods varied considerably. Tocopherols were detected in greater quantity and frequency. The α-tocopherol predominated in egg yolks and olive oil while γ-tocopherol was found in high quantities in soybean and canola oils. Cooking did not cause major losses for most of the vitamin E isomers in egg yolks.

Teores de compostos orgânicos em cachaças produzidas na região norte fluminense - Rio de Janeiro

This work aimed to quantify some organic compounds in "cachaças" (sugar cane spirit). The ethyl alcohol was quantified by densimetry, after distillation. The acetic acid, methyl alcohol, n-propyl alcohol, n-butyl alcohol, isobutyl alcohol, isoamyl alcohol (mixture of 2-methyl-butyl and 3-methyl-butyl), ethyl acetate and acetaldehyde were determined by gas chromatography; and the furfural, 5-hydroxy-methylfurfural and acrolein by high efficiency liquid chromatography. From the 30 samples analyzed, 63.3% showed non-conformity with national legislation regarding at least one of the analyzed components.

Estudio comparativo de la ozonización de aceites de girasol modificados genéticamente y sin modificar

Ozonation of sunflower oils with genetic modification High Oleic and High Oleic-Palmitic (AO and PO respectively) and without modification, High Linoleic (AL) at different applied ozone dosages was carried out with measurement of peroxide and acidity indexes values, fatty acids composition, oxygen percentage content and antimicrobial activity. The comparison of peroxides indexes and oxygen content at different applied ozone dosages in each oil showed good correlation (r = 0,99). Higher amount of oleic acid was consumed at higher applied ozone dosage in PO oil than AO oil, which can be related to the increase of acidity index. The antimicrobial activity was better for AL and PO ozonized oils.

Determination of cetirizine in tablets and compounded capsules: comparative study between CE and HPLC

A capillary electrophoresis (CE) method was developed and validated for determination of cetirizine dihydrochloride in tablets and compounded capsules. The electrophoretic separation was performed in an uncoated fused-silica capillary (40 cm x 50 μm i.d.) using 20 mmol L-1 sodium tetraborate buffer (pH 9.3) as background electrolyte, a hydrodinamic sample injection at 50 mBar for 5 s, 20 KV applied voltage at 25 °C, and detection at 232 nm. The proposed method was compared with the high performance liquid chromatographic (HPLC) method previously validated for this drug, and statistical analysis showed no significant difference between the techniques.

Determinação de corantes marcadores do tipo azo e antraquinona em combustíveis por cromatografia líquida com detecção eletroquímica

An analytical method based on high-performance liquid chromatography with electrochemical detection has been developed and applied to the determination of Solvent blue 14 (SA-14) and Solvent red 24 (SV-24) in fuel samples. The dyes were better separated on C18 column, using a mobile phase composed of acetonitrile and ammonium acetate (90:10, v/v). Detection was carried out at an oxidation potential of +0.85V. The detector response was linear at concentration range of 7.50×10-8 - 1.50×10-6 mol L-1 (r = 0.997) for SA-14 and SV-24, respectively. The method was used to quantify these dyes in fuels samples with satisfactory accuracy and precision.