A polivalent flow system for the spectrophotometric determination of pharmaceuticals

A flow system based on the sandwich technique is proposed for the sequential determination of ascorbic acid, dipyrone, acetylcysteine, captopril and paracetamol. The procedure is based on the reduction of Cu(II) by the analytes followed by the spectrophotometric measurement of the complex of Cu(I) with 2,2'-biquinoline 4,4'-dicarboxylic acid. Linear responses were achieved in the µmol L-1 range, with coefficients of variation better than 1.7%. Sampling rate was estimated as 60 determinations per hour, consuming 230 µg of BQA and generating 2.5 mL of waste per determination. Results for commercial samples agreed with those obtained by procedures recommended by the American and European pharmacopeias at the 95% confidence level.CNPqFAPES

A multicommuted flow system for dissolution studies of Captopril in pharmaceutical preparations

A flow-based analytical procedure exploiting multicommutation is proposed for captopril determination and the construction of dissolution curves. The procedure is based on the redox reaction between Cu(II) and the drug with the subsequent complexation of Cu(I) with 4,4'-dicarboxy-2,2'-bichinoline (BCA) and spectrophotometric detection. A linear response was observed between 25 and 300 µmol L-1 captopril and the detection limit was estimated as 7 µmol L-1 (99.7% confidence level). The coefficient of variation (n = 20) and sampling rate were 2.2% and 47 determinations per hour, respectively, consuming 290 µg of BCA and generating 3.6 mL of waste per determination. The results for seven pharmaceutical samples agreed with those obtained by the reference volumetric procedure at the 95% confidence level. The dissolution profiles attained with a lab-made dissolution apparatus agreed with those reported in the literature, with a coefficient of variation of 1.8% for three replicates of the reference productUm procedimento analítico em sistema de análises em fluxo com multicomutação é proposto para a determinação de captopril e construção de curvas de dissolução de medicamentos. O método é baseado na reação do fármaco com Cu(II), com posterior complexação de Cu(I) com 4,4'-dicarboxi-2,2'-biquinolina (BQA) e detecção espectrofotométrica. Foi observada resposta linear entre 25 e 300 µmol L-1 captopril, com limite de detecção de 7 µmol L-1 (99,7% de confiança). O coeficiente de variação (n = 20) e a frequência de amostragem foram 2,2% e 47 determinações por hora, respectivamente, com consumo de 290 µg de BQA e geração de 3,6 mL de resíduo por determinação. Os resultados para 7 amostras de preparações farmacêuticas concordaram com os obtidos pelo procedimento volumétrico de referência com 95% de confiança. Perfis de dissolução obtidos com um aparato construído no laboratório foram concordantes com os relatados na literatura, com coeficiente de variação de 1,8% para três replicatas do produto de referênci

Indoor NO2 air pollution and lung function of professional cooks

Studies ofcooking- generated NO2 effects are rare in occupational epidemiology. in the present study, we evaluated the lung function of professional cooks exposed to NO2 in hospital kitchens. We performed spirometry in 37 cooks working in four hospital kitchens and estimated the predicted FVC, FEV1 and FEF25-75, based on age, sex, race, weight, and height, according to Knudson standards. NO2 measurements were obtained for 4 consecutive days during 4 different periods at 20-day intervals in each kitchen. Measurements were performed inside and outside the kitchens, simultaneously using Palm diffusion tubes. A time/exposure indicator was defined as representative of the cumulative exposure of each cook. No statistically significant effect of NO2 exposure on FVC was found. Each year of work as a cook corresponded to a decrease in predicted FEV1 of 2.5% (P=0.046) for the group as a whole. When smoking status and asthma were included in the analysis the effect of time/exposure decreased about 10% and lost statistical significance. On predicted FEF25-75, a decrease of 3.5% (P=0.035) was observed for the same group and the inclusion of controllers for smoking status and asthma did not affect the effects of time/exposure on pulmonary function parameter. After a 10-year period of work as cooks the participants of the study may present decreases in both predicted FEV1 and FEF25-75 that can reach 20 and 30%, respectively. the present study showed small but statistically significant adverse effects of gas stove exposure on the lung function of professional cooks.Univ São Paulo, Fac Med, Lab Poluicao Atmosfer Expt, BR-01246903 São Paulo, SP, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Med, Disciplina Clin Med,Grp Fisiopatol Pulmonar & Pol, São Paulo, SP, BrazilABC, Fac Med, Dept Saude Coletividade, Santo Andre, SP, BrazilUniv Catolica Santos, Programa Posgrad Saude Coletiva, Santos, SP, BrazilCtr Univ Araraquara, Lab Fisioterapia Cardioresp, Araraquara, SP, BrazilUniv Estadual Paulista, Inst Quim, Araraquara, SP, BrazilHarvard Univ, Sch Publ Hlth, Dept Environm Hlth, Exposure Epidemiol & Risk Program, Boston, MA 02115 USAUniv Santo Amaro, Fac Med, Programa Pediat Ambiental, São Paulo, SP, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Med, Disciplina Clin Med,Grp Fisiopatol Pulmonar & Pol, São Paulo, SP, BrazilWeb of Scienc

A greener and highly sensitive flow-based procedure for carbaryl determination exploiting long pathlength spectrophotometry and photochemical waste degradation

An environmentally friendly analytical procedure with high sensitivity for determination of carbaryl pesticide in natural waters was developed. The flow system was designed with solenoid micro-pumps in order to improve mixing conditions and minimize reagent consumption as well as waste generation. A long pathlength (100 cm) flow cell based on a liquid core waveguide (LCW) was employed to increase the sensitivity in detection of the indophenol formed from the reaction between carbaryl and p-aminophenol (PAP). A clean-up step based on cloud-point extraction was explored to remove the interfering organic matter, avoiding the use of toxic organic solvents. A linear response was observed within the range 5-200 mu g L(-1) and the detection limit, coefficient of variation and sampling rate were estimated as 1.7 mu g L(-1) (99.7% confidence level), 0.7% (n=20) and 55 determinations per hour, respectively. The reagents consumption was 1.9 mu g of PAP and 5.7 mu g of potassium metaperiodate, with volume of 2.6 mL of effluent per determination. The proposed procedure was selective for the determination of carbaryl, without interference from other carbamate pesticides. Recoveries within 84% and 104% were estimated for carbaryl spiked to water samples and the results obtained were also in agreement with those found by a batch spectrophotometric procedure at the 95% confidence level. The waste of the analytical procedure was treated with potassium persulphate and ultraviolet irradiation, yielding a colorless residue and a decrease of 94% of total organic carbon. In addition, the residue after treatment was not toxic for Vibrio fischeri bacteria. (c) 2010 Elsevier B.V. All rights reserved.Brazilian agencies Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq

Cloud point extraction and concentration of carbaryl from natural waters

An improved procedure is proposed for determination of the pesticide carbaryl in natural waters based on double cloud point extraction. The clean up step was carried out only with Triton X-114 in alkaline medium in order to avoid the use of toxic organic solvents as well as to minimise waste generation. Cloud point preconcentration of the product of the reaction of the analyte with p-aminophenol and cetyltrimethylammonium bromide was explored to increase sensitivity and improve the detection limit. Linear response was achieved within 10 and 500 mu g L-1 and the apparent molar absorptivity was estimated as 4.6 x 105 L mol-1 cm-1. The detection limit was estimated as 7 mu g L-1 at the 99.7% confidence level and the coefficient of variation was 3.4% (n = 8). Recoveries within 91 and 99% were estimated for carbaryl spiked water samples. The results obtained for natural water samples were in agreement with those achieved by the batch of spectrophotometric procedure at the 95% confidence level. The proposed procedure is then a simple, fast, inexpensive and greener alternative for carbaryl determination.Brazilian agencies Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP

Construção de amostrador passivo de baixo custo para determinação de dióxido de nitrogênio

A new passive sampling system for monitoring NO2 in air has been developed to measure gas concentrations in indoor and outdoor air. The sampler is inexpensive, and easy to construct and operate. Nitrogen dioxide forms a derivative after reaction with a filter coated with triethanolamine and ethyleneglycol. The nitrogen dioxide derivative is extracted from the filter, and the concentration is determined by colorimetry. To test the sampler for measuring ambient level nitrogen dioxide, measurements were carried out inside homes and in a range of workplace environments

An improved procedure for flow-based turbidimetric sulphate determination based on a liquid core waveguide and pulsed flows

An improved flow-based procedure is proposed for turbidimetric sulphate determination in waters. The flow system was designed with solenoid micro-pumps in order to improve mixing conditions and minimize reagent consumption as well as waste generation. Stable baselines were observed in view of the pulsed flow characteristic of the systems designed with solenoid micro-pumps, thus making the use of washing solutions unnecessary. The nucleation process was improved by stopping the flow prior to the measurement, thus avoiding the need of sulphate addition. When a 1-cm optical path flow cell was employed, linear response was achieved within 20-200 mg L(-1), described by the equation S = -0.0767 + 0.00438C (mg L(-1)), r = 0.999. The detection limit was estimated as 3 mg L(-1) at the 99.7% confidence level and the coefficient of variation was 2.4% (n = 20). The sampling rate was estimated as 33 determinations per hour. A long pathlength (100-cm) flow cell based on a liquid core waveguide was exploited to increase sensitivity in turbidimetry. Baseline drifts were avoided by a periodical washing step with EDTA in alkaline medium. Linear response was observed within 7-16 mg L(-1), described by the equation S = -0.865 + 0.132C (mg L(-1)), r = 0.999. The detection limit was estimated as 150 mu g L(-1) at the 99.7% confidence level and the coefficient of variation was 3.0% (n = 20). The sampling rate was estimated as 25 determinations per hour. The results obtained for freshwater and rain water samples were in agreement with those achieved by batch turbidimetry at the 95% confidence level. (C) 2008 Elsevier B.V All rights reserved

An environmentally friendly flow system for high-sensitivity spectrophotometric determination of free chlorine in natural waters

A green and highly sensitive analytical procedure was developed for the determination of free chlorine in natural waters, based on the reaction with N,N-diethyl-p-phenylenediamine (DPD). The flow system was designed with solenoid micro-pumps in order to improve mixing conditions by pulsed flows and to minimize reagent consumption as well as waste generation. A 100-cm optical path flow cell based on a liquid core waveguide was employed to increase sensitivity. A linear response was observed within the range 10.0 to 100.0 mu g L(-1), with the detection limit, coefficient of variation and sampling rate estimated as 6.8 mu g (99.7% confidence level), 0.9% (n = 20) and 60 determinations per hour, respectively. The consumption of the most toxic reagent (DPD) was reduced 20,000-fold and 30-fold in comparison to the batch method and flow injection with continuous reagent addition, respectively. The results for natural and tap water samples agreed with those obtained by the reference batch spectrophotometric procedure at the 95% confidence level. (C) 2010 Elsevier By. All rights reserved

Flow-injection iodimetric determination of captopril in pharmaceutical preparations

A simple, fast and low cost procedure for spectrophotometric determination of captopril in pharmaceutical preparations is described. The procedure is based on a flow-injection system exploiting the on-line formation of the triiodide reagent, which is consumed in the presence of the analyte generating a transient signal. Linear response was observed up to 200 µmol L-1 with a detection limit of 1.0 µmol L-1 (99.7% confidence level). The coefficient of variation (n = 20) and the sampling rate were estimated as 1.2% and 72 determinations per hour, respectively. The main excipients found in pharmaceutical preparations did not affect the captopril determination. The zone sampling approach was exploited to implement on-line dilutions, aiming direct analysis of sample extracts. Results of the analysis of commercial samples agreed with the obtained by the titrimetric reference procedure described in the US-Pharmacopeia at the 95% confidence level. The reagent consumption was estimated as 18 µg of KMnO4 and 10 mg of KI per determination, with a cost of US$2.50 per 1000 determinations.Um procedimento simples, rápido e de baixo custo é descrito para a determinação de captopril em preparações farmacêuticas. O procedimento é baseado em um sistema de análises por injeção em fluxo explorando a formação em linha de triiodeto, o qual é consumido na presença do analito gerando um sinal transiente. Resposta linear foi observada até 200 µmol L-1 com limite de detecção de 1,0 µmol L-1 (99,7$ 2,50 por 1000 determinações