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 µg L^− 1, with the detection limit, coefficient of variation and sampling rate estimated as 6.8 µg L^− 1 (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.     

A novel, environmentally friendly dispersive liquid-liquid microextraction procedure for the determination of copper

A novel, simple and environmentally friendly procedure for copper determination has been developed. The method is based on the formation of an ion associate of Cu(I) with 1,3,3-trimethyl-2-[5-(1,3,3-trimethyl-1,3-dihydroindol-2-ylidene)-penta-1,3-dienyl]-3H-indolium (DIDC) in the presence of chloride ions as ligand, followed by dispersive liquid-liquid microextraction (DLLME) of the formed ion associate into organic phase and UV-Vis spectrophotometric detection. The following experimental conditions were used: pH 3, 0.24 mol L^− 1 chloride ions, 0.06 mmol L^− 1 DIDC. The effect of the nature of the extraction solvent, auxiliary solvent and disperser solvent used was studied. A mixture of amyl acetate, tetrachloromethane, and methanol in a 1:1:3 v/v/v ratio was selected for the DLLME procedure. The absorbance of the coloured extracts at 640 nm wavelength obeys Beer's law in the range 0.020-0.090 mg L^− 1 of Cu. The limit of detection calculated from a blank test (n = 10) based on 3s is 0.005 mg L^− 1 of Cu. The developed procedure was applied to the analysis of water samples. The suggested DLLME is compared with two procedures previously reported from our laboratory based on (1) conventional liquid-liquid extraction, and (2) sequential injection extraction performed in a dual-valve sequential injection system. The advantages and disadvantages of each method are discussed.     

An environmentally friendly reflectometric method for ranitidine determination in pharmaceuticals and human urine

This paper describes an environmentally friendly method for quantitative determination of ranitidine using diffuse reflectance spectroscopy. This method is based on the reflectance measurements of the colored product produced from the spot test reaction between ranitidine and p-dimethylaminocinnamaldehyde (p-DAC), in acid medium, using filter paper as solid support. Experimental design methodologies were used to optimize the optimal conditions. All reflectance measurements were carried out at 590 nm and the linear range was from 1.42x10(-3) to 3.42x10(-2) mol L(-1), with a correlation coefficient of 0.997. The limit of detection was estimated to be 1.09x10(-3) mol L(-1) (R.S.D.=1.9%). The proposed method was successfully applied to the determination of ranitidine in commercial brands of pharmaceuticals and no interferences were observed from the common excipients in formulations. The results obtained by the proposed method were favorably compared with those obtained by an official procedure at 95% confidence level. Additionally, the method was also applied to the determination of ranitidine in human urine showing excellent recoveries (99.6-100.3%).     

Multicommutation as an environmentally friendly analytical tool in the hydride generation atomic fluorescence determination of tellurium in milk

The aim of this study is to show the advantages of the emerging multicommutation methodology based on the use of solenoid valves for Te determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS). The delivery of a series of alternating sequential insertions of small volumes of samples and reagents gives rise to new hydrodynamic processes and exciting analytical potentials by controlling the time of flow through the on/off-switched solenoid valves. This drastically reduces the reagent consumption by a factor of 4 and the generation of effluents (590 mL h^–1 instead of 750 mL h^–1 generated by the continuous-mode measurement) and also provides an improvement in the laboratory productivity by an increase of the sample throughput (85 h^–1 compared to 20 h^–1 found in the continuous mode). So, multicommutation is an environmentally and economically sustainable alternative to the methodology based on continuous measurements. The multicommutation-based method developed was applied to tellurium determination in commercially available milk samples; a calibration range of 0.0–0.5 ng mL^–1 and a detection limit of 0.20 ng L^–1 with average relative standard deviation of 2.1% were found. Comparable results were obtained for a series of samples using both continuous and multicommutation HG-AFS modes.     

A environmentally friendly reversed-phase liquid chromatography method for phthalates determination in nail cosmetics

A simple and rapid analytical method was developed for the determination of phthalates, usually employed in nail cosmetic products. The method is based on an ultrasonic extraction of the sample with ethanol-water (90:10, v/v) followed by HPLC separation and quantitation. HPLC was carried out using a C18 column and spectrophotometric detection at 254 nm. A linear gradient elution was performed with ethanol-water starting from 50 to 95% ethanol in 30 min. Standard calibration curves were linear for all the analytes over the concentration range 5-200 μg ml⁻¹ with LOD values of about 0.5 μg ml⁻¹.The proposed green analytical method has been successfully applied for the analysis of commercial samples in order to check the presence of phthalates and to determine their concentration.     

A cost effective,sensitive, and environmentally friendly sample preparation method for determination of polycyclic aromatic hydrocarbons in solid samples

A simple, cost effective, and yet sensitive sample preparation technique was investigated for determining Polycyclic Aromatic Hydrocarbons (PAHs) in solid samples. The method comprises ultrasonic extraction, Stir Bar Sorptive Extraction (SBSE), and thermal desorption–gas chromatography–mass spectrometry to increase analytical capacity in laboratories. This method required no clean-up, satisfied PAHs recovery, and significantly advances cost performance over conventional extraction methods, such as Soxhlet and Microwave Assisted Extraction (MAE). This study evaluated three operational parameters for ultrasonic extraction: solvent composition, extraction time, and sample load. A standard material, SRM 1649 a (urban dust), was used as the solid sample matrix, and 12 priority PAHs on the US Environmental Protection Agency (US EPA) list were analyzed. Combination of non-polar and polar solvents ameliorated extraction efficiency. Acetone/hexane mixtures of 2:3 and 1:1 (v/v) gave the most satisfactory results: recoveries ranged from 63.3% to 122%. Single composition solvents (methanol, hexane, and dichloromethane) showed fewer recoveries. Comparing 20 min with 60 min sonication, longer sonication diminished extraction efficiencies in general. Furthermore, sample load became a critical factor in certain solvent systems, particularly MeOH. MAE was also compared to the ultrasonic extraction, and results determined that the 20-min ultrasonic extraction using acetone/hexane (2:3, v/v) was as potent as MAE. The SBSE method using 20 mL of 30% alcohol-fortified solution rendered a limit of detection ranging from 1.7 to 32 ng L⁻¹ and a limit of quantitation ranging from 5.8 to 110 ng L⁻¹ for the 16 US EPA PAHs.     

An environmentally friendly multicommutated alternative to the reference method for anionic surfactant determination in water

It has been developed a fully mechanized procedure for the spectrophotometric determination of anionic surfactants in water expressed in terms of SDS concentration. The reference method, based on the reaction of SDS with methylene blue (MB) followed by extraction in chloroform, was mechanized in order to reduce the consumption of organic solvents. The system was based on the multicommutation approach and provided a 35 times reduction of the waste production without sacrificing the figures of merit of the method in terms of sensitivity and repeatability, for a dynamic linear range from 0.2 to 1.7 mg l⁻¹. Results obtained for washing water samples were comparable with those obtained using the reference method and no significant differences, at 95% confidence level, were observed. Other useful characteristics are a solvent consumption of 0.7 ml per determination, a sampling throughput of 40 determinations per hour, a relative standard deviation of 5.9% (n = 10) for a sample containing 2 × 10⁻⁶ mol l⁻¹ (576 μg l⁻¹) surfactant and a limit of detection of 6.1 × 10⁻⁹ mol l⁻¹ (1.7 μg l⁻¹).     

Simultaneous determination of cocaethylene and cocaine in blood by gas chromatography with surface ionization detection

Summary Cocaethylene together with cocaine spiked in human whole blood has been found measurable at high sensitivities by capillary gas chromatography with surface ionization detection. The drugs could be rapidly extracted by Sep-Pak C₁₈ cartridges with recovery of more than 60%. The calibration curves for both cocaethylene and cocaine using cocapropylene as internal standard were linear in the range 50–300 pmol mL⁻¹ of whole blood. The detection limits of cocaethylene and cocaine were 5–10 pmol mL⁻¹ (0.1–0.2 pmol on column if recovery is 100%). Cocaethylene could be determined for whole blood obtained from rats (ca. 200 g body wt.), which had received subcutaneous injection of 10 mg cocaine hydrochloride and 2.0 mL of 30% (v/v) ethanol 3 h before sampling; the mean levels of cocaethylene and cocaine were 101 and 1230 pmol mL⁻¹, respectively.     

CYP450 biosensors based on screen-printed carbon electrodes for the determination of cocaine

A new electrochemical method has been described and characterized for the determination of cocaine using screen-printed biosensors. The enzyme cytochrome P450 was covalently attached to screen-printed carbon electrodes. Experimental design methodology has been performed to optimize the pH and the applied potential, both variables that have an influence on the chronoamperometric determination of the drug. This method showed a reproducibility of 3.56% (n = 4) related to the slopes of the calibration curves performed in the range from 19 up to 166 nM. It has been probed the used of this kind of biosensors in the determination of cocaine in street samples, with an average capability of detection of 23.05 ± 3.53 nM (n = 3, α = β = 0.05).     

An environmentally friendly method for the extraction and determination of priority phenols in soils using microwave-assisted micellar extraction

A non-ionic surfactant, polyoxyethylene 10 lauryl ether (POLE), was used for the microwave-assisted extraction (MAE) of priority phenolic compounds from soil samples. A central composite design was applied to optimize the extraction parameters, namely, time and power. Under the optimized conditions, the method was applied to different soil samples in order to analyze the influence of soil characteristics on the phenol extraction. Results demonstrated that most of these compounds can be recovered from the soils investigated in good yields (higher than 80%). The standard deviation is lower than 9% (n = 6) for most analytes. Validation of the method by analyzing a reference soil sample containing eight phenols and a comparison with Soxhlet extraction are also reported.     

Detection of cocaine in the airborne particles of the Italian cities Rome and Taranto

Cocaine was first detected in the air of two Italian cities, Rome and Taranto, where it reached concentrations sometimes exceeding 100 pg/m(3), by HRGC-MS analysis of carbonaceous aerosol samples. By contrast, the drug was virtually absent in Algiers (Algeria). In Italy, atmospheric concentrations of cocaine were, on average, similar to those of other toxic pollutants like polychlorobiphenyls or nitrated polynuclear aromatic hydrocarbons, and higher than those of polychlorodibenzo-p-dioxins/polychlorodibenzofurans. The cocaine concentrations seemed to correlate with regional consumption of the drug in Rome and Taranto. By contrast, it correlated neither with nicotine or caffeine, nor with benzo[a]pyrene, the sole organic compound associated with aerosols that is quoted according to Italian legislation.     

Investigation and development of environmentally friendly processes on zeolite catalysts

The synthesis of alkylphenols, alkylanilines and nitro-aromatic compounds with different substituents in the aromatic ring on highly active and selective zeolite catalysts has been studied with regard to zeolite acidity and structure. These studies open the way for solid, environmentally friendly catalysts instead of liquid ones producing harmful liquid wastes in huge amounts.     

Simultaneous analysis of cocaine,benzoylecgonine, methylecgonine,and ecgonine in plasma using an exchange resin and gas chromatography-mass spectrometry

Summary A gas chromatographic-mass spectrometric method is described for the simultaneous analysis of cocaine and the hydrolytic products benzoylecgonine, methylecgonine and ecgonine from plasma (0.25–2 g/ml). Isopropylecgonine was incorporated as an internal standard. Samples were extracted using a sulfonate cation exchange resin, then derivatized with pentafluoropropionic anhydride and pentafluoropropanol. Analytical separations were on a dimethylsilicone capillary column using a temperature program, and detection was by selected ion monitoring of the electron impact generated fragments m/z 94, 182, 210, and 300.Presented at the poster session of American Association of Pharmaceutical Scientists 1991 Southeast Regional Meeting, Charleston, South Carolina, USA, April 4–5     

Development of a screening method for cocaine and cocaine metabolites in saliva using hollow fiber membrane solvent microextraction

Hollow fiber membrane solvent microextraction (HFMSME) has been applied as a simple and efficient means of sample preparation for the screening of drugs of abuse in saliva. Extraction of cocaine and its metabolites from a 2 ml saliva solution was achieved in 10 min. This was followed by fast GC separation allowing complete analysis to be achieved in 15 min. Using HFMSME, detection limits ranged between 6 and 28 ng ml⁻¹ with average relative standard deviations of 9.0%. The effect of the presence of various foodstuffs was also investigated.     

Enantiospecific synthesis of isomers of AES, a new environmentally friendly chelating agent

Three four-step enantiospecific syntheses of different diastereomers of AES, a new biodegradable chelating agent, are described. The stereocenters in each of the isomers are accessible from l- and d-malic and aspartic acids.     

The first zinc-promoted,environmentally friendly,and highly efficient acetoxyallylation of aldehydes in aqueous ammonium chloride

An exceptionally mild acetoxyallylation of aldehydes in water promoted by zinc is reported, using 3-bromo-1-acetoxyprop-1-ene as starting material; simple diastereoselectivity mainly depends on the nature of the aldehyde.     

Determination of cocaine contamination on banknotes using tandem mass spectrometry and pattern recognition

Tandem mass spectrometry is used to monitor the contamination of banknotes by cocaine. By introducing a series of banknotes into an instrument a distribution of contamination can be obtained. The distribution of samples arising from defendants where the banknotes have been in close proximity to cocaine should differ from the distribution from the general background population. Peak picking and integration is used to produce a series of intensity readings for a batch of banknotes. By visually inspecting these distribution, and applying a variety of chemometric methods (principal components analysis, cluster analysis and class modelling via Mahalanobis distance) it is possible to discriminate effectively between the two classes of distribution (7157 background notes and 4826 case notes alleged to be from drug dealers). By calculating the Mahalonobis distance over 100 bootstrap iterations, background samples were correctly classified 96.48% of the time, while case samples were correctly classified 89.37% of the time.     

An accurate and nondestructive GC method for determination of cocaine on US paper currency

The presence of cocaine on US paper currency has been known for a long time. Banknotes become contaminated during the exchange, storage, and abuse of cocaine. The analysis of cocaine on various denominations of US banknotes in the general circulation can provide law enforcement circles and forensic epidemiologists objective and timely information on epidemiology of illicit drug use and on how to differentiate money contaminated in the general circulation from banknotes used in drug transaction. A simple, nondestructive, and accurate capillary gas chromatographic method has been developed for the determination of cocaine on various denominations of US banknotes in this study. The method comprises a fast ultrasonic extraction using water as a solvent followed by a SPE cleanup process with a C(18) cartridge and capillary GC separation, identification, and quantification. This nondestructive analytical method has been successfully applied to determine the cocaine contamination in US paper currency of all denominations. Standard calibration curve was linear over the concentration range from the LOQ (2.00 ng/mL) to 100 microg/mL and the RSD less than 2.0%. Cocaine was detected in 67% of the circulated banknotes collected in Southeastern Massachusetts in amounts ranging from approximately 2 ng to 49.4 microg per note. On average, $5, 10, 20, and 50 denominations contain higher amounts of cocaine than $1 and 100 denominations of US banknotes.     

Validated spectrophotometric method for quantitative determination of simvastatin in pharmaceutical formulations and human serum

A simple ultraviolet spectrophotometric method for the determination of simvastatin in methanol has been devised and compared with the existing pharmacopoeial RP-HPLC method for the estimation of the drug. Analytical parameters such as stability, selectivity, accuracy, and precision have been established for the method, using SIMS® tablets and human serum samples, and evaluated statistically to assess the application of the method. The method was validated under ICH and USP guidelines and was found to comprise the advantages for simplicity, stability, sensitivity, reproducibility, and accuracy for use as an alternative to existing nonspectrophotometric methods for the routine determination of the drug in pharmaceutical formulations and for pharmaceutical investigations involving simvastatin.