Evaluation of total phenol pollution in water of San Martin Canal from Santiago del Estero, Argentina.

Santiago del Estero is a province located in northwestern Argentina. The Dulce River is used for irrigation through a vast network of channels and ditches, including the San Martin Canal (SMC), which crosses the capital city of Santiago del Estero. This canal's water is used for drinking, as well as recreational use for the general population. However, this river has been seriously polluted for several decades. The present study focuses on the identification and the quantification of the water pollution levels of total phenols in the SMC according to the seasonal periods. Water samples from various areas of the canal in different months of the year, extending from December to September, were collected for analysis. Additionally, the concentration of total dissolved solids (TDS), chlorides, sulphates, nitrites and organic matter, as well as water hardness and alkalinity, were analysed in order to conduct a more complete study of the contamination of this area. The results showed a worrying total phenol concentration that exceeded the limit set by Argentine legislation for drinking water, as well as water for recreational use (5 µg/L). The total phenol (TP) concentration was directly determined by a molecular absorption spectroscopy method based on a new flow injection analysis system (FIA). Under the selected experimental conditions, the detection and quantification limits were 0.0490 and 0.1633 µg/mL, respectively. The developed method provides a number of improvements related to the speed of analysis, the restricted consumption of the reagents and sample volumes and the unnecessary sample treatment that contribute to environmentally friendly analytical chemistry. The results showed that TP make a significant contribution in the SMC pollution, especially during the months of April (400 ±â€¯110 µg/L) and September (240 ±â€¯20 µg/L). A high sulphate concentration that was higher than the limit allowed by the legislation was also found.

Synthesis of a molecularly imprinted polymer for the isolation of 1-hydroxypyrene in human urine.

In the last decades, the assessment of polycyclic aromatic hydrocarbons' exposure has generated great interest and 1-hydroxypyrene (1-OHP) has been commonly used as a biological indicator of exposure to PAHs in many studies in environmental and occupational health. In this research, a molecularly imprinted polymer (MIP) was synthesised by precipitation polymerisation using 1-OHP as template, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, and acetonitrile as porogen. MIP was used as solid-phase extraction (SPE) material for sample pretreatment and isolation of 1-OHP and posterior detection in a reversed-phase HPLC-FLD. Various parameters including washing solvent, elution solvent and volume affecting the extraction efficiency of the polymer have been evaluated to achieve the isolation of 1-OHP from urine samples and to reduce non-specific interactions. Cross-selectivity was studied in the presence of other structural analogues of the 1-OHP as hydroxyphenantrene isomers. The method was validated over a concentration range of 0.15-2.00 µg L(-1), R(2)>0.998. Recovery values were in the range of 78-90% and RSD <6.7%. The limits of detection and quantification were 0.05 µg L(-1) and 0.17 µg L(-1), respectively. In our knowledge, it is the first time that this methodology is applied for analysing urinary hydroxypyrene and it has been demonstrated that this specific MISPE-HPLC-FLD method offers a fast and simple alternative to determine 1-OHP in human urine samples.

An HPLC-DAD method for the simultaneous determination of nine ß-lactam antibiotics in ewe milk.

The presence of ß-lactam residues in foodstuffs constitutes a potential risk to the human health and undesirable effects on consumers, and nowadays these antibiotic residues are also recognised as an emerging environmental problem. In addition, these are of great concern to prestigious Manchego cheese processors (Central Spain denomination of origin) because they reduce the curdling of milk and cause improper cheese ripening, which consequently lead to an important loss of monetary income. This work describes the development of a sensitive and reliable method using liquid chromatography with UV-diode array detection (LC-DAD) for simultaneous determination of the ß-lactam antibiotics, ampicillin (AMP), benzylpenicillin (PEG), cephalexin (CFX), cefazolin (CFL), cefoperazone (CFP), cloxacillin (CLO), dicloxacillin (DCL), oxacillin (OXA) and phenoxymethylpenicillin (PEV), in Manchega ewe milk. The column, mobile phase, temperature and flow rate were optimised to provide the best resolution of these analytes. The extraction method of the antibiotic residues involves the deproteinisation of the milk sample using acetonitrile and centrifugation followed by a solid-phase extraction (SPE) clean-up. The recoveries for the studied ß-lactams ranged from 79% to 96% with relative standard deviations between 0.5% and 4.9%. The limits of quantification (LOQs) for all these compounds were in the range of 3.4-8.6µgkg(-1), which are lower than the maximum residue limits (MRLs) established by the European Union for the studied ß-lactams in milk, making the method suitable for performing routine analyses. The proposed multi-residue LC-UV-diode array detection (LC-DAD) method is a powerful and popular alternative for the determination and confirmation of antibiotic residues in small milk industries and is the first one capable of determining nine ß-lactam antibiotics in samples of Manchega ewe milk.

Development of a molecularly imprinted polymer-matrix solid-phase dispersion method for selective determination of ß-estradiol as anabolic growth promoter in goat milk.

A simple, fast, and sensitive method for determination of 17 ß-estradiol (E2) in goat milk samples has been developed by combining selective molecularly imprinted matrix solid-phase dispersion (MIP-MSPD) and liquid chromatography with diode-array detection (DAD). The molecularly imprinted polymer was synthesized by use of 17ß-estradiol as template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinker monomer, azobisisobutyronitrile as initiator, and acetonitrile as porogen, and was used as selective solid support for matrix solid-phase dispersion. The selected dispersant had high affinity for E2 in the goat milk matrix and the extract obtained was sufficiently clean for direct injection for HPLC analysis without any interferences from the matrix. The proposed MIP-MSPD method was validated for linearity, precision, accuracy, decision limit (CCα) and detection capability (CCß), in accordance with European Commission Decision 2002/657/EC criteria. Linearity ranged from 0.3-10 µg g(-1) (correlation coefficient r(2) > 0.999). Mean recovery of E2 from goat milk samples at different spiked levels was between 89.5 and 92.2%, with RSD values within 1.3-2%. CCα and CCß values were 0.36 and 0.39 µg g(-1), respectively. The developed MIP-MSPD method was successfully applied to direct determination of E2 in goat milk samples.

Selective solid-phase extraction of ethynylestradiol from river water by molecularly imprinted polymer microcolumns.

A selective on-column molecularly imprinted solid-phase extraction (MISPE) for ethynylestradiol (EE2) from water samples was developed. Following a non-covalent molecular imprinting approach, two molecularly imprinted polymers (MIPs) have been synthesised using methacrylic acid (MAA) as functional monomer, ethyleneglycol dimethacrylate (EGDMA) as crosslinker and EE2 as template, in two different polymerisation solvents (acetonitrile or toluene). The optimisation of the on-column MISPE conditions for the selective rebinding of the EE2 resulted in a flow rate of 2.3 mL min(-1) and volumes of 1 mL toluene and 1.5 mL methanol-acetic acid (9:1) for washing and elution steps, respectively. The selectivity of the imprinted polymer towards several related estrogens such as estriol (E3), estrone (E1) and estradiol (E2) was evaluated. The recovery of EE2 from a 50-mL spiked river-water sample was 75% when the optimised on-column MISPE was applied.

A new molecularly imprinted polymer for the on-column solid-phase extraction of diethylstilbestrol from aqueous samples.

The estrogenic compound diethylstilbestrol (DES) is widely studied because of its potential endocrine disruption effects. The prohibition of the use of diethylstilbestrol as a growth promoter has not been enough to ensure the total disappearance of this compound from environmental matrices. Due to the low levels of DES present in the environment, preconcentration and clean up methods are necessary for its analysis. This paper describes the synthesis and use of a molecularly imprinted polymer (MIP) as sorbent for on-column solid-phase extraction of DES from aqueous samples. The selectivity of the DES-MIP was evaluated towards several selected estrogens such as hexestrol (HEX), estrone (E1), estriol (E3), estradiol (E2) and ethynylestradiol (EE2). HPLC-DAD was used to quantify all analytes at 230-nm wavelength. The method has been successfully applied to the analysis of DES in spiked river and tap water samples, with recoveries of 72% and 83% respectively.

Removal of carbaryl, linuron, and permethrin by Lupinus angustifolius under hydroponic conditions.

The metabolism of organic pollutants by plants normally requires contaminant direct uptake by cells. Factors affecting this uptake and the later distribution of chemicals within the plant include the physicochemical properties of the compounds (concentration, structure, solubility, log k(ow), diffusion rate) and the biochemical characteristics of the plant. This paper reports the tolerance, uptake, and effects of the pesticides carbaryl, linuron, and permethrin on Lupinus angustifolius germination and growth as well as contaminant intraplant distribution and possible degradation. Lupine plants were grown in hydroponic culture containing either 1 or 5 mg of the individual pesticides, or combinations of these (1, 5, or 10 mg of each), in 100 mL nutrient and water solutions. Analysis of the remaining solutions 8 days post-germination showed the water solutions to have higher remaining pesticide concentrations than nutrient solutions. Furthermore, in the presence of pesticides, germination was more frequent in the water solutions. After 16 days of growth, the plants were harvested, and their tissues were microwaved digested and analyzed by reversed-phase liquid chromatography. Although only minor quantities of each pesticide were detected in plant tissues, their amount in the roots was higher than in the stems. No accumulation was noted in the cotyledons, and only 2% of linuron was detected in the leaves. Mass recovery at the end of the experiment showed that 57, 53, and 55% of carbaryl, linuron, and permethrin, respectively, were degraded and/or bound in an irreversible manner to plant material. The results suggest that L. angustifolius could be useful for the cleaning/remediation of pesticide-contaminated water.

Liquid chromatography-UV diode-array detection method for multi-residue determination of macrolide antibiotics in sheep's milk.

A rapid, simple and sensitive liquid chromatography-UV diode-array detection method was developed for the simultaneous determination of seven macrolides (erythromycin, oleandomycin, roxithromycin, josamycin, spiramycin, tylosin and ivermectin) in sheep's milk. The column, mobile phase, temperature and flow rate were optimised to provide the best resolution of these analytes. The extraction of the antibiotic residues involves the treatment of protein-free samples with a combination of concentrated sodium hydroxide and ethyl acetate. Necessary defatting is achieved by alkaline hydrolysis. The recovery of each antibiotic was between 55% and 77%, with relative standard deviations ranging from 1% to 6.5%. The limit of quantification was 72.4 microg/kg for ivermectin, 48.3 microg/kg for roxithromycin, and 24.1 microg/kg for erythromycin, oleandomycin, spiramycin, josamycin and tylosin. The procedure was successfully used in the multi-residue determination of these macrolides at levels below the maximum concentrations legally allowed in milk samples.

Simultaneous determination of maneb and its main metabolites in tomatoes by liquid chromatography using diode array ultraviolet absorbance detection.

Liquid chromatography (LC) with diode array ultraviolet absorbance (DAD UV) detection is used for the simultaneous determination of the fungicide maneb and its main metabolites (ethylenethiourea--ETU, ethylenebis (isothiocyanate) sulfide--EBIS, and ethyleneurea--EU) in tomatoes. The identity of EBIS, one of the main UV degradation products of maneb, was verified by both DAD UV detection and mass spectrometry. The analytes were extracted three times with 3 mL of 1:1:1 acetonitrile-dichloromethane-chloroform by 2 min of mechanical shaking and separated on a C-18 column by gradient elution with an acetonitrile-methanol-aqueous 100mM sodium dodecylsulfate (SDS) mixture. The quantification limits of 0.45, 0.04, and 0.35 mg kg(-1) obtained for maneb, ETU, and EU, respectively, show that the proposed method is suitable for their determination in tomatoes.

Optimization of a matrix solid-phase dispersion method with subsequent clean-up for the determination of ethylene bisdithiocarbamate residues in almond samples.

A matrix solid-phase dispersion (MSPD) method with subsequent clean-up has been developed to isolate the ethylene bisdithiocarbamate (EBDC) main metabolites (ethylenethiourea, ETU, and ethylenebis [isothiocyanate] sulphide, EBIS) in almond samples. The optimized experimental set-up configuration involved 0.2 g of almond sample, washed sand as MSPD support and NaOH as defatting agent. A subsequent purification step on alumina using acetonitrile as extraction solvent was enough to remove all interferent matrix components, including the fatty material, and provide clean extracts. Quantitative analysis was performed by reversed phase liquid chromatography (RPLC) with diode-array ultraviolet absorbance (DAD UV) detector. Analytes recoveries were between 76 and 85% with relative standard deviations ranging from 3 to 12%. The low limits of quantification of 0.05 and 0.07 mg kg(-1) achieved for ETU and EBIS, respectively, make the method useful for the determination of EBDC residues on almond samples.

Evaluation of pesticide uptake by Lupinus seeds.

Pesticide uptake by seeds depends on the properties of the chemical, such as structure, stability, log k(ow) and diffusion rate, type of water, pH, temperature, content of organic matter and composition, and on seed characteristics such as permeability of the seed coat. The efficiency with which Lupinus angustifolius seeds retain different herbicides (simazine, atrazine, isoproturon, linuron,) and insecticides (carbaryl, fenamiphos, permethrin) was evaluated using both a batch and a continuous system. Factors which affect pesticide uptake by seeds, such as flow rate, seed biomass, pesticide concentration, contact time, pH, seed saturation and also the speed of the retention process for 17 days, were tested. L. angustifolius showed a high retention capacity for the above mentioned pesticides. The extraction of pesticides from seeds using different organic solvents, such as methanol, acetonitrile, ethyl acetate and n-hexane was evaluated and no pesticide residues were detected in any of the solvents tested. This could be attributed to the capacity of the seed to degrade the pesticides. From the results obtained, L. angustifolius seems to be a promising seed to be applied for phytoremediation of industrial effluents or contaminated water.

Development of a fluoroimmunosensor for theophylline using immobilised antibody.

A flowthrough theophylline fluoroimmunosensor with an antibody covalently immobilised on a solid support has been developed. The immobilisation technique proposed in this paper used Protein-A on control pore glass (Protein A-CPG) in an immunoreactor and dimethylsuberimidate as a cross-linking agent. Several supports and cross-linking reagents were tested in order to obtain oriented immobilisation and thus efficiency of the immunological reaction and reusability of the immunosensor. The immunosensor performance characteristics were established. The precision expressed as RSD, was 1.6%; the detection limit was 3 mug l(-1); the immunoreactor lifetime was established in 80 assays and there were no interferences with structurally similar compounds such as aminophylline, dihydroxypropyltheophylline and caffeine in the determination of the analyte. This fluoroimmunosensor was applied to determine theophylline in human serum samples from patients of the Puerta de Hierro Hospital in Madrid. The results obtained show that there are no significant differences between the proposed immunosensor and the high-pressure liquid chromatographic method with UV detection used by the Hospital, thus demonstrating the validity of the method.

Determination of trace metals in waters and compost by on-line precipitation coupled to flame atomic absorption spectrophotometry or ion chromatography.

A general rapid on-line preconcentration method for the determination of trace metals coupled to flame atomic absorption spectrophotometry (FAAS) or ion chromatography (IC) with spectrophotometric detection is described. The method is based on the on-line precipitation of metal hydroxides with sodium hydroxide and their dissolution in a small volume of nitric acid solution. All the chemical and physical variables that affect the efficiency of metal precipitation and elution in the flow injection system have been studied. The detection limits obtained by FAAS are 0.1, 0.3, 0.5 and 0.5 mug l(-1) for Zn, Cu, Ni and Pb, respectively. When the on-line precipitation is coupled to IC with post-column derivatization with the spectrophotometric reagent 4-(2-pyridylazo) resorcinol (PAR), the detection limits are 3, 1, 5, 3, and 3 mug l(-1) for Cu, Zn, Ni, Co and Mn, respectively. The proposed general method was successfully applied to determine independently the above mentioned metals in compost and tap and river water samples.