Simultaneous voltammetric determination of four triazine herbicides in water samples with the aid of chemometrics

A novel differential pulse voltammetry (DPV) method was developed for the simultaneous analysis of herbicides in water. A mixture of four herbicides, atrazine, simazine, propazine and terbuthylazine was analyzed simultaneously and the complex, overlapping DPV voltammograms were resolved by several chemometrics methods such as partial least squares (PLS), principal component regression (PCR) and principal component���artificial networks (PC���ANN). The complex profiles of the voltammograms collected from a synthetic set of samples were best resolved with the use of the PC���ANN method, and the best predictions of the concentrations of the analytes were obtained with the PC-ANN model (%RPET = 6.1 and average %Recovery = 99.0). The new method was also used for analysis of real samples, and the obtained results were compared well with those from the GC-MS technique. Such conclusions suggest that the novel method is a viable alternative to the other commonly used methods such as GC, HPLC and GC-MS.

Micro-organic compounds in the Humber rivers

<p>The concentrations of a range of micro-organic compounds in the Humber rivers have been measured at weekly intervals over a period of 1 year. The compounds include the triazine herbicides (simazine, atrazine, propazine, desmetryn and prometryn), selected organophosphorus insecticides (fenitrothion, malathion and parathion), phenylurea (chlorotoluron, diuron, isoproturon and linuron) and phenoxyacid herbicides (2,4-D, MCPA, MCPB and mecoprop), phenol derivatives (phenol, 2-ethylphenol, 2-chlorophenol, 4-nitrophenol, 2-methylphenol, 4-ethylphenol and 2,4-dichlorophenol), organochlorine insecticides (HEOD, DDT, TDE, DDE, HCB, alpha-BHC and lindane), PCB's and some synthetic pyrethroid insecticides (cis/trans-permethrin, fenvalerate and cypermethrin). The results indicate the high frequency of occurrence of many compounds in the southern Humber rivers Aire, Calder, Trent and Don compared with the more occasional concentrations found in the upland rivers with catchments dominated by low intensity agriculture. The more water soluble herbicides, atrazine, simazine, isoproturon and diuron are detected frequently in the southern rivers with the highest concentrations and abundance in the rivers Aire, Calder and Trent. The most abundant phenolic compound is 2,4-dichlorophenol usually occurring at concentrations &lt;1 mu g/l. The organochlorine insecticides and PCB's are generally at concentrations &lt;0.01 mu g/l, cis/trans-permethrin are the only synthetic pyrethroids detected and these are found in the rivers Aire and Calder at about equal concentrations of between 0.01 and 0.11 mu g/l. The results of the occurrence of simazine and atrazine in the rivers Trent, Don and Aire illustrate peaks in concentration in the spring and then later in the year during the early autumn coinciding with the first major storm after the summer. In the rivers Trent and Don, the annual exports (March 1994-95) of atrazine are lower than for simazine whereas in the R. Calder the yield of atrazine is higher than for simazine suggesting differences in use in these catchments. The maximum triazine concentration observed, i.e. 8 mu g/l of atrazine in the R. Calder, could have inhibiting effects on the phytoplankton and algal growth, although because of the transient nature of the peaks, recovery is expected to be rapid. The only other compounds measured at concentrations likely to produce detrimental ecotoxicological effects are cis/trans permethrin in the rivers Aire and Calder. (C) 1997 Elsevier Science B.V.</p>

Responsiveness of the interrenal tissue of Jundia (Rhamdia quelen) to an in vivo ACTH test following acute exposure to sublethal concentrations of agrichemicals

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Bioaccumulation of chlorinated pesticides and PCBs in the tropical freshwater fish Hoplias malabaricus: Histopathological, physiological, and immunological findings

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Cortisol response to acute stress in jundi�� Rhamdia quelen acutely exposed to sub-lethal concentrations of agrichemicals

Exposure to agrichemicals can have deleterious effects on fish, such as disruption of the hypothalamus-pituitary-inter-renal axis (HPI) that could impair the ability of fish to respond to stressors. In this study, fingerlings of the teleost jundi�� (Rhamdia quelen) were used to investigate the effects of the commonly used agrichemicals on the fish response to stress. Five common agrichemicals were tested: the fungicide - tebuconazole, the insecticide - methyl-parathion, and the herbicides - atrazine, atrazine + simazine, and glyphosate. Control fishes were not exposed to agrichemicals and standard stressors. In treatments 2-4, the fishes were exposed to sub-lethal concentrations (16.6%, 33.3%, and 50% of the LC50) of each agrichemical for 96��h, and at the end of this period, were subjected to an acute stress-handling stimulus by chasing them with a pen net. In treatments 5-7 (16.6%, 33.3%, and 50% of the LC50), the fishes were exposed to the same concentrations of the agrichemicals without stress stimulus. Treatment 8 consisted of jundi��s not exposed to agrichemicals, but was subjected to an acute stress-handling stimulus. Jundi��s exposed to methyl-parathion, atrazine + simazine, and glyphosate presented a decreased capacity in exhibiting an adequate response to cope with stress and in maintaining the homeostasis, with cortisol level lower than that in the control fish (P < 0.01). In conclusion, the results of this study clearly demonstrate that the acute exposure to sub-lethal concentrations of methyl-parathion, atrazine + simazine, and glyphosate exert a deleterious effect on the cortisol response to an additional acute stressor in the jundi�� fingerlings. �� 2008 Elsevier Inc. All rights reserved.

Resposta cortisol��mica e sensibilidade ao horm��nio adrenocorticotr��fico (ACTH) de jundi�� (Rhamdia quelen) em exposi����o sub-letal a agrot��xicos

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Otimiza����o e valida����o de metodologia anal��tica empregando SPE e LC-ESI-MS/MS para determina����o de multiclasses de agrot��xicos e metab��litos em ��gua de superf��cie e de abastecimento p��blico

A aplica����o de agrot��xicos nas pr��ticas agr��colas aumentou muito nos ��ltimos anos. Isto vem ocorrendo devido ao crescimento populacional, demandando maior produ����o de alimentos. O uso de agrot��xicos e seus res��duos tornaram-se um problema devido a poss��vel contamina����o das ��guas de superf��cie e subterr��nea, podendo impactar o meio ambiente e causar danos �� sa��de p��blica. Na cidade de Rio Grande, RS, Brasil, o suprimento de ��gua pot��vel �� realizado pela CORSAN (Companhia Riograndense de Saneamento), que capta a ��gua do Canal S��o Gon��alo, o qual estabelece uma liga����o entre as duas lagoas: Lagoa dos Patos e Lagoa Mirim. Em suas margens h�� tamb��m a capta����o de ��gua para irriga����o das culturas agr��colas. Esta intera����o entre o uso da ��gua das lagoas e a agricultura, pode resultar na contamina����o das ��guas que s��o captadas para abastecimento dos munic��pios situados na regi��o. Uma metodologia anal��tica empregando Extra����o em Fase S��lida (SPE) e Cromatografia L��quida acoplada a uma fonte de ioniza����o por Electrospray tandem Espectrometria de Massas (LCESI-MS/MS) foi desenvolvida e validada para a determina����o de dezoito agrot��xicos multiclasses (herbicidas, inseticidas e fungicidas) e dois metab��litos em amostras de ��gua superficial e de abastecimento p��blico. Esta metodologia foi aplicada para monitoramento durante dez meses na ��gua superficial do Canal S��o Gon��alo e na ��gua de consumo da cidade de Rio Grande, ap��s o tratamento pela CORSAN. Os agrot��xicos selecionados foram: clomazona, bispiribaque-s��dio, diurom, atrazina, simazina, imazetapir, imazapique, metsulfuron-met��lico, quincloraque, penoxsulam, 2,4-D, pirazosulfuron-et��lico, bentazona, propanil, irgarol, tebuconazol, fipronil e carbofurano. Os metab��litos foram: 3,4-DCA e 3-hidroxicarbofurano. Os limites de detec����o do m��todo variaram entre 0,4 ��� 40,0 ng L -1 , enquanto para os limites de quantifica����o a varia����o foi de 4,0 ��� 100,0 ng L -1 . Todos os compostos apresentaram excelente linearidade, com coeficiente de determina����o maior do que 0,99. As recupera����es empregando SPE com cartuchos contendo 500 mg de C18ec, variaram entre 70 a 120%, para 95% dos compostos, apresentando %RSD 20%. Atrav��s do monitoramento de m��ltiplas rea����es (MRM), duas transi����es diferentes (��on precursor ��� ��on produto) foram selecionadas para cada composto, uma para quantifica����o e outra para confirma����o, o que aumentou a seletividade do m��todo. Para as amostras analisadas, foram detectados agrot��xicos n��vel de ng L -1 . O m��todo desenvolvido �� sens��vel, r��pido e apresenta elevada seletividade, permitindo a identifica����o e a quantifica����o dos agrot��xicos em ��guas superficiais e de abastecimento p��blico, atendendo os n��veis requeridos pelos ��rg��os reguladores como da Uni��o Europ��ia (98/83/EC) e do Brasil segundo a Portaria N��. 518 (25/03/2004).

Otimiza����o e valida����o de m��todos empregando DLLME e DLLME-SFO para a extra����o simult��nea de agrot��xicos multiclasse em ��gua mineral

O Rio Grande Sul destaca-se no cen��rio nacional como grande produtor de diversas culturas, as quais demandam grande quantidade de agrot��xicos das mais diversas classes qu��micas e toxicidades. No entanto a intensa utiliza����o destes compostos torna-se uma preocupa����o devido a poss��veis contamina����es das ��guas superficiais e subterr��neas. Em virtude da degrada����o dos mananciais a ��gua mineral passou a ser uma das fontes mais utilizadas para o consumo humano, pois tem-se a percep����o de que a mesma possui melhor qualidade que a ��gua tratada, al��m disso acredita-se que a mesma esta isenta de subst��ncias org��nicas prejudiciais �� sa��de humana. Neste trabalho, foi realizada a determina����o dos agrot��xicos atrazina, simazina, imazapique, imazetapir, imidacloprido, ciproconazol, tebuconazol e epoxiconazol em ��gua mineral empregando a Microextra����o L��quido-L��quido Dispersiva (DLLME), Microextra����o L��quido-L��quido Dispersiva com Solidifica����o da Gota Org��nica Flutuante (DLLME-SFO) e Cromatografia L��quida acoplada �� Espectrometria de Massas em s��rie com fonte de ioniza����o por Eletronebuliza����o (LC-ESI-MS/MS). Para o m��todo empregando DLLME e LC-ESI-MS/MS foram otimizados alguns fatores como o tipo e volume de solvente extrator e dispersor e pH. Ap��s a otimiza����o dos par��metros de extra����o, fragmenta����o dos compostos e separa����o cromatogr��fica, o m��todo foi validado avaliando-se curva anal��tica, linearidade, limites de detec����o e quantifica����o, precis��o (repetitividade e precis��o intermedi��ria) e exatid��o (recupera����o). Todas as curvas anal��ticas apresentaram valores de r maiores que 0,999. Os Limites de Quantifica����o (LOQs) para o m��todo estiveram na faixa de 5 a 500 ng L-1. Foram obtidas recupera����es entre 102 - 120% para a repetibilidade e entre 92 e 110% para a precis��o intermedi��ria, com RSD de 2 a 10% para todos os compostos. Para o m��todo empregando DLLME-SFO e LC-ESI-MS/MS foram avaliados alguns par��metros que afetam a efici��ncia da extra����o como, tipo e volume de solvente extrator e dispersor, for��a i��nica e pH. Nas condi����es ��timas de extra����o todas as curvas anal��ticas apresentaram valores de r maiores que 0,997. Os LOQs para o m��todo variaram entre 12,5 - 125 ng L-1. As recupera����es foram entre 70 e 118% para a repetitividade e entre 76 e 95% para a precis��o intermedi��ria, com RSD de 2 a 18% para todos os compostos. Com rela����o ao Efeito Matriz (EM) avaliado para todos os compostos pelos dois m��todos, foi observado baixo EM. Isso indicou que n��o �� necess��rio utilizar a curva anal��tica preparada no extrato branco da matriz para a quantifica����o destes analitos. Ambos os m��todos foram aplicados para a determina����o de res��duos de agrot��xicos em amostras de ��gua mineral provenientes de diferentes regi��es do estado do Rio Grande do Sul e n��o foram encontrados res��duos de agrot��xicos nas amostras analisadas. Os m��todos validados apresentaram como principais vantagens baixo consumo de solventes org��nicos e amostra, rapidez, altos fatores de concentra����o e recupera����es dentro da faixa aceit��vel. Os limites de quantifica����o dos m��todos ficaram abaixo dos limites m��ximos de res��duos permitidos pela legisla����o brasileira para agrot��xicos em ��gua mineral.

Otimiza����o do m��todo QuEChERS para determina����o de agrot��xicos, f��rmacos e produtos de cuidado pessoal em lodo de ETA por LC-ESI-MS/MS

O lodo gerado em Esta����o de Tratamento de ��gua (ETA) durante as etapas de flocula����o e decanta����o �� classificado como res��duo n��o inerte. Estudos recentes apontam para uma diminui����o na concentra����o de agrot��xicos, f��rmacos e Produtos de Cuidado Pessoal (PCP) em ��guas, ap��s o seu tratamento. Uma poss��vel explica����o seja que estes compostos possam estar ficando aderidos ao lodo; entretanto, a investiga����o desses compostos no lodo de ETA �� bastante reduzida. Neste trabalho, foi realizada a otimiza����o do m��todo QuEChERS com determina����o por Cromatografia L��quida acoplada a Espectrometria de Massas sequencial para analisar agrot��xicos (atrazina, simazina, clomazona e tebuconazol), f��rmacos (amitriptilina, cafe��na, diclofenaco e ibuprofeno) e PCP (metilparabeno, propilparabeno, triclocarban e bisfenol A) em lodo de ETA, uma matriz bastante complexa, constitu��da basicamente de compostos inorg��nicos (areia, argila e silte) e org��nicos (subst��ncias h��micas). Ap��s otimizado, o m��todo apresentou limites de quantifica����o ente 1 e 50 ��g kg-1 e as curvas anal��ticas apresentaram valores de r maiores que 0,98. As recupera����es variaram entre 50 e 120% com RSD ��� 15%. O efeito matriz foi avaliado e observou-se a supress��o do sinal para a maioria dos compostos, sendo o efeito compensado utilizando a quantifica����o por superposi����o na matriz. O m��todo foi aplicado em amostras de lodo de ETA e foram identificados tebuconazol e metilparabeno em concentra����es <LOQ.

The preparation of a certified reference material of polar pesticides in freeze-dried water (CRM 606)

The preparation of a certified reference material of polar pesticides in freeze-dried water is described. The pesticides selected were atrazine, simazine, carbaryl, propanil, linuron, fenamiphos and permethrin which were added to 6000 litres of tap water at 50���80 ��g �� L���1 (200���320 ��g �� L���1 for permethrin) level in presence of NaCl (2.5 g �� L���1) prior lyophilization. After the freeze-drying process the residue was rehomogenized, filled into amber glass bottles and stored at ���20�����C, +4�����C and +20�����C. All pesticides were determined by HPLC/diode array detector, except permethrin which was determined by GC/ECD. The results obtained for atrazine, simazine, carbaryl, propanil, linuron and fenamiphos showed no within- or between-bottle inhomogeneity, however the material was non-homogeneous for permethrin and therefore this was withdrawn from further studies. With respect to the stability for over one year, all pesticides were stable at ���20�����C. At +4�����C all pesticides were stable for at least 9 months and at +20�����C the stability was demonstrated only during the first month of storage. The content (mass fractions) of atrazine, simazine, carbaryl, propanil and linuron in freeze-dried water (CRM 606) was certified by an interlaboratory testing and a certification campaign.

Development of a sequential injection chromatography (SIC) method for determination of simazine, atrazine, and propazine

This paper describes the development of a sequential injection chromatography (SIC) procedure for separation and quantification of the herbicides simazine, atrazine, and propazine exploring the low backpressure of a 2.5 cm long monolithic C(18) column. The separation of the three compounds was achieved in less than 90 s with resolution > 1.5 using a mobile phase composed by ACN/1.25 mmol/L acetate buffer (pH 4.5) at the volumetric ratio of 35:65 and flow rate of 40 mu L/s. Detection was made at 223 nm using a flow cell with 40 mm of optical path length. The LOD was 10 mu g/L for the three triazines and the quantification limits were of 30 mu g/L for simazine and propazine and 40 mu g/L for atrazine. The sampling frequency is 27 samples per hour, consuming 1.1 mL of ACN per analysis. The proposed methodology was applied to spiked water samples and no statistically significant differences were observed in comparison to a conventional HPLC-UV method. The major metabolites of atrazine and other herbicides did not interfere in the analysis, being eluted from the column either together with the unretained peak, or at retention times well-resolved from the studied compounds.

Understanding the Effect of Adsorption Geometry over Substrate Selectivity in the Surface-Enhanced Raman Scattering Spectra of Simazine and Atrazine

This paper studies the selectivity of Well-defined Au and Ag nanostructures as substrates for the SERS, (surface-enhanced Raman scattering) detection of simazine (6-chloro-N,N`-diethyl-1,3,5-triazine-2,4-diamine) and atrazine (6-chloro-N-ethyl-N`-isopropyl-1,3,5-triazine-2,4-diamine). Our data showed that simazine and atrazine displayed similar SERS spectra when the Au was employed as substrate. Conversely, distinct SERS signatures were obtained upon the utilization of Ag substrates. Density functional theory (DFT) calculations and vibrational assignments suggested that, while simazine and atrazine adsorbed on Au via the N3 position of the triazine ring, simazine adsorbed on Ag via N3 and atrazine via N5. The results presented herein demonstrated that the adsorption geometry of analyte molecules can play a central role over substrate selectivity in SERS, which is particularly important in applications involving ultrasensitive analysis of mixtures containing structurally similar molecules.

Solid Lipid Nanoparticles Co-loaded with Simazine and Atrazine: Preparation, Characterization, and Evaluation of Herbicidal Activity

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Isolation and characterization of a novel simazine-degrading bacterium from agricultural soil of central Chile, Pseudomonas sp MHP41

<p>s-Triazine herbicides are used extensively in South America in agriculture and forestry. In this study, a bacterium designated as strain MHP41, capable of degrading simazine and atrazine, was isolated from agricultural soil in the Quillota valley, central Chile. Strain MHP41 is able to grow in minimal medium, using simazine as the sole nitrogen source. In this medium, the bacterium exhibited a growth rate of mu = 0.10 h(-1), yielding a high biomass of 4.2 x 10(8) CFU mL(-1). Resting cells of strain MHP41 degrade more than 80% of simazine within 60 min. The atzA, atzB, atzC, atzD, atzE and atzF genes encoding the enzymes of the simazine upper and lower pathways were detected in strain MHP41. The motile Gram-negative bacterium was identified as a Pseudomonas sp., based on the Biolog microplate system and comparative sequence analyses of the 16S rRNA gene. Amplified ribosomal DNA restriction analysis allowed the differentiation of strain MHP41 from Pseudomonas sp. ADP. The comparative 16S rRNA gene sequence analyses suggested that strain MHP41 is closely related to Pseudomonas nitroreducens and Pseudomonas multiresinovorans. This is the first s-triazine-degrading bacterium isolated in South America. Strain MHP41 is a potential biocatalyst for the remediation of s-triazine-contaminated environments.</p>