Gas chromatographic determination of diquat and paraquat in crops

Hajšlová, Jana; Cuhra, Petr; Davídek, T.; Davı́dek, J.

doi:10.1016/s0021-9673(01)83340-9

Cited by 46 publications

(14 citation statements)

References 11 publications

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“…The Environmental Protective Agency (EPA) established a maximum concentration of 3 µg L -1 in natural waters, 2 while the European Community established 0.1 µg L -1 for the same kind of sample. A large variety of analytical techniques have been proposed for determination of paraquat, such as molecular absorption spectrophotometry, 7,8 liquid chromatography with UV detection, 9,10 liquid and gas chromatography coupled to mass spectrometry detection, 11,12 gas chromatography with specific detector for nitrogen and phosphorus (NPD), 13 ELISA 14 as well as potentiometric and amperometric sensors. 15,16 More recently, capillary electrophoresis with ultraviolet (CE-UV) 17 or mass spectrometry (CE-MS) 18 detection was proposed.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a nafion coated glassy carbon electrode for determination of paraquat by differential pulse voltammetry

Oliveira¹,

Lichtig²,

Masini³

2004

J. Braz. Chem. Soc.

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Este trabalho apresenta uma avaliação de um eletrodo de carbono vítreo recoberto com filme de Nafion para a determinação de paraquat em águas de rio e urina por voltametria de pulso diferencial. O filme foi formado adicionando-se 4 µL de uma solução de Nafion 4% (m/v) na superfície do eletrodo, seguindo-se evaporação do solvente com luz infra-vermelha. A máxima relação sinal/ruído foi obtida em meio de tampão Britton-Robinson 40 mmol L -1 com pH 12 como eletrólito suporte. Utilizando-se um tempo de acumulação de 5 min em circuito aberto, o limite de detecção foi de 0,7 µg L -1 , enquanto o limite de quantificação foi de 1,0 µg L -1 , com uma faixa de resposta linear até 12 µg L -1 . Nestas condições, uma série de dez experimentos revelou um desvio padrão relativo de 2,2% para uma solução de paraquat 10 µg L -1 . A formação de par iônico em solução foi o principal fator de erro nas análises. Apesar do filme evitar a adsorção de espécies aniônicas na superfície do eletrodo, o paraquat sofre fortes associações em solução com substâncias húmicas, proteínas, argilas, surfactantes aniônicos, etc. Estas interações diminuem a acumulação do paraquat no filme de Nafion e, em conseqüência, diminuem a magnitude da corrente de pico de redução, requerendo que as quantificações sejam feitas por adição de padrão. Recuperações entre 87 e 106% foram obtidas para amostras de água de rio e urina enriquecidas aos níveis de 1,0 e 3,0 µg L -1 . This paper presents an evaluation of a Nafion coated glassy carbon electrode for determination of paraquat in river water and urine by differential pulse voltammetry. The film was formed applying 4 µL of a 1% (m/v) Nafion solution, which was evaporated under an infrared light. The maximum signal to noise ratio was obtained using a 40 mmol L -1 Britton-Robinson buffer at pH 12 as supporting electrolyte. For an accumulation time of 5.0 min in open circuit, the limit of detection was 0.7 µg L -1 , while the quantification limit was 1.0 µg L -1 , with a linear dynamic range up to 12 µg L -1 . In these conditions, a sequence of ten experiments lead to a relative standard deviation of peak current of 2.2% for a 10 µg L -1 paraquat solution. Ion pair formation in solution was the major factor of error in analysis. Despite the film to avoid adsorption of anionic species at the electrode surface, paraquat suffers strong association in solution with humic substances, proteins, clays, anionic surfactants, etc. These interactions decrease the accumulation of paraquat in the Nafion film and, as a consequence, the magnitude of the reduction peak, requiring that quantifications have to be made by standard addition. Recoveries between 87 and 106% were obtained for river waters and urine samples spiked with 1.0 and 3.0 µg L -1 paraquat.Keywords: paraquat determination, river water, urine, modified electrode, voltammetry, ion exchange IntroductionParaquat (1,1'-dimethyl-4,4'-bypiridilium ion), also known as methyl viologen, is a defoliant and desiccant agent used to control herbal growth in terrestrial and aquat...

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Section: Introductionmentioning

confidence: 99%

Evaluation of a nafion coated glassy carbon electrode for determination of paraquat by differential pulse voltammetry

Oliveira¹,

Lichtig²,

Masini³

2004

J. Braz. Chem. Soc.

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“…As such, a quantitative ESI-LC-MS(/MS) (TOF mass spectrometry) method was optimized for the absolute quantification of glycopyrrolate in human plasma in a concentration range from 0.101 to 101 ng/mL using a quadratic calibration function (R 2 (±5.27 × 10 −3 ) × x + 4.08 × 10 −3 (±4.82 × 10 −4 ). For the three QC concentrations (QC 1 0.252, QC 2 2.52, and QC 3 25.2 ng/mL) and the LLOQ (0.101 ng/mL), total precision was under 20% (18.0% (n = 6) at the LLOQ) and maximum accuracy was 112% (88.9% for the LLOQ, n = 6). Absolute matrix effect (maximum 133% ± 9.59, n = 3), absolute recovery (better than 41.8% ± 2.22, n = 3), relative (inter-subject) matrix effect (maximum 10.9% ± 1.45, n = 4) and process efficiency (better than 45.2% ± 5.74, n = 3) too were assessed at the 3 QC concentrations.…”

Section: Introductionmentioning

confidence: 96%

“…Methods using gas chromatography-mass spectrometry (GC-MS) on selected QA drugs have been developed but intact QA compounds cannot be analyzed with GC-MS [9][10][11][12]. One approach is the hydrolysis of the isolated quaternary compound to cyclopentylmandelic acid which is then amenable to detection and confirmation following derivatization and analysis by GC-MS. A broad range of other chromatographic and spectrometric techniques have been reported for the analysis of QA drugs [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. An inherent disadvantage of most of these analytical methods is the lack of specificity, resulting in identification and quantification issues in complex matrices, e.g., plasma [13].…”

Section: Introductionmentioning

confidence: 99%

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Quantitative determination of glycopyrrolate in human plasma by liquid chromatography–electrospray ionization mass spectrometry: The use of a volatile ion-pairing agent during both liquid–liquid extraction and liquid chromatography

Storme

t’Kindt

Goeteyn

et al. 2008

Journal of Chromatography B

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a b s t r a c tThe work presented here deals with the development of a quantitative tool for the determination of the quaternary ammonium anticholinergic glycopyrrolate in human plasma samples. Mepenzolate was used as an internal standard. The plasma samples were subjected to a suitable sample clean-up consisting of a simple and relatively fast, two step liquid-liquid ion-pair extraction procedure. The chromatography, using the same volatile ion-pair reagent heptafluorobutyric acid (HFBA), takes only 10 min. Relative standard deviation of retention times was never above 2.26% (n = 36). The method was fully validated based on the US FDA Bioanalytical Method Validation Guidance for Industry. As such, a quantitative ESI-LC-MS(/MS) (TOF mass spectrometry) method was optimized for the absolute quantification of glycopyrrolate in human plasma in a concentration range from 0.101 to 101 ng/mL using a quadratic calibration function (R 2 = 0.9995), y = −2.21 × 10 −4 (±3.93 × 10 −5 ) × x 2 + 5.85 × 10 −2 (±5.27 × 10 −3 ) × x + 4.08 × 10 −3 (±4.82 × 10 −4 ). For the three QC concentrations (QC 1 0.252, QC 2 2.52, and QC 3 25.2 ng/mL) and the LLOQ (0.101 ng/mL), total precision was under 20% (18.0% (n = 6) at the LLOQ) and maximum accuracy was 112% (88.9% for the LLOQ, n = 6). Absolute matrix effect (maximum 133% ± 9.59, n = 3), absolute recovery (better than 41.8% ± 2.22, n = 3), relative (inter-subject) matrix effect (maximum 10.9% ± 1.45, n = 4) and process efficiency (better than 45.2% ± 5.74, n = 3) too were assessed at the 3 QC concentrations.

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“…Several methods have been applied to simultaneously determine PQ and DQ serum levels; such methods are based on spectrophotometry, 3,4 gas chromatography (GC), 5,6 liquid chromatography (HPLC), [7][8][9][10] or capillary electrophoresis. 11 However, these methods have a limited sensitivity and/or specificity and require laborious and time-consuming sample preparation procedures such as cation-exchange chromatography, ion-pair liquid-liquid extraction and/or solidphase extraction.…”

Section: Introductionmentioning

confidence: 99%

Rapid and Sensitive HPLC Method for the Simultaneous Determination of Paraquat and Diquat in Human Serum

et al. 2007

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A rapid and sensitive HPLC method for the simultaneous determination of paraquat and diquat in human serum has been developed. After deproteinization of the serum with 10% trichloroacetic acid, the samples were separated on a reversedphase column, and subsequently reduced to their radicals with alkaline sodium hydrosulfite solution. These radicals were monitored with a UV detector at 391 nm. This method permitted the reliable quantification of paraquat over linear ranges of 50 ng -10 μg/ml and 100 ng -10 μg/ml for diquat in human serum. The within-and between-day variations are lower than 2.3 and 2.2%, respectively. This technique was also utilized to determine the paraquat and diquat serum levels in a patient who had ingested herbicide (Prigrox L ® ) containing paraquat and diquat.

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Gas chromatographic determination of diquat and paraquat in crops

Cited by 46 publications

References 11 publications

Evaluation of a nafion coated glassy carbon electrode for determination of paraquat by differential pulse voltammetry

Evaluation of a nafion coated glassy carbon electrode for determination of paraquat by differential pulse voltammetry

Quantitative determination of glycopyrrolate in human plasma by liquid chromatography–electrospray ionization mass spectrometry: The use of a volatile ion-pairing agent during both liquid–liquid extraction and liquid chromatography

Rapid and Sensitive HPLC Method for the Simultaneous Determination of Paraquat and Diquat in Human Serum

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