SciELO - Scientific Electronic Library Online

 
vol.34 número3Water temperature and riverine ecosystems: An overview of knowledge and approaches for assessing biotic responses, with special reference to South AfricaWater services with independent providers in peri-urban Maputo: Challenges and opportunities for long-term development índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Artigo

Indicadores

Links relacionados

  • Em processo de indexaçãoCitado por Google
  • Em processo de indexaçãoSimilares em Google

Compartilhar


Water SA

versão On-line ISSN 1816-7950
versão impressa ISSN 0378-4738

Water SA vol.34 no.3 Pretoria Mar. 2008

 

Supercritical fluid extraction of pesticides in sediment from the Okavango Delta, Botswana, and determination by gas chromatography with electron capture detection (GC-ECD) and mass spectrometry (GC-MS)

 

 

Lesego C MmualefeI; Nelson TortoI; Philippa Huntsman-MapilaII; Bontle MbongweIII

IUniversity of Botswana, Dept. of Chemistry, Private Bag UB00704, Gaborone, Botswana
IIUniversity of Botswana, Harry Oppenheimer Okavango Research Centre, Private Bag 285, Maun, Botswana
IIIUniversity of Botswana, Dept. of Environmental Science, Private Bag UB00704, Gaborone, Botswana

Correspondence

 

 


ABSTRACT

The study reports supercritical fluid extraction (SFE) of pesticides in sediment samples from the Okavango Delta, the headwaters of which originate from Angola and traverse through Namibia into Botswana. An acetone modifier and fractional extraction by pressure ramping gave recoveries ranging from 55 to 86% for the 15 pesticides studied. Hexachlorobenzene (HCB), aldrin and 4, 4-dichlorodiphenyltrichloroethane (4, 4'-DDT) were identified at concentration ranges of 1.1 to 30.3, 0.5 to 15.2 and 1.4 to 55.4 µg/g, respectively by gas chromatography with electron capture detection (GC-ECD) and were unequivocally confirmed by gas chromatography time-of-flight mass spectrometry (GC-ToF-MS). The study indicated an increase of pesticide concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. The results show that there are ramifications associated with activities either upstream or downstream; hence close monitoring is required for the long-term preservation of the delta.

Keywords: organochlorine pesticides; sample preparation; modifier; static extraction; dynamic extraction; fractional extraction.


 

 "Full text available in PDF"

 

References

ANDERSSON L, GUMBRICHT T, HUGHES D, RINGROSE D, KNIVERTON D, SAVENJI H, TODD M, WILK J and WOLSKI P (2003) Water flow dynamics in the Okavango River Basin and Delta - a prerequisite for the ecosystems of the Delta. Phys. Chem. Earth 28 1163-1172.         [ Links ]

ANITESCU G and TAVLARIDES LL (2006) Supercritical extraction of contaminants from soils and sediments. J. Supercrit. Fluid. 38 (2) 167-180.         [ Links ]

CAMEL V (1998) Supercritical fluid extraction as a useful method for pesticides determination. Analusis 26 (6) 99-111.         [ Links ]

DAKA PS, OBUSENG VC, TORTO N and HUNTSMAN-MAPILA P (2006) Deltamethrin in sediment samples of the Okavango Delta, Botswana. Water SA 32(4) 483-488.         [ Links ]

DELISTRATY D and YOKEL J (2007) Chemical and ecotoxicological characterization of Columbia River sediments below the Hanford site (USA). Ecotoxicol. Environ. Saf. 66 16-28.         [ Links ]

FIDALGO-USED N, BLANCO-GONZÁLEZ E and SANZ-MEDEL A (2007) Sample handling strategies for the determination of persistent trace organic contaminants from biota samples. Anal. Chim. Acta 590 1-16.         [ Links ]

GABALDÓN JA, MAQUIEIRA A and PUCHADES R (2007) Development of a simple extraction procedure for chlorpyrifos determination in food samples by immunoassay. Talanta 711001-1010.         [ Links ]

GHASEMI E, YAMINI Y, BAHRAMIFAR N and SEFIDKOU F (2007) Comparative analysis of supercritical CO2 extract of Artemisia sieberi. J. Food Eng. 79(1) 306-311.         [ Links ]

GONÇALVES C, CARVALHO JJ, AZENHA MA and ALPENDURA MF (2006) Optimisation of supercritical fluid extraction of pesticide residues in soil by means of central composite design and analysis by gas chromatography-tandem mass spectrometry. J. Chromatogr. A 1110 6-14.         [ Links ]

GUEVARA-RIBA A, RUBIO R, RAURET G, MUNTAU H and SAHUQUILLO A (2006) Method study for the preparation of a wet sediment quality control material. Anal. Chim. Acta 555 384-390.         [ Links ]

HUNTSMAN-MAPILA P, MAPILA T, LETSHWENYO M, WOLSKI P and HEMOND C (2006) Characterisation of arsenic occurrence in the water and sediments of the Okavango Delta, NW Botswana. Appl. Geochem. 211376-1391.         [ Links ]

HU Q, PAN B, XU J, SHENG J and SHI Y (2007) Effects of supercritical carbon dioxide extraction conditions on yields and antioxidant activity of Chlorella pyrenoidosa extracts. J. Food Eng. 80 997-1001.         [ Links ]

HUTTON LG and DINCER T (1976) Investigation of the Okavango Delta as a Primary Water Resource for Botswana. Technical Note 23, UNDP:FAO.AG:DP/BOT/71/506.         [ Links ]

LÉTISSE M, ROZIËRES M, HIOL A, SERGENT M and COMEAU L (2006) Enrichment of EPA and DHA from sardine by supercritical fluid extraction without modifier: I. Optimisation of extraction conditions. J. Supercrit. Fluid. 38 27-36.         [ Links ]

MABASO MLH, SHARP B and LENGELER C (2004) Historical review of malarial control in southern Africa with emphasis on the use of indoor residual house spraying. Trop. Med. Int. Health 9 846-856.         [ Links ]

NAUDE Y, DE BEER WHJ, JOOSTE S, VAN DE MERWE L and VAN RENSBURG SJ (1998) Comparison of supercritical fluid extraction and Soxhlet extraction for the determination of DDT, DDD and DDE in sediment. Water SA 24(3) 205-214.         [ Links ]

NEMOTO S, SASAKI S, TOYODA M and SAYITO Y (1997) Effect of extraction conditions and modifiers on the supercritical fluid extraction of 88 pesticides. J. Chromatogr. Sci. 35 (10) 467-477.         [ Links ]

QUAN C. LI S, TIAN S, XU H, LIN A and GU L (2004) Supercritical fluid extraction and clean-up of organochlorine pesticides in ginseng. J. Supercrit. Fluid. 31 (2) 149-157.         [ Links ]

REVERCHON E and DE MARCO I (2006) Supercritical fluid extraction of natural matter. J. Supercrit. Fluid. 38 (2) 146-166.         [ Links ]

RIAL-OTERO R, GASPAR EM, MOURA I and CAPELO JL (2007) Chromatographic-based methods for pesticide determination in honey- An overview. Talanta 71 503-514.         [ Links ]

RISSATO SR, GALHIANE MS, KNOLL FRN and APON BM (2004) Supercrtical fluid extraction of pesticide multiresidue analysis in honey: determination by gas chromatography with electron capture and mass spectrometric detection. J. Chromatogr. A 1048 153-159.         [ Links ]

RODIL R, CARRO AM, LORENZO RA and CELA R (2007) Multicriteria optimisation of a simultaneous supercritical fluid extraction and clean-up procedure for the determination of persistent organo-halogenated pollutants in aquaculture simples. Chemosphere 67 (7) 1453-1462.         [ Links ]

SANTOS FJ and GALCERAN MT (2002) The application of gas chro-matography to environmental analysis. TrAC Trends Anal. Chem. 21 (9-10) 672-685.         [ Links ]

SEREDA L and MEINHARDT HR (2005) Contamination of the water environment in malaria endemic areas of KwaZulu-Natal, South Africa, by agricultural insecticides. Bull. Environ. Contam. Toxicol. 75 530-537.         [ Links ]

YUAN S, TIAN M and LU X (2006) Electrokinetic movement of hexachlorobenzene in clayed soils enhanced by Tween 80 and β-cyclodextrin. J. Hazard. Mater. B137 1218-1225.         [ Links ]

ZHAO G, XU L, LI W, HAN G and LING B (2007) PCBs and OCPs in human milk and selected foods from Luquiao and Pingquiao in Zhejiang, China. Sci. Total Environ. 378281-292.         [ Links ]

 

 

 Correspondence:
+267-721-446-56
Fax: +267-355-2836
E-mail: lmmualefe@gmail.com

Received 7 August 2007;
Accepted in revised form 15 April 2008.