Sains Malaysiana 39(2)(2010): 175–179
Colourimetric Determination of Features of an Air Sampling Technique Optimal for Detection of
Surfactants
(Penentuan Keadaan Optimum Teknik Pensampelan Udara bagi Pengesanan Surfaktan Secara Kolorimetri)
NUR HAZIMAH ABDUL HALIM1, NORFAZRIN MOHD HANIF1,
MOHAMED ROZALI OTHMAN1 & MOHD TALIB LATIF*,
2
1School of Chemical Sciences & Food Technology
Faculty of Science & Technology, Universiti Kebangsaan Malaysia, 43600 Bangi,
Selangor, Malaysia
2School of Environmental and Natural Resource Sciences
Faculty of Science & Technology, Universiti Kebangsaan Malaysia, 43600 Bangi,
Selangor, Malaysia
Diserahkan:
28 April 2009 / Diterima: 3 Ogos 2009
ABSTRACT
Surfactants in the
atmosphere may act as cloud condensation nuclei, with a potentially negative
impact on the global climate. Therefore, accurate determination of surfactants
is crucial in order to investigate the possible effects of surfactants on the
atmosphere. The aim of this study was to identify the optimum sampling method
for measuring the maximum quantity of surfactants present in ambient air. Air
samples were collected using a range of air sampling pumps that were made to
vary in terms of flow rate, storage period, type of
absorbing solution and the characteristics of the impinger tube. Samples obtained were analysed by colourimetry for anionic and cationic surfactants as methylene blue-active substances (MBAS) and disulphine blue-active substances (DBAS), respectively.
Absorbance was measured at 650 nm for MBAS and
628 nm for DBAS using UV-visible
spectrophotometer. We found that the optimum sampling method consisted of an
absorbent solution (deionised water, buffer solution
and methylene blue/disulphine blue solution) with the flow rate of 1.0 L/min. The concentration of
surfactants in all sampling methods remained constant regardless of the storage
period (1 day and 4 days), indicating that surfactants in the absorbing
solution are quite stable. Covering the impinger tube
was shown to influence the amount of both anionic and cationic surfactants
detected.
Keywords: Ambient air;
anionic and cationic surfactants; colourimetry
ABSTRAK
Surfaktan di atmosfera berpotensi untuk bertindak sebagai nukleus kondensasi awan yang berupaya memberi kesan negatif terhadap iklim global. Kaedah yang tepat bagi penentuan surfaktan adalah penting bagi mengkaji pelbagai kesan surfaktan terhadap atmosfera. Kajian ini bertujuan mengkaji dan membangunkan satu kaedah pensampelan optimum yang berpotensi dalam menyerap kandungan maksimum surfaktan yang hadir di udara. Pensampelan udara dijalankan dengan menggunakan pam udara yang berbeza daripada segi kadar aliran, tempoh penyimpanan, jenis larutan penyerap dan keadaan tiub penyerap. Sampel yang diperoleh kemudiaanya dianalisis secara kaedah kolorimetri sebagai sebatian aktif metilena biru (MBAS) bagi surfaktan anionik dan sebagai sebatian aktif disulfina biru (DBAS) bagi surfaktan kationik. Serapan analit seterusnya diukur dengan menggunakan spektrometer ultra lembayung boleh nampak pada panjang gelombang 650 nm bagi MBAS dan 628 nm bagi DBAS. Hasil kajian menunjukkan bahawa keadaan yang optimum bagi pensampelan surfaktan adalah dengan menggunakan campuran larutan penyerap (air nyahion, larutan penimbal dan larutan metilena biru/disulfina biru) pada kadar alir 1.0 L/min. Kepekatan surfaktan didapati malar bagi tempoh penyimpanan 1 hari dan 4 hari, menunjukkan sukfaktan di dalam larutan penyerap adalah agak stabil. Penutupan tiub penyerap didapati mampu mempengaruhi kepekatan kedua-dua surfaktan yang ditentukan.
Kata kunci: Kaedah kolorimetri; surfaktan anionik dan kationik; udara persekitaran
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*Pengarang untuk surat-menyurat; email: talib@ukm.my
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