Determination of para-arsanilic acid with improved diazotization reaction using differential pulse cathodic stripping voltammetry in aqueous system.
Para-arsanilic acid (p-ASA) has been widely used in the poultry industry to promote growth and prevent dysentery. It is excreted unchanged in the manure and released into non-target sites causing organoarsenic pollution risk to the environment and living system. Therefore, simple and effective analytical strategies are demanded for determining the samples that contain p-ASA. However, direct determination of both p-ASA and ortho-arsanilic acid (o-ASA) using differential pulse cathodic stripping voltammetry (DPCSV) gives the similar voltammograms that directly hamper the analysis used by the DPCSV technique. In this study, a method to determine and differentiate p-ASA from o-ASA via diazotization and coupling reaction of the amine groups followed by the direct DPCSV determination of diazo compounds is presented. The diazotization reaction carried out at pH 1.5 and 0 ± 1°C for 10 min showed two reduction peaks in DPCSV at-70 mV and -440 mV vs. Ag/AgCl (KCl 3 M). However, when the diazotization reaction was performed at pH 12.5 and 0 ± 1°C for 40 min, a coloured azo compound was produced and the DPCSV showed only one reduction peak that appeared at -600 mV vs. Ag/AgCl (3 M of KCl). The results of this study show that only p-ASA compound gave a reduction peak, whereas o-ASA compound did not give any peak. The detection limit of p-ASA was found to be 4 × 10(-8 )M. As a result, the proposed electro-analytical technique might be a good candidate to determine and differentiate the p-ASA present in the poultry and environmental samples.
a Institute of Environmental and Water Resource Management , Universiti Teknologi Malaysia , 81310 Skudai, Bahru , Johor , Malaysia.
Marpongahtun
M
Misni
Palanivel
P
Sathishkumar
Rahmalan
R
Ahamad
Abdull Rahim
AR
MohdYusoff
D000821:Animal Feed / Q000032:analysis; D001147:Arsanilic Acid / Q000032:analysis*; D001391:Azo Compounds / Q000032:analysis; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D057230:Limit of Detection; D014867:Water / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D001391:Azo Compounds; D014874:Water Pollutants, Chemical; D014867:Water; D001147:Arsanilic Acid
arsanilic acid; diazotization; differential pulse cathodic stripping voltammetry; electro-analytical method; organoarsenic pollution; poultry feed