Use of solid-phase extraction, reverse osmosis and vacuum distillation for recovery of aromatic sulfonic acids from aquatic environment followed by their determination using liquid chromatography-electrospray ionization tandem mass spectrometry.
Three different sample preparation techniques (i) solid-phase extraction, (ii) reverse osmosis and (iii) vacuum distillation have been investigated and the recoveries were compared for determination of highly water-soluble benzene and stilbene sulfonic acids in aqueous environment by liquid chromatography with photodiode array (PDA) and electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The recoveries were quite high using vacuum distillation (>90%) compared to solid phase extraction and reverse osmosis. The negative ion ESI mass spectra containing the peaks of quasimolecular ion [M-H]- allow the molecular mass determination of unknown compounds whereas the structures were proposed using fragments obtained from MS/MS analysis of [M-H]- ions. At lower fragmentation voltages only the quasimolecular ion [M-H]- was observed and as fragmentation voltages increased, it led to the formation of fragment ions corresponding to [M-H-SO3]-, [M-H-SO2]-, and SO3-. The detection limits were 1-28 microg/L with LC-ESI-MS. The sample collected from wastewater treatment plant was found to contain 21.1, 13.3, 12.1, 41.8 and 9.9 microg/L of cis-4,4(l)-diaminostilbene-2,2(l)-disulfonic acid (cis-DASDA), trans-4,4(l)-diaminostilbene-2,2(l)-disulfonic acid (trans-DASDA), 3-amino acetanilide-4-sulfonic acid (3-AASA), 4-chloroaniline-2-sulfonic acid (4-CASA), 2-chloroaniline-5-sulfonic acid (2-CASA), respectively.
Analytical Chemistry Division, Discovery Laboratory, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500007, India. rnrao55@yahoo.com
R Nageswara
RN
Rao
N
N
Venkateswarlu
Sara
S
Khalid
R
R
Narsimha
S
S
Sridhar
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D009995:Osmosis; D012680:Sensitivity and Specificity; D012722:Sewage; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013451:Sulfonic Acids / Q000302:isolation & purification*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
D012722:Sewage; D013451:Sulfonic Acids; D014874:Water Pollutants, Chemical