Shivender Singh Saini

Micelle enhanced and terbium sensitized spectrofluorimetric determination of danofloxacin in milk using molecularly imprinted solid phase extraction

An efficient molecularly imprinted solid phase extraction (MISPE)-spectrofluorimetric method was developed to sensitively determine danofloxacin (DAN) in milk samples. Solid phase extraction procedure using MISPE cartridges was first performed on milk samples and then spectrofluorimetric determination was done at 546 nm using an excitation wavelength of 285 nm in presence of terbium and sodium dodecyl benzene sulfonate (SDBS). It was found that SDBS significantly enhanced the fluorescence intensity of the DAN-Tb(3+) complex. Various factors affecting the fluorescence intensity of DAN-Tb(3+)-SDBS system were studied and conditions were optimized. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of DAN over the range of 8.4×10(-9)-3.4×10(-7) mol L(-1) with a correlation coefficient of 0.9996. The detection limit was determined as 2.0×10(-9) mol L(-1) and the limit of quantification was determined as 6.5×10(-9) mol L(-1). The MISPE-spectrofluorimetric procedure was successfully applied to the determination of DAN in milk samples. The method is simple, rapid, sensitive and allows interference free determination of DAN in complex fluorescent matrices like milk. The method can be used to determine whether the DAN residues in milk exceed MRLs or not.

Trace Analysis of di-(2-Ethylhexyl) Phthalate (DEHP) in Drinking Water Using MEPS and HPLC-UV

Abstract Di-(2-ethylhexyl) phthalate (DEHP) is one of the most ubiquitous water contaminants and the most abundant phthalate in drinking water. DEHP is known for its endocrine disrupting properties. To monitor DEHP in water at trace levels is a technical challenge. This research reported a simple, less laborious and highly sensitive analytical protocol for qualitative and quantitaive analysis of DEHP in drinking water, using microextraction by packed sorbent (MEPS) and high performance liquid chromatography-ultraviolet detector (HPLC-UV). Chromatographic separation was achieved with a reversed phase C18 column, with a linear (R2 ≥ 0.999) calibration curve at 210 nm. The limit of quantification was 2.4 pg/mL. The precision and accuracy of the protocol were validated adequately with relative standard deviations ≤ 2.4% and relative errors ≤ 4% respectively. The developed protocol was successfully applied to raw water samples used for drinking purposes without any dilution and results show the presence of DEHP in the range 419.533 pg/mL to 1.297 ng/mL. The result is of particular importance for water quality analysis, providing a potential means of rapid screening to ensure safe drinking water, and to support trace level exposure assessment studies for DEHP through drinking water. Furthermore, this protocol should also allow easy expansion/modification to other phthalates in another types of water matrices, at trace levels.

A miniaturised analytical protocol for highly sensitive determination of bisphenol A in bottled drinking water

This paper proposes a novel, fast, reliable and miniaturised analytical protocol for highly sensitive determination of bisphenol A (BPA) in bottled drinking water. This hybrid approach involves a lucid and expeditious combination of micro-extraction in packed syringe (MEPS) with high performance liquid chromatography coupled to an ultra-violet detector (HPLC-UV). The method was developed, optimised and validated for the determination of BPA in commercial bottled drinking water with remarkable sensitivity to picogram quantities of BPA (ppt level). The important parameters of the MEPS procedure affecting the extraction efficiency were optimized and 50 cycles of draw–eject of the sample with a speed of 10 μl s−1 gave a maximum peak area, with a time of 0.998). Precision studies showed % RSD values less than 2% for BPA in all the selected concentrations. The percentage recoveries of BPA were in the range of 97.50–97.57. The limit of detection (LOD) and limit of quantification (LOQ) were 0.0416 pg ml−1 and 0.1248 pg ml−1 for BPA, respectively. The proposed validated method was successfully applied for the quantitative analysis of BPA in real water and beverage samples to the level of 5.40 pg ml−1 to 14.22 pg ml−1, with an acceptable RSD (%) in the range of 3–9 and is suitable for routine monitoring of BPA in bottled drinking water, for regulatory purposes. Furthermore, this method should also allow easy expansion to water quality records for BPA in different water samples and also related compounds like octyl and nonyl phenol as well as bisphenol S and bisphenol F in water.