Multi-walled Carbon Nanotubes Reinforced into Hollow Fiber by Chitosan Sol-gel for Solid/Liquid Phase Microextraction of NSAIDs from Urine Prior to HPLC-DAD Analysis

CNTs intercalated graphene oxide with interspersed MoS2 nanoparticles for selective preconcentration and determination of trace Hg(II) ions

The carbon nanotubes (CNT) intercalated graphene oxide (GO) nanosheets was functionalized with molybdenum disulfide nanoparticles (MSNP). Intercalation of CNT in between GO nanosheets significantly enhances porosity and avail both surfaces of GO for MSNP decoration. High porosity and densely populated MSNP led to faster Hg(II) ions diffusion and sorption. The material shows high selectivity for Hg(II) sorption due to sulfur rich sites. The GO/CNT@MSNP packed column employed for trace Hg(II) preconcentration and determination in fish, rice, mushroom, sunflower seeds and river and ground water samples. No significant hindrances by co-existing matrices in the determination of Hg(II) was found. The method shows a preconcentration factor of 540 and a preconcentration limit of 0.37 μg L^-1. The method detection limit was found to be 0.03 μg L^-1 and a good precision (RSD 4.2%). The Student's t test score was lower than critical Student's t value of 4.303 at the 95% confidence level. ENVIRONMENTAL IMPLICATION: Metal ions toxicity is a global issue and their trace level analysis from complex matrices is remains challenging. SPE of trace Hg(II) by graphene oxide is challenging due to agglomeration and less selectivity, nevertheless of its high surface area. We prepared a Hg(II) selective nanocomposite of MoS₂ quantum dots grows onto GO surface. The hybrid nanocomposite selectively adsorbed Hg(II) ions from complex sample matrices. Compared to a nascent GO membrane, it were more efficient to preconcentrate and determine Hg(II) from real samples and provide more accurate data for environmental monitoring and assessment of action plan to control the Hg(II) pollution.

Solvent bar microextraction combined with HPLC-DAD for simultaneous determination of diuretics in human urine and plasma samples

BACKGROUND

A simple and powerful microextraction procedure, the solvent bar microextraction (SBME), was used for the simultaneous determination of two diuretics, furosemide and spironolactone in human urine and plasma samples, using high-performance liquid chromatography coupled with diode array detection (HPLC-DAD).

METHODS

The appropriate amount (2 µL) of 1-octanol as an organic solvent confined within (2.5 cm) of a porous hollow fiber micro-tube, sealed at both ends was used for this procedure. The conditions for the SBME were optimized in water and the analytical performance were examined in spiked human urine and plasma samples.

RESULTS

The optimized method exhibited good linearity (R2 > 0.997) over the studied range of higher than 33 to 104 µg L-1 for furosemide and spironolactone in urine and plasma samples, illustrating a satisfactory precision level with RSD values between 2.1% and 9.1%.

DISCUSSION

The values of the limits of detection were found to be in the range of 6.39 to 9.67 µg L-1, and extraction recovery˃ 58.8% for both diuretics in urine and plasma samples. The applicability and effectiveness of the proposed method for the determination of furosemide and spironolactone in patient urine samples were tested.

CONCLUSION

In comparison with reference methods, the attained results demonstrated that SBME combined with HPLC-DAD was proved to be simple, inexpensive, and promising analytical technology for the simultaneous determination of furosemide and spironolactone in urine and plasma samples.