Search Results (5)

Pharmaceutical residues in aquatic environments represent a significant pollution concern, particularly in regions experiencing rapid healthcare and industrial growth. This study presents a sensitive and environmentally sustainable analytical method for monitoring paracetamol (PAR), ibuprofen (IBU), and diclofenac sodium (DIC) in pharmaceutical wastewater from Al-Kharj Governorate, Saudi Arabia. The method integrates off-line solid-phase extraction (SPE) with field-amplified sample stacking (FASS) prior to capillary electrophoresis (CE), enabling effective dual preconcentration and enhanced detection sensitivity. Key parameters affecting separation and enrichment, including background electrolyte composition, pH, injection conditions, stacking efficiency, and SPE sorbent selection, were systematically optimized. Under optimal conditions, the SPE–CE–FASS method demonstrated excellent linearity (r² ≥ 0.997) over the concentration range of 10–1000 ng L⁻¹, with strong precision (intra- and inter-day RSD ≤ 6%) and high recoveries (91.8–98.5%) in pharmaceutical wastewater samples. Matrix-based limits of detection were 4.0 ng L⁻¹ for PAR, 3.5 ng L⁻¹ for IBU, and 3.0 ng L⁻¹ for DIC. The method was successfully applied to real wastewater samples, where all target analytes were detected at environmentally relevant concentrations. Owing to its low solvent consumption, reduced waste generation, and high sensitivity, the proposed SPE–CE–FASS method offers a reliable, cost-effective, and environmentally friendly approach for routine monitoring of pharmaceutical residues in complex wastewater matrices. Full article

To address the issue of low closed-loop feedback bandwidth caused by the long latency of Carrier-Envelope Phase (CEP) measurement systems for amplified femtosecond laser pulses, and to meet the requirements for real-time single-shot measurement in 10 kHz repetition rate systems, this paper proposes a microsecond-level low-latency CEP measurement technique based on a Field-Programmable Gate Array (FPGA). To tackle the problem of non-uniform spectral sampling resulting from nonlinear wavelength-frequency mapping, the system implements a real-time linear interpolation algorithm for the interference spectrum. This approach effectively suppresses computational spurious peaks introduced by non-uniform sampling and significantly reduces measurement errors. Adopting a fully pipelined parallel processing architecture, the system achieves a CEP processing latency of approximately 89 μs, representing an improvement of 2–3 orders of magnitude compared to traditional Central Processing Unit (CPU)-based solutions. Hardware-in-the-loop testing, conducted by injecting a known sinusoidal phase modulation into the interference spectrum of a 10 kHz laser amplification system, demonstrates that the computational error of the proposed algorithm is less than 30 mrad. This work paves the way for achieving single-shot CEP feedback locking in high-repetition-rate laser amplification systems. Full article

An in-capillary derivatization (in-CAP-D) integrated with field amplified sample stacking (FASS) has been developed for the determination of morphine (MOR) and its metabolite, morphine-6-glucuronide (MOR-6-G) in human serum using capillary zone electrophoresis (CZE) and fluorescence detection (in-Cap-D-FASS-CZE). Acetonitrile was employed in removing proteins and extracting MOR and MOR-6-G into the clear supernatant containing codeine (COD) as an internal standard (IS). The derivatization was achieved in an in-capillary mode by introducing the acetonitrile-treated samples into a running electrolyte containing an oxidizing agent of potassium ferricyanide, whereas MOR, MOR-6-G and COD were oxidized into dimer derivatives with highly fluorescent intensity. The effectiveness and sensitivity of the in-Cap-D-FASS-CZE method were affected by many parameters, and the following conditions were found to be optimal: 70 m Mdisodium tetraboratedecahydrate (pH, 10.5), 0.30 mM ferrricyanide and a separation voltage of 10 kV. In order to perform the FASS, samples were electrokinetically injected for 20 s at 20 kV into the capillary that was pre-field with a 4 s water plug. Analysis was performed at ambient temperature (22 ± 1 °C). The method’s validation revealed good linearity with respect to peak area ratios of MOR and MOR-6-G with the IS and the corresponding concentrations over the ranges of 1–2000 and 1.2 to 2000 ng/mL, respectively. Following one oral dose of controlled-release MOR sulphate tablet, the validated in-Cap-D-FASS-CZE method successfully enabled the determination of MOR and MOR-6-G in clinical serum samples. Full article

Two cheap, simple and reproducible methods for the electrophoretic determination of homocysteine thiolactone (HTL) in human urine have been developed and validated. The first method utilizes off-line single drop microextraction (SDME), whereas the second one uses off-line SDME in combination with field amplified sample injection (FASI). The off-line SDME protocol consists of the following steps: urine dilution with 0.2 mol/L, pH 8.2 phosphate buffer (1:2, v/v), chloroform addition, drop formation and extraction of HTL. The pre-concentration of HTL inside a separation capillary was performed by FASI. For sample separation, the 0.1 mol/L pH 4.75 phosphate buffer served as the background electrolyte, and HTL was detected at 240 nm. A standard fused-silica capillary (effective length 55.5 cm, 75 μm id) and a separation voltage of 21 kV (~99 μA) were used. Electrophoretic separation was completed within 7 min, whereas the LOD and LOQ for HTL were 0.04 and 0.1 μmol/L urine, respectively. The calibration curve in urine was linear in the range of 0.1–0.5 μmol/L, with R² = 0.9991. The relative standard deviation of the points of the calibration curve varied from 2.4% to 14.9%. The intra- and inter-day precision and recovery were 6.4–10.2% (average 6.0% and 6.7%) and 94.9–102.7% (average 99.7% and 99.5%), respectively. The analytical procedure was successfully applied to the analysis of spiked urine samples obtained from apparently healthy volunteers. Full article

A field-amplified sample injection-micellar electrokinetic chromatography (FASI-MEKC) method for the determination of 14 benzophenones (BPs) in a food simulant used in migration studies of food packaging materials was developed, allowing almost baseline separation in less than 21 min. The use of a 10 mM sodium dodecyl sulfate (SDS) solution as sample matrix was mandatory to achieve FASI enhancement of the analyzed BPs. A 21- to 784-fold sensitivity enhancement was achieved with FASI-MEKC, obtaining limits of detection down to 5.1–68.4 µg/L, with acceptable run-to-run precisions (RSD values lower than 22.3%) and accuracy (relative errors lower than 21.0%). Method performance was evaluated by quantifying BPs in the food simulant spiked at 500 µg/L (bellow the established specific migration limit for BP (600 µg/L) by EU legislation). For a 95% confidence level, no statistical differences were observed between found and spiked concentrations (probability at the confidence level, p value, of 0.55), showing that the proposed FASI-MEKC method is suitable for the analysis of BPs in food packaging migration studies at the levels established by EU legislation. Full article