Measurement of Free Desipramine in Serum by Ultrafiltration with Immunoassay

Abstract We developed an ultrafiltration method for assaying free desipramine (DMI) in serum. An ultrafiltrate of DMI-containing serum was prepared by centrifugation through an Amicon Centrifree micropartition filter. Syva DMI solid-phase extraction (SPE) columns were used to extract the DMI from the serum and ultrafiltrate. The Syva monoclonal EMIT assay was used to quantify the DMI in the extract. In some experiments, the percent free DMI was quantified with radioactivity. Nonspecific losses of DMI in serum to the ultrafilter system were low (recoveries > 91%). Extraction of [3H]DMI from phosphate-buffered saline (to mimic serum ultrafiltrate) with the Syva SPE system was quantitative (recoveries of 98.4% +/- 4.6%). Free DMI concentrations, derived from serum containing 2.5-2500 micrograms/L DMI, were determined by ultrafiltration; results agreed well with values determined by equilibrium dialysis, the average percent of free DMI being 18.4% +/- 0.25% and 15.9% +/- 0.51%, respectively. To increase the sensitivity of the free DMI assay in the therapeutic range (total DMI 125-300 micrograms/L), we increased fourfold the ultrafiltrate volume applied to the SPE column. For free DMI at 11-130 micrograms/L, the within-run and between-run CVs for the ultrafiltration method were < 9% and < 15%, respectively. Binding of DMI to serum proteins decreased over the pH range 6.0-8.0, although temperatures between 20 and 28 degrees C did not affect binding. The ultrafiltration assay is fast, accurate, simple, and adaptable to standard laboratory instrumentation.

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A silica gel-bound macrocycle system for the selective separation of toxic cadmium from metal-affluent aqueous matrix

Open Chemistry ◽

10.2478/s11532-012-0176-1 ◽

2013 ◽

Vol 11 (3) ◽

pp. 341-347 ◽

Cited By ~ 2

Author(s):

Hiroshi Hasegawa ◽

Ismail Rahman ◽

Zinnat Begum ◽

Yoshihiro Umehara ◽

Teruya Maki ◽

...

Keyword(s):

Molecular Recognition ◽

Solid Phase Extraction ◽

Natural Waters ◽

Solid Phase ◽

Selective Separation ◽

Phase Extraction ◽

Solution Ph ◽

Retention Capacity ◽

Flow Rates ◽

Ph Range

AbstractAbstract Selective separation of cadmium(II) on a macrocycle immobilized solid phase extraction (SPE) system namely AnaLig Cd-01, and commonly known as molecular recognition technology (MRT) gel, have been examined. The MRT-SPE able to retain the cadmium from the metal-affluent aqueous matrix at the pH range of 2 to 8, and the captured species can be recovered via elution with 1 and 6 M HNO3. Besides the effects of solution pH and eluent concentration, the impacts of sample loading flow rates and coexisting matrix ions were also investigated and optimized. The Cd(II) retention capacity of the MRT-SPE was 0.26 mmol g-1, and it can be reused for more than 100 loading and elution cycles. The Cd(II) recovery attained from the metal-spiked natural waters was satisfactory (95.3–98.1%). However, the Cd(II) retention ability of the MRT-SPE was significantly decreased when excess of chelant remain in the aqueous waste matrix. Graphical abstract

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Integration of Solid-Phase Extraction and Reversed-Phase Chromatography in Single Protein-Coated Columns for Direct Injection of Bupivacaine in Human Serum

Journal of Chromatographic Science ◽

10.1093/chromsci/bmaa014 ◽

2020 ◽

Vol 58 (6) ◽

pp. 535-541

Author(s):

Walaa Zarad ◽

Heba El-Gendy ◽

Ahmed Ali ◽

Yasmine Aboulella ◽

Samy Emara

Keyword(s):

Solid Phase Extraction ◽

Human Serum ◽

Serum Proteins ◽

Solid Phase ◽

Direct Injection ◽

Reversed Phase ◽

Clinical Samples ◽

Phase Extraction ◽

Reversed Phase Chromatography ◽

Single Protein

Abstract A rapid, reliable and precise integrated solid-phase extraction (SPE) and reversed-phase liquid chromatography method was developed and validated to determine bupivacaine in human serum using single protein-coated analytical columns. The protein-coated columns were packed with four different sorbents: TSK-ODS, LiChrosorb RP-8, LiChrosorb RP-2 and μ-Bondapak CN-bonded silica. The method involved direct injection of serum sample onto the columns for trapping of the analyte, clean-up from weakly retained serum endogenous components, as well as the final separation. The protein-coated columns operated in two different chromatographic modes. Serum proteins were extracted and cleaned up by SPE, whereas the final separation of bupivacaine was based on reversed-phase chromatography. The protein-coated TSK-ODS column resulted in more accurate peak integration and more reproducible results. A linear relationship between the concentrations of drug and peak areas was confirmed in the range of 100–2000 ng/mL. Detection and quantification limits were 24.85 and 85.36 ng/mL, respectively. The average recovery for bupivacaine ranged from 96.48% to 98.81%. The present methodology was successfully applied, with a high degree of confidence, to analyze clinical samples obtained from patient receiving 0.5% bupivacaine therapy.

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Online Solid-Phase Extraction LC-MS/MS: A Rapid and Valid Method for the Determination of Perfluorinated Compounds at Sub ng·L−1 Level in Natural Water

Journal of Chemistry ◽

10.1155/2018/3780825 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 11

Author(s):

Salvatore Barreca ◽

Maddalena Busetto ◽

Matteo Vitelli ◽

Luisa Colzani ◽

Laura Clerici ◽

...

Keyword(s):

Solid Phase Extraction ◽

Water Samples ◽

Solid Phase ◽

Underground Water ◽

Phase Extraction ◽

Underground Waters ◽

Perfluorinated Compound ◽

Online Solid Phase Extraction ◽

Ph Range

In this research paper, we report a method able to detect perfluorinated compound at pg·L−1 levels in superficial and underground water samples. An online solid phase extraction HPLC-MS/MS method was developed for the analysis of 12 perfluoroalkyl acids (PFASs). The method is based on injection of 5000 µL of water sample in SPE online WAX column followed by chromatography separation and mass spectrometry determination. SPE online elution was performed by water + 0.05% NH4OH and methanol + 0.05% NH4OH, while separation of target compounds was achieved within 10 min by Gemini chromatographic column operating from 1 to 12 pH range and using a mixture of water-methanol + 0.05% NH4OH. Sub ng·L−1 method detection limits (from 0.2 to 5 ng·L−1), linearity (from 0.2 to 250 ng·L−1), accuracy (from 80 to 120%), and precision (RSD less than 15% at LOQs levels) were achieved. The method is capable of measuring PFAS at trace levels, but above all it can reach the limit of 200 pg·L−1 required by European regulation for PFOS determination in surface and underground waters. The method was validated for quantitative analysis of PFASs in real water samples.

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