Separation and determination of β-agonists in serum by capillary zone electrophoresis with amperometric detection

Simultaneous Detection of Clenbuterol and Higenamine in Urine Samples Using Interference-Free SERS Tags Combined with Magnetic Separation

Sports doping remains a significant challenge in competitive sports. Given that urine analysis is the standard for detecting doping, developing rapid, sensitive, accurate, and high-throughput methods for stimulant detection in urine is crucial. Surface-enhanced Raman scattering (SERS) tag-based immunoassays have emerged as powerful analytical tools known for their high sensitivity and specificity, holding particular promise for stimulant detection in urine samples. However, both the Raman signals of typical SERS tags and sample matrices are within the Raman fingerprint region (<1800 cm-1), which could lead to spectrum overlap, potentially reducing detection accuracy and sensitivity. By recognizing this, we designed a competitive immunoassay that integrates two types of zero-background SERS tags and magnetic separation. These innovative SERS tags exhibit distinctive Raman peaks within the Raman-silent region (1800-2800 cm-1), effectively mitigating potential spectrum overlap with background sample signals. Moreover, magnetic separation not only enhances operational simplicity but also improves the system's anti-interference capability. Using clenbuterol (CL) and higenamine (HM) as model targets, the SERS-based competitive immunoassay demonstrated sensitive detection of individual CL or HM standards, with limits of detection (LODs) of 0.87 and 0.71 pg/mL, respectively. In multiplex mode, CL and HM can be simultaneously detected with LODs of 1.0 and 0.81 pg/mL, respectively. Furthermore, the recovery rates in urine samples ranged from 83 to 116% (relative standard deviation, RSD ≤ 6.4%) for CL and from 82 to 103% (RSD ≤ 5.1%) for HM, further confirming the reliability of the SERS-based immunoassay for practical applications.

Green spectrofluorimetric determination of salmeterol xinafoate in its pure forms, medicinal commercial formula, and human plasma: Application for stability studies

A natural, accurate, extremely rapid, and precise spectrofluorometric method has been developed and validated for determination of salmeterol (SAL) xinafoate in its medicinal commercial form and spiked human plasma. The native SAL fluorescence has been measured at 415 nm (after 340 nm as excitation) in distilled water. Different factors affecting the native fluorescence consistency of SAL were surveyed and optimized. The suggested procedure was capable of SAL determination over concentrations ranging 200-2000 ng.mL^-1 with excellent correlation coefficient of 0.9995. The limits of detection and quantification were estimated as 44.44 ng mL^-1 and 134.66 ng mL^-1 , respectively. The method has good accuracy and precision. The green spectrofluorometric method was used for determination of SAL in its commercial preparations and the results were in accordance with other reported methods regarding accuracy and precision. Moreover, the proposed procedure was enforced for stability indicating assay of SAL and for SAL determination in spiked human plasma. Nearly no cost, high sensitivity, and wide application make the proposed method ideally suited for analysis of SAL in quality control laboratories.

A novel microfluidic paper-based analytical device based on chemiluminescence for the determination of β-agonists in swine hair

β-Agonists are illegal feed additives in the feed industries of many countries, especially China. Here, we report a microfluidic paper-based analytical device (μPAD) coupled with the chemiluminescence (CL) method to provide the sensitive, simple and rapid quantitative detection of β-agonists in swine hair samples. In this study, we found that the β-agonists diminished the CL generated by the reaction of K3[Fe(CN)6] and luminol on μPAD, which was different from that observed in the aqueous solution, and the degree of diminishment was proportional to the concentration of β-agonists. The possible mechanism was discussed as well. Also, this detection method showed a wide linear range (from 4.0 × 10-8 to 1.0 × 10-5 mol L-1) and low limit of detection (2.0 × 10-8 mol L-1) with a low consumption of samples and reagents. Satisfactory recovery values (from 78% to 95%) were achieved. Therefore, our μPAD CL sensor will be favorable to develop a miniaturized instrument for the on-site analysis of β-agonists in swine hair samples.

Using gold nanoparticles as probe for detection of salmeterol xinafoate by resonance Rayleigh light scattering

The paper explores the method of determination of salmeterol xinafoate at nanogram level with gold nanoparticles (AuNPs) probe, to measure the intensity of resonance Rayleigh light scattering (RLS) by a common spectrofluorometer. The RLS intensity of salmeterol xinafoate was greatly enhanced by AuNPs, with the maximum scattering peak at 357 nm. The salmeterol xinafoate was determined basing on the binding of salmeterol xinafoate to AuNPs by electrostatic adsorption. Under the optimum conditions, the enhanced RLS intensity was directly proportional to the concentration of salmeterol xinafoate in the range of 0.054-6.038 μg mL(-1) with a good linear relationship (r=0.9928). The limit of detection (LOD) was 9.48 ng mL(-1). The interference tests were performed carefully. With the proposed method, the synthetic samples were analyzed satisfactorily, the recovery and RSD were 102.5-103.0% and 0.67-1.0% respectively.

Minimizing matrix effects in the development of a method for the determination of salmeterol in human plasma by LC/MS/MS at low pg/mL concentration levels

Salmeterol is an inhaled bronchodilator drug used for treatment of asthma. Its concentrations in plasma are very low or undetectable by previously developed methods. The present paper describes a method for analysis of salmeterol in human plasma with 2.5 pg/mL lower limit of quantitation. Despite the basic character of the drug the method uses mixed mode anion-exchange solid phase extraction for sample preparation combined with a column switching approach to minimize matrix effects. Samples are separated and detected by LC/MS/MS. The method is easy to use, only requires 0.5 mL of plasma and was validated for use in bioanalytical applications. The method does not suffer from interference from co-administered fluticasone propionate.

Microchip Capillary Electrophoresis for Point-of-Care Analysis of Lithium

Background: Microchip capillary electrophoresis (CE) is a promising method for chemical analysis of complex samples such as whole blood. We evaluated the method for point-of-care testing of lithium.

Methods: Chemical separation was performed on standard glass microchip CE devices with a conductivity detector as described in previous work. Here we demonstrate a new sample-to-chip interface. Initially, we took a glass capillary as a sample collector for whole blood from a finger stick. In addition, we designed a novel disposable sample collector and tested it against the clinical standard at the hospital (Medisch Spectrum Twente). Both types of collectors require &lt;10 μL of test fluid. The collectors contain an integrated filter membrane, which prevents the transfer of blood cells into the microchip. The combination of such a sample collector with microchip CE allows point-of-care measurements without the need for off-chip sample treatment. This new on-chip protocol was verified against routine lithium testing of 5 patients in the hospital.

Results: Sodium, lithium, magnesium, and calcium were separated in &lt;20 s. The detection limit for lithium was 0.15 mmol/L.

Conclusions: The new microchip CE system provides a convenient and rapid method for point-of-care testing of electrolytes in serum and whole blood.

Factorial design applied to a non-aqueous capillary electrophoresis method for the separation of β-agonists

The aim of this work was to study the effects of both chemical and instrumental parameters on the separation of beta-agonists (clenbuterol (CLE), salbutamol (SAL) and terbutaline (TER)) by non-aqueous capillary electrophoresis (NACE) method. Due to the number of parameters involved and their interactions, factorial experimental designs (EDs) at two levels was applied to investigate the influence of experimental factors (ionic strength of the background electrolyte (BGE), organic solvent, injection time, voltage and temperature) in sets of several CE responses (resolution, (RS), number of theoretical plate (N), tailing factor (TF) and migration time (tm)). As a compromise between the four responses, the optimum condition was obtained in 18 mM ammonium acetate in methanol (MeOH):acetonitrile (ACN):glacial acetic acid (66:33:1%, v/v/v) using an injection time of 4 s, the voltage and the temperature of 28 kV and 24 degrees C, respectively. The proposed NACE permitted the baseline separation of the three beta-agonists within 10.5 min with good repeatability (%RSD < 3.5%) and linearity (r2 > 0.99). The developed method was applicable for the analysis of the beta-agonists in syrup and tablets and the NACE condition was compatible with a mass spectrometer detector.

Study on pharmacokinetics and tissue distribution of norvancomycin in rats by CE with electrochemical detection

In this paper, we developed a sensitive and simple method to study the pharmacokinetics and tissue distribution of norvancomycin (NVCM) in experimental animals by using CE with electrochemical detection. Pharmacokinetics investigation was performed by the collection of blood samples at timed intervals following administration of NVCM. Pharmacokinetic parameters were calculated by the 3P87 pharmacokinetic program. The elimination half-life of NVCM was 42.4742 min with a clearance rate of 0.0233 mL x kg(-1) x min(-1). Additionally, drug distribution was studied by measuring the NVCM levels in kidney, lung, stomach, intestine, spleen, heart, liver, and cerebrum. Electrophoresis conditions such as buffer solution, working potential, separation voltage, and sampling time were also discussed. The linear range was from 0.8 to 540 microg/mL with a correlation coefficient of 0.9991. The detection limit was 0.3 microg/mL. This method was for the first time applied to study the pharmacokinetics and tissue distributions of NVCM in experimental animals.

Determination of salbutamol in syrups by capillary electrophoresis with contactless conductivity detection (CE-C4D)

This paper describes the separation and quantification of salbutamol in pharmaceutical products (salbutamol syrups) by capillary electrophoresis (CE) with contactless conductivity detection (C(4)D). The system was studied by micellar electrokinetic capillary chromatography (MEKC) and free solution capillary electrophoresis (FSCE), being the latter chosen in function of best resolution and sensitivity in comparison with the MEKC method. CE-C(4)D was applied to analysis of salbutamol in syrups utilizing 1.0 x 10(-2) molL(-1) acetic acid/sodium acetate buffer (pH 4.9) as running electrolyte. Tetraethylammonium (TEA) solution was used as internal standard. The results obtained include a linear dynamic range from 7. x 10(-5) to 3.0 x 10(-4) molL(-1) and good repeatability (R.S.D.=4.7% for n=10 for a 7.0 x 10(-5) molL(-1) salbutamol solution). The detection limit was calculated as 1.0 x 10(-5) molL(-1) and the limit of quantification was estimated as 3.3 x 10(-5) molL(-1). For syrups analysis the reproducibility presented deviations between 1.5% and 2.5% (three different days) obtained for measurements in triplicate.

Determination of Salbutamol in Pharmaceuticals by Capillary Electrophoresis

A capillary electrophoresis (CE) method for the separation and determination of salbutamol (SAL) in commercial pharmaceuticals was developed. Several parameters affecting the separations were studied including type and concentration of the carrier ion, counter ion, and the pH of the buffer. A hydrodynamically closed CE separation mode employing a 300 mum I.D. capillary, dynamically coated by polymeric buffer additive, provided good performance parameters (precision, accuracy, sensitivity). The obtained results suggest that the proposed method is suitable for routine assay of SAL in pharmaceutical preparations and can be used as an alternative to the conventional open CE mode for this application.

Sensitive detection of salbutamol using europium-enhanced fluorescence with trioctylphosphine oxide (TOPO) as coligand

In this work a simple and sensitive fluorimetric method for determination of salbutamol (4-[2-(tert-butylamino)-1-hydroxyethyl]-2-(hydroxymethyl) phenol) using an Eu enhanced signal was developed. The employed methodology is based on the formation of a ternary complex formed with Eu, salbutamol and trioctylphosphine oxide (TOPO). Intermolecular transfer of energy from the excited organic molecule to the lanthanide followed by lanthanide emission is responsible for excitation of the lanthanide ion in complex solutions and fluorescent enhancement. The luminescence properties of the ternary complex formed with TOPO and optimum formation conditions were investigated. The calibration curve is linear in the range between 6.92-180 microg l(-1) of salbutamol. The detection limit was 2.31 microg l(-1). Common excipients for these formulations were not found to interfere. A proposed method for the assay in commercial aerosols and nebulizer solutions containing salbutamol was applied with very good precision.

Amperometric and voltammetric detection for capillary electrophoresis

The focus of this article is amperometric and voltammetric detection coupled with capillary electrophoresis. Fundamental concepts and progress in the field of capillary electrophoresis with electrochemical detection (CEEC) that have occurred within the past three years, including new methodologies and unique applications, are highlighted. This review contains 95 references.