Resonance Rayleigh scattering for detection of proteins in HPLC

Utility of Cilefa Pink B, a foodstuff dye as a fluoro-substrate in the devising of the first facile green Molecular-mass-Related Fluorescence Sensor for quantifying amlodipine in batched material and dosage forms; content uniformity evaluation

This study introduces the first and unique Molecular-mass-Related Fluorescence Sensor as the first fluorimetric strategy for determining amlodipine. An environmentally friendly, single-step, and direct spectrofluorimetric approach was utilized to evaluate the analyte. In an acidic setting, combining the amlodipine medication and the fluorescent dye Cilefa Pink B generated an instantaneous ultra-fluorescent product. An increase in dye response after adding amlodipine was proportional to the molecular weight of the generated complex, as measured at 329 nm. was the idea ofthe applied fluorimetric analysis. The complexing process increased the molecular mass from 879.86 to 1288.739 g mol-1. The medication's range of 0.050-1.00 µg mL-1 is directly correlated with this molecular massenlargement. The ideal settings for the changeable parameters of the system were established through an analysis of the response of the amlodipine-Cilefa Pink B system. Furthermore, the developed sensor complied with ICH (International Council for Harmonization) standards. The sensitivity limits were 0.0139 µg mL-1 (for the detection limit, LOD) and 0.042 µg mL-1 (for the quantification limit, LOQ). Additionally, this method effectively recovered the drug in its original and therapeutic dosage forms. Finally, the proposed process's environmental impact was also assessed through different modern greenness evaluation tools.

The unique physical shading pattern of Rayleigh scattering for the generally improved detection of scattering particles

A facile physical shading method, based on the Rayleigh scattering pattern, exhibited excellent performance detection because of its reduced background noise.

High-performance liquid chromatography associated with resonance Rayleigh scattering spectral study of the interactions of palladium(ii)–antimigraine chelates with Erythrosin B and their analytical applications

For the first time, a highly sensitive and selective detection technology of high-performance liquid chromatography associated with resonance Rayleigh scattering spectra (HPLC-RRS) is applied to analyze migraine drugs including zolmitriptan (ZON) and rizatriptan (RIN).

High-performance liquid chromatography study of gatifloxacin and sparfloxacin using erythrosine as post-column resonance Rayleigh scattering reagent and mechanism study

Herein, a highly selective high-performance liquid chromatography (HPLC) coupled with resonance Rayleigh scattering (RRS) method was developed to detect gatifloxacin (GFLX) and sparfloxacin (SPLX). GFLX and SPLX were first separated by HPLC, then, in pH 4.4 Britton-Robinson (BR) buffer medium, protonic quaternary ammonia cation of GFLX and SPLX reacted with erythrosine (ERY) to form 1:1 ion-association complexes, which resulted in a significant enhancement of RRS signal. The experimental conditions of HPLC and post-column RRS have been investigated, including detection wavelength, flow rate, pH, reacting tube length and reaction temperature. Reaction mechanism were studied in detail by calculating the distribution fraction. The maximum RRS signals for GFLX and SPLX were recorded at λ_ex  = λ_em  = 330 nm. The detection limits were 3.8 ng ml^-1 for GFLX and 17.5 ng ml^-1 for SPLX at a signal-to-noise ratio of 3. The developed method was successfully applied to the determination of GFLX and SPLX in water samples. Recoveries from spiked water samples were 97.56-98.85%.

Resonance Rayleigh scattering technique as a detection method for the RP-HPLC determination of local anaesthetics in human urine

A highly selective and sensitive method of reversed phase high-performance liquid chromatography (RP-HPLC) coupled with resonance Rayleigh scattering (RRS) was developed for the determination of procaine, bupivacaine and tetracaine. Separation of three local anaesthetics was achieved at 35 °C on a C₁₈ column. The mobile phase was 30: 70 (v/v) acetonitrile/triethylamine-phosphoric acid buffer (pH 2.9) at flow rate of 0.3 mL/min. The RRS detection was conducted by taking advantage of the strong RRS enhancement of the local anaesthetics with erythrosine reaction in an acidic medium. Under optimum conditions, the limit of detection (S/N = 3) values were in the range of 2.4-11.2 ng/mL. Recoveries from spiked human urine samples were 95.8%-104.5%. The proposed method applied to the determination of local anaesthetics in human urine achieved satisfactory results. In addition, the mechanism of the reaction is fully discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Rayleigh light scattering detection of three α1-adrenoceptor antagonists coupled with high performance liquid chromatograph

Herein, a Rayleigh light-scattering (RLS) detection method combined with high performance liquid chromatograph (HPLC) without any post-column probe was developed for the separation and determination of three α₁-adrenoceptor antagonists. The quantitative analysis is benefiting from RLS signal enhancement upon addition of methanol which induced molecular aggregation to form an hydrophobic interface between aggregates and water that produce a sort of superficial enhanced scattering effect. A good chromatographic separation among the compounds was achieved using a Gemini 5u C₁₈ reversed phase column (250 mm × 4.6 mm; 4 μm) with a mobile phase consisting of methanol and ammonium acetate-formic acid buffer solution (25 mM; pH=3.0) at the flow rate of 0.7 mL min(-1). The RLS signal was monitored at λex=λem=354 nm. A limit of detection (LOD) of 0.065-0.70 μg L(-1) was reached and a linear range was found between peak height and concentration in the range of 0.75-15 μg L(-1) for doxazosin mesylate (DOX), 0.075-3.0 μg L(-1) for prazosin hydrochloride (PRH), and 0.25-5 μg L(-1) for terazosin hydrochloride (TEH), with linear regression coefficients all above 0.999. Recoveries from spiked urine samples were 88.4-99.0% which is within acceptable limits. The proposed method is convenient, reliable and sensitive which has been used successfully in human urine samples.

High performance liquid chromatography coupled with resonance Rayleigh scattering for the detection of three fluoroquinolones and mechanism study

A reliable and versatile high performance liquid chromatography coupled with resonance Rayleigh scattering method was established for the determination of three fluoroquinolones, including levofloxacin, norfloxacin and enrofloxacin in water sample and human urine sample. In pH 4.4-4.6 Britton-Robinson buffer medium, the fluoroquinolones separated by high performance liquid chromatography could react with erythrosine to form 1:1 ion-association complexes, which could make contributions to the great enhancement of RRS. The resonance Rayleigh scattering signal was recorded at λex=λem=330 nm. The resonance Rayleigh scattering spectral characteristics of the drugs and the experimental conditions such as pH, detection wavelength, erythrosine concentration, flow rate, the length of reaction tube were studied. Quantum chemistry calculation, Fourier transform infrared spectroscopy and absorption spectroscopy were used to discuss the reaction mechanism. The recoveries of samples added standard ranged from 97.53% to 102.00%, and the relative standard deviation was below 4.64%. The limit of detection (S/N=3) of 0.05-0.12 μg mL(-1) was reached, and the linear regression coefficients were all above 0.999. The proposed method was proved as a simple, low cost and high sensitivity method.

A high selective and sensitive method for the detection of six psychotropic drugs in human urine by high performance liquid chromatography combined with resonance Rayleigh scattering spectra

A highly selective and sensitive method of high performance liquid chromatography combined with resonance Rayleigh scattering spectra was developed for the detection of six psychotropic drugs: Doxepin, Promethazine, Imipramine, Amitriptyline, Chlorpromazine and Clomipramine.

[Determination of netilmicin in rat serum using high performance liquid chromatography and resonance Rayleigh scattering]

A method was developed for the direct determination of netilmicin in rat serum using high performance liquid chromatography and resonance Rayleigh scattering (RRS). The separation was carried out on a C18 column with the isocratic elution of the mixture of 20 mmol/L sodium acetate aqueous solution and methanol containing 0.22% trifluoroacetic acid (92:8, v/v). With the molecular recognition probe of pontamine sky blue, netilmicin formed an ion-association complex and enhanced the intensity of RRS. The RRS signal was detected by a commercial fluorescence detector at 365 nm of both excitation wavelength (lambda ex) and emission wavelength (lambda em). Under the optimized conditions, the limit of detection (LOD, S/N = 3) for the netilmicin was 0.7 mg/L. With the internal standard (IS) of tobramycin, a linear calibration curve ranged from 1.2 mg/L to 30 mg/L was obtained. The presented method can be used for the pharmacokinetics study of netilmicin in rat serum, and can be a new choice for the determination of aminoglycoside antibiotics in biological samples.

The investigation of the interactions between CdSe quantum dots and human serum albumin by resonance Rayleigh scattering and second-order scattering spectra

Human serum albumin (HSA) was the most abundant protein in human plasma and has significant physiological function. In Tris-HCl buffer solution (pH 7.4), water-soluble semiconductor CdSe quantum dots (QDs) reacted with HSA and the products resulted in a great enhancement of the intensity of resonance Rayleigh scattering (RRS) and second-order scattering (SOS). Based on this, a new method was developed to investigate the interactions between QDs and HSA. The parameters with regard to determination were optimized, and the reaction mechanism was discussed. Under optimal conditions, the increments of scattering intensity (DeltaI) were directly proportional to the concentrations of HSA in the range of 0.4-48.0 micromol L(-1). The detection limits were 0.10 micromol L(-1) for RRS method and 0.25 micromol L(-1) for SOS method. The proposed method was sensitive, simple and rapid. It has been successfully applied to the determination of HSA in human urine samples. Analytical results obtained with this novel assay were satisfactory.