A new magnetic nanodiamond/graphene oxide hybrid (Fe3O4@ND@GO) material for pre-concentration and sensitive determination of sildenafil in alleged herbal aphrodisiacs by HPLC-DAD system
Introduction
Nowadays herbal medicines and dietary supplements are taking an active part in people's health care, therapy and prevention of disease throughout the world [1,2]. However, there is important problem that some manufacturers illegally may add synthetic drugs in their products [3,4]. Most existing determination methods for screening illegal adulterations are time-consuming and liable to false positive due to the extremely complex matrices of those products and low concentration of target species [5,6].
Sildenafil citrate is a common active agent used for erectile dysfunction by acting as a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Its chemical name is known as 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidine-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine citrate as chemically [7,8]. It is rapidly absorbed after oral administration with an absolute bioavailability of about 40%. Recently, consumption of sildenafil citrate has been increasing as legal and illegal. It has a big commercial market for both an active ingredient for trade drugs and supplementary for herbal products.
The use of dietary supplements and herbal products has increased greatly during the past 40 years as an alternative to conventional medicines. As known, the belief about natural products which are inherently safer and healthier is commonly accepted in every country. Over 30% of modern pharmaceuticals are obtained from natural botanical sources, but it can be dangerous if the required controls are carried out by legal establishment [9,10]. The potential health benefits and risk of natural herbals should be considered together.
The high consumption of this molecule as drug or dietary supplements all over the world indicates the importance of the development of new analytical approaches to follow not only the quality but also the authenticity of products including sildenafil citrate [11]. Nevertheless, several analytical methods have been developed for the determination of sildenafil in herbal products [12], pharmaceutical formulations [13], using colorimetry [14], spectrophotometry [15].
The chromatographic methods are mainly preferred for rapid determination of sildenafil derivatives. But, it needs more sensitive and selective methods for real samples. The determination of sildenafil in herbal samples needs pre-treatments due to complex matrix while the determinations in trade drugs are carried out comparably more simple [16,17]. Therefore, it was considered worthwhile to develop rapid and sensitive procedures suitable for the routine quality control analysis of drug and herbal samples [[18], [19], [20]].
Solid phase extraction (SPE) methods are mainly preferred in sample preparation owing to useful and practical properties [21,22]. SPE methods are mainly used as column and batch type. Application of column methods for routine analysis is mostly limited by sample volume, process time, complex structure of sample, and costs. The most important challenge in batch methods are final separation of solid phase and selectivity of solid phase for target species [23]. Use of magnetic solids in SPE methods provided important advantages to overcome these complications [24,25]. Their magnetic properties help easy separation using a magnet, after accumulation of target molecules on particles. Moreover, the required selectivity can be obtained by covering the core with functional groups selective for analyte species. These are ideal properties expected from an effective pre-concentration and separation method.
In recent years, hybrid materials with wonderful chemical and physical features have attracted scientific attention for their potential applications in many areas such as adsorption, catalysis, biosensor, energy conversion, gas sensor, fuel cells and so on. Especially, carbon based new generation hybrid materials consist of carbon nanotubes (CNTs), graphene, graphene oxide and nanodiamond have been intensively investigated for analytical applications as adsorbent because of the their high surface area, high mechanical stability for harsh medium, tailorability and functionality properties. Among of these carbon based materials, graphene and graphene oxide (GO) as two-dimensional material has recently been the subject of analytical chemistry, due to their wonderful chemical and mechanical properties that are comparable to or even better than other used materials in literature. Even so, for the practical application of GO based adsorbents, the main problem is the important π–π stacking interactions between GO nanosheets, which cause serious aggregation and restacking of GO nanosheets, and consequently minimize their specific surface area and block active adsorption sites on GO. To solve this aggregation and restacking problems, the one of the most effective ways is to place nano-sized materials such as CNTs, nanodiamond, metal nanoparticles and so on between the GO sheets to prevent them from sticking and aggregation [26,27]. In this study, in order to remove the above-mentioned difficulties of use of the GO as a good adsorbent and to isolate the synthesized ND@GO hybrid materials from sample and elution solutions, we modified the GO with nanodiamond particles and magnetic particles.
This study describes the synthesis and usability of a new generation magnetic hybrid material as adsorbent for magnetic solid phase extraction of sildenafil citrate prior to reversed-phase HPLC determination. The developed MSPE method was then applied the determination of the sildenafil citrate in commercial herbal products and in the tablet dosage form.
Section snippets
Instrumentation
The FT-IR characterization of the GO, ND@GO and Fe3O4@ND@GO materials were carried out by Perkin-Elmer Spectrum 400 FT-IR spectrometer (Waltham, MA, USA). The Raman spectrums of the GO, pristine nanodiamond and Fe3O4@ND@GO material were obtained by using Raman spectroscopy (WITec alpha 300 M + micro-Raman system with 532 nm laser source). X-ray diffraction (XRD) spectrums of ND@GO and Fe3O4@ND@GO materials were obtained using an advanced XRD diffractometer (Bruker AXS D8). Scanning electron
Characterization of the magnetic adsorbent
The XRD pattern of the pristine ND, GO synthesized and Fe3O4@ND@GO composite synthesized were illustrated in Fig. 3A–C. The diffraction pattern of the pristine ND has a peak at 2θ = 44.0° corresponding to the diamond planes, the other peak around at 24° corresponds to the (002) graphite crystal plane (Fig. 3A). The spectra of pristine GO exhibited the main features related to a reflection peak at 2 h = 11.4°, which is in good agreement with the literature (Fig. 3B) [23,24]. The results of XRD
Conclusions
The proposed MSPE technique based on the synthesized magnetic adsorbent (Fe3O4@ND@GO) was demonstrated to be an efficient strategy for the rapid preconcentration and separation of sildenafil in complex matrices such as herbal products. The described enrichment procedure for the determination of sildenafil is relatively simple and powerful. The magnetic support can be reused up to 10 times. The extraction technique is a robust pre-concentration technique that can be coupled successfully to
References (35)
- et al.
The genus Lycium as food and medicine: a botanical, ethnobotanical and historical review
J. Ethnopharmacol.
(2018) - et al.
URB-754: a new class of designer drug and 12 synthetic cannabinoids detected in illegal products
Forensic Sci. Int.
(2013) - et al.
Application of ultra-high-performance liquid chromatography coupled with LTQ-Orbitrap mass spectrometry for identification, confirmation and quantitation of illegal adulterated weight-loss drugs in plant dietary supplements
J. Chromatogr. B Anal. Technol. Biomed. Life Sci.
(2017) - et al.
Application of an ultrahigh-performance liquid chromatography coupled to quadrupole-orbitrap high-resolution mass spectrometry for the rapid screening, identification and quantification of illegal adulterated glucocorticoids in herbal medicines
J. Chromatogr. B Anal. Technol. Biomed. Life Sci.
(2016) - et al.
The quality of sildenafil active substance of illegal source
J. Pharm. Biomed. Anal.
(2016) - et al.
Analysis of undeclared synthetic phosphodiesterase-5 inhibitors in dietary supplements and herbal matrices by LC-ESI-MS and LC-UV
J. Pharm. Biomed. Anal.
(2004) - et al.
Safety evaluation of functional ingredients
Food Chem. Toxicol.
(2003) - et al.
Extractive spectrophotometric methods for the assay of sildenafil citrate (Viagra) in pure form and in pharmaceutical formulations
Talanta
(2002) A versatile hydrogel including bentonite and gallocyanine for trace Rhodamine B analysis
Colloids Surf. A Physicochem. Eng. Asp.
(2017)- et al.
Disperse magnetic solid phase microextraction and surface enhanced Raman scattering (Dis-MSPME-SERS) for the rapid detection of trace illegally chemicals
Talanta
(2018)
Novel synthesis of nanocomposite for the extraction of Sildenafil Citrate (Viagra) from water and urine samples: process screening and optimization
Ultrason. Sonochem.
Rapid and automated on-line solid phase extraction HPLC–MS/MS with peak focusing for the determination of ochratoxin A in wine samples
Food Chem.
Preparation and characterization of magnetic carboxylated nanodiamonds for vortex-assisted magnetic solid-phase extraction of ziram in food and water samples
Talanta
Preparation and characterization of magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) nanocomposite for vortex assisted magnetic solid phase extraction of some metal ions
Talanta
Magnetic solid-phase extraction based on methylcellulose coated-Fe 3O4-SiO2-phenyl for HPLC-DAD analysis of sildenafil and its metabolite in biological samples
Talanta
Determination of sildenafil by preconcentration on surfactant coated polymeric resin followed by spectrofluorimetry
J. Pharm. Anal.
High-performance liquid chromatographic method with amperometric detection employing boron-doped diamond electrode for the determination of sildenafil, vardenafil and their main metabolites in plasma
J. Chromatogr. A
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