Graphitic carbon nitrides modified hollow fiber solid phase microextraction for extraction and determination of uric acid in urine and serum coupled with gas chromatography-mass spectrometry

CVD graphene as an electrochemical sensing platform for simultaneous detection of biomolecules

“…We compared the results of various methods for the determination of concentration of the five analytes in serum (Table S5 ). In general, the concentrations of AA, DA, UA, and Trp are closer to those obtained by CL 60 , HPLC-CL 61 , GC/MS 62 , and UV methods 63 ; however, the concentration of NO 2 ˉ is significantly higher than that measured by the spectrophotometric methods in the ref. 64 .…”

Advances in Solid Phase Microextraction and Perspective on Future Directions

“…Indeed, various carbon-based extraction phases, which have been discussed in detail under the Coatings section, have been reported to date for the abovementioned applications, including electrochemically reduced graphene oxide, graphene-based nanocomposites, and graphitic carbon nitrides immobilized in hollow fiber wall pores. Such carbon-based coatings have been used for extraction of analytes such as tricyclic antidepressants (via HS) and uric acid (via DI and after solvent desorption and derivatization) in different biofluids prior to GC analysis. − Sol–gel based extraction phases with functionalities such as β-cyclodextrin, polyethylene glycol, and methacrylic acid have also been proposed as mechanically stable coatings capable of facilitating the extraction of polar compounds from urine and serum samples. , Despite the promising results provided by such coating chemistries in selected applications, their applicability in novel SPME studies is somewhat limited by the fact that such materials are mostly made in-house, and therefore, are not easily available for evaluations in new applications. In addition to the employment of alternative coatings, alternative strategies have also been reported to date in bioanalytical applications, such as the use of an electromembrane (EM) to facilitate the analysis of complex biological matrixes via DI .…”

Detection of Purine Metabolite Uric Acid with Picolinic-Acid-Functionalized Metal–Organic Frameworks

“…UA is enzymatically hydrolyzed to produce allantoin and hydrogen peroxide, after which the detection of UA is indirectly achieved by determining the content of hydrogen peroxide . Although it is widely used, this method still has many limitations, e.g., the interference from other biological analytes (ascorbate, bilirubin), long incubation time (∼30 min), strict pH conditions, expensive enzyme, and low determination accuracy. , So far, some methods have been reported to directly detect UA to avoid the shortcomings of enzyme-based assays, such as high-performance liquid chromatography, gas chromatography-mass spectrometry (GC-MS), electrochemistry, and fluorescence . Among them, fluorescence analysis is a very effective method because of the advantages of rapidness, high selectivity and sensitivity, convenience, and low cost. − Until now, only a handful of fluorescent sensors for direct UA detection have been developed including carbon dots, quantum dots, polymers, and metal–organic frameworks (MOFs) …”

“…6 Although it is widely used, this method still has many limitations, e.g., the interference from other biological analytes (ascorbate, bilirubin), long incubation time (∼30 min), strict pH conditions, expensive enzyme, and low determination accuracy. 7,8 So far, some methods have been reported to directly detect UA to avoid the shortcomings of enzyme-based assays, such as high-performance liquid chromatography, 9 gas chromatography-mass spectrometry (GC-MS), 10 electrochemistry, 11 and fluorescence. 12 Among them, fluorescence analysis is a very effective method because of the advantages of rapidness, high selectivity and sensitivity, convenience, and low cost.…”