In-column fiber-optic laser-induced fluorescence detection for CE

A comprehensive review on LED-induced fluorescence in diagnostic pathology

Sensitivity, specificity, mobility, and affordability are important criteria to consider for developing diagnostic instruments in common use. Fluorescence spectroscopy has been demonstrating substantial potential in the clinical diagnosis of diseases and evaluating the underlying causes of pathogenesis. A higher degree of device integration with appropriate sensitivity and reasonable cost would further boost the value of the fluorescence techniques in clinical diagnosis and aid in the reduction of healthcare expenses, which is a key economic concern in emerging markets. Light-emitting diodes (LEDs), which are inexpensive and smaller are attractive alternatives to conventional excitation sources in fluorescence spectroscopy, are gaining a lot of momentum in the development of affordable, compact analytical instruments of clinical relevance. The commercial availability of a broad range of LED wavelengths (255-4600 nm) has opened up new avenues for targeting a wide range of clinically significant molecules (both endogenous and exogenous), thereby diagnosing a range of clinical illnesses. As a result, we have specifically examined the uses of LED-induced fluorescence (LED-IF) in preclinical and clinical evaluations of pathological conditions, considering the present advancements in the field.

A simple and compact fluorescence detection system for capillary electrophoresis and its application to food analysis

A novel fluorescence detection system for CE was described and evaluated. Two miniature laser pointers were used as the excitation source. A Y-style optical fiber was used to transmit the excitation light and a four-branch optical fiber was used to collect the fluorescence. The optical fiber and optical filter were imported into a photomultiplier tube without any extra fixing device. A simplified PDMS detection cell was designed with guide channels through which the optical fibers were easily aligned to the detection window of separation capillary. According to different requirements, laser pointers and different filters were selected by simple switching and replacement. The fluorescence from four different directions was collected at the same detecting point. Thus, the sensitivity was enhanced without peak broadening. The fluorescence detection system was simple, compact, low-cost, and highly sensitive, with its functionality demonstrated by the separation and determination of red dyes and fluorescent whitening agents. The detection limit of rhodamine 6G was 7.7 nM (S/N = 3). The system was further applied to determine illegal food dyes. The CE system is potentially eligible for food safety analysis.

Internal standard method for the measurement of doxorubicin and daunorubicin by capillary electrophoresis with in-column double optical-fiber LED-induced fluorescence detection

An internal standard method has been developed for the simultaneous determination of anthracycline antibiotics, doxorubicin (DOX) and daunorubicin (DAN), in rabbit plasma using capillary electrophoresis (CE) with in-column double optical-fiber LED-induced fluorescence detection (CE-ICDOF-LED-FLD). Rhodamine B (RhB) was selected as an internal standard because its emission wavelength is similar to that of the anthracycline antibiotics. Parameters including buffer pH, buffer concentration, organic solvents and separation voltage have been investigated to explore the sensitivity and separation efficiency of DOX and DAN. The optimal electrophoretic separation conditions were a borate buffer (15 mM, pH 9.0) containing 50% acetonitrile (v/v), 10 s hydrodynamic injection at a height of 20 cm and a separation voltage of 15 kV. The developed CE-ICDOF-LED-FLD method provides limits of detection of 18 and 13 ng/mL for DOX and DAN in rabbit plasma samples, respectively. The recoveries ranging from 93.7 to 104.8% and the relative standard deviations at 1.1-1.7% were achieved for DOX and DAN in spiked rabbit plasma samples.

Improved spectrofluorimetric methods for determination of penicillamine in capsules

Two simple, sensitive and specific fluorimetric methods have been developed for the determination of Penicillamine (PNC), a sulphur containing compound. Method (I) involves the reaction of PNC with 2′,7′-bis(acetoxymercuri)-fluorescein (AMF) in the presence of Kolthoff’s buffer, pH 8.2, with subsequent measurement of fluorescence spectra at 520 nm (λEx 497 nm). Method (II) is based on PNC being oxidized into penicillaminic acid using Cerium (IV) in an acidic medium. Method sensitivity has been improved using sodium triphosphate which enhances the luminescence intensity of Ce(III). Fluorescence spectra were then measured at 348 nm (λEx 293 nm). The reaction conditions and the fluorescence spectral properties have been investigated for both methods. Under the described conditions, the proposed methods were applicable over the concentration ranges 0.0048 − 0.0288 µg mL−1 and 0.096 − 0.288 µg mL−1 with mean percentage recoveries 99.95 ± 1.29 and 100.04 ± 1.10 for methods I and II, respectively. The proposed methods were validated in terms of accuracy, precision, LOD and LOQ and robustness and then were successfully applied to the determination of PNC in bulk powder and in capsules as well as in the presence of the related disulphide. The results obtained were determined to be in good agreement with those obtained using a previously reported method.