Continuous flow hydride generation laser induced fluorescence spectrometry for trace determination of lead in water and sediment samples

Continuous flow hydride generation coupled with laser induced fluorescence spectrometry (HG-LIF) has been used for the determination of Pb in aqueous samples. Lead hydride is generated in K₃Fe(CN)₆-HCl medium using NaBH₄ as the reducing agent. Parameters such as acidity and the concentrations of oxidising and reducing agents have been studied in order to obtain the highest sensitivity. Laser excitation of Pb has been performed at 283.306 nm and fluorescence has been detected at 365 nm and 405.8 nm. The limit of detection calculated for the optimised conditions (1% K₃Fe(CN)₆ in 0.3% Oxalic Acid, 0.055 mol L^?1 HCl, 1% NaBH₄ in 0.1% NaOH) is 0.3 ng mL^?1. However, a significant Pb background was observed for blank measurements, which degraded the limit of detection. The limit of detection that is estimated for a Pb free blank was determined by detuning the laser to a wavelength of 282.806 nm and was found to be 0.45 pg mL^?1. Method repeatability is 3.5% RSD at the 10 ng mL^?1 level. The accuracy of this method has been evaluated by analysis of a water reference material. The results obtained for a multielement standard determined using the HG-LIF approach have been found to be in agreement with those obtained by using a comparison ICP-AES approach. The HG-LIF approach has been applied to the measurement of Pb in a contaminated sediment sample material. The results of this study demonstrate that a small tunable laser system combined with hydride generation sample introduction can be used to measure Pb with high sensitivity, precision and selectivity in different sample matrices.     

Solid phase extraction of trace amounts of Pb(II) in opium, heroin, lipstick, plants and water samples using modified magnetite nanoparticles prior to its atomic absorption determination

A new, simple, fast and reliable solid-phase extraction method has been developed for separation/preconcentration of trace amounts of Pb(II) using dithizone/sodium dodecyl sulfate-immobilized on alumina-coated magnetite nanoparticles, and its determination by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) after eluting with 4.0?mol?L^?1 HNO₃. Optimal experimental conditions including pH, sample volume, eluent concentration and volume, and co-existing ions have been studied and established. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range and relative standard deviation of Pb(II) using FAAS technique were 280 (for 560?mL of sample solution), 0.28?ng?mL^?1, 1.4?C70?ng?mL^?1 and 4.6% (for 10?ng?mL^?1, n?=?10), respectively. These analytical parameters using GFAAS technique were 300 (for 600?mL of sample solution), 0.002?ng?mL^?1, 0.006?C13.2?ng?mL^?1 and 3.1% (for 5?ng?mL^?1, n?=?10), respectively. The presented procedure was successfully applied for determination of Pb(II) content in opium, heroin, lipstick, plants and water samples.     

Monitoring chlorophenols in industrial effluents by solid-phase microextraction–gas chromatography–mass spectrometry

A method for the determination of 19 chlorophenols in industrial effluents samples using solid-phase microextraction (SPME) coupled to gas chromatography–mass spectrometry has been developed. Four kinds of different SPME fibres have been studied. Among them, the polyacrylate and carbowax®-divinylbenzene fibres were the most adequate. The extraction process was optimized by means of the experimental design, which allows the study of a large number of factors with a reasonable number of experiments. The optimized method allows the determination of the studied chlorophenols in complex matrices with a high organic content with detection limits down to 0.07?ng?mL^?1 and RSD ranging from 4.4% to 13.8%. The recovery studies with spiked real effluent samples at low levels of chlorophenols ranged from 59.8% to 142.1% for the lowest level (0.5?ng?mL^?1) and from 79.6% to 115.8% for the highest spiked level (2?ng?mL^?1). These results show the suitability of the proposed method to monitor chlorophenols in complex samples. 2,4,5-TCP was detected at concentrations close to its limits of detection in effluents coming from an oil refinery.     

A Simple and Sensitive LC–MS/MS Method for Simultaneous Determination of Temsirolimus and Its Major Metabolite in Human Whole Blood

A simple, fast and sensitive LC?CMS/MS method was developed and validated for the simultaneous determination of the concentrations of temsirolimus and its major metabolite, sirolimus, in human whole blood. The blood sample (100???L) after adding temsirolimus-d7 and sirolimus-d3 internal standards was precipitated with 0.200?mL of methanol/0.300?M zinc sulfate (70/30, v/v), then analyzed by a Shimatzu LC system coupled to a Sciex API-5000 mass spectrometer. The chromatographic separation was carried out on a BDS Hypersil C8 column (50?×?3.0?mm, 5???m) at 50?°C with a mobile phase composed of methanol/water/formic acid (72/28/0.1) (v/v/v) containing 2.50?mM ammonium acetate. Mass spectrometric detection was performed using electrospray positive ionization with multiple reaction monitoring mode. This method was validated from 0.250 to 100?ng?mL^?1 for temsirolimus and 0.100 to 40.0?ng?mL^?1 for sirolimus. The lower limits of quantitation were 0.25?ng?mL^?1 for temsirolimus and 0.1?ng?mL^?1 for sirolimus. The intra-day and inter-day precisions (CV?%) of spiked quality control (QC) samples were less than 10.4 and 9.6?%, respectively. The accuracies as determined by the relative error for QC samples were less than 12.1?% for intra-day and 7.3?% for inter-day. No significant matrix effect was observed. This method has been successfully applied to analyze clinical pharmacokinetic study samples. The assay reproducibility was also demonstrated by using incurred samples.     

Monoclonal antibody-based enzyme-linked immunosorbent assay for detection of total malachite green and crystal violet residues in fishery products

A rapid easy-to-use trace level direct competitive enzyme-linked immunosorbent assay (dc-ELISA) detection of total residual malachite green (MG), crystal violet (CV) and their corresponding primary metabolites leucomalachite green (LMG) and leucocrystal violet (LCV) in fishery products in a single assay was developed. The monoclonal antibodies, anti-MG and anti-CV mAbs, were prepared using carboxyl-malachite green (CMG) and cationized bovine serum albumin (cBSA) conjugates as immunogen. The linear range for the quantitative detection of total MG, CV and their primary metabolites LMG and LCV was between 0.15 to 4.5?ng?mL^?1 with a half maximal inhibitory concentration (IC₅₀) at 0.56?±?0.04?ng?mL^?1 (n?=?5). The anti-MG mAbs exhibited 98% cross-reactivity to CV, less than 0.1% cross-reactivity with LMG and LCV, and no cross-reactivity with chloramphenicol, enrofloxacin, sulfadiazine, and tetracycline. Application of the dc-ELISA in fish tissue samples gave a limit of detection (LOD) of 0.37?ng?g^?1. The improved total detection lead to a recovery of 74.60?±?8.38% at 0.5?ng?g^?1 and 87.47?±?12.83% at 2.0?ng?g^?1 that was better than existing techniques. The dc-ELISA showed total MG in 7 out of 44 field fish samples that were confirmed with LC-MS/MS. The easy-to-use, inexpensive, and rapid dc-ELISA for the detection of total MG, CV and their corresponding primary metabolites holds promise for field applications.     

Highly Sensitive Chemiluminescent Analysis of Residual Bovine Serum Albumin (BSA) Based on a Pair of Specific Monoclonal Antibodies and Peroxyoxalate–glyoxaline–PHPPA Dimer Chemiluminescent System in Vaccines

Enzyme-linked immunosorbent assay (ELISA), horseradish peroxidase (HRP)-catalyzed fluorescent reaction, and oxalate chemiluminescence analysis have been combined to develop a highly sensitive, simple, and rapid method for analysis of bovine serum albumin (BSA) based on a pair of specific monoclonal antibodies in vaccines. A typical ??sandwich type?? immunoassay was used. Reaction of 3-(4-hydroxyphenyl propionate) (PHPPA) with hydrogen peroxide-urea, catalyzed by HRP, produced fluorescence of 3-(4-hydroxyphenyl propionate) dimer, which was detected by chemiluminescence analysis with the bis(2,4,6-trichlorophenyl)oxalate (TCPO)?CH₂O₂?Cglyoxaline?CPHPPA dimer chemiluminescent system. This method exhibited high performance with a linear correlation between response and amount of bovine serum albumin (BSA) in the range 0.1 to 100.0?ng?mL^?1 (r?=?0.9988), and the detection limit was 0.03?ng?mL^?1 (S/N?=?3). Intra- and interassay coefficient variations were all lower than 9.0% at three concentrations (1.0, 20.0, and 80.0?ng?mL^?1). The proposed method has been used for successful analysis of the amount of residual BSA in vaccines. The results obtained compared well with those obtained by conventional colorimetric ELISA and luminol chemiluminescent ELISA.     

Highly sensitive inhibitory kinetics fluorescence method for determination of arsenic

A new and highly sensitive inhibitory kinetic fluorescence method for the determination of arsenic (III) has been established based on its inhibitory effect on the oxidation reaction of Acridine red (ADR) by KBrO₃ in sulphuric acid medium. The reaction has been followed by measuring the enhancement of fluorescence at 550?nm. It relies on the linear relationship where the change in the fluorescence (ΔF) versus added As(III) amounts in the range of 0–0.450?µg?mL^?1 is plotted, under the optimum conditions. The sensitivity of the proposed method, i.e. the limit of detection, is 2.1?×?10^?2?ng?mL^?1. The method is featured with good accuracy and reproducibility for arsenic (III) determination. This method was successfully applied for the quantitative determination of arsenic (III) in food products samples, and the relative standard deviations and the recoveries were in ranges of 2.31–2.83% and 90.0–107.2%, respectively. A review of recently published catalytic or inhibiting kinetic methods for the determination of arsenic (III) has also been presented for comparison. The mechanism of reaction was studied.     

Optimisation of an in-tube solid phase microextraction method coupled with HPLC for determination of some oestrogens in environmental liquid samples using different capillary columns

A simple on-line method for simultaneous determination of some oestrogens including oestriol (E3), norethisterone (NORE), ethynylestradiol (EE2), D-norgestrel (NORG) and bisphenol A (BPA), in environmental liquid samples was developed by coupling in-tube solid phase microextraction (in-tube SPME) to high-performance liquid chromatography with diode array (DAD) and fluorescence (FLD) detectors. Two capillary chromatographic columns (Supel-Q? and Carboxen? 1006 porous layer open tubular) were selected to develop this method. To achieve optimum extraction performance, several parameters were investigated including number of draw/eject cycles and the sample volume for each of the columns. Reproducibility was satisfactory for inter- and intra-day precision, yielding % RSDs of less than 10% and 7.6%, respectively. Limits of detection (LODs) and quantification (LOQs) for the proposed method using a DAD detector were achieved in the ranges of 0.04–0.63?ng?mL^?1 and 0.12–1.9?ng?mL^?1, depending of the capillary column used. Fluorescence detection improved these parameters for E3, BPA and EE2, obtaining LODs of 0.005–0.03?ng?mL^?1 and LOQs of 0.015–0.08?ng?mL^?1 using Supel-Q and LODs of 0.01–0.015?ng?mL^?1 and LOQs of 0.025–0.04?ng?mL^?1 using Carboxen. The proposed method was successfully applied to spiked environmental waters obtaining recoveries greater than 80%.     

Separation of L-DOPA and four metabolites in plasma using a porous graphitic carbon column in capillary liquid chromatography

Summary A sensitive HPLC method with marbofloxacin (MAR) as internal standard and fluorescence detection is described for the analysis of ofloxacin (OFL) enantiomers in plasma samples. Plasma samples were prepared by adding phosphate buffer (pH 7.4, 0.1m), then extracted with trichloromethane.S-OFL,R-OFL, and the internal standard were separated on a reversed-phase column with water-methanol, 85.5∶14.5, as mobile phase. The concentrations ofS-OFL andR-OFL eluting from the column (retention times 7.5 and 8.7 min, respectively) were monitored by fluorescence detection withλ _ex = 331 andλ _em = 488 nm. The detection and quantitation limits were 10 and 20 ng mL⁻¹, respectively, forS-OFL and 11 and 21 ng mL⁻¹ forR-OFL. Response was linearly related to concentration in the range 10 to 2500 ng mL⁻¹. Recovery was close to 93% for both compounds. The method was applied to determination of the enantiomers of OFL in plasma samples collected during pharmacokinetic studies.     

Simultaneous determination of carbazole-based explosives in environmental waters by dispersive liquid—liquid microextraction coupled to HPLC with UV-Vis detection

Dispersive liquid-liquid microextraction as a rapid, simple and efficient method coupled with high performance liquid chromatography-UV-Vis detection was used for sample preparation and subsequent determination of carbazole, tri nitro carbazole (TrNC) and tetra nitro carbazole in water samples. The influence of several important variables on the extraction efficiency has been evaluated. The methods works best with chloroform as an extractant and acetonitrile as the dispersive solvent. Under optimum conditions, the calibration curve is linear in the range from 0.007 to 1.75?μg?mL^?1 for TNC, 0.006 to 1.52?μg?mL^?1 for TrNC, and 0.008–2.10?μg?mL^?1 for carbazole. The limits of detection (LODs; at a signal-to-noise ratio of 3), range from 1.7 to 1.1?ng?mL^?1, for TNC, TrNC and carbazole. Also, the relative standard deviations (RSD, n?=?6) for the extraction of TNC (at 174?ng?mL^?1), TrNC (at 151?ng?mL^?1) and carbazole (at 84?ng?mL^?1) vary between 4.1 and 5.2%. The enrichment factors range from 179 to 186. The method was successfully applied to the determination of TNC, TrNC and carbazole in environmental samples.

Application of dispersive liquid–liquid microextraction for the determination of donepezil in urine by HPLC using a core–shell column

A rapid and novel method combining dispersive liquid–liquid microextraction and high-performance liquid chromatography coupled with fluorescence detection was developed for the determination of donepezil in human urine. Parameters affecting extraction efficiency and chromatographic determination, such as the type and volume of the extraction and disperser solvent, pH of sample for dispersive liquid–liquid microextraction, mobile-phase composition, pH, column oven temperature, and flow rate for chromatographic determination, were evaluated and optimized. Using a C₁₈ core–shell column (7.5 × 4.6?mm, 2.7?μm), the determination of donepezil was accomplished within 5?min. Under optimum conditions, developed method was linear in the range of 0.5–25?ng?mL^?1 with the correlation coefficient >0.99. Limit of detection was 0.15?ng?mL^?1. The relative standard deviation at three concentration levels (2, 12.5, and 20?ng?mL^?1) was less than 11% with accuracy in the range of 96.9–102.8%. The results of this study demonstrate that the use of dispersive liquid–liquid microextraction and core–shell column can be considered as a powerful tool for the analysis of donepezil in human urine.     

Extraction Spectrophotometric Determination of Trace Amounts of Perchlorate Based on Ion-Pair Formation with Thionine

A simple, rapid, and sensitive extraction-spectrophotometric method has been developed for the determination of trace amounts of perchlorate. This method is based on the extraction of perchlorate as an ion pair with thionine into isobuthyl methyl ketone and measuring the absorbance of the organic phase at 603 nm. The effect of different variables such as pH, reagent concentrations, and standing time was investigated and optimum conditions were established. The effects of other cations and anions on the extraction were also studied. The calibration curve was linear in the range of 40–1000 ng mL^?1 with correlation coefficient of 0.9998. The detection limit based on 3S_b criterion was 23 ng mL^?1 and the relative standard deviation for 400 ng mL^?1 of perchlorate was 1.9%. The proposed method was applied to determination of perchlorate in water samples.     

Enzyme-linked immunosorbent assay and colloidal gold-based immunochromatographic assay for several (fluoro)quinolones in milk

We have developed a heterologous direct competitive enzyme-linked immunosorbent assay (ELISA) and a visual colloidal gold-based immunochromatographic assay (CGIA) for simultaneous determination of ofloxacin, marbofloxacin, and fleroxacin residues in milk using polyclonal antibodies. The half-maximum inhibition concentrations (IC₅₀) of ofloxacin, marbofloxacin, fleroxacin, and limits of detection (LODs; calculated as IC₁₅ values) are between 0.20 and 0.53?ng mL^?1, and between 0.02 and 0.05?ng mL^?1, respectively. The average recoveries range from of 78% to 113%, and the coefficients of variation of intra- and inter-assays are between 2 and 11%, and 3 to 19%, respectively. The LODs for ofloxacin, marbofloxacin, fleroxacin in milk are between 3.5 and 8.9?ng mL^?1. The visual minimum detection limit of the optimized CGIA is 2?ng mL^?1 for milk samples. The detection process can be completed within 10?min. The strips can be stored at 4?°C for 8?weeks without significant loss of activity. The results of the analysis of spiked samples showed that the CGIA can be applied to preliminary, fast, and on-site screening of milk samples. The ELISA and CGIA allow for a rapid, sensitive, and low-cost determination of (fluoro)quinolones residues in milk samples.

Ultrasensitive determination of mercury in human saliva by atomic fluorescence spectrometry based on solidified floating organic drop microextraction

We report on a new, rapid and simple method for the determination of ultra-trace quantities of mercury ion in human saliva. It is based on solidified floating organic drop microextraction and detection by cold vapor atomic fluorescence spectrometry (CV-AFS). Mercury ion was complexed with diethyldithiocarbamate, and the hydrophobic complex was then extracted into fine droplets of 1-undecanol. By cooling in an ice bath after extraction, the droplets in solution solidify to form a single ball floating on the surface of solution. The solidified microdrop containing the mercury complex was then transferred for determination by CV-AFS. The effects of pH value, concentration of chelating reagent, quantity of 1-undecanol, sample volume, equilibration temperature and time were investigated. Under the optimum conditions, the preconcentration of a 25-mL sample is accomplished with an enrichment factor of 182. The limit of detection (3σ) is 2.5?ng?L^?1. The relative standard deviation for seven replicate determinations at 0.1?ng?mL^?1 level is 4.1%. The method was applied to the determination of mercury in saliva samples collected from four volunteers. Two volunteers having dental amalgam fillings had 0.4?ng?mL^?1 mercury in their saliva, whereas mercury was not detectable in the saliva of two volunteers who had no dental fillings.

Pervaporation as a Separation Technique for Direct Determination of Volatile Selenium Species by Atomic Fluorescence Spectrometry

Abstract

This paper reports for the first time a suitable way to determine methylated selenium compounds using the new approach of pervaporation coupled to atomic fluorescence spectrcmetry (PV-AFS).

The method developed allows direct extraction, separation, preconcentration and determination of dimethylselenium (DMSe) and dimethyldiselenium (DMDSe) from slurry samples. Under the optimum conditions, the detection limits (LODs) were found to be 0.66 ng and 0.39 ng for DMSe and DMDSe, respectively, the precision being about 6–9 % for 10 ng mL as selenium concentration. The linearity ranges were from the LOD to 0.7 μg mL^?1 for DMSe and from the LOD to 0.4 μg mL^?1 for DMDSe (as Se). The pervaporation efficiencies were 55 ± 1 % and 85 ± 5 % for DMSe and DMDSe, respectively. The proposed method was successfully applied to determine methylated selenium species in sewage sludge, garlic and oyster samples. The concentrations found were from 0.07 to 1.42 μg g^?1.

As no certified reference materials are available for these analytes, validation was carried out by recovery studies in these matrices, and the results showed that the proposed method performed satisfactorily.     

Comparative study of direct immersion and headspace single drop microextraction techniques for BTEX determination in water samples using GC-FID

In the present work the determination of benzene, toluene, ethylbenzene and o-xylene (BTEX) in environmental sample solutions using gas chromatography with flame ionisation detection (GC-FID) combined with three different sampling techniques, such as; direct single drop microextraction (DI-SDME), headspace single drop microextraction (HS-SDME) and ultrasonic assisted HS-SDME, were compared. In all of these techniques, for the determination of BTEX, the experimental parameters such as organic solvent effect, extraction time, agitation speed and salting effect were optimised. At their optimised conditions of operation the detection limits, times of extraction and precision for the three techniques are established. A detailed comparison of the analytical performance characteristics of these techniques for final GC-FID determination of BTEX in water samples was given. The technique provided a linear range of 50–20000?ng?mL^–1 for DI-SDME and 10–20000?ng?mL^–1 for HS-SDME methods, good repeatability (RSDs <4.72–7.74% for DI-SDME and 1.80–7.05% for HS-SDME (n?=?5), good linearity (r?≥?0.9978) and limits of detection (LODs) in the range of 0.006–10?ng?mL^?1 for DI-SDME, 0.1–3?ng?mL^–1 for HS-SDME methods (S/N?=?3). Then the optimised techniques were also applied to real samples (river and waste waters) containing BTEX and similar precision (RSD?<?8.2,?n?=?3) was obtained.     

Stochastic resonance algorithm applied to quantitative analysis for weak liquid chromatographic signal of pyrene in water samples

The phenomenon of stochastic resonance (SR), which was discovered in recent years, rendered an entirely new way for the detection of weak signals, and it has been widely studied in many different science fields. This phenomenon is manifest in nonlinear systems whereby a weak signal can be amplified when the noise, signal and nonlinear system attain the proper cooperation. The introduced algorithm was employed to detect pyrene in drinking water samples with solid-phase extraction–liquid chromatography. The weak chromatographic peak of the analyte was amplified significantly, and the profiles of the peaks were also satisfactory. The limit of detection and the limit of quantification were improved from 0.022?ng?mL^?1 and 0.08?ng?mL^?1 to 0.004?ng?mL^?1 and 0.01?ng?mL^?1, respectively. The results showed an excellent quantitative relationship between concentrations and chromatographic responses. It is expected that the SR will be an effective tool to detect weak chromatographic peaks quantitatively in trace analysis.     

A miniaturized flow-injection analysis ( μ FIA) system with on-line chemiluminescence detection for the determination of iron in estuarine water

A miniaturized flow-injection analysis system constructed from a glass base plate and polydimethylsiloxane (PDMS) top plate was employed for the determination of iron in river water. Two designs were investigated, one utilizing a syringe pump and the other utilizing EOF pumping with a mini-filtration system incorporated. The syringe pump system was used to optimize the analytical method on chip, where the pump was used to deliver both the analyte and the reagents to the reactor chip. The highly sensitive chemiluminescence reaction between alkaline luminol (3-aminophthalhydrazide) and 0.1?M of hydrogen peroxide (H₂O₂) in the presence of iron(II) was utilized. The bright blue light (λ _max?～?440?nm) emitted was detected using a miniaturized photomultiplier tube interfaced directly under the chip. The light intensity signals were recorded, and the corresponding concentration of iron(II) concentration was determined. The calibration for iron(II) standards was linear up to 0.75?µg?mL^?1 (y?=?5.7839x?+?0.0378, r² ?=?0.9939) with a precision value of up to 3.72% RSD, for n?=?3. The limits of detection (blank?+?3s _y/x) were found to be 28?ng?mL^?1. The system which utilized EOF pumping and incorporated a minifiltration unit provided a linear calibration for 0–5?µg?mL^?1 (y?=?3.316x?+?0.1831; correlation coefficient, r ²?=?0.9996) over a working range of 0.0–0.5?µg?mL^?1. This system provided lower limits of detection 5.1?ng?mL^?1 and better repeatability (%RSD less than 0.5% for n?=?4), but problems occurred with the mini-filtration system at higher iron(II) concentrations. The EOF pumping system provided slightly higher results for the concentration of iron(II) in the Humber estuary (0.058?µg?mL^?1), but these results were in line with the results expected by the Environment Agency.     

Porous carbon derived from a metal–organic framework as an efficient adsorbent for the solid‐phase extraction of phthalate esters

A porous carbon designated as MOF‐5‐C was prepared by directly carbonizing a metal–organic framework (MOF‐5). The morphology and microstructure of MOF‐5‐C were characterized by scanning electron microscopy, N₂ adsorption, and powder X‐ray diffraction. The MOF‐5‐C retained the original porous structures of MOF‐5, and showed a high Brunauer–Emmett–Teller surface area (1808 m² g^?1) and large pore volume (3.05 cm³ g^?1). To evaluate its adsorption performance, the MOF‐5‐C was used as an adsorbent for the solid‐phase extraction of four phthalate esters from bottled water, peach juice, and soft drink samples followed by high‐performance liquid chromatographic analysis. Several parameters that could affect the extraction efficiencies were investigated. Under the optimum conditions, a good linearity was achieved in the concentration range of 0.1–50.0 ng mL^?1 for bottled water sample and 0.2–50.0 ng mL^?1 for peach juice and soft drink samples. The limits of detection of the method (S/N = 3) were 0.02 ng mL^?1 for bottled water sample, and 0.04–0.05 ng mL^?1 for peach juice and soft drink samples. The results indicated that the MOF‐5‐C exhibited an excellent adsorption capability for trace levels of phthalate esters, and it could be a promising adsorbent for the preconcentration of other organic compounds.     

An Indirect Competitive Enzyme-linked Immunosorbent Assay for Simultaneous Determination of Florfenicol and Thiamphenicol in Animal Meat and Urine

A high-affinity polyclonal antibody was prepared by immunizing animals with haptens FFD and FFM. Under the optimal combination of coating antigen and antibody, an indirect competitive enzyme-linked immunosorbent assay (icELISA) for simultaneous detection of florfenicol and thiamphenicol residues in animal meat and urine samples was developed. The icELISA showed an IC₅₀ value of 1.32 ng mL^?1 for florfenicol and 2.13 ng mL^?1 for thiamphenicol, respectively. The linear ranges were from 0.31 to 5.61 ng mL^?1 with a limit of detection of 0.12 ng mL^?1 for florfenicol, and 0.41 to 11.2 ng mL^?1 with a limit of detection of 0.15 ng mL^?1 for thiamphenicol, respectively. The average recoveries of florfenicol and thiamphenicol in spiked samples ranged from 77.2% to 116.0% with a relative standard deviation of less than 15%. Therefore, this proposed icELISA provided a valid detection method for florfenicol and thiamphenicol residues in animal tissue and urine samples.