Simultaneous determination of salbutamol sulphate, bromhexine hydrochloride and etofylline in pharmaceutical formulations with the use of four rapid derivative spectrophotometric methods

Four simple, rapid, accurate, precise, reliable and economical spectrophotometric methods have been proposed for simultaneous determination of salbutamol sulphate (SS), bromhexine hydrochloride (BH) and etofylline (ET) in pure and commercial formulations without any prior separation or purification. They were first derivative zero crossing spectrophotometry (method 1), simultaneous equation method (method 2), derivative ratio spectra zero crossing method (method 3) and double divisor ratio spectra derivative method (method 4). The ranges for SS, BH and ET were found to be 1-35 μg mL⁻¹, 4-40 μg mL⁻¹ and 5-80 μg mL⁻¹. For methods 1 and 2, the values of limit of detection (LOD) were 0.2314 μg mL⁻¹, 0.4865 μg mL⁻¹ and 0.2766 μg mL⁻¹ and the values of limit of quantitation (LOQ) were 0.7712 μg mL⁻¹, 1.6217 μg mL⁻¹ and 0.9221 μg mL⁻¹ for SS, BH and ET, respectively. For method 3, LOD values were 0.3297 μg mL⁻¹, 0.2784 μg mL⁻¹ and 0.7906 μg mL⁻¹ and LOQ values were 0.9325 μg mL⁻¹, 0.9282 μg mL⁻¹ and 2.6352 μg mL⁻¹ for SS, BH and ET, respectively. For method 4, LOD values were 0.3161 μg mL⁻¹, 0.2495 μg mL⁻¹ and 0.2064 μg mL⁻¹ and LOQ values were 0.9869 μg mL⁻¹, 0.8317 μg mL⁻¹ and 0.6879 μg mL⁻¹ for SS, BH and ET. The precision values were less then 2% R.S.D. for all four methods. The common excipients and additives did not interfere in their determinations. The results obtained by the proposed methods have been statistically compared by means of Student t-test and by the variance ratio F-test.     

Determination of beta-lactam antibiotics in milk using micro-flow chemiluminescence system with on-line solid phase extraction

In this paper, a chemiluminescence (CL) micro-flow system combined with on-line solid phase extraction (SPE) is presented for determination of β-lactam antibiotics (penicillin, cefradine, cefadroxil, cefalexin) in milk. It is based on the enhancement effect of β-lactam antibiotics on the luminol-K₃Fe(CN)₆ CL system. The micro-flow system was fabricated from two polymethyl methacrylate (PMMA) plates (50 mm × 40 mm × 5 mm) with the microchannels of 200 μm wide and 150 μm deep. C₁₈-modified silica gel was packed into the microchannel (length: 10 mm; width: 1 mm; depth: 500 μm) to serve as SPE device. Extraction and preconcentration of the analytes were carried out using on-line SPE micro-flow system and the selectivity of CL detection was improved. The detection limits were 0.5 μg mL⁻¹ of penicillin, 0.04 μg mL⁻¹ of cefradine, 0.08 μg mL⁻¹ of cefadroxil and 0.1 μg mL⁻¹ of cefalexin. The proposed method was also applied to analyze the β-lactam antibiotics in milk. Experimental results were in good agreement with those obtained by high performance liquid chromatography (HPLC) method with UV detection.     

A rapid, acetonitrile-free, HPLC method for determination of melamine in infant formula

A simple, precise, accurate and validated, acetonitrile-free, reverse phase high performance liquid chromatography (HPLC) method is developed for the determination of melamine in dry and liquid infant formula. The separation is performed on a Kromasil C18 column (150 mm × 3.2 mm I.D., 5 μm particle size) at room temperature. The mobile phase (0.1% TFA/methanol 90:10) is pumped at a flow rate of 0.3 mL min⁻¹ with detection at 240 nm. Melamine elutes at 3.7 min. A linear response (r > 0.999) is observed for samples ranging from 1.0 to 80 μg mL⁻¹. The method provides recoveries of 97.2-101.2% in the concentration range of 5-40 μg mL⁻¹, intra- and inter-day variation in <1.0% R.S.D. The limit of detection (LOD) and limit of quantification (LOQ) values are 0.1 μg mL⁻¹ and 0.2 μg mL⁻¹, respectively.     

Flow injection spectrophotometric determination of andrographolide from Andrographis paniculata

A simple flow injection colourimetric procedure for determining andrographolide was proposed. It is based on the reaction between andrographolide with 3,5-dinitrobenzoic acid, resulting in an intense purplish red complex with a suitable absorption at 536 nm. A standard or sample solution was injected into the 3,5-dinitrobenzoic acid stream (flow rate of 1.0 ml min⁻¹) which was then merged with potassium hydroxide stream with the same flow rate. Optimum conditions for determining andrographolide were investigated by univariate method. Under the optimum conditions, a linear calibration graph was obtained over the range 5.0-150.0 μg ml⁻¹ and the detection limit was 1.50 μg ml⁻¹ (3σ). The relatives standard deviation of the proposed method calculated from 10 replicate injections of 10.0 and 80.0 μg ml⁻¹ andrographolide were 0.66% and 1.64%, respectively. The sample throughput was 50 h⁻¹. The proposed method has been satisfactorily applied to the determination of andrographolide in herb plant samples.     

Determination of mono- and dichloroacetic acids in betaine media by liquid chromatography

A simple and sensitive method has been developed for the analysis of residue amounts of chloroacetic acids in betaine samples based on derivatization by 1-naphthylamine (NA). The derivatized compounds are analyzed by reverse phase high performance liquid chromatography using methanol and water as mobile phase in the ratio of 32/68 (v/v) and phenyl column and PDA detection at 222 nm. The detection limits (LOD) of monochloroacetic acid (MCA) and dichloroacetic acid (DCA) are 0.1 and 0.15 μg mL⁻¹, respectively. The limits of quantification (LOQ) and the linear dynamic ranges (LDR) of MCA are found to be 1 and 1-400 μg mL⁻¹, respectively, and for DCA are found to be 3 and 3-400 μg mL⁻¹, respectively. The precision at the 5 ppm level for MCA and DCA are about 3% and 2%, (n = 5), respectively. The average recovery for MCA and DCA spiked to betaine samples are 98% and 97%, respectively.     

Development and validation of an HPLC-PDA method for the determination of myrsinoic acid B in the extracts of Rapanea ferruginea Mez

New, simple, rapid and precise HPLC-PDA method has been developed and validated for quantification of biomarker myrsinoic acid B in stem bark extracts of Rapanea ferruginea Mez. The method employs a Phenomenex C18 column (250 mm × 4.6 mm I.D., 5 μm) with acetonitrile:methanol:water (pH 2.6 with phosphoric acid) at 48:30:22 as mobile phase, at a flow rate of 0.7 mL min⁻¹ and photo diode array (PDA) detection at 270 nm. The validation data show that the method is specific, accurate, precise and robust. The method was linear, over a range of 5-100.0 μg mL⁻¹, with a limit of detection of 0.369 μg mL⁻¹ and limit of quantification of 1.233 μg mL⁻¹. The method has also shown consistent recoveries (average of 101.3% and 0.12% RSD) of the biomarker, with low intra and inter-day relative standard deviation (1.26% and 1.62%, respectively). The evaluated hydroethanolic extract and dry extract presented MAB values of 63.53 and 36.07 mg g⁻¹, respectively.     

Development of a validated liquid chromatographic method for the quality control of Prunellae Spica: Determination of triterpenic acids

A simple and rapid reversed-phase HPLC-UV method was developed for the determination of triterpenic acids in the crude extract of Prunellae Spica. Five triterpenic acids were extracted and isolated from P. Spica as marker compounds for use in the quality control of herbal medicines. Various solvent extraction techniques were evaluated, and the greatest efficiency was observed with sonication in 100% ethanol. Elemental compositions of the five marker compounds were determined by high-resolution mass spectroscopy. The dynamic range of the HPLC-UV method depended on the specific analyte, and acceptable quantitation was obtained between 10 and 250 μg mL⁻¹ for oleanolic acid, between 10 and 300 μg mL⁻¹ for ursolic acid, between 3 and 75 μg mL⁻¹ for 2α,3α,24-trihydroxyolean-12en-28oic acid, between 5 and 100 μg mL⁻¹ for euscaphic acid, and between 5 and 100 μg mL⁻¹ for 2α,3α-dihydroxyurs-12en-28oic acid. The method was deemed satisfactory by inter- and intra-day validation and exhibited both high accuracy and precision (relative standard deviation <9.4%). Overall limits of quantitation and detection were approximately 0.5-2.5 μg mL⁻¹ at a signal-to-noise ratio (S/N) of 3 and were about 3.0-10.0 μg mL⁻¹ at a S/N of 10. In addition, principal component analysis (PCA) was performed on the analytical data of 15 different P. Spica samples in order to classify samples collected from different regions.     

Chromogenic platform based on recombinant Drosophila melanogaster acetylcholinesterase for visible unidirectional assay of organophosphate and carbamate insecticide residues

In this study we propose a chromogenic platform for rapid analysis of organophosphate (OP) and carbamate (CM) insecticide residues, based on recombinant Drosophila melanogaster acetylcholinesterase (R-DmAChE) as enzyme and indoxyl acetate as substrate. The visible chromogenic strip had the advantages identical to those of commonly used lateral flow assays (LFAs) with utmost simplicity in sample loading and result observation. After optimization, depending on the color intensity (CI) values, the well-established assay has the capabilities of both qualitative measurement via naked eyes and quantitative analysis by colorimetric reader with the desirable IC₅₀ values against the tested six insecticides (0.06 μg mL⁻¹ of carbofuran, 0.28 μg mL⁻¹ of methomyl, 0.03 μg mL⁻¹ of dichlorvos, 31.6 μg mL⁻¹ of methamidophos, 2.0 μg mL⁻¹ of monocrotophos, 6.3 μg mL⁻¹ of omethoate). Acceptable matrix effects and satisfactory detection performance were confirmed by in-parallel LC–MS/MS analysis in different vegetable varieties at various spiked levels of 10⁻³ to 10¹ μg g⁻¹. Overall, the testified suitability and applicability of this novel platform meet the requirements for practical use in food safety management and environmental monitoring, especially in the developing world.     

A reversed-phase high performance liquid chromatography coupled with resonance Rayleigh scattering detection for the determination of four tetracycline antibiotics

A new reversed-phase high performance liquid chromatography with resonance Rayleigh scattering detection (HPLC-RRS) was developed for simultaneous separation and determination of four tetracycline antibiotics (TCs). A good chromatographic separation among the compounds was achieved using a Synergi Fusion-RP column (150 mm × 4.6 mm; 4 μm) and a mobile phase consisting of methanol-acetonitrile-oxalic acid (5 mM) at the flow rate of 0.8 mL min⁻¹. Column temperature was 30 °C. The RRS signal was detected at λ_ex = λ_em = 370 nm. The recoveries of sample added standard ranged from 95.3% to 103.5%, and the relative standard deviation was below 2.79%. A detection limit of 2.12-5.12 μg mL⁻¹ was reached and a linear range was found between peak height and concentration in the range of 10.36-518.0 μg mL⁻¹ for oxytetracycline (OTC), 12.11-605.5 μg mL⁻¹ for tetracycline (TC), 11.79-589.5 μg mL⁻¹ for chlortetracycline (CTC) and 10.32-516.0 μg mL⁻¹ for doxycycline (DC). The linear regression coefficients were all above 0.999. The method has been applied successfully to the determination of OTC, TC, CTC, DC in pharmaceutical formulations and in honey. The method was simple, rapid and showed a better linear relation and high repeatability.     

On-line continuous flow ultrasonic extraction coupled with high performance liquid chromatographic separation for determination of the flavonoids from root of Scutellaria baicalensis Georgi

An on-line method, based on coupling dynamic ultrasonic extraction (DUE), continuously sampling the suspension of sample and solvent, high performance liquid chromatographic separation with diode array detection, has been developed for the determination of the flavonoids, including baicalin, baicalein and wogonin, from the root of Scutellaria baicalensis Georgi. Variables influencing the DUE were evaluated by orthogonal test. The extraction yields of baicalin, baicalein and wogonin in the roots of S. baicalensis Georgi obtained from five different cultivated areas are 73.8–131.5 μg mg⁻¹ (RSD ≤ 6.24%), 6.8–15.9 μg mg⁻¹ (RSD ≤ 5.36%) and 4.4–14.3 μg mg⁻¹ (RSD ≤ 5.30%), respectively. The limits of detection for baicalin, baicalein and wogonin are 0.30, 0.37 and 0.41 μg mL⁻¹, respectively. Linearity is from 0.55 to 109 μg mL⁻¹ for baicalin, from 0.51 to 105 μg mL⁻¹ for baicalein and from 0.53 to 102 μg mL⁻¹ for wogonin. Compared with off-line continuous flow-DUE, the proposed method would be more convenient for the determination of the analytes and the rapid optimization of the extraction process. The extraction yields of flavonoids obtained by the proposed method are comparable with those obtained by dynamic microwave assisted extraction, static ultrasonic extraction and reflux extraction. The result indicated that the proposed method is suitable to determine the active components in Chinese herbal medicine.     

High extraction efficiency for polar aromatic compounds in natural water samples using multiwalled carbon nanotubes/Nafion solid-phase microextraction coating

A novel solid-phase microextraction (SPME) fiber coated with multiwalled carbon nanotubes (MWCNTs)/Nafion was developed and applied for the extraction of polar aromatic compounds (PACs) in natural water samples. The characteristics and the application of this fiber were investigated. Electron microscope photographs indicated that the MWCNTs/Nafion coating with average thickness of 12.5 μm was homogeneous and porous. The MWCNTs/Nafion coated fiber exhibited higher extraction efficiency towards polar aromatic compounds compared to an 85 μm commercial PA fiber. SPME experimental conditions, such as fiber coating, extraction time, stirring rate, desorption temperature and desorption time, were optimized in order to improve the extraction efficiency. The calibration curves were linear from 0.01 to 10 μg mL⁻¹ for five PACs studied except p-nitroaniline (from 0.005 to 10 μg mL⁻¹) and m-cresol (from 0.001 to 10 μg mL⁻¹), and detection limits were within the range of 0.03–0.57 ng mL⁻¹. Single fiber and fiber-to-fiber reproducibility were less than 7.5 (n = 7) and 10.0% (n = 5), respectively. The recovery of the PACs spiked in natural water samples at 1 μg mL⁻¹ ranged from 83.3 to 106.0%.     

Simultaneous determination of amiodarone and its metabolite desethylamiodarone by high-performance liquid chromatography with chemiluminescent detection

A novel method was developed for the determination of amiodarone and desethylamiodarone by high-performance liquid chromatography (HPLC) coupled with chemiluminescent (CL) detection. The procedure is based on the post-column photolysis of the analytes into photoproducts which are active in the tris(2,2′-bipyridyl)ruthenium(III) [Ru(bpy)₃³⁺] CL system. Ru(bpy)₃³⁺ was on-line generated by photo-oxidation of the Ru(II) complex in the presence of peroxydisulfate. The separation was carried out on a Mediterranea C₁₈ column with isocratic elution using a mixture of methanol and 0.017 mol L⁻¹ ammonium sulfate buffer of pH 6.8. Under the optimum conditions, analytical curves, based on standard solutions, were linear over the range 0.1-50 μg mL⁻¹ for amiodarone and 0.5-25 μg mL⁻¹ for desethylamiodarone. The detection limits of amiodarone and desethylamiodarone were 0.02 and 0.11 μg mL⁻¹, respectively. Intra- and inter-day precision values of 0.9% relative standard deviation (R.S.D.) (n = 10) and 1.6% R.S.D. (n = 15), respectively, were obtained. The method was applied successfully to the determination of these compounds in serum and pharmaceutical formulations.     

Separation and determination of benzene, toluene, ethylbenzene and o-xylene compounds in water using directly suspended droplet microextraction coupled with gas chromatography-flame ionization detector

The directly suspended droplet microextraction (DSDME) technique coupled with the capillary gas chromatography-flame ionization detector (GC-FID) was used to determine BTEX compounds in aqueous samples. The effective parameters such as organic solvent, extraction time, microdroplet volume, salt effect and stirring speed were optimized. The performance of the proposed technique was evaluated for the determination of BTEX compounds in natural water samples. Under the optimal conditions the enrichment factors ranged from 142.68 to 312.13, linear range; 0.01-20 μg mL⁻¹, limits of detection; 0.8-7 ng mL⁻¹ for most analytes. Relative standard deviations for 0.2 μg mL⁻¹ of BTEX in water were in the range 1.81-2.47% (n = 5). The relative recoveries of BTEX from surface water at spiking level of 0.2 μg mL⁻¹ were in the range of 89.87-98.62%.     

Synthesis and application of a carbamazepine-imprinted polymer for solid-phase extraction from urine and wastewater

A molecularly imprinted polymer (MIP) designed to enable the selective extraction of carbamazepine (CBZ) from effluent wastewater and urine samples has been synthesised using a non-covalent molecular imprinting approach. The MIP was evaluated chromatographically in the first instance and its affinity for CBZ also confirmed by solid-phase extraction (SPE). The optimal conditions for SPE consisted of conditioning of the cartridge using acidified water purified from a Milli-Q system, loading of the sample under basic aqueous conditions, clean-up using acetonitrile and elution with methanol. The attractive molecular recognition properties of the MIP gave rise to good CBZ recoveries (80%) when 100 mL of effluent water spiked with 1 μg L⁻¹ was percolated through the polymer. For urine samples, 2 mL samples spiked with 2.5 μg L⁻¹ CBZ were extracted with a recovery of 65%. For urine, the linear range was 0.05-24 mg L⁻¹, the limit of detection was 25 μg L⁻¹ and precision, expressed as relative standard deviation at 0.5 mg L⁻¹ (n = 3), was 3.1% and 12.6% for repeatability and reproducibility between days, respectively.     

A cataluminescence gas sensor for carbon tetrachloride based on nanosized ZnS

A novel and sensitive gas sensor was proposed for the determination of carbon tetrachloride based on its cataluminescence (CTL) by oxidation in the air on the surface of nanosized ZnS. The luminescence characteristics and the optimal conditions were investigated in detail. Under the optimized conditions, the linear range of the CTL intensity versus the concentration of carbon tetrachloride was 0.4-114 μg mL⁻¹, with a correlation coefficient (R) of 0.9986 and a limit of detection (S/N = 3) of 0.2 μg mL⁻¹. The relative standard deviation (R.S.D.) for 5.9 μg mL⁻¹ carbon tetrachloride was 2.9% (n = 5). There was no or weak response to common foreign substances including methanol, ethanol, benzene, acetone, formaldehyde, acetaldehyde, dichloromethane, xylene, ammonia and trichloromethane. There was no significant change of the catalytic activity of the sensor for 40 h over 4 days, with a R.S.D. of less than 5% by collecting the CTL intensity once an hour. The proposed method was simple and sensitive, with a potential of detecting carbon tetrachloride in environment and industry grounds. The possible mechanism was also discussed briefly.     

Monolithic silica spin column extraction and simultaneous derivatization of amphetamines and 3,4-methylenedioxyamphetamines in human urine for gas chromatographic-mass spectrometric detection

A simple, sensitive, and specific method with gas chromatography-mass spectrometry was developed for simultaneous extraction and derivatization of amphetamines (APs) and 3,4-methylenedioxyamphetamines (MDAs) in human urine by using a monolithic silica spin column. All the procedures, such as sample loading, washing, and elution were performed by centrifugation. APs and MDAs in urine were adsorbed on the monolithic silica and derivatized with propyl chloroformate in the column. Methamphetamine-d₅ was used as an internal standard. The linear ranges were 0.01-5.0 μg mL⁻¹ for methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA) and 0.02-5.0 μg mL⁻¹ for amphetamine (AP) and 3,4-methylenedioxyamphetamine (MDA) (coefficient of correlation ≧0.995). The recovery of APs and MDAs in urine was 84-94%, and the relative standard deviation of the intra- and interday reproducibility for urine samples containing 0.1, 1.0, and 4.0 μg mL⁻¹ of APs and MDAs ranged from 1.4% to 13.6%. The lowest detection limit (signal-to-noise ratio ≧ 3) in urine was 5 ng mL⁻¹ for MA and MDMA and 10 ng mL⁻¹ for AP and MDA. The proposed method can be used to perform simultaneous extraction and derivatization on spin columns that have been loaded with a small quantity of solvent by using centrifugation.     

Simultaneous analysis of anionic, amphoteric, nonionic and cationic surfactant mixtures in shampoo and hair conditioner by RP-HPLC/ELSD and LC/MS

A simple and simultaneous analysis method for four (anionic, amphoteric, nonionic, and cationic) classes of surfactants in shampoo and hair conditioner was newly developed. Analysis of the surfactants was performed using a reversed-phase HPLC (RPLC) combined with evaporative light scattering detection (ELSD) without any pre-treatment. An optimum analysis condition for the resolution of both four main surfactant mixtures used in shampoo and five main surfactants used in hair conditioner could be established under a gradient mobile phase condition with acetonitrile, tetrahydrofuran and water. The detection limits were 2.5-30 μg mL⁻¹ except for SLES (150 μg mL⁻¹), and the calibration curves, i.e. the log-log plots, were linear in the working range of 2.5-5250 μg mL⁻¹ with R² values of above 0.998. The observed precision was less than 5% R.S.D. The elution peaks were identified by a liquid chromatography-mass spectrometer (LC-MS) equipped with an electrospray interface operating in mixed-mode.     

Sensitive quantitative determination of oxymatrine and matrine in rat plasma by capillary electrophoresis with stacking induced by moving reaction boundary

A quantitative method of capillary electrophoresis with sample stacking induced by moving reaction boundary (MRB) was developed for sensitive determination of oxymatrine (OMT) and matrine (MT) in rat plasma. The experimental conditions were optimized firstly. Below are the optimized experimental conditions: 20 mM sodium formate solution (HCOONa, adjusted to pH 10.70 by ammonia) as sample solution, 3 min 14 mbar sample injection, 40 mM formic buffer (HCOOH-HCOONa, pH 2.60) as stacking buffer, 7 min 14 mbar injection of stacking buffer, 100 mM HCOOH-HCOONa (pH 4.80) as separation buffer, 73 cm capillary (effective length 64 cm), 21 kV voltage, 210 nm wavelength. Under the optimized conditions, higher than 60-fold sensitivity improvement of the stacking was simply achieved as compared with capillary zone electrophoresis, and the detectable limits obtained for OMT and MT were 0.26 and 0.19 μg mL⁻¹, respectively. Then, numerous demonstrations were carefully performed for the methodological validations of OMT and MT in rate plasma, including high specificity of method, good linearity (r = 0.9993 for OMT, r = 0.9991 for MT), fair wide linear concentration range (1.30-65.00 μg mL⁻¹ for OMT, 0.84-42.00 μg mL⁻¹ for MT), low limit of detection (1.03 μg mL⁻¹ for OMT, 0.38 μg mL⁻¹ for MT), less than 5% intra- and inter-day variance value, and higher than 96% recovery of OMT and MT in plasma. The developed method could be used for the trace analyses of OMT and MT in plasma and was finally used for the investigation on pharmacokinetic study of OMT in rat plasma.     

Mixed-mode solid-phase extraction followed by acetylation and gas chromatography mass spectrometry for the reliable determination of trans-resveratrol in wine samples

This work presents an advantageous analytical procedure for the accurate determination of free trans-resveratrol in red and white wines. The proposed method involves solid-phase extraction (SPE), acetylation of the analyte in aqueous media and further determination by gas chromatography (GC) with mass spectrometry detection (MS). The use of a mixed-mode SPE sorbent provides an improvement in the selectivity of the extraction step; moreover, the presence of several intense ions in the electron impact mass spectra of its acetyl derivative guarantees the unambiguous identification of trans-resveratrol. Considering a sample intake of 10 mL, the method provides a limit of quantification (LOQ) of 0.8 ng mL⁻¹ and linear responses for concentrations up to 2.5 μg mL⁻¹, referred to wine samples. The average recovery, estimated with samples fortified at different concentrations in the above range, was 99.6% and the inter-day precision stayed below 8%. Trans-resveratrol levels in the analyzed wines varied from 3.4 to 1810 ng mL⁻¹. Cis-resveratrol was also found in all samples. In most cases, equal or higher responses were measured for this latter form than for the trans-isomer. The reduced form of resveratrol, dihydro-resveratrol, was systematically identified in red wines.     

Screening and determination of melamine residues in tissue and body fluid samples

Melamine is a chemical product that was sporadically mixed into animal feeds to boost protein content. Excessive melamine in animal feed can induce renal failure and even death in animals. The residue of melamine in edible animal products also threatens human health. Currently, there is no real-time and high throughput method to detect residual melamine in animal tissues. Successful development of such methods is very important for fast and on-site screening of melamine residue in animal tissues to eliminate the potential threat to human health. Here we demonstrate the detection of residual melamine from swine and chicken tissues and body fluids using indirect competitive enzyme-linked immunosorbent assay (ELISA) method. A detection sensitivity of 0.5 μg mL⁻¹ and a limit of detection of 0.05 μg mL⁻¹ were achieved with this method. A gas chromatography-mass spectrometry (GC-MS) method was also developed to act as a confirmatory and quantitative procedure for the ELISA results. The limits of quantitation (LOQ) of were 0.01 μg g⁻¹ and 0.005 μg mL⁻¹ for tissues and body fluids, respectively. The two methods showed good agreement (r² > 0.992). The method developed was performed on samples of tissues from chickens fed with melamine-spiked feed.