Determination of doxorubicin in human plasma by excitation-emission matrix fluorescence and multi-way analysis

Direct determination of doxorubicin (DXR), a cytotoxic anthracycline antibiotic, in human plasma was accomplished based on excitation-emission matrix (EEM) fluorescence measurements and multi-way chemometric methods based on parallel factor analysis (PARAFAC) and N-PLS. Several different procedures, such as residual analysis, core consistency diagnostic (CONCORDIA) and split-half analysis were employed to determine the correct number of factors in PARAFAC. These procedures converged to a choice of two factors, attributed to DXR and to the sum of two fluorescence species present in the plasma. Sample PARAFAC loadings were employed to build a regression model against concentration, resulting in a RMSECV of 0.060 μg ml⁻¹. N-PLS using two factors produced a RMSECV of 0.045 μg ml⁻¹. Figures of merit (FOM), such as sensitivity (SEN), selectivity (SEL) and limit of detection (L_D) were determined for both PARAFAC and N-PLS.     

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%.     

Determination of the steroid hormone levels in water samples by dispersive liquid-liquid microextraction with solidification of a floating organic drop followed by high-performance liquid chromatography

In this study, the steroid hormone levels in river and tap water samples were determined by using a novel dispersive liquid-liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO). Several parameters were optimized, including the type and volume of the extraction and dispersive solvents, extraction time, and salt effect. DLLME-SFO is a fast, cheap, and easy-to-use method for detecting trace levels of samples. Most importantly, this method uses less-toxic solvent. The correlation coefficient of the calibration curve was higher than 0.9991. The linear range was from 5 to 1000 μg L⁻¹. The spiked environmental water samples were analyzed using DLLME-SFO. The relative recoveries ranged from 87% to 116% for river water (which was spiked with 4 μg L⁻¹ for E1, 3 μg L⁻¹ for E2, 4 μg L⁻¹ for EE2 and 9 μg L⁻¹ for E3) and 89% to 102% for tap water (which was spiked with 6 μg L⁻¹ for E1, 5 μg L⁻¹ for E2, 6 μg L⁻¹ for EE2 and 10 μg L⁻¹ for E3). The detection limits of the method ranged from 0.8 to 2.7 μg L⁻¹ for spiked river water and 1.4 to 3.1 μg L⁻¹ for spiked tap water. The methods precision ranged from 8% to 14% for spiked river water and 7% to 14% for spiked tap water.     

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.     

Improved porous silicon microarray based prostate specific antigen immunoassay by optimized surface density of the capture antibody

Enriching the surface density of immobilized capture antibodies enhances the detection signal of antibody sandwich microarrays. In this study, we improved the detection sensitivity of our previously developed P-Si (porous silicon) antibody microarray by optimizing concentrations of the capturing antibody. We investigated immunoassays using a P-Si microarray at three different capture antibody (PSA – prostate specific antigen) concentrations, analyzing the influence of the antibody density on the assay detection sensitivity. The LOD (limit of detection) for PSA was 2.5 ng mL⁻¹, 80 pg mL⁻¹, and 800 fg mL⁻¹ when arraying the PSA antibody, H117 at the concentration 15 μg mL⁻¹, 35 μg mL⁻¹, and 154 μg mL⁻¹, respectively. We further investigated PSA spiked into human female serum in the range of 800 fg mL⁻¹ to 500 ng mL⁻¹. The microarray showed a LOD of 800 fg mL⁻¹ and a dynamic range of 800 fg mL⁻¹ to 80 ng mL⁻¹ in serum spiked samples.     

In situ derivatization hollow fibre liquid-phase microextraction for the determination of biogenic amines in food samples

Hollow fibre liquid-phase microextraction with in situ derivatization using dansyl chloride has been successfully developed for the high-performance liquid chromatography-ultraviolet (HPLC-UV) determination of the biogenic amines (tryptamine, putrescine, cadaverine, histamine, tyramine, spermidine) in food samples. Parameters affecting the performance of the in situ derivatization process such as type of extraction solvent, temperature, extraction time, stirring speed and salt addition were studied and optimized. Under the optimized conditions (extraction solvent, dihexyl ether; acceptor phase, 0.1 M HCl; extraction time, 30 min; extraction temperature, 26 °C; without addition of salt), enrichment factors varying from 47 to 456 were achieved. Good linearity of the analytes was obtained over a concentration range of 0.1–5 μg mL⁻¹ (with correlation coefficients of 0.9901–0.9974). The limits of detection and quantification based on a signal-to-noise ratio of 3–10, ranged from 0.0075 to 0.030 μg mL⁻¹ and 0.03 to 0.10 μg mL⁻¹, respectively. The relative standard deviations based on the peak areas for six replicate analysis of water spiked with 0.5 μg mL⁻¹ of each biogenic amine were lower than 7.5%. The method was successfully applied to shrimp sauce and tomato ketchup samples, offering an interesting alternative to liquid–liquid extraction and solid phase extraction for the analysis of biogenic amines in food samples.     

Electropolymerized multiwalled carbon nanotubes/polypyrrole fiber for solid-phase microextraction and its applications in the determination of pyrethroids

A novel solid-phase microextraction (SPME) fiber coated with multiwalled carbon nanotubes/polypyrrole (MWCNTs/Ppy) was prepared with an electrochemical method and used for the extraction of pyrethroids in natural water samples. The results showed that the MWCNTs/Ppy coated fiber had high organic stability, and remarkable acid and alkali resistance. In addition, the MWCNTs/Ppy coated fiber was more effective and superior to commercial PDMS and PDMS/DVD fibers in extracting pyrethroids in natural water samples. Under optimized conditions, the calibration curves were found to be linear from 0.001 to 10 μg mL⁻¹ for five of the six pyrethroids studied, the exception being fenvalerate (which was from 0.005 to 10 μg mL⁻¹), and detection limits were within the range 0.12-0.43 ng mL⁻¹. The recoveries of the pyrethroids spiked in water samples at 10 ng mL⁻¹ ranged from 83 to 112%.     

Modified iron oxide nanoparticles as solid phase extractor for spectrophotometeric determination and separation of basic fuchsin

This study presents a novel separation, preconcentration and determination of basic fuchsin (BF) in an aqueous solution by sodium dodecyl sulfate (SDS)-bounded iron oxide nanoparticles (S-IONPs). It is shown that the novel magnetic nano-adsorbent is quite efficient for the adsorption and desorption of BF at 25 °C. Different parameters such as pH, temperature, ionic strength and composition of desorbent solvent were optimized. The effect of some co-existing ions on the determination was investigated. The nanoparticles were analyzed by transmission electron microscopy (TEM) and the sizes of S-IONPs were in the range of 20-100 nm. The method showed good linearity for the determination of BF in the range of 10-300 ng mL⁻¹ with a regression coefficient of 0.9989. The limit of detection (LOD) (signal-to-noise ratio of 3:1) was 0.0073 μg L⁻¹ and the relative standard deviation (RSD) for 0.03 μg mL⁻¹ and 0.2 μg mL⁻¹ of BF were 4.53% and 4.73%, respectively. The BF was determined successfully in spiked samples of Karoon River water.     

Determination of azoxystrobin residues in grapes, musts and wines with a multicommuted flow-through optosensor implemented with photochemically induced fluorescence

In this paper, the conversion of azoxystrobin in a strongly fluorescent degradation product by UV irradiation with quantitative purposes and its fluorimetric determination are reported for the first time. A multicommuted flow injection-solid phase spectroscopy (FI-SPS) system combined with photochemically-induced fluorescence (PIF) is developed for the determination of azoxystrobin in grapes, must and wine. Grape samples were homogenized and extracted with methanol and further cleaned-up by solid-phase extraction on C₁₈ silica gel. Wine samples were solid-phase extracted on C₁₈ sorbent using dichloromethane as eluent. Recoveries of azoxystrobin from spiked grapes (0.5-2.0 mg Kg⁻¹), must (0.5-2.0 μg mL⁻¹) and wine (0.5-2.0 μg mL⁻¹) were 84.0-87.6%, 95.5-105.9% and 88.5-111.2%, respectively. The quantification limit for grapes was 0.021 mg Kg⁻¹, being within European Union regulations, and 18 μg L⁻¹ and 8 μg L⁻¹ for must and wine, respectively.     

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.     

Second-order multivariate calibration procedures applied to high-performance liquid chromatography coupled to fast-scanning fluorescence detection for the determination of fluoroquinolones

Different second-order multivariate calibration algorithms, namely parallel factor analysis (PARAFAC), N-dimensional partial least-squares (N-PLS) and multivariate curve resolution-alternating least-squares (MCR-ALS) have been compared for the analysis of four fluoroquinolones in aqueous solutions, including some human urine samples (additional four fluoroquinolones were simultaneously determined by univariate calibration). Data were measured in a short time with a chromatographic system operating in the isocratic mode. The detection system consisted of a fast-scanning spectrofluorimeter, which allows one to obtain second-order data matrices containing the fluorescence intensity as a function of retention time and emission wavelength. The developed approach enabled us to determine eight analytes, some of them with overlapped profiles, without the necessity of applying an elution gradient, and thus significantly reducing both the experimental time and complexity. The study was employed for the discussion of the scopes of the applied second-order chemometric tools. The quality of the proposed technique coupled to each of the evaluated algorithms was assessed on the basis of the figures of merit for the determination of fluoroquinolones in the analyzed water and urine samples. Univariate calibration of four analytes led to limits of detection in the range 20–40 ng mL⁻¹ and root mean square errors for the validation samples in the range 30–60 ng mL⁻¹ (corresponding to relative prediction errors of 3–8%). The ranges for second-order multivariate calibration (using PARAFAC and N-PLS) of the remaining four analytes were: limit of detection, 2–8 ng mL⁻¹, root mean square errors, 3–50 ng mL⁻¹ and relative prediction errors, 1–5%.     

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.     

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%.     

Determination of osthole in rat plasma by high-performance liquid chromatograph using cloud-point extraction

A new straightforward method based on cloud-point extraction (CPE) was developed to determine osthole in rat plasma by reversed phase high-performance liquid chromatography with ultraviolet detection using a photodiode array detector. The non-ionic surfactant Triton X-114 was chosen as the extract solvent. Variable parameters affecting the CPE efficiency were evaluated and optimized. A Zorbax SB-C₁₈ column was used for elution separation at 25 °C with detection wavelength at 322 nm. Under the optimum conditions, the method was shown to be reproducible and reliable with intra-day precision below 7.62%, inter-day precision below 6.37%, and accuracy within ±5.02% and mean extraction recovery more than 90.4%, which were all calculated using a range of spiked samples at three concentrations of 0.5, 5.0 and 15.0 μg mL⁻¹ for osthole in plasma. The calibration curve for the analyte was linear in the range from 0.1 to 20 μg mL⁻¹ with the correlation coefficients greater than 0.9981. Limit of detection (S/N = 3) was less than 0.03 μg mL⁻¹and limit of quantification (S/N = 10) was less than 0.1 μg mL⁻¹. After strict validation, the method was successfully applied to the pharmacokinetic study of osthole in rats after oral and intravenous administration, respectively.     

Gas chromatographic determination of carbonyl compounds in biological and oil samples by headspace single-drop microextraction with in-drop derivatisation

A suitable method for the gas chromatographic determination of 10 characteristic carbonyls in biological and oil samples based on the in-drop formation of hydrazones by using 2,4,6-trichlorophenylhydrazine (TCPH), has been developed. The derivatisation-extraction procedure was optimized separately for aqueous and oil samples with respect to the appropriate organic drop solvent, drop volume, in-drop TCPH concentration, sample stirring rate, temperature during single-drop microextraction (SDME), reaction time and headspace-to-sample volume ratio. The optimization showed differentiation of optimum values between the studied matrices. The limits of detection were found to range from 0.001 to 0.003 μg mL⁻¹ for the aqueous biological samples and from 0.06 to 0.20 μg mL⁻¹ for the oil samples. The limits of quantification were in the range of 0.003-0.010 μg mL⁻¹ and 0.020-0.059 μg mL⁻¹ for aqueous and oil samples, respectively. The overall relative standard deviations of the within-day repeatability and between-day reproducibility were <4.4% and <8.2% for the aqueous biological samples and <3.9% and <7.4% for the oxidized oil samples.     

Optimization and comparison of chemical and electrochemical hydride generation for optical emission spectrometric determination of arsenic and antimony using a novel miniaturized microwave induced argon plasma exiting the microstrip wafer

Continuous flow (CF) chemical hydride generation (CHG) and electrochemical hydride generation (ECHG) directly coupled to a novel 40 W, atmospheric pressure, 2.45 GHz microwave microstrip Ar plasma exiting a microstrip wafer has been developed for the emission spectrometric determination of As and Sb using a miniaturized optical fiber spectrometer and a CCD-array detector. The experimental conditions for both procedures were optimized with respect to the relative net intensities of the As I 228.8 nm and Sb I 252.8 nm lines and their signal-to-background intensity ratios. Additionally, the susceptibility to interferences from Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn and other hydride-forming elements in the determination of As and Sb using the CHG and ECHG techniques was investigated in detail. Under the optimized conditions, it was found that ECHG is more prone to interferences compared to CHG. The detection limits (3σ) of As (6 ng mL⁻¹) and Sb (7 ng mL⁻¹) obtained for the ECHG-MSP-OES method are about three times lower than in the case of the CHG-MSP-OES method due to a two-fold lower amount of H₂ introduced into the MSP in case of the ECHG, resulting in a better plasma stability and reduced background level. The linearity ranges for both calibration curves to a concentration of up to 5 μg mL⁻¹ and a precision between 2% and 7% (2 μg mL⁻¹ and 0.050 μg mL⁻¹ of As and Sb, respectively) were found for both methods. The developed ECHG-MSP-OES method was validated for As through the analysis of a certified coal fly ash standard reference material (NIST SRM 1633a) after sample dissolution. The derived concentration (140 ± 8 μg g⁻¹) was found to agree well with the certified data (145 ± 15 μg g⁻¹). The method was also successfully applied to the analysis of both a galvanic bath sample, which contained Sb and was spiked with As, and a tap water sample spiked with both analytes. Recovery rates of 99-101% and a Sb concentration of 6.6 μg mL⁻¹ in the galvanic bath sample were revealed. The latter value showed a good agreement with the data obtained from ICP-OES analysis, which was also used for validation purpose.     

In-syringe demulsified dispersive liquid–liquid microextraction and high performance liquid chromatography–mass spectrometry for the determination of trace fungicides in environmental water samples

An in-syringe demulsified dispersive liquid–liquid microextraction (ISD–DLLME) technique was developed using low-density extraction solvents for the highly sensitive determination of the three trace fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water samples by high performance liquid chromatography–mass spectrometry chromatography–diode array detector/electrospray ionisation mass spectrometry. In the proposed technique, a 5-mL syringe was used as an extraction, separation and preconcentration container. The emulsion was obtained after the mixture of toluene (extraction solvent) and methanol (dispersive solvent) was injected into the aqueous bulk of the syringe. The obtained emulsion cleared into two phases without centrifugation, when an aliquot of methanol was introduced as a demulsifier. The separated floating organic extraction solvent was impelled and collected into a pipette tip fitted to the tip of the syringe. Under the optimal conditions, the enrichment factors for azoxystrobin, diethofencarb and pyrimethanil were 239, 200, 195, respectively. The limits of detection, calculated as three times the signal-to-noise ratio (S N⁻¹), were 0.026 μg L⁻¹ for azoxystrobin, 0.071 μg L⁻¹ for diethofencarb and 0.040 μg L⁻¹ for pyrimethanil. The repeatability study was carried out by extracting the spiked water samples at concentration levels of 0.02 μg mL⁻¹ for all the three fungicides. The relative standard deviations varied between 4.9 and 8.2% (n = 5). The recoveries of all the three fungicides from tap, lake and rain water samples at spiking levels of 0.2, 1, 5 μg L⁻¹ were in the range of 90.0–105.0%, 86.0–114.0% and 88.6–110.0%, respectively. The proposed ISD–DLLME technique was demonstrated to be simple, practical and efficient for the determination of different kinds of fungicide residues in real water samples.     

Sensitive determination of hydrazine in water by gas chromatography–mass spectrometry after derivatization with ortho-phthalaldehyde

A gas chromatography–mass spectrometric (GC–MS) method has been established for the determination of hydrazine in drinking water and surface water. This method is based on the derivatization of hydrazine with ortho-phthalaldehyde (OPA) in water. The following optimum reaction conditions were established: reagent dosage, 40 mg mL⁻¹ of OPA; pH 2; reaction for 20 min at 70 °C. The organic derivative was extracted with methylene chloride and then measured by GC–MS. Under the established condition, the detection and the quantification limits were 0.002 μg L⁻¹ and 0.007 μg L⁻¹ by using 5.0-mL of surface water or drinking water, respectively. The calibration curve showed good linearity with r² = 0.9991 (for working range of 0.05–100 μg L⁻¹) and the accuracy was in a range of 95–106%, and the precision of the assay was less than 13% in water. Hydrazine was detected in a concentration range of 0.05–0.14 μg L⁻¹ in 2 samples of 10 raw drinking water samples and in a concentration range of 0.09–0.55 μg L⁻¹ in 4 samples of 10 treated drinking water samples.     

Simultaneous determination of aflatoxins B2 and G2 in peanuts using spectrofluorescence coupled with parallel factor analysis

In the present study a method for the simultaneous determination of aflatoxins B₂ and G₂ in peanuts has been developed. The method uses second order standard addition method and excitation–emission fluorescence data together with parallel factor analysis (PARAFAC). The aflatoxin analysis was based on extraction with methanol–water and carried out using immunoaffinity clean-up. The results of PARAFAC on a set of spiked and naturally contaminated peanuts indicated that the two aflatoxins could be successfully determined. The method was validated and analytical figures of merit were obtained for both analytes. The limits of detection (LOD) were 0.05 and 0.04 μg kg⁻¹ for aflatoxins B₂ and G₂, respectively. The limits of quantification (LOQ) were 0.16 and 0.12 μg kg⁻¹ for aflatoxins B₂ and G₂, respectively. Coupling of spectrofluorimetry with PARAFAC can be considered as an alternative method for quantification of aflatoxins in the presence of unknown interferences obtained through analysis of highly complex matrix of peanuts samples at a reduced cost per analysis.     

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.