Photometric Detection Research Articles

Determination of organotin compounds (OTC) at low levels in seawater by solid-phase extraction (SPE) and gas chromatography-pulsed flame photometric detection (GC-PFPD)

ABSTRACTIn this work, a simple, sensitive and affordable analytical method for the simultaneous determination of nine organotin compounds (butyltins, phenyltins and methyltins) in seawater using solid-phase extraction (SPE) and gas chromatography-pulsed flame photometric detection was developed and validated. The performance of three different SPE cartridges (Envi C18, Oasis HLB and Oasis MCX) and three elution solvents of different polarity (hexane, methanol and acetonitrile) was evaluated. The extraction parameters, such as solvent volume, presence of complexing and ion-pairing reagents, sample volume and pH and breakthrough volume, were also investigated. Tributyltin, as the organotin compound of special interest, was efficiently extracted using any of the cartridges and solvents tested. However, the simultaneous extraction of all nine organotin compounds was the most efficient using reversed-phase Envi C18 cartridge and 0.1% (w/v) tropolone in methanol as eluent. The optimised method resulted in good recovery, precision and linearity for all compounds, particularly for tri- and disubstituted species. Method detection limits ranged from 0.22 to 1.27 ng(Sn) L−1 for butyltins, 0.37 to 4.91 ng(Sn) L−1 for phenyltins and 0.45 to 1.16 ng(Sn) L−1 for methyltins. The accuracy of butyltins determination was further verified by the comparison with purchased derivatised standards. The developed method was successfully applied to the environmental samples.

Wavelet/PSO-Based Segmentation and Marker-Less Tracking of the Gallbladder in Monocular Calibration-free Laparoscopic Cholecystectomy

This paper presents an automatic segmentation and monocular marker-less tracking method of the gallbladder in minimally invasive laparoscopic cholecystectomy intervention that can be used for the construction of an adaptive calibrationfree medical augmented reality system. In particular, the proposed method consists of three steps, namely, a segmentation of 2D laparoscopic images using a combination of photometric population-based statistical approach and edge detection techniques, a PSO-based detection of the targeted anatomical structure (the gallbladder) and, finally, the 3D model waveletbased multi-resolution analysis and adaptive 2D/3D registration. The proposed population-based statistical segmentation approach of 2D laparoscopic images differs from classical approaches (histogram thresholding), in that we consider anatomical structures and surgical instruments in terms of distributions of RGB color triples. This allows an efficient handling, superior robustness and to readily integrate current intervention information. The result of this step consists in a set of point clouds with a loosely gradient information that can cover various anatomical structures. In order to enhance both sensitivity and specificity, the detection of the targeted structure (the gallbladder) is based on a modified PSO (particles swarm optimization) scheme which maximizes both internal features density and the divergence with neighboring structures such as, the liver. Finally, a multi-particles based representation of the targeted structure is constructed, thanks to a proposed wavelet-based multi-resolution analysis of the 3D model of the targeted structure which is registered adaptively with the 2D particles generated during the previous step. Results are shown on both synthetic and real data. © 2018, (IJACSA) International Journal of Advanced Computer Science and Applications.

GAS CHROMATOGRAPHIC DETERMINATION OF 23 ORGANOPHOSPHORUS PESTICIDES RESIDUE IN BOTTLE GUARD MATRIX

Objective: To validate in-house QuEChERS method, which scrutinizes and quantify the residue levels of some most frequently used organophosphorus pesticides and to prove a complete workflow for routine multi-residue pesticide analysis in representative bottle guard matrices and study the persistence of 23 organ phosphorus pesticides.Methods: QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction method was followed. Method validation and residue screening of bottle guard samples were conducted by GC-FPD (Gas Chromatography-Flame Photometric Detector) were used to analyse the presence of pesticides whereas confirmation of pesticides was done by GC-MS (Gas Chromatographic-Mass Spectrometer). Results: For bottle guard matrix, LOD (limit of detection) and LOQ (limit of quantification) values are lowest for phorate (0.005 mg/kg and 0.015 mg/kg) and highest for parathion-methyl (0.1 mg/kg and 0.3 mg/kg) respectively. Calibration curve, was plotted between an area of 23 pesticide standard mixture against seven different concentration levels of 0.01, 0.02, 0.05, 0.10, 0.20, 0.50, 1.00 mg/kg with regression coefficient (R2) are in the range of 0.978-0.994. The mean recovered amount at 0.05 mg/kg spikeing concentration are in the range of lowest 0.0413 mg/kg to highest 0.0467 mg/kg and relative standard deviation are in the range of lowest 2.2 to highest 8.571.Conclusion: For ensuring exposure to contaminants, especially by dietary intake, Robust analytical methods were validated for carrying out both research and monitoring programmes and thus for defining limitations and supporting enforcement of regulations.

Identification of Soil Properties and Organophosphate Residues From Agricultural Land in Wanasari Sub-District, Brebes, Indonesia

Organophosphates have been used to eradicate pests and prevent losses from harvest failures caused by pest attack. It is undeniable that the organophosphate persist in soil. This study aims to identify the organophosphate residue and soil properties include pH, soil texture, and permeability. The soil samples were taken from cropland in 10 villages, Wanasari sub-district, Brebes, Indonesia. Organophosphate residue determined by gas chromatography using Flame Photometric Detector. Soil texture was determined by soil texture triangle from NRCS USDA, and the permeability value was determined by falling head method. The mean value of chlorpyrifos, profenofos, diazinon were 0.0078; 0.0388; 0.2271 mg/l respectively. The soil texture varies from clay, silt clay, loam, silt loam, and silt clay loam with permeability value at 10-7 with the soil pH value between 6.4 – 8.1. The results showed that organophosphate residues found in the soil and its potential affect the soil fertility decline. We recommend to conduct routine soil quality analysis to prevent soil damage in the agricultural environment.

Dissipation of Chlorpyriphos and Profenophos in Cabbage (Brassica oleracea var. capitata L.)

The persistence of organophosphorus insecticides chlorpyriphos and profenophos @ 300 and 500 g a.i. ha−1 in cabbage following two foliar applications at 15 d interval during the head formation stage, is reported. Samples collected at 0 (2h), 1, 3, 5, 7, 10 and 15 d after the last (second) spray were extracted by QuEChERS method and residues estimated by gas liquid chromatography equipped with flame photometric detector (FPD). The mean initial deposits of chlorpyriphos and profenophos were 1.52 and 1.02 μg g−1 respectively which dissipated with time and reached below the quantitation level of 0.05 μg g−1 within 15 d with half-life values of 1.91 and 2.01 d, respectively. The Limit of detection (LOD) and limit of quantitation (LOQ) of the two insecticides in cabbage were 0.01 and 0.05 μg g−1, respectively.

Headspace solid-phase microextraction and gas chromatographic analysis of low-molecular-weight sulfur volatiles with pulsed flame photometric detection and quantification by a stable isotope dilution assay.

Low-molecular-weight volatile sulfur compounds such as thiols, sulfides, disulfides as well as thioacetates cause a sulfidic off-flavor in wines even at low concentration levels. The proposed analytical method for quantification of these compounds in wine is based on headspace solid-phase microextraction, followed by gas chromatographic analysis with sulfur-specific detection using a pulsed flame photometric detector. Robust quantification was achieved via a stable isotope dilution assay using commercial and synthesized deuterated isotopic standards. The necessary chromatographic separation of analytes and isotopic standards benefits from the inverse isotope effect realized on an apolar polydimethylsiloxane stationary phase of increased film thickness. Interferences with sulfur-specific detection in wine caused by sulfur dioxide were minimized by addition of propanal. The method provides adequate validation data, with good repeatability and limits of detection and quantification. It suits the requirements of wine quality management, allowing the control of oenological treatments to counteract an eventual formation of excessively high concentration of such malodorous compounds.

Detecting transit signatures of exoplanetary rings using SOAP3.0

Context. It is theoretically possible for rings to have formed around extrasolar planets in a similar way to that in which they formed around the giant planets in our solar system. However, no such rings have been detected to date. Aims. We aim to test the possibility of detecting rings around exoplanets by investigating the photometric and spectroscopic ring signatures in high-precision transit signals. Methods. The photometric and spectroscopic transit signals of a ringed planet is expected to show deviations from that of a spherical planet. We used these deviations to quantify the detectability of rings. We present SOAP3.0 which is a numerical tool to simulate ringed planet transits and measure ring detectability based on amplitudes of the residuals between the ringed planet signal and best fit ringless model. Results. We find that it is possible to detect the photometric and spectroscopic signature of near edge-on rings especially around planets with high impact parameter. Time resolution ≤7 min is required for the photometric detection, while 15 min is sufficient for the spectroscopic detection. We also show that future instruments like CHEOPS and ESPRESSO, with precisions that allow ring signatures to be well above their noise-level, present good prospects for detecting rings.

Machine learning search for variable stars

Photometric variability detection is often considered as a hypothesis testing problem: an object is variable if the null hypothesis that its brightness is constant can be ruled out given the measurements and their uncertainties. The practical applicability of this approach is limited by uncorrected systematic errors. We propose a new variability detection technique sensitive to a wide range of variability types while being robust to outliers and underestimated measurement uncertainties. We consider variability detection as a classification problem that can be approached with machine learning. Logistic Regression (LR), Support Vector Machines (SVM), k Nearest Neighbours (kNN), Neural Nets (NN), Random Forests (RF), and Stochastic Gradient Boosting classifier (SGB) are applied to 18 features (variability indices) quantifying scatter and/or correlation between points in a light curve. We use a subset of Optical Gravitational Lensing Experiment phase two (OGLE-II) Large Magellanic Cloud (LMC) photometry (30 265 light curves) that was searched for variability using traditional methods (168 known variable objects) as the training set and then apply the NN to a new test set of 31 798 OGLE-II LMC light curves. Among 205 candidates selected in the test set, 178 are real variables, while 13 low-amplitude variables are new discoveries. The machine learning classifiers considered are found to be more efficient (select more variables and fewer false candidates) compared to traditional techniques using individual variability indices or their linear combination. The NN, SGB, SVM, and RF show a higher efficiency compared to LR and kNN.

Determination of propineb and its metabolites propylenethiourea and propylenediamine in banana and soil using gas chromatography with flame photometric detection and LC–MS/MS analysis

ABSTRACTA sensitive and specific method for the determination of propineb and its metabolites, propylenethiourea (PTU) and propylenediamine (PDA), using gas chromatography with flame photometric detection (GC-FPD) and LC–MS/MS was developed and validated. Propineb and its metabolite residue dynamics in supervised field trials under Good Agricultural Practice (GAP) conditions in banana and soil were studied. Recovery of propineb (as CS2), PDA and PTU ranged from 75.3 to 115.4% with RSD (n = 5) of 1.3–11.1%. The limit of quantification (LOQ) of CS2, PDA and PTU ranged from 0.005 to 0.01 mg kg−1, and the limit of detection (LOD) ranged from 0.0015 to 0.0033 mg kg−1. Dissipation experiments showed that the half-life of propineb in banana and soil ranged from 4.4 to 13.3 days. PTU was found in banana with a half-life of 31.5–69.3 days, while levels of PDA were less than 0.01 mg kg−1 in banana and soil. It has been suggested that PTU is the major metabolite of propineb in banana. The method was demonstrated to be reliable and sensitive for the routine monitoring of propineb and its metabolites in banana and soil. It also serves as a reference for the detection and monitoring of dithiocarbamates (DTCs) residues and the evaluation of their metabolic pathway.

Multi-residue levels of organophosphorus pesticides in cocoa beans from some cocoa farms in Ekiti state, Nigeria

This study investigated the level and occurrence of 13 organophosphorus pesticides (OPPs) residues in cocoa beans from some cocoa farms in Ekiti state, Nigeria. The pesticides in the cocoa beans were extracted and cleaned up on silica gel adsorbent. A gas chromatograph coupled with flame photometric detector (FPD) was used to quantify the pesticides. The reliability of the analytical method was examined by spiking the beans with known concentration of the pesticides and analysed following similar procedure of extraction and clean-up. The percentage of pesticides recovered ranged from 88% to 92%. Dichlorvos, mevinfos, diazinon, chlorpyrifos, dimethoate and parathion were detected with varying concentration in the bean samples whilst phosphamidon, pirimiphos-methyl, fenthion, bromophos, isofenfos, diclofenthion and ethion showed no detectable level. The concentration of OPPs ranged from ND - 58μg/kg and ND - 85μg/kg for the dry and wet seasons respectively. Analysis of variance (ANOVA) showed no significant variation (p ˃ 0.05) in the levels of all detectable pesticides among the sampled farms whilst dichlorvos, diazinon, dimethoate and chlorpyrifos showed significant difference between both seasons. Residual levels of these detectable pesticides were below the maximum residue limits (MRLs) set by the European Union in food. Hence, the cocoa beans from the study areas are considered safe for consumption.Bangladesh J. Sci. Ind. Res. 52(4), 281-288, 2017

Characterization of the key aroma compounds in mulberry fruits by application of gas chromatography–olfactometry (GC-O), odor activity value (OAV), gas chromatography-mass spectrometry (GC–MS) and flame photometric detection (FPD)

The volatile compounds of mulberries obtained from three cultivars (M. nigra, Y1, M. Macroura, Y2 and M. Alba, Y3) were investigated by gas chromatography–olfactometry (GC-O), odor activity value (OAV), gas chromatography-mass spectrometry (GC–MS) and flame photometric detection (FPD). The results showed that 41, 37 and 41 compounds were detected in Y1, Y2 and Y3 samples, respectively. In addition, 12, 11, and 12 sulfur compounds were identified in three samples by FPD, respectively. Quantitative analysis showed 2-(methylthio)ethanol, methionol, dimethyl sulfide, methional and 3-ethylthiophene were present in relatively high amounts in each of the three samples. Furthermore, benzaldehyde, ethyl butanoate, (E)-2-nonenal, 1-hexanol, hexanal, methional, 3-mercaptohexyl acetate and 3-mercaptohexanol were present with much higher OAVs than other compounds. Finally, four compounds (pentanal, ethyl acetate, acetic acid, methionol) were selected to investigate possible effects on six descriptors, which indicated that the volatile compounds at sub-threshold concentrations are likely to contribute to overall aroma.

Human health risk assessment of organophosphorus pesticides in maize (Zea mays L.) from Yushu, Northeast China

ABSTRACTIn order to investigate organophosphorus pesticides (OPs) concentrations in maize and estimate the health risk to consumers, a total of 55 samples were collected from Yushu, one of the most important maize production areas. The concentrations of the eleven detected OPs in maize were analyzed by gas chromatography coupled with flame photometric detector (GC-FPD). The results showed that OPs concentrations of all maize were not higher than maximum residue limit (MRL), 67.3% of samples below MRL and only in 32.7% of samples was not found OPs. The mean concentrations obtained for the eleven OPs in μg kg-1 were as follows: omethoate (0.8), quinalphos (0.8), phorate (0.7), dimethoate (0.7), parathion-methyl (0.6), isocarbophos (0.6), diazinon (0.5), fenitrothion (0.5), and malathion (0.5), with parathion (0.5) and fenthion (0.3). Phorate (16.4%), dimethoate (16.4%) and quinalphos (16.4%) had the highest frequency in the eleven OPs. 29.1% samples contained two or more kinds of OPs, while 38.2% samples detected one kind of OPs. The target hazard quotients (THQ) values were all less than one and the total acute hazard index (aHI) values for adults and children were 0.051 and 0.121, respectively indicating that consumer may not pose significant chronic and acute health risk through maize.

Determination of alkyl- and alkanolamines in drinking and natural waters by capillary electrophoresis with isotachophoretic on-line preconcentration

A procedure is developed for the determination of several amines in drinking and natural waters by capillary electrophoresis with isotachophoretic on-line preconcentration without sample preparation. A background electrolyte based on acridine as an absorbing ion is proposed for analysis with isotachophoretic on-line preconcentration and indirect photometric detection. The sample was injected in the hydrodynamic mode. The procedure was tested on drinking and natural water samples. The accuracy of data obtained was confirmed by the added–found method. The analytical range was from 0.25 to 5 mg/L. The time of one analysis was 5–6 min.

Trace Iodide Dramatically Accelerates the Peroxidase Activity of VOx at ppb‐Concentration Levels

AbstractDespite artificial nanozymes, as compared to natural enzymes, exhibit distinct superiorities of low cost, robustness against harsh environments, high stability and easy mass‐production, the relatively lower activity and efficiency still seriously restrict their application in high‐performance photometric chemosensing and biosensing. Promoting the activity and efficiency of nanozymes turns to be a significant yet challenging goal of the nanozyme community. Here we found, for the first time, that trace I− can dramatically boost the peroxidase‐like activity (over 50‐fold higher) of VOx at ppb‐concentration levels. It was deduced that the significant enhancement of nanozymatic activity mainly results from the synergetic modulation of surface redox and electronic structure of VOx. Based on this finding, ultrasensitive photometric detection of both H2O2 and I− (down to nM) was realized.

Photometric flow analysis system for biomedical investigations of iron/transferrin speciation in human serum

The Multicommutated Flow Analysis (MCFA) system for the estimation of clinical iron parameters: Serum Iron (SI), Unsaturated Iron Binding Capacity (UIBC) and Total Iron Binding Capacity (TIBC) has been proposed. The developed MCFA system based on simple photometric detection of iron with chromogenic agent (ferrozine) enables a speciation of transferrin (determination of free and Fe-bound protein) in human serum. The construction of manifold was adapted to the requirements of measurements under changing conditions. In the course of studies, a different effect of proteins on SI and UIBC determination has been proven. That was in turn the reason to perform two kinds of calibration methods. For measurements in acidic medium for SI/holotransferrin determination, the calibration curve method was applied, characterized by limit of determination and limit of quantitation on the level of 3.4 μmol L−1 and 9.1 μmol L−1, respectively. The determination method for UIBC parameter (related to apotransferrin level) in physiological medium of pH 7.4 forced the use of standard addition method due to the strong influence of proteins on obtaining analytical signals. These two different methodologies, performed in the presented system, enabled the estimation of all three clinical iron/transferrin parameters in human serum samples. TIBC corresponding to total transferrin level was calculated as a sum of SI and UIBC.

Elimination of background color interference by immobilizing Prussian blue on carbon cloth: A monolithic peroxidase mimic for on-demand photometric sensing

Prussian blue (PB) is widely used as an artificial peroxidase for electrochemical biosensors, yet it is rarely utilized in photometric detection because of its intrinsic color interference. Herein, we proposed a new strategy, growing PB on common carbon cloth (CC), to obtain a monolithic peroxidase mimic with no background interference for colorimetric detection. Through a one-pot two-step electrodeposition procedure, a robust PB film composed of compactly assembled cubes was coated on CC surface. Since the active PB is immobilized on a bulk substrate (not like previous nanozymes that were dispersed in solution), the color interference from PB itself is efficiently avoided. In addition, the obtained monolithic nanozyme can be put into and taken out from reaction systems expediently and promptly with just a tiny pair of tweezers, which makes it possible for on-demand detection. As demonstrated, the PB-based nanozyme exhibited excellent peroxidase-like activity and could trigger the color reaction of 3,3′5,5′-tetramethylbenzidine in the presence of H2O2, leading to a detection limit of as low as 1.7μM for H2O2 sensing. A uric acid (UA) colorimetric assay was further established by incorporating the PB/CC peroxidase mimic with natural uricase, providing a linear absorbance response in the analyte concentration scope of 10–700μM. Reliable analysis of UA in human serum and urine verified the practicability of the fabricated assay.

Rapid gas chromatography with flame photometric detection of multiple organophosphorus pesticides in Salvia miltiorrhizae after ultrasonication assisted one-step extraction.

A simple and rapid gas chromatography-flame photometric detection (GC-FPD) method was developed for the determination of 12 organophosphorus pesticides (OPPs) in Salvia miltiorrhizae by using ultrasonication assisted one-step extraction (USAE) without any clean-up steps. Some crucial parameters such as type of extraction solvent were optimized to improve the method performance for trace analysis. Any clean-up steps were negligent as no interferences were detected in the GC-FPD chromatograms for sensitive detection. Under the optimized conditions, limits of detection (LODs) and quantitation (LOQs) for all pesticides were in the range of 0.001-0.002mg/kg and 0.002-0.01mg/kg and 0.002-0.01mg/kg, respectively, which were all below the regulatory maximum residue limits suggested. RSDs for method precision (intra- and inter-day variations) were lower than 6.8% in approval with international regulations. Average recovery rates for all pesticides at three fortification levels (0.5, 1.0 and 5.0mg/kg) were in the range of 71.2-101.0% with relative standard deviations (RSDs) <13%. The developed method was evaluated for its feasibility in the simultaneous pre-concentration and determination of 12 OPPs in 32 batches of real S. miltiorrhizae samples. Only one pesticide (dimethoate) out of the 12 targets was simultaneously detected in four samples at concentrations of 0.016-0.02mg/kg. Dichlorvos and omethoate were found in the same sample from Sichuan province at 0.004 and 0.027mg/kg, respectively. Malathion and monocrotophos were determined in the other two samples at 0.014 and 0.028mg/kg, respectively. All the positive samples were confirmed by LC-MS/MS. The simple, reliable and rapid USAE-GC-FPD method with many advantages over traditional techniques would be preferred for trace analysis of multiple pesticides in more complex matrices.

New Study Concerning the Biodegradation of Dimethoate, Chlorpyrifos and Chlorfenvinphos in some Medicinal Plants

Herbal drugs are widely used in pharmaceutical industry due to their beneficial effects on human health. The current research was carried out to evaluate the organic pollutant degradation in the flower part of the plant after a foliar application of pesticides. Also, based on the fact that selected pesticides are highly toxic to bees, it is important to monitor the removal rate of the pollutant. Under laboratory conditions, the marigold and French flowers (Calendula Officinalis and Tagetes Patula) were spiked with a mix of organophosphorus insecticide, dimethoate, chlorpyrifos and chlorfenvinphos, where the first two substances are still used on Romanian territory. The samples were extracted at different time moments over 300 min after sprayed treatment in order to evaluate the concentration in flower. The analytes were quantified by using gas chromatography with flame photometric detection (GC-FPD) technique. The developed method ensures the quality and comparability of analytical results, with a good sensitivity in determining the analytes over the concentration range 5-250 �g/L.

Photometric Detection of Multiple Populations in Globular Clusters Using Integrated Light

Abstract We investigate the multiple stellar populations of the globular clusters (GCs) M3, M5, M13, and M71 using and intermediate-band CN- photometry obtained with the WIYN 0.9 m telescope on Kitt Peak. We find a strong correlation between red giant stars’ CN colors and their spectroscopic sodium abundances, thus demonstrating the efficacy of the two-filter system for stellar population studies. In all four clusters, the observed spread in red giant branch CN colors is wider than that expected from photometric uncertainty, confirming the well-known chemical inhomogeneity of these systems. M3 and M13 show clear evidence for a radial dependence in the CN-band strengths of its red giants, while the evidence for such a radial dependence of CN strengths in M5 is ambiguous. Our data suggest that the dynamically old, relatively metal-rich M71 system is well mixed, as it shows no evidence for chemical segregation. Finally, we measure the radial gradients in the integrated CN color of the clusters and find that such gradients are easily detectable in the integrated light. We suggest that photometric observations of color gradients within GCs throughout the Local Group can be used to characterize their multiple populations, and thereby constrain the formation history of GCs in different galactic environments.

Health risks due to consumption of pesticides in ready-to-eat vegetables (salads) in Kumasi, Ghana

BackgroundPesticide residue levels were determined in ready-to-eat vegetables collected from 16 sites along the food chain; which is, farms, markets, cafeterias and street food vending sites in Kumasi, Ghana. The aim of the study was to determine the concentrations of pesticides residues in two ready-to-eat vegetables and assess the health risks due to consumption of these contaminated vegetables.MethodsPesticide residues in ready-to-eat vegetables or salads were extracted by means of the QuEChERS method. Synthetic pyrethroid and organophosphorus pesticides residues in samples were determined using Gas Chromatography with Electron Capture Detector and Pulsed Flame Photometric Detector respectively. Consumption data of ready-to-eat vegetables were obtained from a questionnaire-based dietary survey in the study area. The hazard index and the relative potency factor (RPFs) approaches were used to assess the health risk from chronic cumulative dietary exposure to pesticides.ResultsThere were six synthetic pyrethroid residues detected in the ready-to-eat samples at varying concentrations. They were bifenthrin, permethrin, cypermethrin, deltamethrin, lambda-cyhalothrin and fenvalerate. Also, two organophosphates were detected in the samples; which were chlorpyrifos and diazinon. Lambda-cyhalothrin residues was present in all the samples in the study, with the mean concentration of 4.5 × 10−2 mgkg−1. The mean concentration of diazinon in all the samples (0.040 mgkg−1) exceeded the EU MRLs (0.01 mgkg−1), chlopyrifos exceeded its MRL in one sample from the street food vending site and cafeteria each. Deltamethrin, Fenvalerate and Permethrin exceeded their respective MRL in samples from Asafo (Street food vending sites) and Adum (Cafeteria) and KNUST (Farm) respectively. However, the health index of all pesticides residues detected were below the permissible limit. The cumulative intake from the RPF approach for the pesticides were relatively lower than the ADI of the index chemicals.ConclusionThe concentrations of chlorpyrifos, deltamethrin, fenvalerate, diazinon and permethrin exceeded their respective EU MRLs in some ready-to-eat vegetable samples in the study. The health index and comparison of cumulative intake from RPF with ADI of the index chemicals suggest that pesticide residues in ready-to-eat vegetables could not be considered a major public health problem.