Quantitative Thin-layer Chromatography Research Articles

Eutectic Thin-Layer Chromatography as a New Possibility for Quantification of Plant Extracts—A Case Study

Deep eutectic solvents (DES), compared to classic ones, have interesting properties, such as the ability to solubilize compounds differing in polarity or increased dissolution of selected chemical compounds. They also offer specific interactions between the mobile and stationary phases. Those features make them promising solvents in chromatographic techniques, including the use in the separation of complicated samples. The first quantitative analysis with eutectic thin-layer chromatography (TLC) is presented in the paper. As a case study, five alkaloids from Chelidonium maius were selected as target compounds. A wide range of terpene-based DESs was investigated to develop the chromatographic system, both pure and after dilution. Moreover, a novel approach was employed to adjust polarity, involving mixing DESs differing in chromatographic properties. This procedure has proved to be effective. The best results were obtained with a 2:1 (wt/wt) mixture of DESs: camphor + phenol and menthol + limonene, with a 20% addition of methanol. The chromatographic system was validated and checked on the real sample, which made it the first applicable and operational quantitative eutectic TLC system.

Quantitative thin layer chromatography for the determination of medroxyprogesterone acetate using a smartphone and open-source image analysis

Intramuscular medroxyprogesterone acetate (MPA) products are commonly used to treat endometriosis and are the most widely used injectable contraceptives worldwide. Therefore, dependable quality screening of MPA injectables is a crucial measure necessary for ensuring that consumers are provided with safe and effective medications. Here, a thin-layer chromatography (TLC) method for MPA identification is combined with image analysis using a smartphone, 3D-printed light box, and open-source ImageJ software. The method's validation included two brands of MPA injectables, both at 150 mg mL−1 dosage. The TLC procedure used was based on the identity test found in The International Pharmacopoeia's Medroxyprogesterone injection monograph. Spots produced on the TLC plates were then photographed using a smartphone camera and quantified using ImageJ's image analysis software. The pixel data collected from each plate's standard spots were compared to the data generated from its sample spots. Data sets collected across multiple TLC plates and numerous days of method performance were evaluated to assess linearity, accuracy, precision, specificity, and robustness. Across the range of 75–125% of the target concentration, the method was found to have linearity of standard spots (with R2 generally greater than 0.99), overall accuracy of 101.0% (4.1% RSD), repeatability pooled standard deviation of 2.44%, intermediate precision pooled standard deviation of 3.68%, and observed demonstration of specificity and robustness. In low and middle-income countries (LMICs), quality screening of pharmaceutical products like MPA injectables can be challenging when testing resources are expensive, difficult to procure, or complex to utilize. The results of the TLC/ImageJ method validation suggest that this simple procedure that requires minimal resources may serve as a viable option for reliable quality screening of MPA levels in injectable suspensions.

Elucidation of Chemical Interactions between Crude Drugs Using Quantitative Thin-Layer Chromatography Analysis.

To elucidate the interactions between crude drugs in Kampo medicines (traditional Japanese medicines), it is important to determine the content of the constituents in a cost-effective and simple manner. In this study, we quantified the constituents in crude drug extracts using thin-layer chromatography (TLC), an inexpensive and simple analytical method, to elucidate the chemical interactions between crude drugs. We focused on five crude drugs, for which quantitative high-performance liquid chromatography (HPLC) methods are stipulated in the Japanese Pharmacopoeia XVIII (JP XVIII) and compared the analytical data of HPLC and TLC, confirming that the TLC results corresponded with the HPLC data and satisfied the criteria of JP XVIII. (Z)-ligustilide, a major constituent in Japanese Angelica Root, for which a method of quantification has not been stipulated in JP XVIII, was also quantitatively analyzed using HPLC and TLC. Furthermore, Japanese Angelica Root was combined with 26 crude drugs to observe the variation in the (Z)-ligustilide content from each combination by TLC. The results revealed that combinations with Phellodendron Bark, Citrus Unshiu Peel, Scutellaria Root, Coptis Rhizome, Gardenia Fruit, and Peony Root increased the (Z)-ligustilide content. Quantifying the constituents in crude drug extracts using the inexpensive and simple TLC method can contribute to elucidating interactions between crude drugs in Kampo medicines, as proposed by the herbal-pair theory.

Reaction rate differences between organotrifluoroborates and boronic acids in BINOL-catalyzed conjugate addition to enones

Enantioselective organocatalysis has been successfully employed in combination with trifluoroborate reagents for novel organic transformations over the last decade. However, no experimental rate studies of these reactions have been reported. Herein we report Hammett plot analysis of the organocatalyzed enantioselective conjugate addition of alkenyl, aryl, and heteroaryl trifluoroborate salts to chalcone derivatives with substitution at both the β-aryl and keto-aryl positions. The rate trend for keto-aryl substitution diverges from that of boronic acid nucleophiles in that the keto-aryl substituent for trifluoroborate salts does not measurably impact reaction rate in a manner consistent with charge stabilization. In addition, variable temperature NMR in combination with quantitative thin-layer chromatography (TLC) analysis suggests that the reaction is impacted by the low solubility of the trifluoroborate salts, so particle size and stirring speed affect reaction rates.

Development and validation of quantitative thin layer chromatographic technique for determination of total aflatoxins in poultry feed and food grains without sample clean-up.

Objective:The purpose of this work is to develop and validate an appropriate solvent solution and quantitative thin layer chromatography (TLC) method for determining the aflatoxins content of chicken feeds and dietary grains.Materials and Methods:To obtain the optimal mobile phase, samples were extracted with methanol/water (3:1) + 5% sodium chloride and partitioned using several solvent systems using preparative TLC. Camag TLC scanner 3 was used to scan the TLC plates at 366 nm and quantify them using JustTLC software. The method was tested for linearity, specificity, accuracy, precision, sensitivity, and robustness in accordance with ICH recommendations, and then utilized to screen 132 Nigerian poultry/food samples for total aflatoxins (TAFs).Results:The best separation of aflatoxins was achieved using acetonitrile and dichloromethane (3:17) mobile phase over an average run time of 45 min, resulting in linear calibration curves (R2 > 0.99) in the concentration range limit of quantitation (LoQ) to 50 ng/spot with a limit of detection of <2.0 ng/g and a LoQ of <4.0 ng/gm for all aflatoxins in all spiked samples. When the proposed TLC method was compared to an optimized high-performance liquid chromatography method, an excellent linear regression was obtained (R2 > 95%). Seventy seven (58.33%) of the 132 samples examined were positive for aflatoxins, with mean values ranging from 3.57 ± 2.55 to 37.31 ± 34.06 ng/gm for aflatoxin B1 and 6.67 ± 0.00 to 38.02 ± 31.52 ng/gm for TAFs, respectively.Conclusions:The results demonstrate the feasibility of using the suggested TLC method in conjunction with a novel solvent solution (free of carcinogenic chloroform) for the rapid and accurate measurement of TAFs in foods/feeds.

Preparation and Drug Entrapment Properties of Asymmetric Liposomes Containing Cationic and Anionic Lipids.

We have developed cyclodextrin-catalyzed lipid exchange methods to prepare large unilamellar vesicles (LUVs) with asymmetric charge distributions, i.e., with different net charges on the lipids in the inner and outer leaflets. LUVs contained a mixture of a zwitterionic lipid (phosphatidylcholine), cholesterol, and various cationic lipids (O-ethyl phosphatidylcholine or dioleoyl-3-trimethylammonium propane) or anionic lipids (phosphatidylglycerol, phosphatidylserine, or phosphatidic acid). Symmetric and asymmetric LUVs with a wide variety of lipid combinations were prepared. The asymmetric LUVs contained cationic or anionic outer leaflets and inner leaflets that had either the opposite charge or were uncharged. The behavior of symmetric LUVs prepared with zwitterionic, anionic, or cationic leaflets was compared to those of asymmetric LUVs. Lipid exchange was confirmed by quantitative thin-layer chromatography, and lipid asymmetry by a novel assay measuring binding of a cationic fluorescent probe to the LUV outer leaflet. For both symmetric and asymmetric LUVs, the level of entrapment of the cationic drug doxorubicin was controlled by the charge on the inner leaflet, with the greatest entrapment and slowest leakage in vesicles with an anionic inner leaflet. This shows that it is possible to choose inner leaflet lipids to maximize liposomal loading of charged drugs independently of the identity of outer-leaflet lipids. This implies that it should also be possible to independently vary outer-leaflet lipids to, for example, impart favorable bioavailability and biodistribution properties to lipid vesicles.

Thin-layer chromatographic quantification of magnolol and honokiol in dietary supplements and selected biological properties of these preparations

Two isomeric biphenyl neolignans, magnolol and honokiol, are considered as constituents responsible for the healing effect of magnolia bark, a traditional Oriental medicine. To survey the increasing number of dietary supplements that contain magnolia bark or its extract, an affordable quantitative thin-layer chromatography (TLC) – densitometry method was developed. The methanol extracts were analyzed on the silica gel plates after manual sample application using n-hexane – ethyl acetate – ethanol (16:3:1, v/v/v) as a mobile phase. For quantitation, the chromatograms were scanned in the absorbance mode at the wavelength λ = 290 nm. The limits of detection and quantitation were 90 and 280 ng/zone for magnolol and 70 and 200 ng/zone for honokiol, respectively. None of the two targeted neolignans were detected in two of the six analyzed supplements. In the other four samples, the measured amounts were between 0.95-114.69 mg g−1 for magnolol and 4.88-84.86 mg g−1 for honokiol. Moreover, separations of these two neolignans on the TLC and high-performance TLC (HPTLC) layers were compared and HPTLC was combined with antioxidant (DPPH) and antibacterial (Bacillus subtilis and Aliivibrio fischeri) assays and mass spectrometry (MS), using the elution-based interface. Both magnolol and honokiol exhibited effects in all bioactivity assays. The HPTLC-MS tests confirmed purity of neolignan zones in the extracts of dietary supplements and supported tentative identification of the alkaloid piperine and the isoflavone daidzein as additional bioactive components of the investigated dietary supplements. Using the same mobile phase in the orthogonal directions 2D-HPTLC-MS experiments proved degradation, i.e., instability of magnolol and honokiol on the silica gel adsorbent.

Isolation, Characterization and Quantification of Civetone from Civet Musk

Civet is an important commodity of commerce because of its use in perfume industry. It is also used to some extent in traditional medicine. Civetone is the main component of civet that is responsible for its characteristic odor. The amount of civetone in the musk of civet cat is not determined yet. In this project, rapid, simple and sensitive quantitative thin-layer chromatography method for the quantification of civetone in civet was developed and validated. The method involved extracting samples with dichloromethane by sonication, and analysis by CAMAG TLC scanner 3, after using a civetone dervatizing reagent. The densitometric scanning and analysis was done in absorbance mode at 371 nm. A new method for quantifying civetone in civet was developed in the course of this study. This involved taking a known amount of civet adding to it, a dervatizing agent 2,4-dintrophenylhydrazine, which now raises the absorption maximum to the visible range, thus making quantification work possible. The linear regression analysis data for calibration plots showed good linear relationship with r2=0.999 in the concentration range of 1-5 μg spot-1 with respect to peak area. The method was validated for accuracy, precision and recovery. The civetone value in crude civet samples, quantified by TLC was 0.8-1.2%.

Transfer of TLC screening methods to quantitative HPTLC–densitometry methods for pharmaceutical products containing amlodipine besylate, cefpodoxime proxetil, cetirizine 2HCl, diclofenac sodium, efavirenz, mefenamic acid, and atovaquone + proguanil HCl

Transfer of seven thin-layer chromatography (TLC) Global Pharma Health Fund E.V. Minilab protocols for screening counterfeit pharmaceutical products in the field to quantitative high-performance TLC (HPTLC)–densitometry methods was performed using a model process published previously. The developed and validated methods for tablets containing amlodipine besylate, cefpodoxime proxetil, cetirizine 2HCl, diclofenac sodium, efavirenz, mefenamic acid, and atovaquone + proguanil HCl involved the use of only relatively inexpensive and nontoxic solvents, Merck KGaA Premium Purity HPTLC silica gel 60 F254 plates, semi-automated sample and standard solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for detection, identification, and quantification. In addition, previously transferred HPTLC–densitometry methods for azithromycin and for cephalexin were used to analyze a new product of each drug to demonstrate the applicability of the methods.

Development of quantitative HPTLC-densitometry methods following a model process for transfer of TLC screening methods for pharmaceutical products containing moxifloxacin HCl, ofloxacin, amoxicillin trihydrate, acetylsalicylic acid + acetaminophen + caffeine, nimesulide, irbesartan, and pantoprazole

Transfer of thin-layer chromatography (TLC) Global Pharma Health Fund E.V. Minilab Manual and U.S. Food and Drug Administration (FDA) Compendium protocols for detecting falsified or substandard drugs in pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods suitable for support of regulatory authorities was performed following a previously published model process for moxfloxacin HCl, ofloxacin, and amoxicillin trihydrate. In addition, the guidelines of the process were followed to develop and validate HPTLC-densitometry methods for pharmaceutical products containing acetylsalicylic acid + acetaminophen + caffeine, nimesulide, irbesartan, and pantoprazole that are not included in the Minilab Manual or FDA Compendium. The new methods involved silica gel 60 F254 plates; semiautomated bandwise sample and standard solution application; ascending mobile phase development of plates in a glass chamber; and automated slit scanning densitometry for detection, identification, and quantification. Data for standard and sample solution preparation, calibration curves, assay of pharmaceutical products compared to label declarations, standard addition validation, and peak purity and peak identity are provided. Supplemental FDA Compendium screening methods corresponding to the HPTLC-densitometry methods for caffeine, nimesulide, irbesartan, pantoprazole, and acetylsalicylic acid co-formulated with acetaminophen and caffeine were developed and published online with open access on the website www.layloff.net.

Primary study on computer-aided qualitative and quantitative radial thin-layer chromatography methods for analysis of Yiqing tablets

Radial thin-layer chromatography (RTLC) is a form of chromatography in which the sample and developing agent/solvent are applied at the edge of a circle on the silica-layered TLC plate. The sample components are radially transported from the center of the circle toward the periphery by the solvent flow. RTLC is an efficient separation and semi-preparation method, with the advantages of fast separation, low diffusion, and absence of tailing at a certain distance. Although RTLC isolation has been well documented in the literature, there are only a few qualitative and quantitative reports on this technique. In this study, a self-programming module combined with image processing software was adopted for digital processing of RTLC images, and a digital atlas was created. Qualitative and quantitative verification of RTLC was then conducted. With the aid of computer technology, qualitative and quantitative methods of radially expanded TLC for Yiqing tablets were investigated. The results showed that the qualitative RTLC method has good reliability, but the quantitative RTLC method has inherent drawbacks, which may be associated with the experimental environment. We strongly believe that better separation and data acquisition equipment, as well as the combination of computer image processing and programming methods, will open up infinite possibilities of analysis/separation using RTLC-based techniques. We also believe that TLC will take a new step in the future with the assistance of computer technology.

Development of quantitative HPTLC–Densitometry methods for the analysis of amiodarone HCl, carvedilol, doxylamine succinate, magnesium salicylate, metoprolol succinate, nebivolol HCl, and salicylamide using a model process developed earlier for the transfer of TLC screening methods

A model process, previously developed in a series of studies, allows for the transfer of thin-layer chromatography (TLC) methods for qualitative screening of counterfeit drug products published in the Global Pharma Health Fund (GPHF) Minilab manual and US Food and Drug Administration (FDA) Compendium of Unofficial Methods for Screening of Pharmaceuticals by TLC to quantitative high-performance TLC (HPTLC)–densitometry methods. This article describes HPTLC–densitometry methods developed and validated according to this model process for pharmaceutical products of amiodarone HCl, carvedilol, doxylamine succinate, magnesium salicylate, metoprolol succinate, nebivolol HCl, and salicylamide, for which qualitative screening methods have not been published in the Minilab manual or FDA Compendium. These methods use relatively inexpensive and nontoxic “green solvents” for sample and standard solution and mobile phase preparation, Merck Premium Purity silica gel 60 F254 plates, automated standard and sample solution bandwise application, and automated densitometry for the assessment of peak purity and identity and quantification. Corresponding to the quantitative HPTLC–densitometry methods, qualitative TLC screening methods for these drug products were developed and posted online with open access as supplements to the FDA Compendium.

A review of thin layer chromatography methods for determination of authenticity of foods and dietary supplements

This paper reviews advances in qualitative and quantitative thin layer chromatography analytical methods published from 2000–2018 for assessing quality, adulteration, and authenticity of foods, beverages, and dietary supplements. Samples covered include animal and butter fats, oils, spices, flavorings, grains, honeys, soft drinks and juices, tea, sweeteners, wine and other alcoholic beverages, and vegetables, which are analyzed for a wide variety of characteristic analytes. It is suggested that TLC methods of the kind cited will continue to be used to complement the LC-MS/MS based peptide analysis methods that are being developed for food allergen detection and food fraud testing.

Development of quantitative HPTLC-densitometry methods following a model approach for transfer of TLC screening methods for pharmaceutical products of atenolol, chloramphenicol, furosemide, glibenclamide, penicillin V potassium, and praziquantel

ABSTRACTTransfer of six thin-layer chromatography (TLC) Global Pharma Health Fund E.V. Minilab manual protocols for detecting fake drugs in pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods was performed following a previously published model process. The developed and validated methods for tablets or capsules containing atenolol, chloramphenicol, furosemide, glibenclamide, penicillin V potassium, and praziquantel involved use of a limited list of inexpensive, relatively nontoxic, readily available solvents and other reagents; silica gel 60 F254 plates; automated bandwise sample and standard solution application; ascending mobile phase development of plates in a chamber; and automated slit scanning densitometry for detection, identification, and quantification. Validation data for methods developed in an early version of the transfer model process that did not include standard addition validation are reported for pharmaceutical products containing amitriptyline HCl, amodiaquine, diphenhydramine HCl, and mebendazole.

Development of quantitative HPTLC–densitometry methods following a model approach for transfer of TLC screening methods for pharmaceutical products of cefixime, cefuroxime axetil, cephalexin⋅H2O, ciprofloxacin HCl, levofloxacin, and metronidazole

Transfer of six thin-layer chromatography (TLC) Global Pharma Health Fund Minilab kit protocols for detecting fake or markedly substandard drugs in pharmaceutical products in the field to quantitative high-performance TLC (HPTLC)–densitometry methods was carried out using a model process published earlier. The developed and validated methods for tablets or capsules containing cefixime, cefuroxime axetil, cephalexin·H2O, ciprofloxacin HCl, levofloxacin, and metronidazole involved use of EMD Millipore Premium Purity silica gel 60 F254 plates, automated sample and standard solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for detection, identification, and quantification.

English

Chemical profiling and standardization of the defatted methanol extract of the leaves of Vitex negundo L. were carried out using 13C nuclear magnetic resonance (NMR) analysis followed by chemometric analysis of the chemical shift data. Chemical profile was obtained using a k-means cluster profile and chemical standardization which was achieved using a multivariate control chart. The V. negundo samples were made up of four groups: the training set, submitted samples from production farms, commercial samples, such as tablets, capsules and teas, and experimental samples (samples which were allowed to degrade). Four groups were generated in k-means cluster, which generally corresponded to the four types of samples. The multivariate control chart identified samples whose quality exceeded the upper control limit, all of which were commercial samples and experimental samples. The samples were also analyzed by quantitative thin layer chromatography (qTLC) using agnuside as marker compound. Comparison of the qTLC results with the k-means cluster and the multivariate control chart showed poor correspondence. This means that a univariate analysis of a plant sample using a marker compound is useful only for quantification of the target compound. On the other hand, chemical profiling and standardization of medicinal plants should use a multivariate method. Key words: Vitex negundo, 13C NMR, multi-variate cluster profile, multi-variate control chart.

Use of a model process for transfer of minilab TLC screening methods for quinine sulfate, mefloquine, and dihydroartemisinin—piperaquine phosphate tablets to quantitative HPTLC—densitometry methods

Transfer of four thin-layer chromatography (TLC) Global Pharma Health Fund Minilab mobile kit protocols for detecting fake pharmaceutical products to quantitative high-performance TLC (HPTLC)—densitometry methods was carried out using a model process published earlier. The developed and validated methods were for the drugs quinine sulfate, mefloquine, dihydroartemisinin, and piperaquine phosphate. EMD Millipore Premium Purity silica gel 60 F254 glass plates, automated standard and sample solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for detection, identification, and quantification were used. Sample peak identity and purity validation were carried out by spectral comparison checks available in the winCATS software, and accuracy was estimated by the standard addition approach. HPTLC gives better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Minilab TLC procedures to support regulatory compliance actions. These new methods should be fully validated according to International Conference on Harmonization guidelines or by interlaboratory studies if required by their applications. In addition, a previously reported transferred simultaneous HPTLC–densitometry method for lumefantrine and artemether was used to analyze a new combination tablet to demonstrate its applicability.

Genetic diversity and cryptolepine concentration of Cryptolepis sanguinolenta (Lindl). Schlt. from selected regions of Ghana

Cryptolepis sanguinolenta is a medicinal plant widely used in the treatment of malaria in Ghana. The increasing demand for its roots coupled with harvesting of the plant in non-sustainable ways has resulted in a substantial decline in its wild populations. The study was conducted to (1) determine the relatedness among C. sanguinolenta wild populations, (2) identify genotypes with high active ingredient (cryptolepine) concentrations and (3) understand the extent to which cryptolepine levels are influenced by soil. Root and stem samples for the study was collected from the Eastern, Ashanti, Brong Ahafo and Volta Regions of Ghana. C. sanguinolenta plants were found in sandy loam/sandy clay loam textured soils of acidic (4.3) to near neutral (6.7) pH ranges.Semi Quantitative Thin Layer Chromatography (SQ-TLC) and High Performance Liquid Chromatography (HPLC) methods were used to quantify the cryptolepine content in the stem and root samples. Cryptolepine concentrations in the stem and roots were not significantly influenced by location. No correlation was found between the soil properties studied and the cryptolepine content in the roots.Results from both SQ-TLC and HPLC analyses indicated that cryptolepine concentrations were on average, twice as much in the roots (0.84mg/100mg plant material) compared to the stem (0.42mg/100mg plant material).Results of the genetic diversity study showed a genetic diversity of 25% with genetic distances ranging between 0.08 and 0.14. Samples from the same location had the least genetic distances. Bootstrapping performed on the marker data and coefficient of variation calculated from distance resolutions obtained from 800 markers, proved to be of sufficient resolution. Sample sites did not reflect distinct sub-populations, a result of possible gene flow between sampling locations. Findings from this study will be useful for developing domestication protocols for C. sanguinolenta and subsequently the cultivation of elite genotypes.

Simultaneous Determination of Cinnarizine and Dimenhydrinate in Binary Mixture Using Chromatographic Methods.

Two accurate and sensitive chromatographic methods have been developed and validated for simultaneous determination of cinnarizine (CIN) and dimenhydrinate (DIM). The first method uses simultaneous quantitative thin layer chromatography (TLC) spectrodensitometric evaluation of them, using ethyl acetate:methylene chloride (8 : 2 by volume) as a mobile phase. Chromatograms are scanned at 254 nm. This method analyzes CIN in a concentration range of 0.5-6 µg per band with mean percentage recovery of 99.78 ± 1.001 and DIM in a concentration range of 1-6 µg per band with mean percentage recovery of 99.87 ± 1.319. The second method is high-performance liquid chromatography using methanol:acetonitrile:water [85 : 10 : 5, by volume +0.5% tri ethyl amine (TEA)] as a mobile phase. The linearity was found to be in the range of 10-60 and 5-60 µg mL(-1) for CIN and DIM, respectively. The methods were successfully applied to the simultaneous determination of CIN and DIM in bulk powder, laboratory-prepared mixtures and pharmaceutical dosage forms. The validity of results was assessed by applying standard addition techniques. The results obtained are found to agree statistically with those obtained by a reported method, showing no significant difference with respect to accuracy and precision.

Seasonal and geographical differences in aflatoxin exposures in Senegal

The aim of the study was to determine the geographical and seasonal variations in aflatoxin dietary exposure levels in adults from Senegal. A total of 168 adults (50% male) were recruited from three districts: Nioro du Rip (n=90), located in the Sudan Savannah agro-ecological zone where rainfall is sufficient for groundnut growth; Saint-Louis (n=40) and Mboro (n=38), located in the Sahel zone where groundnuts are produced under irrigated conditions. Diet information and samples were collected at groundnut harvest and post-harvest seasons. Plasma aflatoxin-albumin adducts (AF-alb) and total aflatoxin in household groundnut samples were measured by ELISA and a quantitative thin layer chromatography method, respectively. The blood AF-alb geometric mean was 45.7 pg/mg albumin (range 5.5-588.2 pg/mg). Nioro du Rip had a higher AF-alb level at harvest than Saint-Louis and Mboro (80.0 vs 15.6 and 33.3 pg/mg,P&lt;0.001). Similar trends were observed at post-harvest (P&lt;0.05). Seasonal trends were not consistent across the districts as Nioro du Rip had a higher AF-alb level at harvest than post-harvest (80.0 vs 58.6 pg/mg,P=0.026), whereas Saint-Louis had a higher level at post-harvest than harvest (25.6 vs 15.6 pg/mg,P=0.032). It is clear that aflatoxin exposure is prevalent in adults from Senegal and that season and geographical location are strong determinants of aflatoxin exposure.