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Rivaroxaban is one of the most prescribed anticoagulants. The ingestion of the correct dosage is a key to the success of the therapy. A procedure to evaluate the content of active principle ingredient in rivaroxaban pharmaceutical formulations, based on micellar liquid chromatography, has been developed. Tablets were solved in the mobile phase and directly injected, thus avoiding the use of large volumes of organic solvents. Analysis was performed using a C18 column and a mobile phase containing 0.05 M sodium dodecyl sulfate—12.5% 1-propanol, buffered at pH 7 with phosphate salt, running under isocratic mode at 1 mL/min. The analyte was resolved in less than 6.0 min. Detection was by UV absorption at 250 nm. The method was successfully validated by the guidelines of the International Conference of Harmonization in terms of specificity, calibration range (0.01–1.00 mg/L), linearity, limit of detection (0.002 mg/L), limit of quantification (0.006 mg/L), trueness (99.6–99.7%), precision (

The present work mainly highlights the simultaneous detection of four skin whitening agents i.e. hydroquinone (HQ), resorcinol (RS), catechol (CC) and 3,3′-dichlorobenzidine (DCB) in facial creams and body lotion. Among these, the first three are positional isomers of dihydroxybenzene so simultaneous separation is difficult with the conventional reverse-phase high-performance liquid chromatographic technique (RP-HPLC). The selected skin whitening agents were detected in facial cream and body lotion using micellar liquid chromatography coupled to a photodiode array detector (MLC-PDA). In the present study, optimization of the method was accomplished using response surface methodology (RSM) with central composite design (CCD). The second-order polynomial model for predicting the optimal chromatographic run time was evaluated by the analysis of variance (ANOVA) and 3D response surface plots for the interactions between three variables were constructed. Three experimental parameters which were chosen as independent variables were; surfactant concentration (SDS), the volume percentage of organic modifier (OM) and pH of the mobile phase. The second-order polynomial model for predicting the optimal chromatographic run time was evaluated by the analysis of variance (ANOVA) and 3D response surface plots for the interactions between three variables were constructed. Three experimental parameters which were chosen as independent variables were; surfactant concentration (SDS), percentage of organic modifier (OM) and pH of the mobile phase. The second-order polynomial model for predicting the optimal chromatographic run time was evaluated by the analysis of variance (ANOVA) and 3D response surface plots for the interactions between three variables were constructed. Three experimental parameters which were chosen as independent variables were; surfactant concentration (SDS), percentage of organic modifier (OM) and pH of the mobile phase. The optimized mobile phase was 0.15 M SDS and 7% 1-butanol, buffered at pH 7 with 0.01 M NaH2PO4. The chromatographic run time for simultaneous determination of selected analytes was 7.5 min. The correlation coefficient (r2) values were satisfactory between 0.998–0.999 over the linear concentration range. Limits of detection (LODs) and the limits of quantification (LOQs) for the four skin whitening agents were in the range of 0.05–0.07 μg/mg and 0.11–0.14 μg/mg, respectively. Trueness (98.4–102.7%) and precision (< 4.3%) were acceptable. The developed method was fast, cost-effective, and green which could easily analyze complex matrices (facial creams, body lotion) without any pretreatment other than filtration. The results indicated that the MLC-PDA method proved to be more suitable for the simultaneous separation of selected positional isomers.

An easy and selective thin layer chromatographic method has been developed and experimentally validated for the simultaneous screening of most commonly used anthelmintic drugs i.e. albendazole and ivermectin. Separation of these compounds was attained on silica gel 60 F254 pre-coated thin layer chromatographic plate using an optimized mobile phase of diisopropyl ether:ethyl acetate:glacial acetic acid in the ratio of 7:3:0.1 (v/v), respectively at pH 3.5. The calculated Rf values for albendazole and ivermectin were 0.65 and 0.38, respectively and the LOD was found to be 25 μg/ml and 30 μg/ml for albendazole and ivermectin, respectively. The developed method is selective, sensitive, robust, cost effective, eco-friendly, rapid as well as easy to perform. The developed method was successfully applied for the analysis of albendazole and ivermectin in pharmaceutical preparations marketed as oral suspensions, powder, tablets and injectable of the single or combined dosage forms for human as well as veterinary use. It could also be applied for the simultaneous analysis of both the compounds in other samples.

Mebendazole is an anthelmintic drug used in cattle production. However, residues may occur in produced food and in excretions, jeopardizing population health. A method based on micellar liquid chromatography (MLC) was developed to determine mebendazole in dairy products (milk, cheese, butter, and curd) and nitrogenous waste (urine and dung) from bovine animals. Sample treatment was expedited to simple dilution or solid-to-liquid extraction, followed by filtration and direct injection of the obtained solution. The analyte was resolved from matrix compounds in less than 8 min, using a C18 column and a mobile phase made up of 0.15 M sodium dodecyl sulfate (SDS)&ndash, 6% 1-pentanol phosphate buffered at pH 7, and running at 1 mL/min under isocratic mode. Detection was performed by absorbance at 292 nm. The procedure was validated according to the guidelines of the EU Commission Decision 2002/657/EC in terms of: specificity, method calibration range (from the limit of quantification to 25&ndash, 50 ppm), sensitivity (limit of detection 0.1&ndash, 0.2 ppm, limit of quantification, 0.3&ndash, 0.6 ppm), trueness (92.5&ndash, 102.3%), precision (&lt, 7.5%, expressed at RSD), robustness, and stability. The method is reliable, sensitive, easy-to-handle, eco-friendly, safe, inexpensive, and provides a high sample-throughput. Therefore, it is useful for routine analysis as a screening or quantification method in a laboratory for drug-residue control.

We have developed a method, based on micellar liquid chromatography, to determine albendazole and ivermectin in dairy products and biological waste from bovine, as well as edible tissues from poultry. Anthelmitics were resolved in less than 10 min using a C18 column and a mobile phase of 0.15 mol/L sodium dodecyl sulfate – 6% 1-pentanol at buffered at pH 7 with a 0.01 M phosphate salt, running under isocratic mode at 1 mL/min. Detection was by absorbance at 292 nm. Method was successfully validated following official validation guidelines, in terms of: selectivity, sensitivity, calibration range (0.0125−0.5 mg/kg to 25−50 mg/kg), linearity (r2 > 9990), trueness (86.3–105.6%), precision (

A method based on micellar liquid chromatography was developed to determine oxolinic acid, ciprofloxacin, enrofloxacin, and sarafloxacin in eggs and egg products. The antimicrobial drugs were obtained in a micellar solution which was directly injected. The analytes were resolved using a C18 column and a mobile phase of 0.05 M sodium dodecyl sulfate—7.5% 1-propanol—0.5% triethylamine, buffered at pH 3 with phosphate salt, running under the isocratic mode. The signal was monitored by fluorescence. Validation was successfully performed according to the EU Commission Decision 2002/657/EC in terms of specificity, calibration range (LOQ to 1 mg/kg), linearity (R2 &gt, 0.9991), limit of detection and decision limit (0.01–0.05 mg/kg), limit of quantification (0.025–0.150 mg/kg), detection capability (&lt, 0.4 times decision limit), trueness (−14.2% to +9.8%), precision (&lt, 14.0%), robustness, and stability. The procedure was environmentally friendly, safe, easy-to-conduct, inexpensive, and had a high sample throughput, thus it is useful for routine analysis as a screening method in a laboratory for food residue control.

The subject “Chemistry Laboratory I” is taught in the first academic year of the Degree in Chemistry. Its main objective is for the student to get a first contact with the basic laboratory operations and become aware of the importance of preparing the experimental work, in addition to manage registration, analysis and the presentation of results. It is therefore a basic knowledge which will be in the future of great help in further chemistry laboratory subjects, regardless of the specific topic (analytical, physical, inorganic, organic and general). The course consists of 10 laboratory sessions and 5 seminars. The final score obtained by the student is based on the assessment of laboratory notebook, the resolution of a test prior to the practical (to ensure that the student have prepared this practical) and a written exam. The qualification is calculated by the average of the score obtained at each activity, with the following weighing: laboratory / seminars / notebook / test / exam 30: 10: 20: 10: 30; respectively. In this study, the results of 72 students were analyzed, noticing that the average score was 7.7 (24/9/15/7/22 at each evaluation item, respectively). From these results we deduced: firstly, the attitude of students in the laboratory is excellent (laboratory and seminars scores are very high), and second, we have to focus on the organization of the laboratory notebook, the preparation of the practical, the attention from the teacher explanation and the study of the content of the subject, as the scores of notebook, test and final exam can be ameliorated.

A Micellar Liquid Chromatographic method is described to determine Rifampicin and Rifabutin in plasma from Tuberculosis patients. Samples were diluted in mobile phase and then directly injected, avoiding long and tedious extraction steps. The analytes were resolved from the matrix without interferences from endogenous compounds using a mobile phase of sodium dodecyl sulfate 0.15 mol L-1–6%(v/v) 1-pentanol and phosphate buffer at pH 3, running at 1 mL min−1 through a C18 column at 25 °C. Detection was carried out by UV absorbance at 270 nm. Under these conditions, the final chromatographic analysis time was 22 min. The analytical methodology was validated following the FDA 2018 Bioanalytical Method Validation Guidance for Industry. The response of the drugs in plasma was linear in the 0.05–5 μg/mL range, with r 2 > 0.9993. Trueness and precision were

A simple and easy liquid chromatographic procedure was developed for the separation and analysis of α,β-arteether. The developed method uses a reversed-phase Luna C18 column (250 mm × 4.6 mm), a hybrid micellar mobile phase containing 0.15 M SDS–6% (v/v) butanol–0.01 M phosphate buffered at pH 7, and detection at 218 nm. Under these conditions, the analysis time was less than 6 min. Validation studies were performed according to the International Conference on Harmonization guideline, including linearity (R2 > 0.9998) in the 0.1–50 µg/mL range, accuracy (99.8–100.8%), repeatability [RSD (%) 1.8–2.8], intermediate precision [RSD (%) 1.8–2.9], and robustness, which were found satisfactory. Method was applied to the determination of α,β-arteether in different pharmaceutical preparations and wrapper/label free ampoules obtaining recoveries in the 97.7–102.2% range. Compared to other chromatographic techniques, micellar liquid chromatography has the advantages of avoiding sample extraction from matrices, thus ...

A high-performance liquid chromatography (HPLC) method with photodiode array detection (PDA) was developed for the determination of three commonly used stupefacients, lidocaine, diazepam, and ketamine, in foodstuff and drinks used for cheating or deceiving a person. The method involves extraction of the selected drugs using ethanol at room temperature. Using the optimum mobile phase of acetonitrile–water (40:60, v/v, pH 3.0, 0.01 M sodium dihydrogen phosphate) and a flow rate of 1.0 mL/min, the separation was achieved on a PrincetonSPHER-100 C18 (250 mm × 4.6 mm, 5 µm particle size) column and UV detection at 252 nm. The limit of detection achieved was 0.025 µg/mL, 0.1 µg/mL, and 0.1 µg/mL for lidocaine, diazepam, and ketamine, respectively. The developed method is simple, precise, and sensitive and could be applied successfully for the determination of laced foodstuff.

Objective: Systematic toxicological analysis by gas chromatography-mass spectrometry has been applied for the analysis of Indian herbal ready-to-chew pouches. Material and methods: These small packages containing a powder formed by areca nut slices, tobacco, menthol and lime, are available in traditional markets and web sites. Their consumption has been recently spread in the asiatic countries not only among adults but especially among young people. Acute and chronic side effects, an increase in the incidence of oral and esophagus cancer and the possibility to develop dependence and tolerance phenomena following repeated pouches consumption prompted the systematic toxicological analysis of gutka and panmasala pouches. Gas chromatography mass spectrometry was used to verify the presence of declared substances, and to investigate the possible presence of licit and illicit psychoactive compounds. Results: Arecoline (1.35–1.91 mg/g) and nicotine (0.31–0.71 mg/g) and arecoline alone (1.67–2.74 mg/g) were identified in gutkha and panmasala pouches, respectively, together with menthol (1.89–2.78 mg/g gutka and 1.91–2.84 mg/g panmasala) . No other pharmacological active compounds were identified. Conclusion: The mg amounts of the two alkaloids found in the pouches together with the reported consumption of several pouches a day may be consistent with health risks.

A capillary zone electrophoresis method is developed to achieve the separation and determination of two cardiac drugs, trandolapril and verapamil. Optimisation of the method is based on the use of a factorial design, which is applied in order to obtain more information in the factorial space and to minimise the number of experiments needed to obtain the optimum values for the pH and concentration of electrolyte buffer, the voltage applied and the effects of certain modifiers. Following these studies, the conditions selected for use were running buffer of 10 mM phosphate at pH 7.0, and a voltage of 15 kV. Under these conditions, calibration curves were constructed with good linearity (R>0.999) and suitable LODs. The intra‐ and inter‐day repeatabilities were also evaluated with RSD below 4% for trandolapril and verapamil. The proposed method was applied to the determination of verapamil and trandolapril in pharmaceutical formulations and the recoveries obtained were in agreement with the stated con...

Paroxetine is a potent selective serotonin reuptake inhibitor used for the treatment of depression and related mood disorders. A micellar liquid chromatographic method was developed for the determination of paroxetine in serum and urine. Detection of paroxetine was carried out using a C18 column and a mobile phase of 0.15 M sodium dodecyl sulfate, 6% 1-pentanol at pH 3 (buffer salt 0.01 M NaH2PO4) running under isocratic mode at 1.0 mL/min and electrochemical detection at 0.8 V. The analyte was eluted without interferences in 0.9999; 0.5–5 μg/mL range), accuracy (88–97.5%, recovery), repeatability (RSD < 0.54%), intermediate precision (RSD < 0.54%), limit of detection and quantification (0.001 and 0.005 μg/mL, respectively) and robustness (RSD < 3.63%). Developed method was successfully applied to real blood and urine samples as well as in spiked serum and urine samples. The developed method was specific, rapid, precise, reliable, accurate, inexpensive and then suitable for routine analysis of paroxetine in monitorized samples.

A simple, fast, and robust micellar LC method was developed for the separation and identification of the nonpermitted color malachite green in green pea and some ready-to-eat foodstuffs. Malachite green (4-[(4-dimethylaminophenyl) phenyl-methyl]-N,N-dimethylaniline) is a hazardous dye that is used to treat fungal and protozoan infections in fish and is a common adulterant (coloring agent) in green pea and other green vegetables because of its green color. In the present work, malachite green was determined in various foodstuffs using a direct injection technique on an RP C18 column with isocratic elution. The optimum mobile phase consisted of 0.15 M sodium dodecyl sulfate (SDS), 6% pentanol buffered at pH 5. Detection was carried out at 620 nm. Malachite green was eluted in 9.2 min without any interference caused by endogenous compounds. Linearities (r > 0.9999), intraday and interday precision (RSD less than 1.00%) in micellar media, and robustness were studied for method validation. LOD and LOQ were 0.10 and 0.25 ppm, respectively. The simplicity of the developed method makes it useful for routine analysis in the area of food QC.

The plasma level determination of catecholamines and their metabolites is necessary in studies aimed at evaluating neuroendocrine disorders. A micellar liquid chromatographic procedure was developed for the determination of epinephrine, norepinephrine, and their naturally occurring derivatives, metanephrine and nor‐metanephrine, in serum samples using direct injection. The optimisation studies were performed in a C18 column, using solutions containing sodium dodecyl sulphate (SDS) modified with propanol, butanol, or pentanol as mobile phases. The method proposed for the determination of these catecholamines used a hybrid micellar mobile phase of 0.075 M SDS–1.6% butanol–0.01 M phosphate buffer (pH 7) at 25°C, and electrochemical detection. The serum samples were injected directly without any pretreatment and eluted in 14 min, in accordance with their relative polarities as indicated by their octanol–water partition coefficients. Calibration was linear in the 0.5–50 ng mL−1 range with r 2>0.999. T...

A micellar liquid chromatographic (MLC) procedure was developed for the clinical monitoring of imipramine and its active metabolite, desipramine. The determination of these highly hydrophobic substances was carried out after direct injection of the serum samples using a mobile phase composed of 0.15 m SDS–6% (v/v) pentanol buffered at pH 7, pumped at 1.5 mL/min into a C18 column (250 × 4.6 mm), and electrochemical detection at 650 mV. Using this MLC method, calibration was linear (r > 0.995) and the limits of detection (ng/mL) were 0.34 and 0.24 for imipramine and desipramine, respectively. Repeatabilities and intermediate precision were tested at three different concentrations in the calibration range and a CV (%) below 2.2 was obtained. In this MLC procedure, the serum is determined without treatment, thus allowing repeated serial injections without changes in retention factors, and reducing the time and consumables required to carry out the pretreatment process. The assay method can be applied to the routine determination of serum imipramine and its metabolite in therapeutic drug monitoring. Copyright © 2004 John Wiley & Sons, Ltd.

A micellar liquid chromatographic (MLC) procedure was developed for the determination of carbaryl and other carbamates (carbofuran, desmedipham, methiocarb and propoxur), using a C18 column and UV detection. Optimisation was performed using the anionic surfactant sodium dodecyl sulphate (SDS) and the non-ionic Brij-35. Both surfactants yielded similar selectivities, but Brij-35 gives shorter retention times than SDS and for this reason was preferred to speed up the analysis of the carbamates. In the selected mobile phase (0.07 M of Brij-35), the analysis time was 22 min. The procedure was applied for the determination in commercial pesticide formulations and spiked samples (distilled, tap, reservoir tank, irrigation ditch, sea and waste water). This method proved to be competitive against the EPA reference method, recommended for the determination of some N-methylcarbamates, which uses a gradient of acetonitrile. The results of the pesticide formulations obtained with both methods are in agreemen...

The performance of a commercially available electrochemical detector cell has been evaluated for use in capillary electrophoresis (CE). It was shown that with proper installation of the capillary, the zone broadening caused by the cell is limited by the depletion of the analytes on the electrode surface. Despite the relatively large geometric volume of the cell, its contribution to zone widths was therefore only in the order of 1–2 s. When coupled to a CE set-up, plate numbers up to 100 000 could be obtained. With a 1-mm diameter glassy carbon electrode the detector noise was 3–5 pA, depending on the applied separation voltage. With this noise level detection limits of 10−8 mol l−1 could be obtained. The cell has been used for the determination of catecholamines, chlorophenols and o-phthalaldehyde derivatives of amino acids.

A liquid chromatographic procedure has been developed for the determination of carbaryl, a phenyl-N-methylcarbamate, and its main metabolite 1-naphthol, using a C18 column (250’mm’ × ’4.6’mm) with a micellar mobile phase and fluorescence detection at maximum excitation/emission wavelengths of 225/333’nm, respectively. In the optimization step, surfactants sodium dodecyl sulphate (SDS), Brij-35 andN-cetylpyridinium chloride monohydrate, and organic solvents propanol, butanol, and pentanol were considered. The selected mobile phase was 0.15’M SDS-6% (v/v)-pentanol-0.01’M NaH2PO4buffered at pH 3. Validation studies, according to the ICH Tripartite Guideline, included linearity (r>0.999), limit of detection (5 and 18’ng mL-1, for carbaryl and 1-naphthol, resp.), and limit of quantification (15 and 50’ng mL-1, for carbaryl and 1-naphthol, resp.), with intra- and interday precisions below 1%, and robustness parameters below 3%. The results show that the procedure was adequate for the routine analysis of these two compounds in water, soil, and vegetables samples.

Aromatic amines are extensively used in industry but they are classified as a potential environment and health hazard. A new high performance liquid chromatography method has been developed and optimized, for the determination of eight banned aromatic amines: benzidine, o-anisidine, o-phenylenediamine, o-nitroaniline, 2-methoxy-5-methylaniline (p-cresidine), o-toluidine, p-toluidine and p-chloroaniline. The chromatographic conditions used were: C18 column, 0.085 M SDS, 3.2% (v/v) pentanol mobile phase buffered at pH 7.0, with detection at 280 nm. Under these conditions, the eight aromatic amines were separated and quantified in industrial waste waters in less than 16 min. Method validation studies were performed according to the ICH Guideline. The possibility of direct injection using micellar liquid chromatography reduces the cost and the total time of analysis, and decreases error sources owing to minimized risks of losses and chemical changes in the analytes. The proposed method is a good candidate for application in the routine analysis in the area of environmental monitoring.

A procedure based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) is described for the determination of nicotine and its principal metabolites cotinine, trans-3-hydroxycotinine and cotinine-N-oxide, caffeine and arecoline in breast milk, using N-ethylnorcotinine as internal standard. Liquid/liquid extraction with chloroform/isopropanol (95:5, v/v) was used for nicotine, cotinine, trans-3-hydroxycotinine, cotinine-N-oxide and caffeine under neutral conditions and for arecoline under basic conditions. Chromatography was performed on a C(8) reversed-phase column using a gradient of 50 mM ammonium formate, pH 5.0, and acetonitrile as a mobile phase at a flow rate of 0.5 mL/min. Separated analytes were determined by electrospray ionization tandem mass spectrometry in the positive ion mode using multiple reaction monitoring. Limits of quantification were 5 microg/L for nicotine, cotinine, trans-3-hydroxycotinine, cotinine-N-oxide and caffeine, and 50 microg/L for arecoline using 1 mL human milk per assay. Calibration curves were linear over the calibration ranges for all the substances under investigation, with a minimum r(2) > 0.998. At three concentrations spanning the linear dynamic range of the assay, mean recoveries from breast milk ranged between 71.8 and 77.4% for different analytes. This method was applied to the analysis of analytes in human milk to assess substance exposure in breast-fed infants in relation to eventual clinical outcomes. This LC/MS/MS assay provides adequate sensitivity and performance characteristics for the simultaneous quantification of biomarkers of three of the drugs most commonly used worldwide (tobacco, caffeine and areca nut).

A rapid multiresidue method to quantify three different classes of plant hormones has been developed. The reduced concentrations of these metabolites in real samples with complex matrixes require sensitive techniques for their quantification in small amounts of plant tissue. The method described combines high-performance liquid chromatography with electrospray ionization tandem mass spectrometry. Deuterium-labeled standards were added prior to sample extraction to achieve an accurate quantification of abscisic acid, indole-3-acetic acid, and jasmonic acid in a single run. A simple method of extraction and purification involving only centrifugation, a partition against diethyl ether, and filtration was developed and the analytical method validated in four different plant tissues, citrus leaves, papaya roots, barley seedlings, and barley immature embryos. This method represents a clear advantage because it extensively reduces sample preparation and total time for routine analysis of phytohormones in real plant samples.

Acetaminophen is determined in serum and urine samples by a rapid, sensitive, and precise chromatographic method without any pretreatment step in a C18 column using a pure micellar mobile phase of 0.02M sodium dodecyl sulfate at pH 7. Acetaminophen is eluted in less than 5 min with no interference of the protein band. The use of electrochemical and UV detection is compared. Linearities (r > 0.999), as well as intra- and interday precision, are studied in the validation of the method. Limits of detection (LOD) are also calculated to be 0.56, 0.83, and 0.74 ng/mL in micellar solution, serum, and urine using electrochemical detection. The developed micellar liquid chromatographic method is useful for the quantitation of acetaminophen in serum and urine. Recoveries in the biological matrices are in the 98-107% range and results are compared with those obtained using a reference method. Drug excretion (in urine) and serum distribution are studied in several healthy volunteers, and no interference from metabolites is found. The developed procedure can be applied in routine analyses, toxicology, and therapeutic monitoring.

A procedure was developed for the determination of caffeine and theophylline using a C 18 column (5 μm, 250 mm × 4.6 mm) and micellar liquid chromatography using hybrid mobile phases containing sodium dodecyl sulfate (SDS) and propanol, butanol or pentanol as modifiers. Detection was performed with a variable wavelength UV–vis detector at 272 nm. After the application of an interpretative strategy for the selection of the optimimum mobile phase, caffeine and theophylline can be resolved and determined in serum samples by direct injection, using a mobile phase made up of 50 mM SDS–2.5% (v/v) propanol–10 mM KH 2 PO 4 , pH 7, with an analysis time below 5 min. Calibration was linear in the range 0.05 to 50 μg mL −1 with r > 0.999. The statistical evaluation of the method was examined by performing intra-day ( n = 6) and inter-day calibration ( n = 7) and was found to be satisfactory, with highly accurate and precise results. The proposed method was suitably validated and applied to the determination of caffeine and theophylline in serum samples of patients treated with bronchodilators.

Introduction Amitriptyline and nortriptyline are tricyclic antidepressants which act by enhancing the actions of norepinephrine and serotonin caused by blocking the re-uptake of various neurotransmitters at the neuronal membrane. A micellar liquid chromatographic procedure was developed to determine these drugs in serum samples for use in clinical monitoring. Methods The chromatographic determination of these highly hydrophobic substances was carried out using a 0.15 M SDS-6% ( v / v ) pentanol buffered at pH 7, in a C18 column, and electrochemical detection at 650 mV. The flow-rate was 1.5 mL/min. The analysis time was 14 min. Results The limits of detection (ng/mL) in serum were 0.25 and 0.31 for amitriptyline and nortriptyline, respectively. Repeatability and intermediate precision were evaluated at three different concentrations in serum samples. Discussion Untreated serum samples were injected directly into the HPLC system after filtration, leading to be a simple procedure that can be applied in routine analyses for Therapeutic Drug Monitoring.