UV Densitometry Research Articles

Development and comprehensive greenness assessment for MEKC and HPTLC methods for simultaneous estimation of sertaconazole with two co-formulated preservatives in pharmaceutical dosage forms

Four greenness assessment tools: National Environmental Methods Index (NEMI), Ecoscale Assessment (ESA), Green Analytical Procedure Index (GAPI) and the most recent Analytical GREEness metric (AGREE) were tested to evaluate two proposed MEKC and HPTLC methods for the simultaneous determination of the antifungal drug sertaconazole (SER) and two co-formulated preservatives methyl paraben (MEP) and sorbic acid (SOR). Method I was micellar electrokinetic capillary chromatography (MEKC). Electrophoretic conditions were optimized to improve separation, sensitivity, and rapidity. The proposed method used a fused silica capillary (50 cm × 50 μm id), and the background electrolyte was 50 mM acetate buffer pH 4.6 containing 15 mM SDS with 17 s injection time. The applied voltage was 30 kV. The diode array detector (DAD) was set at 210 nm for measurement of SER and 254 nm for both MEP and SOR. The Three compounds were resolved in less than 6 min with migration times 3.07, 4.29, and 5.97 min for SER, MEP, and SOR respectively. The described method was linear over the range of 5–100 μg/mL for SER, MEP and SOR with correlation coefficients >0.9995. For method II: high-performance thin-layer chromatography (HPTLC) analysis was carried out on aluminum-backed sheet of silica gel using chloroform-ethyl acetate (3:7) as mobile phase. Retardation factors were 0.20, 0.71, and 0.88 for SER, MEP, and SOR respectively. Quantification was achieved with UV densitometry at 210 nm for SER and 254 nm for MEP and SOR. The linearity ranges were 0.1–1 μg/spot for the three drugs with correlation coefficients >0.9998. The analytical performance of both methods was thoroughly validated according to International Conference on Harmonization (ICH) guidelines with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. The proposed MEKC and HPTLC methods were successfully applied for estimation of the studied drugs in laboratory prepared mixtures and in the cream and spray dosage forms.

Estimating Limits of Detection and Quantification of Ibuprofen by TLC-Densitometry at Different Chromatographic Conditions

Ibuprofen is one of the best-known nonsteroidal anti-inflammatory and analgesic drugs. Following the previous work, the current study is focused on estimating the effect of different chromatographic conditions on the sensitivity of thin-layer chromatography in combination with UV densitometry, i.e., the detection and quantification of ibuprofen in a wide range of its concentrations including the lowest limits of detection (LOD) and quantification (LOQ). For this purpose, a reliable and easy-to-use calculation procedure for LOD and LOQ determination is presented in this work. In addition, the impact of type plates and mobile phase composition on the LOD and LOQ, respectively, of this active substance is accurately described. The results of detection and the quantification level of ibuprofen obtained under applied chromatographic conditions confirmed the utility of silica gel plates as well as silica gel bonded phases (i.e., reversed-phase (RP) plates) in the thin-layer chromatography (TLC)-densitometric analysis of ibuprofen at a low level, i.e., from several nanograms (below one microgram) to a few micrograms/spot. Among all chromatographic systems tested, the best are those consisting of silica gel 60F254 plates with concentrating zone (1.05583) and the mixture of n-hexane:ethyl acetate:glacial acetic acid in ratio 36:12:2 (v/v/v) as well as RP plates, i.e., RP-18F254 aluminum plates developed with methanol:water in volume composition 40:10 (v/v). These chromatographic systems allowed quantifying ibuprofen in the amount of 0.229 µg/spot and 0.228 µg/spot, which is less than 1 µg/spot. It can be stated that different chromatographic systems in combination with UV densitometric scanning at 224 nm proposed in this work can be successfully applied for the cost-effective and sensitive determination of ibuprofen as a widely used drug component as well as a residual in domestic wastewater. It was found that the modification of silica gel as well as the layer thickness of unmodified or modified silica gel 60 can influence the quality of chromatograms and the detection/quantification of ibuprofen in both normal phase (NP) and RP systems. Therefore, to obtain the best possible LOD and LOQ values of ibuprofen with precoated layers, suitable mobile phase and chromatographic plates are required.

Speciation of Metals in Asphaltenes by High-Performance Thin-Layer Chromatography and Laser Ablation Inductively Coupled Plasma-Mass Spectrometry

Asphaltenes are considered to be the most problematic components of heavy oils because they can self-aggregate which leads to precipitation and causes various problems during oil recovery, transportation, and refining. The contribution of the porphyrins present in asphaltenes to the aggregation was previously studied by gel permeation chromatography inductively coupled plasma-mass spectrometry (GPC-ICP MS). The molecular weight of asphaltene aggregates was shown to be increased by free metal-containing porphyrins (corresponding to the lower molecular weight fraction) interacting with the aggregate’s surfaces by weak forces. The characterization of free porphyrins within the asphaltenes is therefore for the understanding of the mechanism of the aggregation, coprecipitation, and demetalation processes. Here, we developed a method for the separation of free porphyrins from asphaltenes on the basis of their polarity using high-performance thin-layer chromatography (HPTLC). This technique, using disposable plates, is particularly well suited for asphaltene analysis since it eliminates the risk of clogging typical of column chromatography. Cellulose plates were used in this study. The lower polarity of their hydroxyl groups limit the irreversible adsorption and improves the detection limit by the ICP-MS. Two well-separated peaks were obtained from purified asphaltene (Asphaltene 2017; Asphaltene Characterization Interlaboratory Study for PetroPhase 2017. In Proceedings of the 18th International Conference on Pretroleum Phase Behavior and Fouling, Le Havre, France, June 11–15, 2017; Total, the University of Pau, and the University of Rouen-Normandy: Le Havre, France, 2017.) and its corresponding whole crude oil and C5 and C7 fractions. The distribution of vanadium due to migration was determined by laser ablation (LA) ICP MS. The eluted fraction contained the free porphyrins, whereas the major fraction did not migrate and corresponded to trapped porphyrins. A comparison with the signal obtained by UV densitometry allowed the ratio between the inorganic and organic material to be measured.

A Simple and Cost-Effective TLC-Densitometric Method for the Quantitative Determination of Acetylsalicylic Acid and Ascorbic Acid in Combined Effervescent Tablets.

A new, simple, and cost-effective TLC-densitometric method has been established for the simultaneous quantitative determination of acetylsalicylic acid and ascorbic acid in combined effervescent tablets. Separation was performed on aluminum silica gel 60F254 plates using chloroform-ethanol-glacial acid at a volume ratio of 5:4:0.03 as the mobile phase. UV densitometry was performed in absorbance mode at 200 nm and 268 nm for acetylsalicylic acid and ascorbic acid, respectively. The presented method was validated as per ICH guidelines by specificity, linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. Method validations indicate a good sensitivity with a low value of LOD and LOQ of both examined active substances. The linearity range was found to be 1.50–9.00 μg/spot and 1.50–13.50 μg/spot for acetylsalicylic and ascorbic acid, respectively. A coefficient of variation that was less than 3% confirms the satisfactory accuracy and precision of the proposed method. The results of the assay of combined tablet formulation equal 97.1% and 101.6% in relation to the label claim that acetylsalicylic acid and ascorbic acid fulfill pharmacopoeial requirements. The developed TLC-densitometric method can be suitable for the routine simultaneous analysis of acetylsalicylic acid and ascorbic acid in combined pharmaceutical formulations. The proposed TLC-densitometry may be an alternative method to the modern high-performance liquid chromatography in the quality control of above-mentioned substances, and it can be applied when HPLC or GC is not affordable in the laboratory.

TLC–direct bioautography as a method for evaluation of antibacterial properties of Thymus vulgaris L. and Salvia officinalis L. essential oils of different origin

ABSTRACTThe dot-blot bioautography was used to evaluate the antibacterial properties of Thymus vulgaris L. and Salvia officinalis L. essential oils (EOs) produced by three different manufacturers. The whole samples were applied at three concentrations on thin-layer chromatography (TLC) plates which were then subjected to bioautography against Bacillus subtilis. The samples of the highest activity were found. Then, they were separated using TLC and once again subjected to bioautography against B. subtilis. As was proved, only the essential oils of T. vulgaris L. possessed strong antibacterial properties for which mostly thymol and carvacrol were responsible. Their contents were calculated using TLC–UV densitometry. The highest contents were found in the essential oils of the highest antibacterial activity revealed in the dot-blot test. It means that a dot-blot test can be used for simple and fast evaluation of antibacterial properties of essential oils.

Employing response surface methodology for the optimization of ultrasound assisted extraction of lutein and β-carotene from spinach.

The extraction of lutein and β-carotene from spinach (Spinacia oleracea L.) leaves is important to the dietary supplement industry. A Box-Behnken design and response surface methodology (RSM) were used to investigate the effect of process variables on the ultrasound-assisted extraction (UAE) of lutein and β-carotene from spinach. Three independent variables, extraction temperature (°C), extraction power (%) and extraction time (min) were studied. Thin-layer chromatography (TLC) followed by UV visualization and densitometry was used as a simple and rapid method for both identification and quantification of lutein and β-carotene during UAE. Methanol extracts of leaves from spinach and authentic standards of lutein and β-carotene were separated by normal-phase TLC with ethyl acetate-acetone (5:4 (v/v)) as the mobile phase. In this study, the combination of TLC, densitometry, and Box–Behnken with RSM methods were effective for the quantitative analysis of lutein and β-carotene from spinach extracts. The resulting quadratic polynomial models for optimizing lutein and β-carotene from spinach had high coefficients of determination of 0.96 and 0.94, respectively. The optimal UAE settings for output of lutein and β-carotene simultaneously from spinach extracts were an extraction temperature of 40 °C, extraction power of 40% (28 W/cm3) and extraction time of 16 min. The identity and purity of each TLC spot was measured using time-of-flight mass spectrometry. Therefore, UAE assisted extraction of carotenes from spinach can provide a source of lutein and β-carotene for the dietary supplement industry.

QUANTITATIVE SIMULTANEOUS DETERMINATION OF FENOFIBRATE, ATORVASTATIN, AND EZETIMIBE IN TABLETS USING GRADIENT HIGH-PERFORMANCE COLUMN LIQUID CHROMATOGRAPHY AND HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHY

Simple, accurate, precise, sensitive, and validated high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC)-densitometric methods were developed for simultaneous determination of fenofibrate (FEN), atorvastatin (ATO), and ezetimibe (EZE) in combined tablet dosage form. In Method A, the gradient RP-HPLC analysis was performed on a Shim-pack C18 column (150 × 6 mm id), using a mobile phase consisting of 0.1% formic acid and acetonitrile in solvent gradient elution for 25 min at a flow rate of 1.5 mL min−1. Quantification was carried out using a photodiode array UV detector at 245 nm. The employment of diode array detector allowed selectivity confirmation by peak purity evaluation. In Method B, the HPTLC analysis was carried out on an aluminum-backed sheet of silica gel 60F254 layer using toluene: methanol:triethylamine (8:1.5:0.1, v/v/v) as the mobile phase. Quantification was achieved with UV densitometry at 245 nm. The analytical methods were validated according to International Conference on Harmonization guidelines. Low relative standard deviation values indicated good precision. Both the methods were successfully applied for the analysis of drugs in laboratory-prepared mixtures and commercial tablets. No chromatographic interference from tablet excipients was found, and hence these methods are applicable for simultaneous determination of FEN, ATO, and EZE in pharmaceutical formulations.

Validated Analytical Method Development of Inosine Pranobex in Drug Products by Thin Layer Chromatography

Thin layer chromatography (TLC) with densitometry has been established for the identification and the quantification of inosine pranobex in drug substance and drug products. Inosine pranobex is a combination of inosine, acetamidobenzoic acid, and dimethylaminoisopropanol. UV densitometry was performed in absorbance mode at 260 nm. The separation was carried out on aluminum sheet of silica gel 60 f 254 [chloroform - methanol- - toluene -10% ammonia solution (6:5:1: 0.1% v/v)] as mobile phase. Linearity range was found to be 1-12, 2-12, 2-20 and 2-16 µg/ml for inosine pranobex, inosine, acetamidobenzoic acid, and dimethylaminoisopropanol with the mean percentage recoveries 99.74± 1.73%, 99.88 ± 1.75%, 99.56 ±1.08%, and 99.36 ± 0.71% respectively, (Correlation coefficient r2 = 0.9998 for inosine pranobex, r2 = 0.09999 for inosine, r2 = 0.9998 for acetamidobenzoic acid and r2= 0.9998 for dimethylaminoisopropanol). The detection and quantification limits for inosine pranobex and other components are also reported. The presented method was validated according to ICH guidelines. Statistical comparison of the results was performed using Student's t-test and F-ratio at 95% confidence level, and there was no significant difference between the reference and proposed method with regard to accuracy and precision. It could be said that the validated TLC-densitometry method is suitable for the routine analysis of inosine pranobex in quantity control laboratories.

USE OF TLC FOR THE QUANTITATIVE DETERMINATION OF ACETYLSALICYLIC ACID, CAFFEINE, AND ETHOXYBENZAMIDE IN COMBINED TABLETS

Adsorption thin layer chromatography (NP-TLC) with densitometry has been established for the identification and the quantification of acetylsalicylic acid, caffeine, and ethoxybenzamide in combined tablets. UV densitometry was performed in absorbance mode at 200 nm, 275 nm, and 300 nm for acetylsalicylic acid, caffeine, and o-ethoxybenzamide, respectively. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. It could be said that the NP-TLC-densitometric method is suitable for the routine analysis of acetylsalicylic acid, caffeine, and ethoxybenzamide in combined tablets in quantity control laboratories.

Validation Thin Layer Chromatography for the Determination of Acetaminophen in Tablets and Comparison with a Pharmacopeial Method

Adsorption thin layer chromatography (NP-TLC) with densitometry has been established for the identification and the quantification of acetaminophen in three leading commercial products of pharmaceutical tablets coded as brand: P1 (Product no. 1), P2 (Product no. 2), and P3 (Product no. 3). Applied chromatographic conditions have separated acetaminophen from its related substances, namely, 4-aminophenol and and 4′-chloroacetanilide. UV densitometry was performed in absorbance mode at 248 nm. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. The TLC-densitometric method was also compared with a pharmacopeial UV-spectrophotometric method for the assay of acetaminophen, and the results confirmed statistically that the NP-TLC-densitometric method can be used as a substitute method. It could be said that the validated NP-TLC-densitometric method is suitable for the routine analysis of acetaminophen in quantity control laboratories.

Solid phase extraction and high-performance thin-layer chromatography quantification of some antibiotics from surface waters

Summary Excessive use of antibiotics leads to their occurrence into the environment. In spite of their benefit properties and desired effects during the therapeutic applications, the same properties can be disadvantageous for the environment having negative influences over the plants and microorganisms and the potential risks for human health. Regarding the monitoring of antibiotics and their subsequent elimination from environment, it is necessary to develop analytical procedures for their determination. In the present study, the quantitative determination of seven antibiotics belonging to three different classes is reported: tetracyclines (tetracycline and doxycycline), cephalosporins (ceftazidime and ceftriaxone), and penicillins (amoxicillin, ampicillin, and penicillin G) from surface waters. The proposed procedure consists of the solid phase extraction (SPE) of studied antibiotics from river water samples, their separation by high-perfomance thin-layer chromatography (HPTLC), and quantification by UV densitometry. The antibiotics were extracted from water matrices using hydrophilic–lipophilic-balanced Oasis HLB cartridges. The cartridge efficiency of the SPE method was checked by recovery experiments and evaluated by HPTLC. The chromatographic separation was performed on pre-coated Alugram SIL G/UV254 plates with ethyl acetate–methanol–acetone–water 5:2.5: 2.5:1.5 (v/v) mobile phase. The bands were detected and quantified at 254 nm by densitometry. For method validation, studies of selectivity, linearity, limits of detection and quantification, and precision and accuracy were achieved. The proposed procedure was applied to the determination of studied antibiotics on surface water samples collected from Someoul Mic River (Romania).

DETERMINATION OF ACETYLSALICYLIC ACID IN PHARMACEUTICAL DRUGS BY TLC WITH DENSITOMETRIC DETECTION IN UV

Adsorption thin layer chromatography (NP-TLC) with densitometry has been established for the identification and the quantification of acetylsalicylic acid in tablets. UV densitometry was performed in absorbance mode at 200 nm. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. The TLC-densitometric method was also compared with a pharmacopeial UV-spectrophotometric method for the assay of acetylsalicylic acid, and the results confirmed statistically that the NP-TLC-densitometric method can be used as a substitute method. It could be said that the NP-TLC-densitometric method is suitable for the routine analysis of acetylsalicylic acid in quantity control laboratories.

QUANTITATIVE SIMULTANEOUS DETERMINATION OF AMLODIPINE, VALSARTAN, AND HYDROCHLOROTHIAZIDE IN “EXFORGE HCT” TABLETS USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHY

Simple, accurate, precise, sensitive, and validated HPLC and HPTLC-densitometric methods were developed for simultaneous determination of amlodipine (AML), valsartan (VAL), and hydrochlorothiazide (HYD) in combined tablet dosage form. Method A, the gradient RP-HPLC analysis was performed on a Phenomenex Luna C18 (4.60 mm × 150 mm, 5 µ particle size) column, using a mobile phase consisting of 10 mM ammonium acetate buffer (pH 6.7) and methanol in solvent gradient elution for 20 min at a flow rate of 1 mL min−1. Quantification was carried out using a photodiode array UV detector at 238 nm. The employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. Method B, the HPTLC analysis was carried out on an aluminum-backed sheet of silica gel 60F254 layers using chloroform: glacial acetic acid:n-butyl acetate (8:4:2, v/v/v) as the mobile phase. Quantification was achieved with UV densitometry at 320 nm. The analytical methods were validated according to International Conference on Harmonization (ICH) guidelines. No chromatographic interference from tablet excipients was found and hence these methods are applicable for simultaneous determination of AML, VAL, and HYD in pharmaceutical formulations and biological fluids.

VALIDATION THIN LAYER CHROMATOGRAPHY FOR THE DETERMINATION OF NAPROXEN IN TABLETS AND COMPARISON WITH A PHARMACOPEIL METHOD

Adsorption thin layer chromatography with densitometry has been established for the identification and the quantification of naproxen in tablets. UV densitometry was performed in absorbance mode at 230 nm. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. The TLC-densitometric method was also compared with a pharmacopeial UV-spectrophotometric method for the assay of naproxen, and the results confirmed statistically that the TLC-densitometric method can be used as a substitute method.

DETERMINATION OF HYDROCORTISONE IN PHARMACEUTICAL DRUG BY TLC WITH DENSITOMETRIC DETECTION IN UV

Adsorption thin layer chromatography with densitometry has been established for the identification and the quantification of hydrocortisone in tablets. UV densitometry was performed in absorbance mode at 250 nm. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. The TLC-densitometric method was also compared with a pharmacopeil UV-spectrophotometric method for the assay of hydrocortisone, and the results confirmed statistically that the TLC-densitometric method can be used as a substitute method.

Quantitative analysis of major dibenzocyclooctane lignans in schisandrae fructus by online TLC‐DART‐MS

Direct analysis in real time (DART) ion source is a powerful ionising technique for the quick and easy detection of various organic molecules without any sample preparation steps, but the lack of quantitation capacity limits its extensive use in the field of phytochemical analysis. To improvise a new system which utilize DART-MS as a hyphenated detector for quantitation. A total extract of Schisandra chinensis fruit was analyzed on a TLC plate and three major lignan compounds were quantitated by three different methods of UV densitometry, TLC-DART-MS and HPLC-UV to compare the efficiency of each method. To introduce the TLC plate into the DART ion source at a constant velocity, a syringe pump was employed. The DART-MS total ion current chromatogram was recorded for the entire TLC plate. The concentration of each lignan compound was calculated from the calibration curve established with standard compound. Gomisin A, gomisin N and schisandrin were well separated on a silica-coated TLC plate and the specific ion current chromatograms were successfully acquired from the TLC-DART-MS system. The TLC-DART-MS system for the quantitation of natural products showed better linearity and specificity than TLC densitometry, and consumed less time and solvent than conventional HPLC method. A hyphenated system for the quantitation of phytochemicals from crude herbal drugs was successfully established. This system was shown to have a powerful analytical capacity for the prompt and efficient quantitation of natural products from crude drugs.

Simultaneous Determination of Atorvastatin Calcium and Ramipril in Capsule Dosage Forms by High-Performance Liquid Chromatography and High-Performance Thin Layer Chromatography

Two simple and accurate methods to determine atorvastatin calcium and ramipril in capsule dosage forms were developed and validated using HPLC and HPTLC. The HPLC separation was achieved on a Phenomenex Luna C18 column (250 x 4.6 mm id, 5 microm) in the isocratic mode using 0.1% phosphoric acid-acetonitrile (38 + 62, v/v), pH 3.5 +/- 0.05, mobile phase at a flow rate of 1 ml/min. The retention times were 6.42 and 2.86 min for atorvastatin calcium and ramipril, respectively. Quantification was achieved with a photodiode array detector set at 210 nm over the concentration range of 0.5-5 microg/mL for each, with mean recoveries (at three concentration levels) of 100.06 +/- 0.49% and 99.95 +/- 0.63% RSD for atorvastatin calcium and ramipril, respectively. The HPTLC separation was achieved on silica gel 60 F254 HPTLC plates using methanol-benzene-glacial acetic acid (19.6 + 80.0 + 0.4, v/v/v) as the mobile phase. The Rf values were 0.40 and 0.20 for atorvastatin calcium and ramipril, respectively. Quantification was achieved with UV densitometry at 210 nm over the concentration range of 50-500 ng/spot for each, with mean recoveries (at three concentration levels) of 99.98 +/- 0.75% and 99.87 +/- 0.83% RSD for atorvastatin calcium and ramipril, respectively. Both methods were validated according to International Conference on Harmonization guidelines and found to be simple, specific, accurate, precise, and robust. The mean assay percentages for atorvastatin calcium and ramipril were 99.90 and 99.55% for HPLC and 99.91 and 99.47% for HPTLC, respectively. The methods were successfully applied for the determination of atorvastatin calcium and ramipril in capsule dosage forms without any interference from common excipients.

Determination of Rosuvastatin and Ezetimibe in a Combined Tablet Dosage Form Using High-Performance Column Liquid Chromatography and High-Performance Thin-Layer Chromatography

This paper describes validated HPLC and HPTLC methods for the simultaneous determination of rosuvastatin (ROS) and ezetimibe (EZE) in a combined tablet dosage form. The isocratic RP-HPLC analysis was performed on a Chromolith C18 column (100 x 6 mm id) using 0.1% (v/v) orthophosphoric acid solution (pH 3.5)-acetonitrile (63 + 37, v/v) mobile phase at a flow rate of 1 mL/min at ambient temperature. Quantification was carried out using a photodiode array UV detector at 245 nm over the concentration range of 0.5-10 microg/mL for ROS and EZE. The HPTLC separation was carried out on an aluminum-backed sheet of silica gel 60F(254) layers using n-butyl acetate-chloroform-glacial acetic acid (1 + 8 + 1, v/v/v) mobile phase. Quantification was achieved with UV densitometry at 245 nm over a concentration range of 0.1-0.9 micro/spot for ROS and EZE. The analytical methods were validated according to International Conference on Harmonization guidelines. Low RSD values indicated good precision. Both methods were successfully applied for the analysis of the drugs in laboratory-prepared mixtures and commercial tablets. No chromatographic interference from the tablet excipients was found. These methods are simple, precise, and sensitive, and are applicable for simultaneous determination of ROS and EZE in pure powder and tablets.

COMPARISON OF NP-TLC AND RP-TLC WITH DENSITOMETRY TO QUANTITATIVE ANALYSIS OF IBUPROFEN IN PHARMACEUTICAL PREPARATIONS

NP-TLC and RP-TLC techniques with densitometry have been established for the identification and the quantification of ibuprofen in selected pharmaceutical preparations, namely: Nurofen, Ibuprom, and Ibum. Analyses were performed on silica gel 60 F254 plates using n-hexane-ethyl acetate-acetic acid, 15:5:0.7, v/v (NP-TLC) and on RP18 F254s plates using methanol-water, 9:1, v/v (RP-TLC). UV densitometry was performed at 200 and 224 nm for NP-TLC and RP-TLC analysis, respectively. NP-TLC and RP-TLC techniques with the densitometry and the spectrodensitometry applied to the investigation and the determination of ibuprofen in pharmaceutical preparations are selective, precise, and accurate. The techniques also realize the criterion of the linearity in the required range of ibuprofen concentrations.

RP-TLC separation of antiarrhythmic drugs. Densitometric analysis of flecainide in tablets

The chromatographic behavior of some antiarrhythmic compounds has been studied on commercially available TLC plates coated with octylsilane and octadecylsilane silica gel (RP-C8 and RP-C18, respectively) with organic-aqueous mobile phases containing citrate or acetate buffers at different pH. The best separations of individual and mixed drug standards were achieved on both RP-C8 and RPC18 with 3:7 ( v/v ) tetrahydrofuran-citrate buffer pH 4.45 as mobile phase. To determine the usefulness of these chromatographic systems for analysis of tablet samples, flecainide acetate was identified and quantified by UV densitometry at two wavelengths, 225 and 310 nm. Linear relationships were obtained between peak height or peak area and amount in the range 6.0 to 12.0 μg per spot, the correlation coefficient, r , was ∼0.990. The method was successfully applied to the analysis of flecainide in a pharmaceutical preparation, with satisfactory precision (RSD 1.14–5.93%) and accuracy (96.19–103.59%).