White sustainable luminescent determination of nifuroxazide using nitrogen-sulphur co-doped carbon quantum dots nanosensor in bulk and various pharmaceutical matrices.

Nifuroxazide (NFX) is an antimicrobial agent that is frequently used as an intestinal antiseptic and recently was proven to have anticancer properties. This work employs the use of nitrogen and sulphur co-doped carbon quantum dots (NSC-dots) luminescent nanoparticles to propose a highly sensitive, sustainable, white and green spectrofluorometric method for NFX detection in bulk and pharmaceutical dosage forms. l-Cysteine and citric acid were the precursors to synthesize water soluble NSC-dots by a quick and environmentally-friendly hydrothermal process. NSC-dots' native fluorescence was measured at λem = 416 nm following excitation at 345 nm. Addition of NFX resulted in quantitative quenching of NSC-dots' luminescence, which represents the principle over which this luminescent method was based. Additionally, the mechanism of fluorescence quenching was studied and discussed. The analytical procedure was validated according to the ICH-guidelines. Linear response for NFX was obtained in the dynamic range 0.04-15 µg mL-1. The estimated NFX detection and quantification limits were 0.005 and 0.015 µg mL-1, respectively. The proposed method was employed for NFX quantification into two commercial pharmaceutical dosage forms. The calculated percentage recoveries (R%), percentage relative standard deviations (RSD%), and percentage error (Er%) were satisfactory. Comparison with other reported methods showed that the proposed method is superior in several aspects. Evaluation of the whiteness of the proposed method using the RGB 12 algorithm combined with the most widely used greenness evaluation tools, the Analytical Eco-Scale and AGREE, demonstrated its superiority and sustainability over other previously published spectrofluorimetric methods for the assay of NFX in various dosage forms.

Multiple green spectroscopic methods for erdosteine determination in bulk and dosage form with extensive greenness evaluation.

Four simple, sensitive, economical, and eco-friendly spectrophotometric and spectrofluorimetric methods for the assay of erdosteine (ERD) in bulk and dosage form have been developed and validated as per the current ICH guidelines. Method I involved the addition of the powerful oxidizing agent, potassium permanganate to ERD and measuring the oxidation product at 600 nm. Another oxidizing agent; ceric ammonium sulfate was used in Method II where ERD is oxidized resulting in a decline in the absorbance intensity of cerium (IV) ions, measured at 320 nm. Similarly, Method III employed the use of ceric ammonium sulfate, However, the fluorescence intensity of the resulting cerium (III) ions was recorded at λex/λem 255/355 nm, respectively. Whereas in Method IV, ERD was added to acriflavine leading to a proportional decrease in its native fluorescence. Various reaction conditions affecting the intensity of measurement were attentively investigated, optimized, and validated. All the suggested methods did not require any tedious extraction procedures nor organic solvents. The implementation of the proposed methods in ERD assay resulted in linear relationships between the measured signals and the corresponding concentrations of ERD in the range of 1-6, 0.1-1.0, 0.01-0.1, and 10-100 µg/mL with LOD values 0.179, 0.024, 0.0027 and, 3.2 µg/mL for methods I, II, III and IV respectively. The suggested methods were successfully applied to ERD analysis in pure form and in commercial capsules. Furthermore, the eco-friendliness of the proposed methods was thoroughly checked using various greenness testing tools. Lastly, this work, not only presents highly sensitive, green, mix-and-read methods for ERD determination, but also, describes the determination of ERD spectrofluorimetrically for the first time in the literature.

Development of a sustainable multianalyte MEKC method for quantitation of the antihyperlipidemic drugs ezetimibe together with three statins. Greenness and whiteness appraisal studies.

Implementing powerful and sustainable research that complies with green analytical chemistry (GAC) and white analytical chemistry (WAC) fundamentals can downsize the environmental compliance costs and fruitfully affects practical and economic issues. Within this framework, rapid and white analytical micellar electrokinetic capillary chromatography (MEKC) methodology was developed for the synchronized estimation of the antihyperlipidemic drugs Ezetimibe (EZE), Atorvastatin (ATO), Rosuvastatin (ROS) and Simvastatin (SIM). The technique was established using fused silica capillary (50 cm, 50 µm id) and the background electrolyte was 0.025 M borate buffer pH 9.2 containing 0.025 M sodium dodecyl sulfate (SDS) and 10% v/v acetonitrile as the organic modifier. Diode array detector was adjusted at 243 nm for ATO and ROS and 237 nm for EZE and SIM. Separation was accomplished within 10 min with migration times of 4.12, 5.42, 8.23 and 8.74 min for ROS, ATO, EZE and SIM respectively. The 4 drugs were quantitated in the concentration range of 10-100 µg/mL and the correlation coefficients were not less than 0.9993. The high sensitivity was illustrated by values of the detection and quantitation limits. The limits of detection for ROS, ATO, EZE and SIM were 0.52, 0.75, 0.42 and 0.64 µg/mL, respectively, whereas, the limits of quantitation values were 1.73, 2.50, 1.40 and 2.13 µg/mL for the studied drugs, respectively. In addition to validation, as reported by the ICH guidelines, greenness and whiteness assessment using the novel AGREE calculator and the holistic functionality model RGB12 were performed. The results proved the efficiency and whiteness of the suggested technique to be routinely implemented in quality control laboratories for the assay of the four drugs and the binary mixtures of EZE with either ATO, ROS or SIM in fixed-dose combined tablets.

Green "turn-off" luminescent nanosensors for the sensitive determination of desperately fluorescent antibacterial antiviral agent and its metabolite in various matrices.

Nitazoxanide (NTX) is an antimicrobial drug that was used for the treatment of various protozoa. However, during the coronavirus pandemic, NTX has been redirected for the treatment of such virus that primarily infect the respiratory tract system. NTX is now used as a broad-spectrum antiviral agent. In this study, a highly sensitive and green spectrofluorometric method was developed to detect NTX in various dosage forms and its metabolite, tizoxanide (TX), in human plasma samples using nitrogen and sulfur co-doped carbon quantum dots nanosensors (C-dots). A simple and eco-friendly hydrothermal method was used to synthetize water soluble C-dots from citric acid and l-cysteine. After excitation at 345 nm, the luminescence intensity was measured at 416 nm. Quenching of C-dots luminescence occurred upon the addition of NTX and was proportional to NTX concentration. Assessment of the quenching mechanism was performed to prove that inner filter effect is the underlying molecular mechanism of NTX quenching accomplished. After optimizing all experimental parameters, the analytical procedure was evaluated and validated using the ICH guidelines. The method linearity, detection and quantification limits of NTX were 15 × 10-3-15.00 µg/mL, 56.00 × 10-4 and 15 × 10-3 µg/mL, respectively. The proposed method was applied for the determination of NTX in its commercial pharmaceutical products; Nanazoxid® oral suspension and tablets. The obtained % recovery, relative standard deviation and % relative error were satisfactory. Comparison with other reported spectrofluorimetric methods revealed the superior sensitivity of the proposed method. Such high sensitivity permitted the selective determination of TX, the main metabolite of NTX, in human plasma samples making this study the first spectrofluorimetric method in literature that determine TX in human plasma samples. Moreover, the method greenness was assessed using both Eco-Scale and AGREE approaches to prove the superiority of the proposed method greenness over other previously published spectrofluorimetric methods for the analysis of NTX and its metabolite, TX, in various dosage forms and in human plasma samples.

Fast and Sensitive Bioanalytical Method for the Determination of Deucravacitinib in Human Plasma Using HPLC-MS/MS: Application and Greenness Evaluation.

Plaque psoriasis is a common, long-lasting illness that affects the immune system and causes significant negative impacts on a patient's physical health, well-being, and ability to work effectively. Deucravacitinib (DEU) is the first oral medication used in the treatment of plaque psoriasis, a chronic skin condition that causes red, scaly patches on the skin. DEU is a type of medication called an oral Janus kinase (JAK) inhibitor, which works by blocking specific enzymes that play a role in the inflammation and immune response associated with psoriasis. Therefore, a quick, easy, novel, reliable, sensitive, and straightforward liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was used to analyze DEU in plasma samples. The LC-MS/MS method for the determination of DEU in human plasma was based on using trimethoprim as an internal standard (IS). The separation of DEU and IS was carried out via liquid-liquid extraction (LLE). The extract was then subjected to the chromatographic system separation using the ACE-C18 column (4.6 × 100 mm, 5 µm). The mobile phase employed consisted of methanol and a solution of 2 mM ammonium formate (80:20 v/v, respectively). The flow rate used was set at 0.9 mL min-1. The creative strategy was performed by running an ABSCIEX API 4000 mass spectrometer with an electron spray ionization source in multiple reaction monitoring (MRM) mode. The ion transitions m/z 426.3 → 358.2 were used for DEU quantitation, while the ion transitions m/z 291.1 → 261.1 were used for trimethoprim quantitation. The accuracy, precision, linearity, recovery, and selectivity of DEU were deemed acceptable when validated for a concentration range between 0.500 and 601.050 ng/mL, utilizing a weighting factor of 1/x2.

Forced Degradation and Stability-Indicating Study for the Binary Mixture of Allopurinol and Thioctic Acid Using Validated HPLC-DAD Method.

BACKGROUND: Careful review of the scientific databases revealed that no stability-indicating analytical method is available for the binary mixture of allopurinol (ALO) and thioctic acid (THA). OBJECTIVE: A comprehensive stability-indicating HPLC-DAD procedure has been executed for concurrent analysis of ALO and THA. METHOD: Successful chromatographic separation of the cited drugs was reached using a Durashell C18 column (4.6 × 250 mm, 5 µm particle size). The mobile phase consisted of a mixture of acidified water (pH 4.0) using phosphoric acid and acetonitrile pumped in gradient elution mode. For quantification of ALO and THA, their respective peak areas were recorded at 249 and 210 nm. A systematic validation of analytical performance was investigated in terms of system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. RESULTS: ALO and THA peaks emerged at retention times 4.26 and 8.15 min, respectively. Linear ranges for ALO and THA were 5-100 and 10-400 µg/mL, respectively, with correlation coefficient values exceeding 0.9999. Both drugs were exposed to conditions of neutral, acidic, and alkaline hydrolysis, oxidation, and thermal decomposition. Stability-indicating features have been demonstrated by resolution of the drugs from their forced degradation peaks. For verification of peak identity and purity, the diode-array detector (DAD) was used. In addition, degradation pathways for the cited drugs were postulated. Furthermore, separation of both analytes from about 13 medicinal compounds of different therapeutic classes disclosed optimum specificity of the proposed method. CONCLUSIONS: Advantageous application of the validated HPLC method for the concurrent analysis of ALO/THA in their tablet dosage form was accomplished. HIGHLIGHTS: So far, the described HPLC-DAD method is considered the first detailed stability-indicating analytical study for this pharmaceutical mixture.

HPLC-Fluorescence Detection Method for Concurrent Estimation of Domperidone and Naproxen. Validation and Eco-Friendliness Appraisal Studies.

This work demonstrates a simple and reliable HPLC method with fluorimetric detection for simultaneous estimation of domperidone (DOM) and naproxen (NAP). Successful chromatographic separation was accomplished using Inertsil ODS C18 column (5 µm, 4.6 × 150 mm) with gradient elution of the mobile phase consisting of 0.01 M phosphate buffer (pH 5.5) solution and acetonitrile. The gradient elution started with 25% acetonitrile increased linearly to 65% in 5 min, then kept at this percentage till the end of the run. The mobile phase was pumped at a flow rate of 1.0 mL/min. The excitation wavelength at 284 nm was found suitable for both DOM and NAP since it corresponds to a maximum for the minor component DOM and measurable excitation for NAP, while using 316 and 355 nm as emission wavelengths for DOM and NAP, respectively. Peaks eluted with excellent resolution at retention times 4.4 and 6.3 min for DOM and NAP, respectively. Performance of the proposed method was tested according to ICH guidelines in regard to linearity, ranges, precision, accuracy, robustness, detection and quantitation limits. Calibration curves were linear in the ranges of 0.8-3.6 and 1.0-2.5 µg/mL for DOM and NAP respectively with correlation coefficients not less than 0.9996. The validated method was successfully applied to the analysis of DOM and NAP in their laboratory prepared tablets resembling the commercial dosage form, and assay results were favorably compared with a published reference HPLC method. The method's greenness was assessed using the Analytical Eco-Scale and the novel Analytical Greenness metric (AGREE).

Inexpensive bioluminescent genosensor for sensitive determination of DNA damage induced by some commonly used sunscreens.

Sunscreens (SSs) are highly applied all over the world on large areas of human body. Benzophenone chemical group constitute a major part in most SSs. Benzophenones are reported to induce changes in nucleic acids upon UV-irradiation. These alterations may potentially lead to DNA mutation, cell apoptosis, and eventually skin cancer. This work compares the kinetics of the induced DNA damage by some SSs after UV-irradiation. Six commonly used SSs; 4-t-butyl-4-methoxy dibenzoyl methane, 4-methoxycinnamic acid, 2-hydroxy-4-methoxybenzophenone (BZ-3), Dibenzoyl methane, 2,2'-dihydroxy-4-methoxy benzophenone (BZ-8) and p-methylbenzoic acid; are investigated. In this work, terbium chloride bioluminescent genosensor is used for sensitive, simple and inexpensive determination of induced DNA-damage. Results reveal that only BZ-3 and BZ-8 induced DNA-damage upon UV-irradiation that are confirmed by both absorption spectroscopy and viscosity measurements. Moreover, viscosity studies indicated the possible intercalation of the SS into DNA prior to initiation of DNA damage. Furthermore, the potency of BZ-3 and BZ-8 to induce DNA damage upon UVA irradiation was assessed on calf thymus DNA. The low cost of the proposed bioluminescent genosensor allows it to be an automatic simple process for the investigation of any DNA-drug interactions without the need of coupling with other analytical methods.

Simultaneous Quantitation of Paracetamol and Lornoxicam in the Presence of Five Related Substances and Toxic Impurities by a Selective HPLC-DAD Method.

OBJECTIVE: This research describes the simultaneous quantitation of paracetamol (PRM) and lornoxicam (LRX) with five of their related substances and toxic impurities, including, 4-nitrophenol (NTP), 4-aminophenol (AMP), 4-chloroacetanilide (CAC), N-phenylacetamide (NPA), and 2-aminopyridine (APD) using a specific HPLC-diode array detector (DAD) method. METHODS: The chromatographic separation involves the use of a XTerra C18 column as the stationary phase and a mobile phase consisting of acetonitrile and 0.025 M phosphate buffer (pH 6). The separation was performed using gradient elution mode at 1.0 mL/min flow rate and detection at 260 nm for the determination of PRM and LRX. For detecting PRM and LRX in the presence of their toxic impurities, 270 nm was used. Validation of the suggested HPLC method was accomplished with regard to linearity, ranges, detection and quantitation limits, robustness, accuracy, precision, and specificity. RESULTS: Excellent resolution of the mixture components was accomplished at retention times 4.2, 4.8, 7.4, 11.1, 13.5, 14.7, and 15.3 min for APD, AMP, PRM, NPA, LRX, NTP, and CAC, respectively. Linearity was established for PRM and LRX within concentration ranges of 10-100 and 10-60 µg/mL, respectively. The correlation coefficients obtained were >0.9997. The suggested method was confirmed to be a specific stability-indicating through the selective separation of PRM and LRX from their related substances, degradants, and impurities. CONCLUSION: The proposed method was successfully utilized for the sensitive and selective determination of PRM and LRX in their pharmaceutical formulation. HIGHLIGHTS: To the best of our knowledge, this is the first impurity profiling assay method for this combination in the presence of five of their toxic related substances and impurities. Taking into consideration that at least two of the studied impurities (AMP and APD) are actually reported degradation products for the main drugs, the suggested method can be considered stability-indicating as well.

Development and greenness assessment of a stability-indicating HPLC-DAD method for simultaneous determination of allopurinol and benzbromarone.

The growing interest in Green Analytical Chemistry (GAC) principles through the replacement of polluting analytical procedures with greener ones, has encouraged us to develop an eco-friendly stability-indicating HPLC with diode array detection method (HPLC-DAD) for simultaneous determination of allopurinol (ALP) and benzbromarone (BNZ). Effective separation was accomplished using Durashell C18 column (4.6 × 250 mm, 5 µm particle size) with gradient elution of the mobile phase composed of 0.02 M ammonium acetate (pH 5.0) and methanol. Quantification of ALP and BNZ was based on measuring their peak areas at 251 nm. ALP and BNZ peaks eluted at retention times 4.85 and 10.30 min respectively. The proposed HPLC procedure was carefully validated in terms of system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. The linearity range for both ALP and BNZ was 5-100 µg/mL with correlation coefficients >0.9999. Forced degradation conditions of neutral, acidic, and alkaline hydrolysis, oxidation, and thermal degradation were applied on both drugs. Good resolution of the drugs from their forced degradation products proved that the proposed method is stability-indicating. In addition, the resolution of both drugs from about 10 pharmacologically or chemically related pharmaceutical compounds of different medicinal categories showed the high specificity of the proposed method. The validated HPLC method was successfully applied to the simultaneous determination of both drugs in their tablet dosage forms. Furthermore, greenness assessment and comparison with previously published methods were carried out using two different GAC metrics, namely, the national environmental method index (NEMI) and the analytical Eco-Scale.

Application of MEKC and UPLC with Fluorescence Detection for Simultaneous Determination of Amlodipine Besylate and Bisoprolol Fumarate.

OBJECTIVE: Two chromatographic methods were described for simultaneous determination of the antihypertensive drugs amlodipine besylate (AML) and bisoprolol fumarate (BIS). METHODS: Method I applies micellar electrokinetic capillary chromatography using a deactivated fused silica capillary (25 cm effective length × 50 µm internal diameter). The background electrolyte consisted of 0.01 M borate buffer (pH 9.2) containing 0.025 M sodium dodecyl sulphate and methanol in the ratio of 80:20 (v/v). Valsartan (VAL) was used as an internal standard. Diode array detector was set at 238, 224, and 210 nm for measuring AML, BIS, and VAL, respectively. Method II involves using ultra-performance liquid chromatography with fluorescence detection. Zorbax SB-C8 column (2.1 × 100 mm, 1.8 µm particle size) was used with isocratic elution of the mobile phase composed of 0.1% trifluoroacetic acid, acetonitrile, and methanol in the ratio of 55:35:10 (v/v) at a flow rate of 0.6 mL/min. Fluorescence detection was done using excitation wavelengths 230 and 370 nm and emission wavelengths 305 and 450 nm for BIS and AML, respectively. Validation parameters were carefully studied including linearity, ranges, precision, accuracy, robustness, detection, and quantification limits. RESULTS: Method I showed good linearity over the range 10-100 µg/mL for both dugs. Method II's linear ranges were 0.001-0.1 and 0.02-1 µg/mL for BIS and AML, respectively. CONCLUSION: The proposed methods were successfully validated and applied for assay of the studied drugs in their fixed-dose combination tablets. HIGHLIGHTS: To the best of our knowledge, this study suggests the first electro-chromatographic and LC with fluorescence detection methods for simultaneous determination of amlodipine and bisoprolol.

Validated specific HPLC-DAD method for simultaneous estimation of paracetamol and chlorzoxazone in the presence of five of their degradation products and toxic impurities.

This work demonstrates a specific and reliable HPLC with diode array detection (DAD) method for the simultaneous estimation of paracetamol (PAR) and chlorzoxazone (CZ) in the presence of five of their degradation products and toxic impurities; namely; 4-aminophenol (AP), 4-nitrophenol (NP), acetanilide (AT), 4-chloroacetanilide (CA) and 2-amino-4-chlorophenol (ACP). Successful chromatographic separation was accomplished using Waters Symmetry C8 column (3.9 × 150 mm, 5 µm) with gradient elution of the mobile phase consisting of 0.05 M phosphate buffer pH 7.5 and methanol. The gradient elution started with 5% (by volume) methanol ramped up linearly to 50% in 10 min, and then maintained at this percentage afterward till the end of the run. The mobile phase was pumped at a flow rate of 1.0 mL/min. The multiple wavelength detector was adjusted at 244 and 285 nm to quantify PAR and CZ, respectively. Additionally, the wavelength 270 nm was found suitable for monitoring the separation of the entire mixture of PAR, CZ, and their impurities. Seven peaks eluted with excellent resolution at retention times 3.4, 5.7, 8.0, 10.1, 10.8, 13.5, and 14.4 min for AP, PAR, NP, AT, ACP, CZ, and CA, respectively. Performance of the proposed method was validated with respect to linearity, range, precision, accuracy, specificity, robustness, detection, and quantitation limits. Calibration curves were linear in the ranges of 10-75 and 10-100 µg/mL for PAR and CZ, respectively with correlation coefficients not less than 0.9998. The proposed method proved to be specific and stability indicating by the resolution of both drugs from their degradation products and toxic impurities. Validated HPLC method was successfully applied to the analysis of PAR and CZ in their combined capsules dosage form, and assay results were favorably compared with a published reference HPLC method. DAD served as an efficient tool for peak identity and purity verification.

Analytical investigation of ternary mixture of phenylephrine hydrochloride, dimetindene maleate and benzalkonium chloride using validated stability indicating HPLC-DAD method.

A stability-indicating high performance liquid chromatography method with diode array detection (HPLC-DAD) was developed and validated for simultaneous determination of phenylephrine hydrochloride (PHR), dimetindene maleate (DMD) and benzalkonium chloride (BZM) in nasal drops and gel dosage forms. Effective liquid chromatographic separation was accomplished by employing Venusil XBP Cyano column (4.6 × 250 mm, 5 µm particle size) with gradient elution of the mobile phase consisting of buffer solution of potassium dihydrogen phosphate (0.025 M) and sodium 1-butane sulfonate (SBS) (0.025 M) (adjusted to pH 6.0) and acetonitrile. Peak areas of PHR, DMD and BZM at 271, 256 and 206 nm, respectively were measured and correlated to their concentrations. Peaks of PHR and DMD eluted at retention times 3.76 and 9.06 min, respectively, while BZM eluted as a couple of peaks at 11.88 and 12.51 min. The proposed HPLC procedure was carefully validated in terms of system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. The linearity range for both PHR and BZM was 10-400 µg/mL and DMD was 5-300 µg/mL with correlation coefficients >0.9999. The studied compounds were subjected to stress conditions of neutral, acidic and alkaline hydrolysis, oxidation and thermal degradation. Good resolution of the three compounds from their forced degradation products proves specificity and stability-indicating merits of the proposed method. In addition, resolution of the three drugs under investigation from some pharmaceutical compounds of different medicinal categories showed the high specificity of the described method.

Sensitive spectrofluorimetric and mass spectroscopic methods for the determination of nucleic acid damage induced by photosensitized anti-inflammatory drugs: Comparative study.

Anti-inflammatory drugs are reported to induce changes in nucleic-acids upon UV-irradiation. Such changes have the potential to cause apoptosis, carcinogenesis, and mutagenesis. In this work, the kinetics of the damage induced in DNA by some anti-inflammatory drugs were compared after UV-irradiation. Five commonly used anti-inflammatory drugs; diclofenac, ketoprofen, leflunomide, piroxicam and tolmetin, were studied. Simple, sensitive and eco-friendly methods for the analysis of DNA-damage were proposed including absorption spectroscopy, MALDI-TOF mass spectrometry and fluorescence using TbCl3. Results show that all drugs induced DNA-damage after UV-irradiation. Absorption spectroscopy results demonstrated hyperchromic shift in the absorption band characteristic to DNA, indicating distortion of the double-strand. Mass spectra showed a significant decrease of the molecular-ion-peak of DNA, together with peaks of smaller m/z that indicated the formation of DNA strand-breaks. TbCl3 fluorescence was observed to increase with incubation time of each drug with DNA, indicating the presence of more single-stranded regions in DNA due to damage. TbCl3 fluorescence was used to obtain the kinetics of the induced damage. Results show that DNA-damage occurred via photoinduced oxidative mechanism. Also, the potency of the studied drugs was examined on calf-thymus real DNA samples using TbCl3 fluorescence with ketoprofen and leflunomide being the most photogenotoxic anti-inflammatory drugs.

Quick Test for Determination of N-Bombs (Phenethylamine Derivatives, NBOMe) Using High-Performance Liquid Chromatography: A Comparison between Photodiode Array and Amperometric Detection.

The emergence of a new class of novel psychoactive substances, N-benzyl-substituted phenethylamine derivatives so-called "NBOMes" or "Smiles", in the recreational drug market has forced the development of new sensitive analytical methodologies for their detection and quantitation. NBOMes' hallucinogenic effects mimic those of the illegal psychedelic drug lysergic acid diethylamide (LSD) and are typically sold as LSD on blotter papers, resulting in a remarkable number of fatalities worldwide. In this article, four halide derivatives of NBOMe, namely, 2-(4-fluoro-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, 2-(4-chloro-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, 2-(4-bromo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, and 2-(4-iodo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethan-1-amine, were detected and quantified simultaneously using a high-performance liquid chromatographic method, and two detection systems were compared: photodiode array detection (detection system I) and amperometric detection via a commercially available impinging jet flow-cell system incorporating embedded graphite screen-printed macroelectrodes (detection system II). Under optimized experimental conditions, linear calibration plots were obtained in the concentration range of 10-300 and 20-300 µg mL-1, for detection systems I and II, respectively. Detection limit (limit of detection) values were between 4.6-6.7 and 9.7-18 µg mL-1, for detection systems I and II, respectively. Both detectors were employed for the analysis of the four NBOMe derivatives in the bulk form, in the presence of LSD and adulterants commonly found in street samples (e.g. paracetamol, caffeine, and benzocaine). Furthermore, the method was applied for the analysis of simulated blotter papers, and the obtained percentage recoveries were satisfactory, emphasizing its advantageous applicability for the routine analysis of NBOMes in forensic laboratories.

Comprehensive stability-indicating high-performance liquid chromatography coupled with diode array detection method for simultaneous determination of amprolium hydrochloride and ethopabate in powder dosage form for veterinary use.

This research deals with the development of a stability-indicating high-performance liquid chromatography method for simultaneous determination of amprolium hydrochloride and ethopabate. To the best of our knowledge, no comprehensive stability-indicating method has been reported for analysis of this mixture. Separation was achieved using Kromasil cyano column with gradient elution of the mobile phase composed of sodium hexane sulfonate solution and methanol. Quantification was based on measuring peak areas at 266 nm. Amprolium and ethopabate peaks eluted at retention times 10.42 and 18.53 min, respectively. The proposed procedure was validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Linearity ranges for amprolium and ethopabate were 1.5-240 and 1-160 µg/mL, respectively. Analytes were subjected to stress conditions of hydrolysis, oxidation and thermal degradation. The proposed method enabled resolution of drugs from their forced-degradation products and amprolium related substance (2-picoline). Moreover, specificity was verified by resolution of the analytes from about 22 drugs used in antimicrobial veterinary products. The validated method was successfully applied to assay of the combined veterinary powder dosage form, additionally it was implemented in the accelerated stability study of the dosage form when stored for six months at 40°C and 75% relative humidity.

Simple mix-and-read assays for the determination of baclofen in pharmaceutical formulation.

This study demonstrates three simple and inexpensive spectrophotometric mix-and-read assays for the determination of the skeletal muscle relaxant, baclofen (BAC) in pharmaceutical formulations. The proposed methods are based on the reaction of the primary amine group of BAC with various derivatizing reagents to yield different colored products. Method I depends on the reaction of BAC with vanillin in borate buffer pH 11.5 to give a yellow colored product with maximum absorbance at 401 nm. While method II describes the reaction with eosin Y in citric-phosphate buffer pH 2.2 forming an orange-red product measured at 548 nm. Method III depends on Hantzsch condensation reaction that yields a yellow product measured at 339 nm. Different experimental variables influencing development and stability of the obtained colored product are optimized. Validation of the three methods regarding linearity, ranges, precision, accuracy and limits of detection and quantification was performed. Regression analysis showed good linearity over the concentration ranges of 10-35, 5-20 and 5-25 µg/mL for methods I, II and III, respectively with correlation coefficient values not less than 0.999. Additionally, detection limits of BAC are 1.58, 0.94 and 0.79 µg/mL for methods I, II and III, respectively. Finally, the suggested procedures are successfully used for assay of BAC in its tablets. The main advantages of the proposed mix-and-read assays are being inexpensive and rapid with no requirement for laborious extraction techniques with equivalent or superior sensitivity compared to other published spectrophotometric procedures. Such advantages promote the suggested methods for the high throughput assay of BAC dosage forms, a critical component in quality control studies for pharmaceutical industries.

Development and validation of a versatile HPLC-DAD method for simultaneous determination of the antiviral drugs daclatasvir, ledipasvir, sofosbuvir and ribavirin in presence of seven potential impurities. Application to assay of dosage forms and dissolution studies.

This study describes a simple, sensitive, specific and generic HPLC-DAD method for simultaneous determination of four drugs prescribed for treatment of Hepatitis C Virus (HCV) infection. Investigated drugs include daclatasvir (DAC), ledipasvir (LED), sofosbuvir (SOF) and ribavirin (RIB). Successful separation was accomplished using Thermohypersil BDS-C8 column (4.6 × 250 mm, 5 µm) with gradient elution of the mobile phase consisted of mixed phosphate buffer pH 7.5 and methanol. Gradient elution started with 25% methanol, ramped up linearly to 80% in 15 min then kept constant till the end of the run. Flow rate was 1.5 mL/min. Peak areas were measured at 235, 260, 315, and 332 nm for RIB, SOF, DAC, and LED, respectively. Peaks of the analytes were perfectly resolved with retention times 2.0, 12.1, 14.7, and 17.2 min for RIB, SOF, DAC, and LED, respectively. The developed method was validated according to ICH guidelines with respect to system suitability, linearity, ranges, accuracy, precision, specificity, robustness, and limits of detection and quantification. The proposed method showed good linearity in the ranges 5-500, 2-300, 0.5-75, and 0.5-75 µg/mL for RIB, SOF, DAC, and LED respectively. Limits of detection were 0.10-0.66 µg/mL for the analyzed drugs. Specificity was established by separation of target drugs from 7 process-related impurities for SOF including its major metabolite (GS-331007). Applicability of the proposed method to real life situations was assessed through the analysis of four different pharmaceutical formulations and satisfactory results were obtained. Additionally, dissolution profiles of the 4 drugs were studied using the developed method.

Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Infrared (GC-IR) Analyses of the Chloro-1- n-pentyl-3-(1-naphthoyl)-Indoles: Regioisomeric Cannabinoids.

The analytical differentiation of the indole ring regioisomeric chloro-1- n-pentyl-3-(1-naphthoyl)-indoles is described in this report. The regioisomeric chloroindole precursor compounds, N- n-pentyl chloroindole synthetic intermediates, and the target chloro-substituted naphthoylindoles showed the equivalent gas chromatographic elution order based on the position of chlorine substitution on the indole ring. The regioisomeric chloro-1- n-pentyl-3-(1-naphthoyl)-indoles yield electron ionization mass spectra having equivalent major fragments resulting from cleavage of the groups attached to the central indole nucleus. Fragment ions occur at m/z 127 and 155 for the naphthyl and naphthoyl cations common to all indoles having the naphthoyl group substituted at the indole-3 position. Fragments resulting from the loss of the naphthoyl and/or n-pentyl groups from the molecular radical cation yield the cations at m/z 318, 304, 248, and 178. The characteristic (M-17)+ fragment ion at m/z 358 resulting from the loss of OH radical is significant in the mass spectra of all these compounds with 1-naphthoyl groups substituted at the indole-3 position. The vapor phase infrared spectra provide a number of characteristic absorption bands to identify the individual isomers.

[Parinaud syndrome caused by corpus pineale tumour in a 14-year-old boy].

Parinaud syndrome (PS) can manifest in a pineal tumour. Major components of PS include restriction of gazing upwards, light-near dissociation and convergence retraction nystagmus. A 14-year-old boy presented with diplopia and restricted ability to gaze upwards. The objective examination revealed signs, which were compatible with the major manifestations of PS. A magnetic resonance scan (MRI) of cerebrum indicated pinealoma, and a pathological examination identified the lesion as a germ cell carcinoma. The patient received chemotherapy and stereotactic radiosurgery. The ophthalmic symptoms improved, and a follow-up MRI demonstrated complete regression of the tumour.