Chromatographic Methods and Sample Pretreatment Techniques for Aldehydes, Biogenic Amine, and Carboxylic Acids in Food Samples.

This review paper critically examines the current state of research concerning the analysis and derivatization of aldehyde, aromatic hydrocarbons and carboxylic acids components in foods and drinks samples, with a specific focus on the application of Chromatographic techniques. These diverse components, as vital contributors to the sensory attributes of food, necessitate accurate and sensitive analytical methods for their identification and quantification, which is crucial for ensuring food safety and compliance with regulatory standards. In this paper, High-Performance Liquid Chromatography (HPLC) and Gas Chromatographic (GC) methods for the separation, identification, and quantification of aldehydes in complex food matrices were reviewed. In addition, the review explores derivatization strategies employed to enhance the detectability and stability of aldehydes during chromatographic analysis. Derivatization methods, when applied judiciously, improve separation efficiency and increase detection sensitivity, thereby ensuring a more accurate and reliable quantification of aldehyde aromatic hydrocarbons and carboxylic acids species in food samples. Furthermore, methodological aspects encompassing sample preparation, chromatographic separation, and derivatization techniques are discussed. Validation was carried out in term of limit of detections are highlighted as crucial elements in achieving accurate quantification of compounds content. The discussion presented by emphasizing the significance of the combined HPLC and GC chromatography methods, along with derivatization strategies, in advancing the analytical capabilities within the realm of food science.

A review of the currently developed analytical methods for the determination of biogenic amines in food products.

Biogenic amines (BAs) are group of substances that are formed from amino acids by decarboxylation or amination and transamination of aldehydes and ketones. They may have either aliphatic, aromatic or heterocyclic structure. Their quantity determines their effects, optimum amounts are essential for physiological functions, but excess of BAs causes various toxic effects through out human body. BAs are presented in a wide variety of fermented foods such as fish, meat, milk products and some kinds of beverages like wine, beer and some fruit juices. In order to quantify their intake by food products are important, the methods that provide determination of BAs in food products are a matter of priority. Mostly, liquid chromatographic (LC) methods are preffered. Their amine groups are able to be derivatized by so many fluorogenic reagents. It is possible to combine LC systems with UV-vis. absorption spectrometric, fluorimetric and mass spectrometric detectors. Due to the fact that BAs are important markers for food quality and important for health, in this article LC methods for the determination of BAs in foods were reviewed from 2012 to present.

A very simple high-performance liquid chromatographic method with fluorescence detection for the determination of gemifloxacin in human breast milk.

A high-performance liquid chromatographic method with fluorescence detection was developed and validated for the determination of gemifloxacin in human breast milk. The proposed method allows the determination of gemifloxacin in breast milk samples without complex sample preparation. The samples were mixed with a mobile phase and filtered with a 0.45 µm polytetrafluoroethylene filter before analysis. Chromatographic separation was carried out on a C18 column (150 × 4.6 mm, 5 µm I.D.) using methanol:50 mM ortho-phosphoric acid solution (40:60) as the mobile phase with a 1.0 mL/min flow rate. Quantitation was performed using fluorescence detection with an excitation wavelength at 272 nm and an emission wavelength at 395 nm. The linear range was found to be 0.1-2.5 µg/mL. The method was applied successfully for the determination of gemifloxacin in breast milk obtained from a breastfeeding mother after oral administration of a single tablet that included 320 mg gemifloxacin per gemifloxacin tablet.

Development of sensitive spectrofluorimetric and spectrophotometric methods for the determination of duloxetine in capsule and spiked human plasma.

A new, sensitive and selective spectrofluorimetric method has been developed for the determination of duloxetine (DLX) in capsule and spiked human plasma. DLX, as a secondary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl), a highly sensitive fluorogenic and chromogenic reagent used in many investigations. The method is based on the reaction between the drug and NBD-Cl in borate buffer at pH 8.5 to yield a highly fluorescent derivative that is measured at 523 nm after excitation at 478 nm. The fluorescence intensity was directly proportional to the concentration over the range 50-250 ng/mL. The reaction product was also measured spectrophotometrically. The relation between the absorbance at 478 nm and the concentration is rectilinear over the range 1.0-12.0 µg/mL. The methods were successfully applied for the determination of this drug in pharmaceutical dosage form. The spectrofluorimetric method was also successfully applied to the determination of duloxetine in spiked human plasma. The suggested procedures could be used for the determination of DLX in pure form, capsules and human plasma being sensitive, simple and selective.

Spectrofluorimetric determination of tobramycin in human serum and pharmaceutical preparations by derivatization with fluorescamine.

A simple, sensitive and selective spectrofluorimetric method has been developed for the determination of tobramycin (TOB) in human serum and pharmaceutical preparations. The method is based on the reaction between the primary amino group of TOB and fluorescamine in borate buffer, pH 8.5, to give a highly fluorescent derivative which is measured at 469 nm after excitation at 388 nm. The fluorescence intensity was directly proportional to the concentration over the range 300-1500 ng/mL, with a limit of detection of 65 ng/mL and limit of quantitation of 215 ng/mL. All variables were investigated to optimize the reaction conditions. The method was validated according to International Conference on Harmonization guidelines in terms of specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. Good recoveries were obtained ranging from 97.4 to 100.64%, indicating that no interference was observed from concomitants usually present in pharmaceutical dosage forms. The method was successfully, applied for the analysis of the drug substance in its pharmaceutical preparations and spiked serum samples.

A review of the liquid chromatographic methods for the determination of biogenic amines in foods.

Biogenic amines (BAs) are biologically active molecules which have aliphatic (putrescine, cadaverine, spermine, spermidine), aromatic (tyramine, phenylethylamine) or heterocyclic (histamine, tryptamine) structures. They can be detected in raw and processed foods which are formed and degraded through several pathways during the metabolic processes of animals, plants and microorganisms. The identification and quantitation procedures of BAs in food samples are very important, because BAs are considered as the indicators of food quality and freshness. The determination of BAs are commonly achieved by separation techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC) and capillary electrophoresis (CE). In this article, analysis of BAs in foods were reviewed from 2007 to present.

Determination of eprosartan mesylate and hydrochlorothiazide in tablets by derivative spectrophotometric and high-performance liquid chromatographic methods.

Two new simple and selective assay methods have been presented for the analysis of eprosartan mesylate (EPR) and hydrochlorothiazide (HCT) in pharmaceutical formulations. The first method is based on first-derivative ultraviolet spectrophotometry with zero-crossing measurements at 246 and 279 nm for EPR and HCT, respectively. The assay was linear over the concentration ranges 3.0-14.0 µg/mL for EPR and 1.0-12.0 µg/mL for HCT. The quantification limits for EPR and HCT were found to be 1.148 and 0.581 µg/mL, respectively, while the detection limits were 0.344 µg/mL for EPR and 0.175 µg/mL for HCT. The second method involved isocratic reversed-phase liquid chromatography using a mobile phase composed of acetonitrile-10 mM phosphoric acid (pH 2.5) (40:60, v/v). Olmesartan was used as internal standard and the substances were detected at 272 nm. The linearity ranges were found to be 0.5-30 and 0.3-15.0 µg/mL for EPR and HCT, respectively. The limits of detection were found to be 0.121 µg/mL for EPR and 0.045 µg/mL for HCT. The limits of quantification were found to be 0.405 and 0.148 µg/mL for EPR and HCT, respectively. The proposed methods were successfully applied to the determination of commercially available tablets with a high percentage of recovery and good accuracy and precision.

A new HPLC method with fluorescence detection for the determination of memantine in human plasma.

A sensitive, selective, simple and fast HPLC method based on the formation of derivative with fluorescamine was developed for the determination of memantine (ME) in human plasma. Separation was achieved on a CN column (200 mm×4.6 mm) using acetonitrile-10 mM orthophosphoric acid containing 1 mL/L triethylamine (45:55, v/v) at a flow rate of 1 mL/min. Emission and excitation wavelengths were 480 and 380 nm, respectively. Amantadine was used as an internal standard. Calibration graphs were rectilinear over the range of 1.0-100.0 ng/mL. Limit of detection and limit of quantification were found to be 0.3 and 1.0 ng/mL, respectively. Intra-day and inter-day relative standard deviation values were found to be <2.03%. Average recovery was also found to be around 94%. Proposed method was applied for the pharmacokinetic study in a healthy volunteer after a single oral administration of 20 mg of ME.

Spectrofluorimetric methods for the determination of gemifloxacin in tablets and spiked plasma samples.

Two new, sensitive and selective spectrofluorimetric methods have been developed for the determination of gemifloxacin (GFX) in tablets and spiked plasma samples. Gemifloxacin, as a primary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl) (for method A) and fluorescamine (for method B) which are a highly sensitive fluorogenic reagents used in many investigations. For method A, the reaction product was measured spectrofluorimetrically at 516 nm with excitation at 451 nm. The reaction proceeded quantitatively at pH 8.5, 80 °C in 7 min. For method B, the method was based on the reaction between GFX and fluorescamine in borate buffer solution of pH 8.5 to give highly fluorescent derivatives that were measured at 481 nm using an excitation wavelength of 351 nm. The fluorescence intensity was directly proportional to the concentration over the range 40-200 ng mL(-1) and 100-1,200 ng mL(-1) for method A and B, respectively. Successful applications of the developed methods, for the drug determination in pharmaceutical preparations and spiked plasma samples, were performed.

Detection of methamphetamine, methylenedioxymethamphetamine, and 3,4-methylenedioxy-N-ethylamphetamine in spiked plasma by HPLC and TLC.

HPLC and TLC methods were developed for separation and detection of some amphetamine analogs: methamphetamine (MA); 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy"); and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) in spiked plasma samples. The methods are based on purple chromogens formed by displacement reaction of these secondary aliphatic amine-bearing drugs with 7,7,8,8-tetracyanoquinodimethane at 80 degrees C for 25 min. For HPLC, both normal phase (silica gel) and RP (C18) columns were used. With the former, good detection limits in plasma were obtained with a 6 min run: 70, 100, and 500 ng/mL for MDMA, MA, and MDEA, respectively. For TLC, hexane-chloroform (1 + 9) and benzene-diethyl ether-petroleum ether (40-60 degrees)-acetonitrile-ethyl methyl ketone (2 + 3.5 + 3.5 + 0.5 + 0.5) were used as mobile phases for silica gel 60 TLC and cyano-bonded silica gel HPTLC plates, respectively. The former offered more sensitive results than the latter. Influence of evaporation steps on recovery and interferences for the HPLC and TLC methods were investigated. The developed methods are selective, simple, and easily applicable.

Spectrophotometric and HPLC determinations of anti-diabetic drugs, rosiglitazone maleate and metformin hydrochloride, in pure form and in pharmaceutical preparations.

In this study, three spectrophotometric methods and one HPLC method were developed for analysis of anti-diabetic drugs in tablets. The two spectrophotometric methods were based on the reaction of rosiglitazone (RSG) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and bromocresol green (BCG). Linear relationship between the absorbance at lambda(max) and the drug concentration was found to be in the ranges 6.0-50.0 and 1.5-12 microg ml(-1) for DDQ and BCG methods, respectively. The third spectrophotometric method consists of a zero-crossing first-derivative spectrophotometric method for simultaneous analysis of RSG and metformin (MTF) in tablets. The calibration curves were linear within the concentration ranges of 5.0-50 microg ml(-1) for RSG and 1.0-10.0 microg ml(-1) for MTF. The fourth method is a rapid stability-indicating HPLC method developed for the determination of RSG. A linear response was observed within the concentration range of 0.25-2.5 microg ml(-1). The proposed methods have been successfully applied to the tablet analysis.

Spectrophotometric and spectrofluorimetric methods for the determination of pregabalin in bulk and pharmaceutical preparation.

Two new, sensitive and selective spectrofluorimetric and spectrophotometric methods have been developed for the determination of the gamma-amino-n-butyric acid derivative pregabalin (PGB) in bulk drug and capsule. Pregabalin, as a primary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl) which is a highly sensitive fluorogenic and chromogenic reagent used in many investigations. According to this fact, spectrophotometric and spectrofluorimetric methods for the determination of pregabalin in capsules were developed for the first time. The relation between the absorbance at 460 nm and the concentration is rectilinear over the range 0.5-7.0 microg mL(-1). The reaction product was also measured spectrofluorimetrically at 558 nm after excitation at 460 nm. The fluorescence intensity was directly proportional to the concentration over the range 40-400 ng mL(-1). The method was applied successfully to the determination of this drug in pharmaceutical dosage form. The mean recovery for the commercial capsules was 99.93% and 99.96% for spectrophotometric and spectrofluorimetric study, respectively. The suggested procedures could be used for the determination of PGB in pure and capsules being sensitive, simple and selective.

Determination of linezolid in human breast milk by high-performance liquid chromatography with ultraviolet detection.

A rapid and simple HPLC method was developed for the determination of linezolid (LNZ) in human breast milk after a simple protein precipitation with methanol. The chromatographic separation was achieved on a C18 column (5 microm, 250 x 4.6 mm id) using a mobile phase of acetonitrile-10 mM acetic acid (25:75, v/v) at a flow rate of 1 mL/min. The LNZ peak was measured by photodiode array detection at 250 nm. The calibration graph was linear over the range of 0.5-20.0 microg/mL. The limits of detection and quantitation were found to be 0.1 and 0.5 microg/mL, respectively. The precision of the assay and the recovery of LNZ from breast milk at three different concentrations were assessed. The intraday and interday RSD values were found to be < 5%. The mean absolute recovery was 85.33%. The developed method was successfully applied to the determination of LNZ in breast milk obtained from the breastfeeding mother after oral administration of LNZ.

Spectrophotometric determination of dopaminergic drugs used for Parkinson's disease, cabergoline and ropinirole, in pharmaceutical preparations.

Simple and reproducible spectrophotometric methods have been developed for determination of dopaminergic drugs used for Parkinson's disease, cabergoline (CAB) and ropinirole hydrochloride (ROP), in pharmaceutical preparations. The methods are based on the reactions between the studied drug substances and ion-pair agents [methyl orange (MO), bromocresol green (BCG) and bromophenol blue (BPB)] producing yellow colored ion-pair complexes in acidic buffers, after extracting in dichloromethane, which are spectrophotometrically determined at the appropriate wavelength of ion-pair complexes. Beer's law was obeyed within the concentration range from 1.0 to 35 microg ml(-1). The developed methods were applied successfully for the determination of these drugs in tablets.

A highly sensitive spectrofluorometric method for the determination of a new antidepressant drug, reboxetine, in tablets.

A highly sensitive, selective, and rapid spectrofluorometric method has been developed for the determination of reboxetine (REB) in tablets. The method is based on derivatization with 7-chloro-4-nitrobenzofurazan. The product showed an absorption maximum at 476 nm and a fluorescence emission peak at 533 nm in ethyl acetate. The optimum conditions of the reaction were investigated, and it was found that the reaction proceeded quantitatively at pH 8.5, 70 degrees C in 5 min. The calibration graph is rectilinear over the range of 0.02-0.40 microg/mL. The relative standard deviation values for intraday and interday precision were 0.40-0.93 and 0.54-1.37%, respectively. The proposed method was applied to the assay of REB in tablets. Mean recovery of REB from the tablets ranged between 99.91-100.20%. The results were compared statistically with those obtained by a method reported in the literature. The method is sensitive, simple, and selective, and can be used for routine quality control analysis.

Spectrophotometric determination of certain antidepressants in pharmaceutical preparations.

Simple and reproducible spectrophotometric methods have been developed for determination of sertraline, fluoxetine, and venlafaxine in pharmaceutical preparations. The methods are based on the reactions between the studied drug substances and ion-pair agents (bromothymol blue, bromocresol green, or bromophenol blue) to produce yellow-colored ion-pair complexes in acidic buffers. After extracting in chloroform, the ion-pair complexes are spectrophotometrically determined at the optimum wavelength. Optimizations of the reaction conditions were carried out. Beer's law was obeyed within the concentration range from 1 to 15 microg/mL. The molar absorptivity, Sandell sensitivity, and detection and quantification limits were also determined. The developed methods were applied successfully for the determination of these drugs in some available commercial preparations. The results were compared statistically with those obtained from reported high-performance liquid chromatography methods.

Determination of gabapentin in human plasma and urine by high-performance liquid chromatography with UV-vis detection.

A simple and reliable high-performance liquid chromatographic (HPLC) method with UV-vis detection has been developed and validated for the determination of gabapentin (GBP) in human plasma and urine. The clean up of the sample was carried out by solid-phase extraction with C18-cartridge. After the clean up procedure, the samples were pre-column derivatizated with 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS). A chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile and 10mM orthophosphoric acid (pH 2.5) with isocratic elution (35:65). Baclofen was used as an internal standard (I.S.). The method developed for GBP was linear over the concentration range of 0.05-5.0 microg/ml and 0.1-10.0 microg/ml for plasma and urine, respectively. The method is precise (relative standard deviation, R.S.D. <4.05%) and accurate (relative mean error, RME <0.15%); mean absolute recoveries were 72.21% for plasma and 72.73% for urine.

Determination of paroxetine in human plasma by high-performance liquid chromatography using 7,7,8,8-tetracyanoquinodimethane as the derivatization reagent.

A selective and sensitive reversed-phase HPLC method was developed for the determination of the antidepressant paroxetine in plasma. The method is based on the purple chromogen formed by a displacement reaction of paroxetine with 7,7,8,8-tetracyanoquinodimethane (TCNQ) in acetonitrile at 80 degrees C for 20 minutes. For the assay, the drug was extracted from 1 mL of plasma with chloroform and, after sample alkalinization, derivatized with TCNQ; then the reaction mixture was directly injected into a C18 column. Desipramine was used as internal standard. The mobile phase was acetonitrile-water (70:30) at a flow-rate of 1.0 mL/min, and the derivatives were eluted at 13.1 and 15.5 minutes for paroxetine and desipramine, respectively, and detected at 567 nm. Calibration curve was found linear over the range of 20-400 ng/mL, and the detection limit was 2 ng/mL at a signal-to-noise ratio of 3/1. Recoveries determined for 3 concentrations range between 81.3% and 88.1%. Intraday and interday relative standard deviation values were found to be within 3.8%-13.5% and 8.2%-14.6%, respectively. With this developed method, a pharmacokinetic study was performed for paroxetine.

A selective high-performance liquid chromatography method for the determination of reboxetine in bulk drug and tablets.

Reboxetine is used as a selective noradrenaline reuptake inhibitor for the treatment of major depressive disorders. It is effective in the treatment of severe depression and safer to use than traditional tricyclic antidepressants. In this study, a novel, simple, and rapid stability-indicating high-performance liquid chromatography (HPLC) method for reboxetine methansulfonate was successfully developed and validated for the assay of tablets. The method was used to quantify reboxetine in tablets; it employed a C18 column (150 x 4.6 mm id) with an isocratic mobile phase consisting of methanol-phosphate buffer (pH 7, 0.02 M; 55 + 45, v/v) at a flow rate of 1.0 mL/min. Reboxetine was detected by an ultraviolet detector at 277 nm. The retention time of reboxetine was about 4.5 min. The developed HPLC method was validated with respect to linearity, precision, sensitivity, accuracy, and selectivity. The method was linear over the concentration range 1-50 microg/mL (r = 0.9999). The limits of detection and the quantitation of reboxetine were 0.1 and 0.3 microg/mL, respectively. The relative standard deviation values for intraday and interday precision were 0.78-1.01 and 1.08-1.37%, respectively. Selectivity was validated by subjecting a stock solution of reboxetine to neutral, acid, and alkali hydrolysis, as well as oxidation, dry heat treatment, and photodegradation. The peaks of the degradation products did not interfere with the peak of reboxetine. The results indicated that the proposed method could be used in a stability assay. The proposed method was successfully applied to the determination of reboxetine in tablets. Excipients present in the tablets did not interfere with the analysis.

Spectrophotometric methods for the determination of the antidepressant drug paroxetine hydrochloride in tablets.

Simple, sensitive, and accurate visible spectrophotometric methods are described for the determination of paroxetine hydrochloride (PA) in tablets. Among them, the first 3 methods are based on the ion-pair complexes of PA formed with bromothymol blue (BTB), bromophenol blue (BPB), and bromocresol green (BCG) in aqueous acidic buffers. The complex species extracted into chloroform were quantitatively measured at 414 nm with BTB and BCG and at 412 nm with BPB. Beer's law was obeyed over the concentration ranges of 2-20, 2-16, and 2-16 microg/mL, respectively. The fourth method described is based on a coupling reaction between PA and 7-chloro-4-nitrobenzofurazon (NBD-Cl) in borate buffer, pH 8.5, in which a yellow reaction product that was measured at 478 nm was formed. The Beer's law range for this method was 2-10 microg/mL. The last method developed describes the interaction of PA base, as an n-electron donor, with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as a pi-acceptor, in acetonitrile to give blue-colored TCNQ- radical anion with absorption maxima at 750 and 845 nm. Measured at 845 nm, the absorbance-concentration plot was rectilinear over the range of 1.5-15 microg/mL. The new methods developed were successfully applied to the determination of PA in tablets without any interference from common tablet excipients. The results of the methods were in good agreement with those obtained with an official liquid chromatographic method. This report describes first colorimetric methods for the determination of PA.