Photodiode Array UV Research Articles

Quantification of Etoricoxib in Low Plasma Volume by UPLC-PDA and Application to Preclinical Pharmacokinetic Study.

An ultra-performance liquid chromatography with photodiode array (UPLC-PDA) UV detection method was developed here for the first time for simple, rapid, selective and sensitive quantification of the commonly prescribed selective cyclooxygenase-2 (COX-2) inhibitor etoricoxib in low plasma volumes (50 μL). The method includes protein precipitation followed by liquid-liquid extraction, evaporation and reconstitution. A gradient mobile phase of 75:25 going to 55:45 (v/v) water:acetonitrile (1 mL/min flow rate) was applied. Total run time was 8 min, representing a significant improvement relative to previous reports. Excellent linearity (r2 = 1) was obtained over a wide (0.1-12 µg/mL) etoricoxib concentration range. Short retention times for etoricoxib (4.9 min) and the internal standard trazodone (6.4 min), as well as high stability, recovery, accuracy, precision and reproducibility, and low etoricoxib LOD (20 ng/mL) and LOQ (100 ng/mL), were achieved. Finally, the method was successfully applied to a pharmacokinetic study (single 20 mg/kg orally administered etoricoxib mini-capsule) in rats. In conclusion, the advantages demonstrated in this work make this analytical method both time- and cost-efficient for drug monitoring in pre-clinical/clinical settings.

Utility of “flip-flop” chromatography employing silica hydride stationary phases with simultaneous photodiode array ultraviolet and single quadrupole mass detection for the analysis of seized drugs

For confirmation and/or screening purposes, rapid, selective, and precise chromatographic methods are required. In this vein, the utility of SiH columns (C18, UDC Cholesterol, and Diamond Hydride) with photodiode array UV absorption and single quadrupole MS detection for multi-modal separation of representative drugs from different drug classes on a single column using the same solvent reservoirs was investigated. For a conventional two column approach employing a combination of conventional C18 and silica columns operating in both the reversed phase chromatographic and hydrophilic interaction chromatographic modes, gradient analysis is required for the first column and there is a lack of retention on the second column for non-amine analytes. In comparison, all analytes are retained for two relatively rapid (< 10 min), precise (% RSD <0.4%), and non-correlated isocratic separations (R2=0.2115) when using a UDC Cholesterol column.

New Validated RP-HPLC Method for Simultaneous Estimation of Valsartan and Nebivolol in Bulk and Dosage Forms

The main reason of this work to develop a sensitive, rapid, economic, precise reverse phase liquid chromatographic method to separate and assay the simultaneous determination of Valsartan and Nebivolol as a minor component in bulk and dosage forms. The separation was carried out using SHIMADZU UV-photo diode array detector at 200, 245 nm for Nebivolol and Valsartan respectively equipped with reverse phase C18 column Sunniest 5μm, 4.6 mm, 250 mm at 40˚C oven temperature, flow rate of 1 mL/min with mobile phase consist of 70:30 methanol: 10 mM phosphate buffer pH=3. The retention time of Nebivolol and Valsartan were to be found at 4.3 min and 8 min respectively. The method was validated according to ICH guidelines. The linearity of the proposed method was investigated in concentration range of 45.8-229% r=0.9997 for Nebivolol and the range 55-166%, r=0.9999 for Valsartan. Robustness in the case of little change of some chromatographic conditions. Validation of the proposed method was carried out for its linearity, accuracy, precision, robustness and assay. This method can be applied easily in routine work analysis to detrmine the estimation of nebivolol and valsartan in bulk and dosage forms.

Curcumin degradation kinetics in micellar solutions: Enhanced stability in the presence of cationic surfactants

In this work, the rate of curcumin degradation in the presence of various surfactants (anionic, cationic, and nonionic) and salts (i.e., NaCl, NaHCO3, Na2CO3, and NaOH) was investigated by photodiode-array UV–vis spectroscopy. The curcumin degradation at neutral pH or in the presence of NaCl during the first 16 h of the study was negligible (i.e., zero rate constant). Depending on the type and concentration of added alkaline salt, the color of the curcumin surfactant solution changed from yellow (λmax. = 420−430 nm) to orange (λmax. = 450−500 nm). The degradation rate constants and the final degradation percentage were obtained and reported for various conditions. The maximum curcumin degradation for the investigated surfactants was observed in the presence of 28.5 mM Na2CO3 at pH ∼10.8. The curcumin degradation rate was much lower in the presence of cationic surfactants (monomeric and gemini type). The gemini cationic surfactant (12-4-12) was even more efficient than the single chain cationic surfactant (DTAB) to suppress the curcumin degradation indicating the importance of cationic charge density of the surfactant head group on the electrostatic interaction with curcumin. Curcumin is deprotonated in alkaline conditions and carries negative charges; therefore, cationic surfactants can accommodate and protect it much better than anionic or nonionic surfactants against further degradation.

A review on the recent advances in HPLC, UHPLC and UPLC analyses of naturally occurring cannabinoids (2010-2019).

Organic molecules that bind to cannabinoid receptors are called cannabinoids, and they have similar pharmacological properties like the plant, Cannabis sativa L. Hyphenated liquid chromatography (LC), incorporating high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC, also known as ultrahigh-performance liquid chromatography, UHPLC), usually coupled to an ultraviolet (UV), UV-photodiode array (PDA) or mass spectrometry (MS) detector, has become a popular analytical tool for the analysis of naturally occurring cannabinoids in various matrices. To review literature on the use of various LC-based analytical methods for the analysis of naturally occurring cannabinoids published since 2010. A comprehensive literature search was performed utilising several databases, like Web of Knowledge, PubMed and Google Scholar, and other relevant published materials including published books. The keywords used, in various combinations, with cannabinoids being present in all combinations, in the search were Cannabis, hemp, cannabinoids, Cannabis sativa, marijuana, analysis, HPLC, UHPLC, UPLC, quantitative, qualitative and quality control. Since 2010, several LC methods for the analysis of naturally occurring cannabinoids have been reported. While simple HPLC-UV or HPLC-UV-PDA-based methods were common in cannabinoids analysis, HPLC-MS, HPLC-MS/MS, UPLC (or UHPLC)-UV-PDA, UPLC (or UHPLC)-MS and UPLC (or UHPLC)-MS/MS, were also used frequently. Applications of mathematical and computational models for optimisation of different protocols were observed, and pre-analyses included various environmentally friendly extraction protocols. LC-based analysis of naturally occurring cannabinoids has dominated the cannabinoids analysis during the last 10 years, and UPLC and UHPLC methods have been shown to be superior to conventional HPLC methods.

ISOLATION AND CHARACTERISATION OF RAPAMYCIN, TEMSIROLIMUS REGIO ISOMER (MONOESTER) AND TEMSIROLIMUS DIESTER IN TEMSIROLIMUS DRUG

Objective: Separation and identification of the process impurities in the manufacture of temsirolimus drug viz., rapamycin, temsirolimus regioisomer (monoester) (TS monoester), and temsirolimus diester (TS diester).&#x0D; Methods: During the process development of temsirolimus (TS), three process impurities-rapamycin, temsirolimus regioisomer (monoester) and temsirolimus diester-were detected by high-performance liquid chromatography (HPLC). Impurities were isolated by medium pressure liquid Chromatography (MPLC) and characterized by ESI-MS/MS, 1H NMR, FT-IR spectral data.&#x0D; Results: These impurities are characterised with the help of ESI MS/MS, 1H NMR, and FT-IR data. The impurities are identified and characterised as the process impurities. One of them is the starting material i.e. rapamycin and the other two are formed during the manufacture of the drug. This method offers advantages over using photodiode-array UV detection (LC-PDA) for the determination of peak purity, viz. components with similar UV spectra can be distinguished.&#x0D; Conclusion: The structures of these impurities were characterized as rapamycin, TS Monoester, and TS Diester. Out of these process impurities, rapamycin has been previously identified while the other two are previously unreported.

Poly(lauryl methacrylate-co-1,6-hexanediol ethoxylate diacrylate) modified silica-based dispersive solid-phase extraction for determination of phenylurea herbicides in environmental water samples

ABSTRACTIn this study, poly(lauryl methacrylate-co-1,6-hexanediol ethoxylate diacrylate) (LMA-HEDA) was synthesised on silanised silica through free-radical cross-linking polymerisation process. The optimal preparation process was obtained by investigating the effects of polymerisation temperature and reaction time. Characterisation of the LMA-HEDA-modified silica was achieved using diffuse reflectance FT-IR. The resulting LMA-HEDA-modified silica was then utilised as a sorbent for dispersive solid-phase extraction (dSPE) of phenylurea herbicides (PUHs) from various environmental water samples. The optimisation of LMA-HEDA-based dSPE process was achieved by investigating the effect of the following parameters including extraction time, pH of sample solution, composition of elution solvent and addition of salt on the extraction recovery of PUHs from water samples. Gradient elution was performed to analyse the extracted PUHs by high performance liquid chromatography (HPLC) with UV-photodiode array detection. Acceptable matrix effect was observed using the proposed LMA-HEDA-based dSPE-HPLC-UV for determining PUHs in environmental water samples. Relatively low detection limits (0.027–0.053 ng mL−1) and good linearity (0.1–4.0 ng mL−1; r2 > 0.999) for individual PUHs were obtained using the proposed method. The proposed method offered detection limits lower than the allowed permissible level (0.1 ng mL−1) set by European Union. The enrichment factors of target PUHs were also estimated at 40.3–47.7. Good extraction recoveries (80.1–97.9%) for PUHs-spiked water samples were obtained with relative standard deviations lower than 8.7%. The intra-day/inter-day precision (0.7–4.6%/0.2–5.9%) and accuracy (96.7–104.2%/95.3–103.6%) of the proposed method were also evaluated in this study. In addition, the applicability of the developed method was demonstrated by the measurement of PUHs in various environmental water samples.

Comparative Analysis of Phenolic Compounds in Seven Hypericum Species and Their Antioxidant Properties

A comparative analysis of the phenolic compounds in the 70% EtOH extracts of Hypericum acutum, H. androsaemum, H. barbatum, H. hirsutum, H. maculatum, and H. richeri has been carried out using high-performance liquid chromatography coupled with photodiode array UV detection and high resolution TOF mass spectrometry. Quercetin, astilbin, I3, II8-biapigenin, orientin, 2”- O-acetylorientin, three phenolcarboxylic acids, and eight flavonols 3- O-glycosides were identified in the extracts on the basis of their on-line UV spectra, accurate mass spectral data, and in comparison of retention times with those from the standards. Fingerprint analysis of the extracts revealed significant differences in the qualitative and quantitative chemical composition of the studied species. Antioxidant assays with various reaction mechanisms were used including ferric reducing antioxidant power (FRAP) assay, DPPH, ABTS, superoxide anion radical scavenging capacity and inhibition of liposome peroxidation induced by Fe2+. The most potent were extracts of H. acutum and H. maculatum indicating this Hypericum species interesting for further research aimed as a potentially new source of biologically active compounds.

Acetogenins and alkaloids during the initial development of Annona muricata L. (Annonaceae).

In plants, the presence and distribution of specialized metabolites during the early stages of development are not documented enough, even though their biosynthesis is one of the most important strategies for survival. In this study, five alkaloids and four acetogenins were detected in Annona muricata L. during early development seedling, including three phases of root emergence and three of seedling formation. Hexane and alkaloid extracts were obtained from each organ, which were analyzed in a gas-mass chromatograph and in a high-performance liquid chromatograph coupled with a photodiode array UV detector (HPLC-DAD). This research shows the presence of the acetogenins cis-uvarimicin IV, mosinone, muricina B, and cis-annonacin-10-one, as well as of the alkaloids reticuline, coreximine, anonaine, asimilobine, and nornuciferine, both groups with a variable organ-specific distribution, related with the formation of organs and tissues.

Sensitive determination of nitrophenol isomers by reverse-phase high-performance liquid chromatography in conjunction with liquid–liquid extraction

ABSTRACTA method for the highly sensitive determination of 2-, 3- and 4-nitrophenols was developed using reverse-phase high-performance liquid chromatography (RP-HPLC) with a UV photodiode array detector. Using a reverse-phase column and 40% aqueous acetonitrile as an eluent (i.e. isocratic elution), the integrated peak area of detector output was linear up to 300 mg/L and the detection limit was 150 µg/L. The sensitivity of this detection method was improved by pretreating the sample solutions with a solvent extraction procedure that makes use of the high partition coefficient of ethyl acetate (EA)/water system. To find an optimum condition for the extraction procedure, this process was simulated by plotting the concentration of nitrophenol extracted in organic solvent against the volume multiplication factor at various partition coefficient of solute. This simulation demonstrated that EA is a superior extractant to other organic solvents. With the newly developed method, the detection limit was extended to 0.3 µg/L. This method offers fast, reliable and more sensitive determination of nitrophenol isomers than any other HPLC method.

Bioanalytical Method Validation for Dronedarone and Duloxetine in Blood Serum

The present work relates to the development and validation of reversed-phase HPLC-UV-photodiode array methods for the estimation of two drugs in blood serum: dronedarone hydrochloride (DDN), a class III antiarrhythmic drug, and duloxetine hydrochloride (DLX), an antidepressant. Chromatographic analysis of DLX was carried out on a Nucleodur C18 column (250 × 4.6 mm, 5 μm) using ammonium acetate buffer (32 mM, pH 5.5) and acetonitrile (40 + 60, v/v; flow rate of 1.0 mL/min; detection wavelength of 290 nm) as the mobile phase. A Waters XTerra C18 column (250 × 4.6 mm, 5 μm) was used for the chromatographic analysis of DDN using an acetonitrile-ammonium formate buffer (20 mM, pH 3.0, with formic acid; 45 + 55, v/v; flow rate 1.0 mL/min) as the mobile phase. Pentazocine and bupropion HCl were used as the internal reference standards for DLX and DDN, respectively. Excellent linearity was observed for DLX (r2 = 0.9996; concentration range 0.2-10.0 μg/mL) and DDN (r2 = 0.9997; concn. range 2.0-50.0 μg/mL). The LODs for DLX and DDN were 0.022 and 0.78 μg/mL, respectively, and the LOQs 0.066 and 2.4 μg/mL, respectively.

Simultaneous Determination of the Five Marker Compounds in Melandrium firmum using High-Performance Liquid Chromatography with Photodiode-Array Detection

In Korean folk medicine, Melandrium firmum Rohrbach (Caryophyllaceae) has been used to treat various diseases, including anuria, breast cancer, and gonorrhea. In this study, a high-performance liquid chromatography method with photodiode-array UV detection (HPLC-PDA) was established and then validated for the simultaneous determination of five flavonoids in M firnum: schaftoside, homoorientin, cytisoside, vitexin, and isovitexin. Separation of the five compounds was performed on a Gemini C18 column at 40'C by gradient elution of two mobile phases. The flow rate and injection volume were 1.0 m/min and 10 pL, respectively. The HPLC-PDA method showed excellent linear regression with r2 values of 0.9999 within the test ranges. The limits of -detection and quantification of all components were 0.01-0.11 and 0.04-0.34 pg/mL, respectively. The extraction recovery of the five analytes was 97.6-- 105.6% and the RSD values were < 2.0%. The relative standard deviation values of intra- and interday precision for all analytes were < 1.71 and < 1.46%,. respectively. As determined using the established and validated HPLC-PDA method described here, the amounts of the five marker compounds in M firmuin .were 0.02-2.54 mg/g.

How to solve the problem of co-elution between two compounds in liquid chromatography through the first UV derivative spectrum. A trial on alternative plasticizers to di(2-ethylhexyl) phthalate

To meet new regulations, alternative plasticizers to di(2-ethylhexyl) phthalate (DEHP) are now commonly used in the manufacturing of medical devices. These are: acetyl tri-n-butyl citrate (ATBC), bis (2-ethylhexyl)adipate (DEHA), dioctyl terephtalate (DEHT), di-isononylphtalate (DINP), diisononylcyclohexane-1.2-dicarboxylate (DINCH) and trioctyltrimellilate (TOTM). An HPLC-UV analysis was previously developed to characterize four of them. However, two compounds were systematically co-eluated: DEHP with DEHA and DEHT with DINP. The first derivative of UV spectra and photodiode array detection allow the quantification of DEHA and DINP. Moreover, for each plasticizer, maximum wavelength absorbance was chosen to be as specific as possible. Quantification ranged from 0.3 to 750µg/mL according to the plasticizer. The assays were validated by analysis of variance. Our method was validated by determining the following parameters: specificity, linearity, limits of detection and quantification. The relative biases were inferior to 5% for ATBC, DEHP, DEHA and DINCH and inferior to 10% for DEHT, DINP and TOTM. Plasticizers were extracted with tetrahydrofuran and methanol. The developed method was then used to determine the composition of plasticizers in several medical devices used in clinical service. The major plasticizers were quantified from 19% to 40% w/w, traces of DEHT were found in six medical devices and DEHP in five.

Overview of accessibility and quality of antiepileptic drugs in Madagascar

PurposeTo determine the accessibility of treatment and the quality of antiepileptic drugs (AEDs) in the Haute Matsiatra district of Madagascar. MethodsCross-sectional descriptive study and interviews. Samples of 10 units of each available AED were collected, and the active ingredient was quantified by reversed-phase high-performance liquid chromatography (RP-HPLC) with photodiode-array UV detection. The quality of an AED was considered satisfactory if the quantity of active ingredient in each tablet was in the range ±15% of the average value according to the European Pharmacopeia (6th edition, 2008). ResultsThe area was well served with health infrastructure but rescue facilities were poorly distributed. Available AEDs were all first-generation, and 73% were generic formulations. People with epilepsy (PWE) surveyed consulted traditional healers and most were treated with plants. PWE did not consider themselves sick but believed they were “possessed”; they consulted a doctor only immediately after a seizure, following the advice of traditional healers. The most prescribed AED was phenobarbital, costing between 0.03 and 0.12 US Dollar (US$) per 100mg. The purchase of full treatment was difficult for 77% of PWE and as a result, 39% took nothing. The quality of AEDs were considered unsatisfactory in 2.8% of cases. ConclusionThe AEDs collected in Haute Matsiatra were globally of good quality. The main limiting elements were a lack of knowledge among PWE that epilepsy is a disease, and the cost of traditional treatments.

HPLC-based Assay to Monitor Extracellular Nucleotide/Nucleoside Metabolism in Human Chronic Lymphocytic Leukemia Cells.

This method describes a sensitive, specific, reliable and reproducible reverse phase high-performance liquid chromatography (RP-HPLC) assay developed and validated for the quantification of extracellular purine nucleotides and nucleosides produced by purified chronic lymphocytic leukemia (CLL) cells under different culture conditions. The chromatographic separation of adenosine 5'-monophosphate (AMP), adenosine (ADO) and inosine (INO) is performed at RT on a silica-based, reversed-phase column that is used for polar compound retention. The method includes a binary mobile phase, which consists of 7 mM ammonium acetate and acetonitrile with a flow rate of 1.00 ml/min. The eluates are monitored using a Photodiode Array UV detector set at 260 nm. A standard calibration curve is generated to calculate the equation for the analytical quantification of each purine compound. System control, data acquisition and analysis are then performed. Applying this protocol, AMP, INO and ADO elute at 7, 11 and 11.9 min, respectively, and the total run time for each sample is 20 min. This protocol may be applied to different cell types and cell lines (both suspension and adherent), using culture media as matrix. The advantages are easy and fast sample preparation and the requirement of a small amount of supernatant for analysis. Furthermore, the use of a serum-free medium allows skipping the protein precipitation step with acetonitrile that impacts the final concentration of purine compounds. One of the limitations of the method is the requirement of the equilibration column run before each single sample run, making the total run time of the experiment longer and preventing high throughput screening applications.

Simultaneous determination of amlodipine and telmisartan from pharmaceutical products by way of capillary electrophoresis

Abstract A rapid, simple and sensitive capillary zone electrophoresis method was developed for the simultaneous determination of amlodipine besylate and telmisartan, in fixed-dose combinations, through the utilization of a UV photodiode array detector. Electrophoretic parameters such as buffer concentration and pH, system temperature, applied voltage and injection parameters, were optimized in order to improve the efficiency of the separation. The best results were obtained when employing fused silica capillary (48 cm length X 50 μm ID) and 50 mM phosphate buffer electrolyte at pH 4.50, + 25 kV applied voltage, as well as 25°C system temperature. The separation was achieved in approximately 3 minutes, with a resolution of 4.90, while the order of migration was amlodipine followed by telmisartan. The analytical performance of the method was verified with regard to linearity, precision and robustness. In addition, the limit of detection and the quantification were calculated.

Polymer monolith microextraction using poly(butyl methacrylate-co-1,6-hexanediol ethoxylate diacrylate) monolithic sorbent for determination of phenylurea herbicides in water samples

In this study, recently developed 1,6-hexanediol ethoxylate diacrylate (HEDA)-based polymeric monoliths were utilized as sorbents for efficient extraction of phenylurea herbicides (PUHs) from water samples. The HEDA-based monolithic sorbents were prepared in a fused silica capillary (0.7mm i.d., 4.5-cm long) for polymer monolith microextraction (PMME). The experimental parameters of PMME microextraction including sample loading speed, pH of sample solution, composition of elution solvent, and addition of salt were optimized to efficiently extract PUHs from environmental water samples. The extracted PUHs were determined using ultra-high performance liquid chromatography (UHPLC) with UV-photodiode array detection. The extraction recoveries for PUHs-spiked water samples were 91.1–108.1% with relative standard deviations lower than 5%. The linearity range was 0.025–25ngmL−1 for each PUH and the detection limits of PUHs were estimated at 0.006–0.019ngmL−1. In addition, good intra-day/inter-day precision (0.1–8.7%/0.2–8.9%) and accuracy (92.0–108.0%/96.5–105.2%) of the proposed method were obtained. The extraction capacity of the monolith-filled capillary was also determined to be approximately 1μg. Moreover, each monolith-filled capillary could be reused up to 8 times without carry-over. According to the European Union regulations, the allowed permissible limit of any single herbicide in drinking water is 0.1ngmL−1. This permissible level fell in the linear range examined in this study. In addition, the proposed method provided detection limits lower than the allowed permissible level, which demonstrated the feasibility of utilizing the HEDA-based monolithic sorbent to perform PMME for determining contaminants, such as PUHs, in environmental application.

Development of Simultaneous Derivative Spectrophotometric and HPLC Methods for Determination of 17-Beta-Estradiol and Drospirenone in Combined Dosage Form.

Simple, rapid spectrophotometric, and reverse-phase high performance liquid chromatographic methods were developed for the concurrent analysis of 17-beta-estradiol (ESR) and drospirenone (DRS). The spectrophotometric method was based on the determination of first derivative spectra and determined ESR and DRS using the zero-crossing technique at 208 and 282 nm, respectively, in methanol. The linear range was 0.5–32.0 µg·mL−1 for DRS and 0.5–8.0 µg·mL−1 for EST. The limit of detection (LOD) values were 0.14 µg·mL−1 and 0.10 µg·mL−1 and limit of quantification (LOQ) values were 0.42 µg·mL−1 and 0.29 µg·mL−1 for ESR and DRS, respectively. The chromatographic method was based on the separation of both analytes on a C18 column with a mobile phase containing acetonitrile and water (70 : 30, v/v). Detection was performed with a UV-photodiode array detector at 279 nm. The linear range was 0.08–2.5 µg·mL−1 for DRS and 0.23–7.5 µg·mL−1 for EST. LOD values were 0.05 µg·mL−1 and 0.02 µg·mL−1 and LOQ values were 0.15 µg·mL−1 and 0.05 µg·mL−1 for ESR and DRS, respectively. These recommended methods have been applied for the simultaneous determination of ESR and DRS in their tablets.

Simultaneous determination of aliskiren, amlodipine and hydrochlorothiazide in spiked human plasma and urine by high performance liquid chromatography

A reversed-phase (RP) liquid chromatographic technique for the simultaneous determination of aliskiren (ALS), amlodipine (AMD) and hydrochlorothiazide (HCT) in spiked human plasma and urine is presented. The method employs a gradient elution using 10 mM orthophosphoric acid containing 0.1% triethylamine (pH 2.5, v/v) and acetonitrile and an RP-C18 column (4.6 mm × 250 mm, 5 μm, Phenomenex) at 1 mL/min of flow rate, with a UV photo diode array detector at 271 nm. The linear ranges were 0.01–10 μg/mL in plasma and 0.05–10 μg/mL in urine for both ALS and AMD. The linearty of HCT was in the range of 0.0125–2.5 μg/mL in plasma and urine. Correlation coefficients (r2) were higher than 0.9983 for all of the analytes, indicating good linear relationship. The method validation was performed with respect to linearity, recovery, accuracy, precision and stability. The developed method could be applied in the routine clinical analysis.

Optimization and validation of an HPLC-photodiode array detector method for determination of organic acids in vinegar.

A novel isocratic RP-HPLC method with UV photodiode array detection for the determination of seven organic acids in vinegar samples was developed and optimized. Samples were analyzed on a C18 (150 × 4.6 mm id, 5 μm) analytical column. Methanol-0.010 M sodium dihydrogen phosphate buffer adjusted with H3PO4 to pH 2.80 (2 + 98, v/v), was used as the mobile phase. The column oven temperature was optimized at 23.0°C, the flow rate was 0.80 mL/min, and the detection wavelength was 210 nm. Matrix-matched calibration curves were prepared for all analytes, and the correlation coefficients were greater than 0.99. LOD and LOQ ranged from 0.10 to 10.0 and 0.30 to 30.0 μg/mL, respectively. The results for interday and intraday precision and accuracy fell within the ranges specified. Vinegar samples were quantified by the standard addition method. The main advantages of this method are its selectivity, which is one of the main weaknesses of most methods when determining organic acids in complex matrixes, and its simplicity since little sample preparation is needed. Moreover, it is safe and inexpensive with low organic solvent usage.