Determination of gatifloxacin and ornidazole in tablet dosage forms by high-performance thin-layer chromatography.

A simple and sensitive high-performance thin-layer chromatography (HPTLC) method has been developed for the quantitative estimation of gatifloxacin and ornidazole in its combined dosage forms. Gatifloxacin and ornidazole were chromatographed on silica Gel 60 F(254) TLC plate using n-butanol:methanol:ammonia (6 M) (8:1:1.5 v/v) as the mobile phase and scanned at 302 nm using a Camag TLC Scanner 3. The R(f) value of gatifloxacin and ornidazole was found to be 0.21 +/- 0.02 and 0.76 +/- 0.04, respectively. The linearity of gatifloxacin and ornidazole were in the range of 100 - 500 ng/spot and 250 - 1250 ng/spot, respectively. The limit of detection was found to be 40 ng/spot for gatifloxacin and 100 ng/spot for ornidazole. The proposed method was applied for the determination of gatifloxacin and ornidazole in combined dosage forms.     

Image analysis of phenylisothiocyanate derivatised and charge-couple device-detected glyphosate and glufosinate in food samples separated by thin-layer chromatography

The paper presents the application of pre-chromatographic derivatisation reaction of aminophosphonic acids (glyphosate and glufosinate) with phenylisothiocyanate in thin-layer chromatography (TLC). Silica gel as stationary phase and a mixture of methanol–water–diethyl ether (2:1:1, v/v/v) and ethanol–water–diethyl ether (4:1:2, v/v/v) were used as the mobile phase, respectively. Detection was performed by spraying TLC plates with a freshly prepared mixture of sodium azide (1%), starch solution (1% for glyphosate and 2% for glufosinate), and potassium iodide (1.0 × 10^–2 mol L^?1) adjusted to pH 6.0 and exposed to iodine vapour for 15 s. Both glyphosate and glufosinate as phenylthiocarbamates (PTC-derivatives) were visible as white spots against a violet background which were converted into chromatograms using TLSee software. The calibration curves for glyphosate and glufosinate were within the ranges of 8.45–84.5 ng and 1.98–79.2 ng per spot, respectively. The limits of detection and quantification for glyphosate were at a level of 4 and 8.45 ng per spot, and for glufosinate were 0.99 and 1.78 ng per spot, respectively. The proposed method was successfully used in the determination of aminophosphonic acids in spiked plants samples.     

Direct determination of four fluoroquinolones,enoxacin, norfloxacin,ofloxacin, and ciprofloxacin,in pharmaceuticals and blood serum by HPLC

A rapid, accurate and sensitive method has been developed for the quantitative determination of four fluoroquinolone antimicrobial agents, enoxacin, norfloxacin, ofloxacin and ciprofloxacin, with high in-vitro activity against a wide range of Gram-negative and Gram-positive organisms.A Kromasil 100 C(8) 250 mm x 4 mm, 5 microm analytical column was used with an eluting system consisting of a mixture of CH(3)CN-CH(3)OH-citric acid 0.4 mol L(-1) (7:15:78 %, v/v). Detection was performed with a variable wavelength UV-visible detector at 275 nm resulting in limits of detection: 0.02 ng per 20 microL injection for enoxacin and 0.01 ng for ofloxacin, norfloxacin and ciprofloxacin. Hydrochlorothiazide (HCT) was used as internal standard at a concentration of 2 ng microL(-1). A rectilinear relationship was observed up to 2 ng microL(-1) for enoxacin, 12 ng microL(-1) for ofloxacin, 3 ng microL(-1) for norfloxacin, and 5 ng microL(-1) for ciprofloxacin. Separation was achieved within 10 min. The statistical evaluation of the method was examined by performing intra-day (n=8) and inter-day precision assays (n=8) and was found to be satisfactory with high accuracy and precision. The method was applied to the direct determination of the four fluoroquinolones in human blood serum. Sample pretreatment involved only protein precipitation with acetonitrile. Recovery of analytes in spiked samples was 97+/-6% over the range 0.1-0.5 ng microL(-1).     

Simultaneous Separation and Determination of Lamivudine and Zidovudine in Pharmaceutical Formulations Using the HPTLC Method

Abstract

A high-performance thin-layer chromatographic method (HPTLC) for the simultaneous determination of lamivudine and zidovudine in a binary mixture has been developed. The method developed was based on HPTLC separation of the two drugs followed by densitometric measurements of spots at 276 and 271 nm for lamivudine and zidovudine, respectively. Separation was carried out on Merck HPTLC silica-gel 60 F₂₅₄ plates, using toluene/chloroform/methanol (1:6:3 v:v) as the mobile phase. Validation of the method was performed based on The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines in terms of linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. Second-order polynomial equations were obtained for the regression line in the ranges of 250–1400 and 250–1700 ng/spot for lamivudine and zidovudine respectively. Correlation coefficient (r) values were 0.9998 for both analytes. The method provides sufficient accuracy as indicated by recovery percentages given for lamivudine and zidovudine. For system precision study, the low coefficient of variation values (<2%) for both lamivudine and zidovudine ensured reproducible performance of the instrument. In the method precision study, coefficients of variation <2% were obtained, which showed that the proposed method provides acceptable intraday and interday variation. The detection and quantification limits and were 3.06 and 9.28 ng/spot for lamivudine and 3.34 and 10.13 ng/spot for zidovudine, respectively. Parameters such as mobile-phase composition, volume of mobile phase, time from spotting to development, and time from development to scanning were employed while testing for robustness of the method, and the standard deviation of peak areas was calculated for each parameter. The low coefficient of variation values indicated the robustness of the method. Statistical manipulation did not show any significant effect of one parameter over the others on the robustness of the method.     

HPTLC determination of rabeprazole and domperidone in capsules and its validation

This paper describes a validated high-performance thin-layer chromatography (HPTLC) method for simultaneous estimation of rabeprazole (RA) and domperidone (DO) in pure powder and in capsule formulations. An HPTLC method separation is achieved on an aluminum sheet of silica gel 60F(254) using ethyl acetate-methanol-benzene-acetonitrile (30:20:30:20 v/v) as mobile phase. Quantitation is achieved with UV detection at 287 nm over a concentration range of 400-1200 ng/spot and 600-1800 ng/spot with mean recovery of 99.82 +/- 0.74 and 99.43 +/- 0.68 for RA and DO, respectively, in the HPTLC method. This method is simple, precise, and sensitive, and it is applicable for the simultaneous determination of RA and DO in pure powder and in capsule formulation.     

气相色谱-质谱法测定酱猪蹄和酱猪肘中5种胆固醇氧化物

建立了气相色谱-质谱（GC-MS）测定酱猪蹄和酱猪肘中7 β-羟基胆固醇、5 α，6 α-环氧化胆固醇、胆甾烷-3 β，5 α，6 β-三醇、25-羟基胆固醇和7-酮基胆固醇5种胆固醇氧化物（COPs）含量的方法。样品经甲醇-氯仿（1：2，v/v）混合溶液提取，硅胶固相萃取小柱净化后，加入N，O-双（三甲基硅基）乙酰胺-三甲基氯硅烷-三甲基硅基咪唑（3：2：3，v/v/v）（Sylon BTZ）进行衍生化处理，设置合理的柱温升温程序，采用选择离子扫描（SIM）模式进行检测。在优化条件下，5种COPs在22 min内实现分离，且分离度良好。5种COPs的线性范围满足测定要求，3个加标水平下的平均回收率为61.16%~96.96%，相对标准偏差≤ 7.80%（n=3），检出限（以信噪比为3计）和定量限（以信噪比为10计）分别为0.02~47.07 ng/g和0.06~156.90 ng/g。该法快速简便，线性范围广，灵敏度高，可作为测定实际样品中COPs的有效方法。     

Direct determination of five fluoroquinolones in chicken whole blood and in veterinary drugs by HPLC

A direct, accurate, and sensitive chromatographic analytical method for the quantitative determination of five fluoroquinolones (enoxacin, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin) in chicken whole blood is proposed in the present study. For quantitative determination lamotrigine was used as internal standard at a concentration of 20 ng/microL. The developed method was successfully applied to the determination of enrofloxacin, as the main component of commercially available veterinary drugs. Fluoroquinolone antibiotics were separated on an Inertsil (250 x 4 mm) C8, 5 microm, analytical column, at ambient temperature. The mobile phase consisted of a mixture of citric acid (0.4 mol L(-1))-CH3OH-CH3CN (87:9:4% v/v) leading to retention times less than 14 min, at a flow rate 1.4 mL min(-1). UV detection at 275 nm provided limits of detection of 2 ng/mL per 20 microL injected volume for enoxacin, norfloxacin, and ciprofloxacin, 0.4 ng/mL for ofloxacin, and 4 ng/mL for enrofloxacin. Preparation of chicken blood samples is based on the deproteinization with acetonitrile while the pharmaceutical drug was simply diluted with water. Peaks of examined analytes in real samples were identified by means of a photodiode array detector. The method was validated in terms of within-day (n=6) precision and accuracy after chicken whole blood sample deproteinization by CH3CN. Using 50 microL of chicken blood sample, recovery rates at fortification levels of 40, 60, and 80 ng ranged from 86.7% to 103.7%. The applicability of the method was evaluated using real samples from chicken under fluoroquinolone treatment.     

RP-HPLC method with electrochemical detection for the determination of metoclopramide in serum and its use in pharmacokinetic studies.

A rapid and sensitive reversed-phase high performance liquid chromatographic method has been developed for the determination of metoclopramide in serum. The assay was performed after single extraction with ethyl ether using methyl parahydroxybenzoate as internal standard. Chromatographic separations were performed on C(18) stationary phase with a mobile phase composed of methanol-phosphate buffer pH 3 (30:70 v/v). Analytes were detected electrochemically. The quantification limit for metoclopramide in serum was 2 ng mL(-1). Linearity of the method was confirmed in the range of 5-120 ng mL(-1) (correlation coefficient 0.9998). Within-day relative standard deviations (RSDs) ranged from 0.3 to 5.5% and between-day RSDs from 0.8 to 6.0%. The analytical method was successfully applied for the determination of pharmacokinetic parameters after ingestion of 10 mg dose of metoclopramide. Studies were performed on 18 healthy volunteers of both sexes.     

Liquid chromatographic high-throughput analysis of the new ultra-short acting hypnotic 'HIE-124' and its metabolite in mice serum using a monolithic silica column

For the first time, a fast, high-performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of the new ultra-short hypnotic HIE-124 and its metabolite in mice serum. Each compound, together with carbamazepine (internal standard) was extracted from the serum matrix using liquid-liquid extraction (LLE). Chromatographic resolution of the analytes was performed on a Chromolith Speed Rod monolithic silica column (100 mm × 4.6 mm i.d.) under isocratic conditions using a mobile phase of 65:35 (v/v), 20 mM phosphate buffer (pH 7.0 adjusted with phosphoric acid)-acetonitrile. The elution of the analytes were monitored at 240 nm and conducted at ambient temperature. Because of high column efficiency the mobile phase was pumped at a flow rate of 2.5 mL min(-1). The total run time of the assay was 2 min. The method was validated over the range of 60-2000 ng mL(-1) for HIE-124 and 200-1600 ng mL(-1) for the metabolite (r(2) = 0.99). The limit of detection (LOD) for HIE-124 and its metabolite were 20 ng mL(-1) and 65 ng mL(-1), respectively. The proposed method was validated in compliance with ICH guidelines, in terms of accuracy, precision, limits of detection and quantitation and other aspects of analytical validation. The developed method could be used for the trace analyses of HIE-124 and its metabolite in serum and was finally used for the pharmacokinetic study investigation of HIE-124 in mice serum.     

Development of a highly sensitive high‐performance thin‐layer chromatography method for the screening and simultaneous determination of sofosbuvir,daclatasvir, and ledipasvir in their pure forms and their different pharmaceutical formulations

The combination of sofosbuvir and daclatasvir or sofosbuvir and ledipasvir is now widely used as an ideal treatment for hepatitis C virus infection. For this purpose, a simple, sensitive, accurate, economic, and precise high‐performance thin‐layer chromatography was developed and validated for the determination of sofosbuvir, daclatasvir, and ledipasvir in their pure form as well as their different pharmaceutical products. The method used Merck high‐performance thin‐layer chromatography aluminum plates precoated with silica gel 60 F254 as a stationary phase and mobile phase consisting of methylene chloride/methanol/ethyl acetate/ammonia (25%) (6:1:4:1, v/v/v/v). This system was found to give compact symmetric peaks of sofosbuvir, daclatasvir, and ledipasvir with retardation factors of 0.27 ± 0.01, 0.50 ± 0.007, and 0.68 ± 0.008, respectively. The densitometric scanner was set at 275 nm using a deuterium lamp. The calibration curves were linear over the range of 100–3000 ng/spot for sofosbuvir, and daclatasvir, and range of 50–3000 ng/spot for ledipasvir. The detection limits were 22.5, 31.90, and 15.80 for sofosbuvir, daclatasvir, and ledipasvir. The quantitation limits were 67.50, 95.60, and 47.50 for sofosbuvir, daclatasvir, and ledipasvir. The proposed method was validated according to International Conference on Harmonization (ICH) guidelines and the results were acceptable.     

Reversed-Phase High Performance Liquid Chromatographic and Thin Layer Chromatographic Methods for the Simultaneous Determination of Benazepril Hydrochloride and Hydrochlorothiazide in Cibadrex Tablets

ABSTRACT

Two procedures were developed for simultaneous determination of benazepril hydrochloride (I) and hydrochlorothiazide (II) in pure, laboratory made mixtures and in pharmaceutical dosage form “Cibadrex tablets® using reversed phase high performance liquid chromatographic and thin layer chromatographic methods.

For reversed phase HPLC, a new very sensitive, rapid, selective method was developed. The linearity ranges were 32-448 ng/20 μl and 40-560 ng/20 μl for benazepril hydrochloride and hydrochlorothiazide, respectively. The corresponding recoveries were 99.38 ± 1.526 and 99.2 ± 1.123.

The minimum detection limits were 7 ng/20 μl and 14 ng/20 μl for benazepril hydrochloride and hydrochlorothiazide respectively.

On the other hand, a new, simple, sensitive and fast thin layer chromatographic scanning densitometric method was developed for simultaneous determination of benazepril hydrochloride and hydrochlorothiazide using ethyl acetate: methanol: ammonia (85: 20: 10 v/v) as the developing system. The R_f values were 0.33 & 0.68 for benazepril hydrochloride and hydrochlorothiazide respectively. The minimum detection limit obtained was 0.12 μg/spot for benazepril hydrochloride and 0.24 μg/spot for hydrochlorothiazide. The mean percentage recoveries were 100.04 ± 1.102 and 99.31 ± 1.009 for benazepril hydrochloride and hydrochlorothiazide respectively.

The two proposed methods were simple, precise, sensitive and could be successfully applied for the determination of pure, laboratory made mixtures and pharmaceutical dosage forms. The results obtained were compared with those obtained by A ^1%.     

Simultaneous HPLC-UV determination of ketamine, xylazine, and midazolam in canine plasma

An isocratic reversed-phase high-performance liquid chromatography method with UV detection is developed and validated for the simultaneous determination of ketamine, xylazine, and midazolam in canine plasma. Analytes are extracted from alkalinized samples into diethyl ether-methylene chloride (7:3, v:v) using single-step liquid-liquid extraction. Chromatographic separation is performed on a C(18) column using a mobile phase containing an acetonitrile-methanol-10 mM sodium heptanesulfonate buffer adjusted to pH 3, with glacial acetic acid (44:10:46, v:v) at a detection wavelength of 210 nm, with a total runtime of 10 min. The calibration is linear over the range of 78.125-5000 ng/mL for ketamine and 15.625-1000 ng/mL for xylazine and midazolam. The limits of detection are 17.8, 10.3, and 15.1 ng/mL for ketamine, xylazine, and midazolam, respectively. The extraction recoveries are 76.1% for ketamine, 91.0% for midazolam, and 78.2% for xylazine. The method is successfully used for clinical and pharmacokinetic studies of the three-drug fixed dose combination formulations.     

High-performance liquid chromatography and thin-layer chromatography for the simultaneous quantitation of rabeprazole and mosapride in pharmaceutical products

Simple, sensitive high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) methods are developed for the quantitative estimation of rabeprazole and mosapride in their combined pharmaceutical dosage forms. In HPLC, rabeprazole and mosapride are chromatographed using 0.01M 6.5 pH ammonium acetate buffer-methanol-acetonitrile (40:20:40, v/v, pH 5.70+/-0.02) as the mobile phase at a flow rate of 1.0 mL/min. In TLC, the mobile phase is ethyl acetate-methanol-benzene (2:0.5:2.5, v/v). Both the drugs are scanned at 276 nm. The retention times of rabeprazole and mosapride are found to be 4.93+/-0.01 and 9.79+/-0.02, respectively. The Rf values of rabeprazole and mosapride are found to be 0.42+/-0.02 and 0.61+/-0.02, respectively. The linearities of rabeprazole and mosapride are in the range of 400-2000 ng/mL and 300-1500 ng/mL, respectively, for HPLC; in TLC, the linearities of rabeprazole and mosapride are in the range of 400-1200 ng/spot and 300-900 ng/spot, respectively. The limit of detection is found to be 97.7 ng/mL for rabeprazole and 97.6 ng/mL for mosapride in HPLC; in TLC the limit of detection is found to be 132.29 ng/spot for rabeprazole and 98.25 ng/spot for mosapride. The proposed methods can be applied to the determination of rabeprazole and mosapride in combined pharmaceutical products.     

Determination of four lignans in Phyllanthus niruri L. by a simple high-performance liquid chromatography method with fluorescence detection

A new and simple analytical method using HPLC with fluorescence detection was developed for the simultaneous determination of four lignans (phyllanthin, hypophyllanthin, phyltetralin and niranthin) in Phyllanthus niruri L. plant samples. Optimal separation was achieved with an isocratic mobile phase consisting of acetonitrile-water (55:45 v/v). The method recorded limits of detection (S/N=5) for phyllanthin at 0.61 ng/mL, hypophyllanthin at 6.02 ng/mL, phyltetralin at 0.61 ng/mL and niranthin at 1.22 ng/mL, being 80, 8, 80 and 40 times, respectively, lower when compared with those derived using HPLC-UV detection. The limits of quantification (S/N=12) were 4.88 ng/mL for phyllanthin and phyltetralin, 9.76 ng/mL for niranthin and 24.4 ng/mL for hypophyllanthin showing 40, 8 and 20 times, respectively, lower than those from the UV detection method. The within-day and between-day accuracy for the four lignans were between 98.1% and 102.9% while their precision values were below 2.2%. The mean recovery was between 92.5% and 110.1%. The method was then successfully applied for the quantification of lignans in P. niruri plant samples. The highest amount of lignans was found in the leaves followed by fruits, branches and stem, whilst the roots have the least amount of lignans.     

Development of an HPLC method for the monitoring of tricyclic antidepressants in biofluids

A simple, rapid and sensitive HPLC method was developed and validated for the determination of four tricyclic antidepressants (TCAs): amitriptyline, doxepin, clomipramine (CLO) and imipramine, in pharmaceutical formulations and biological fluids. A Kromasil C(8 )analytical column (250 x 4 mm, 5 microm) was used for the separation, with a mobile phase consisting of 0.05 M CH(3)COONH(4) and CH(3)CN (45:55 v/v) delivered at 1.5 mL/min isocratically. Quantification was performed at 238 nm, with bromazepam (1.5 ng/microL) as the internal standard. The determination of TCAs in blood plasma was performed after protein precipitation. Urine analysis was performed by means of SPE using Lichrolut RP-18 Merck cartridges providing high absolute recoveries (> 94%). Direct analysis of urine was also performed after two-fold dilution. The developed method was fully validated in terms of selectivity, linearity, accuracy, precision, stability and sensitivity. Repeatability (n = 5) and between-day precision (n = 5) revealed RSD <13%. Recoveries from biological samples ranged from 91.0 to 114.0%. The absolute detection limit of the method was calculated as 0.1-0.6 ng in blood plasma and 0.2-0.5 ng in extracted urine or 0.4-0.7 in diluted urine. The method was applied to real samples of plasma from a patient under CLO treatment.     

Polyamide as an efficient sorbent for simultaneous interference-free determination of three Sudan dyes in saffron and urine using high-performance liquid chromatography-ultra violet detection北大核心CSCD

With polyamide( PA)as an efficient sorbent for solid phase extraction( SPE)of Sudan dyes II,III and Red 7B from saffron and urine,their determination by HPLC was performed. The optimum conditions for SPE were achieved using 7 mL methanol/water( 1:9,v/v,pH 7)as the washing solvent and 3 mL tetrahydrofu-ran for elution. Good clean-up and high( above 90%)recoveries were observed for all the analytes. The opti-mized mobile phase composition for HPLC analysis of these compounds was methanol-water( 70:30,v/v). The SPE parameters,such as the maximum loading capacity and breakthrough volume,were also determined for each analyte. The limits of detection( LODs),limits of quantification( LOQs),linear ranges and recoveries for the analytes were 4. 6-6. 6 μg/L,13. 0-19. 8 μg/L,13. 0-5 000 μg/L( r2> 0. 99)and 92. 5% -113. 4%,respec-tively. The precisions( RSDs)of the overall analytical procedure,estimated by five replicate measurements for Sudan II,III and Red 7B in saffron and urine samples were 2. 3%,1. 8% and 3. 6%,respectively. The developed method is simple and successful in the application to the determination of Sudan dyes in saffron and urine sam-ples with HPLC coupled with UV detection.     

Use of gas chromatography/mass spectrometry with positive chemical ionization for the determination of opiates in human oral fluid

An analytical method for the simultaneous determination of codeine, morphine and 6-acetylmorphine (6AM) in human oral fluid was developed. The method involves liquid-liquid extraction in Toxitubes A, derivatization with 99:1 (v/v) N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)/trimethylchlorosilane (TMCS), and gas chromatography/mass spectrometry with positive chemical ionization (GC/PCI-MS) determination. The detector response was linear over the concentration range 30-500 ng/mL with coefficients of correlation higher than 0.99. The precision was acceptable with coefficients of variation less than 7.5%. The limits of detection achieved were 0.7 ng/mL for codeine, 2.0 ng/mL for morphine, and 0.6 ng/mL for 6AM. The method proposed was applied to 80 oral fluid samples from opiates users, 98% of which were positive for the three analytes. Human oral fluid is a suitable biological fluid for the determination of opiates by GC/PCI-MS.     

Development and validation of a stability-indicating method for determination of free sterols in the Asian medicinal leech Hirudo manillensis

A rapid, simple, sensitive, selective, precise and robust thin-layer chromatography densitometric method for the determination of free sterols in leech was developed and validated on silica gel layer using carbon tetrachloride-methanol-formic acid (9.5:1.5:0.55, v/v/v). Spectrodensitometric scanning was carried using a Camag TLC scanner III at 366 nm after spraying 2% methanolic sulphuric acid, which gave compact spots for cholesterol (R(F) = 0.35 ± 0.02). The regression analysis data for calibration plot implied a good linear relationship (r(2) = 0.99958) between response and concentration over the range 100-600 ng per spot with respect to peak area. The limits of detection and quantification were found to be 13.8 ± 0.51 and 45.01 ± 1.29 ng per spot, respectively. Validation was in accordance to the International Conference on Harmonization guidelines. Cholesterol was subjected to forced stress conditions of oxidation, hydrolysis and heat. Degradation products resulting from the forced stress did not interfere with detection because the degradant peaks were well separated from the cholesterol peak. The densitometric method can be regarded as stability-indicating and can be used for quality control assay of cholesterol in leech extract.     

Determination of Camptothecin and 10-Hydroxycamptothecin in Camptotheca acuminata by LC-ESI-MS/MS

A rapid and sensitive liquid chromatography-tandem mass spectrometry method with multiple reaction monitoring was developed for the simultaneous determination of camptothecin and 10-hydroxycamptothecin in Camptotheca acuminata. The separation of camptothecin and 10-hydroxycamptothecin was performed on an Agilent Eclipse XDB-C18 column with a mixture of methanol and water (1:1, v/v) containing 0.2% formic acid as a mobile phase. The limits of detection of camptothecin and 10-hydroxycamptothecin were 4.0 ng/mL and 7.0 ng/mL (S/N = 3), respectively. Analysis took 10 minutes, making the method suitable for rapid determination of camptothecin and 10-hydroxycamptothecin in C. acuminata.     

Combined isolation and purification procedures prior to the high-performance liquid chromatographic-ion-trap tandem mass spectrometric determination of estrogens and their conjugates in river sediments

A fast and sensitive analytical procedure has been developed for the simultaneous separation and determination of alpha-estradiol, beta-estradiol, estriol, estrone and ethynylestradiol and their sulfate, glucuronide and acetate conjugates in river sediments. The procedure includes a microwave-assisted extraction (MAE) with aqueous methanol (25:75, v/v) at 100 degrees C in 10 min, a clean-up on Oasis WAX cartridge and a high-performance liquid chromatography-ion-trap tandem mass spectrometry (HPLC-IT-MS/MS) with electrospray ionization. The recovery for each compounds ranged from 83 to 107% and the repeatability represented as RSDs ranged from 4.9 to 9.6%. The limits of detection (LODs) were down to 1 ng g(-1). The analytical performance of the method was evaluated using determination of free and conjugated estrogens in river sediments.