High-performance liquid chromatography with fluorescence detection for the simultaneous determination of 3,4-methylenedioxymethamphetamine, methamphetamine and their metabolites in human hair using DIB-Cl as a label

This paper describes a highly sensitive HPLC method for the simultaneous determination of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), amphetamine (AP) and methamphetamine (MP) in human hair samples. The amphetamines investigated were derivatized with the fluorescent reagent, DIB-Cl to yield highly fluorescent DIB-derivatives, which were then analyzed by HPLC with fluorescence detection at excitation and emission wavelengths of 325 nm and 430 nm, respectively. The separation was achieved on an ODS column with an isocratic mobile phase composed of acetonitrile-methanol-water (30:40:30, v/v/v). The limits of detection for the four compounds obtained by the proposed method ranged from 11 to 200 pg/mg. The method was successfully applied to the determination of MDMA and MDA in hair samples obtained from MDMA abuser.     

Quantification of MDMA and MDA in abusers' hair samples by semi-micro column HPLC with fluorescence detection

A sensitive semi-micro column high-performance liquid chromatography with fluorescence detection method was developed for the determination of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), methamphetamine (MP) and amphetamine (AP) in human hair. 4-(4,5-Diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) and 1-methyl-3-phenylpropylamine were used as labeling reagent and internal standard, respectively. These drugs were extracted from hair into 5% trifluoroacetic acid in methanol, and fluorescent labeled with DIB-Cl. The separation of DIB-derivatives was achieved on a reversed-phase semi-micro ODS column with an acetonitrile-methanol-water (30:40:30, v/v/v%) mixture as a mobile phase. The limits of detection at a signal-to-noise ratio of 3 for MDMA, MDA, MP and AP were 0.25, 0.15, 0.25 and 0.19 ng/mg, respectively. Precision of intra- and inter-day assay as the relative standard deviation were in the range 1.5-6.8% (n = 5) and 2.7-4.7% (n = 5), respectively. The proposed method was highly sensitive and able to detect MDMA and its related compounds in small amounts of hair sample, and could be applied to quantification of six abusers' hair samples.     

Optimization of microwave‐assisted extraction of analgesic and anti‐inflammatory drugs from human plasma and urine using response surface experimental designs†

The performance of microwave‐assisted extraction and HPLC with photodiode array detection method for determination of six analgesic and anti‐inflammatory drugs from plasma and urine, is described, optimized, and validated. Several parameters affecting the extraction technique were optimized using experimental designs. A four‐factor (temperature, phosphate buffer pH 4.0 volume, extraction solvent volume, and time) hybrid experimental design was used for extraction optimization in plasma, and three‐factor (temperature, extraction solvent volume, and time) Doehlert design was chosen to extraction optimization in urine. The use of desirability functions revealed the optimal extraction conditions as follows: 67°C, 4 mL phosphate buffer pH 4.0, 12 mL of ethyl acetate and 9 min, for plasma and the same volume of buffer and ethyl acetate, 115°C and 4 min for urine. Limits of detection ranged from 4 to 45 ng/mL in plasma and from 8 to 85 ng/mL in urine. The reproducibility evaluated at two concentration levels was less than 6.5% for both specimens. The recoveries were from 89 to 99% for plasma and from 83 to 99% for urine. The proposed method was successfully applied in plasma and urine samples obtained from analgesic users.     

An improved HPLC method for rapid quantitation of diazepam and its major metabolites in human plasma

A rapid and specific HPLC method was developed and validated for simultaneous determination of diazepam and its main active metabolites, desmethyldiazepam, oxazepam and temazepam in human plasma. Plasma samples were extracted using toluene. HPLC system included a Chromolith Performance RP-18e 100 mm x 4.6mm column, using 10mM phosphate buffer (pH 2.5)-methanol-acetonitrile (63:10:27, v/v) as mobile phase running at 2 mL min(-1). UV detector (lambda=230 nm) was used. The calibration curves were linear in the concentration range of 2-800 ng mL(-1) for diazepam and 2-200 ng mL(-1) for the three metabolites (r(2)>0.99). The lower limit of quantification was 2 ng mL(-1) for all analytes. Within and between-day precisions in the measurement of QC samples were in the range of 1.8-18.0% for all analytes. The developed procedure was used to assess the pharmacokinetics of diazepam and its main metabolites following single dose administration of 10mg diazepam orally to healthy subjects.     

Analysis of methylphenidate and its metabolite ritalinic acid in monkey plasma by liquid chromatography/electrospray ionization mass spectrometry

Methylphenidate (MP, Ritalin) is a psychotropic drug widely prescribed to children for treating the symptoms of attention deficit disorder with and without hyperactivity. Because little information exists about the effects of chronic MP administration on cognitive function in children, measures of behavior changes in non-human primates are important surrogates. An essential component of such studies is the determination of MP plasma levels under chronic and acute dosing conditions. An analytical method was developed that provided sufficient sensitivity to measure low levels of the active parent drug (lower limit of quantitation = 0.25 ng/mL) and the inactive metabolite, ritalinic acid (RA), in monkey plasma as well as the ability to conveniently analyze large numbers of samples. The method uses a polymeric reversed-phase sorbent for solid phase extraction, an efficient reverse-phase high performance liquid chromatography (HPLC) separation, deuterated internal standards for isotope dilution quantification of MP and RA, and detection by sensitive electrospray ionization mass spectrometry (ES-MS) with a single quadrupole instrument. The method responses are linear over the range of plasma concentrations of MP and RA observed in monkeys, gives respective analyte recoveries of 75 and 60% with reasonable precision and accuracy, and demonstrates robust MS performance for rapid determination of MP/RA plasma levels. The average peak MP concentration (ca. 16 ng/mL) and half-lives for MP and RA elimination in monkeys (1.79 and 2.31 h, respectively) were not significantly different under acute vs. chronic dosing conditions and were comparable to values previously reported from human studies.     

HPLC method for determination of diclofenac in human plasma and its application to a pharmacokinetic study in Turkey

A simple high-performance liquid chromatography (HPLC) method has been developed for determination of diclofenac in human plasma. The method was validated on Ace C(18) column using UV detection. The mobile phase consisted of 20 mM phosphate buffer (pH 7) containing 0.1% trifluoroacetic acid-acetonitrile (65:35, v/v). Calibration curve was linear between the concentration range of 75-4000 ng/mL. Intra- and inter-day precision values for diclofenac in plasma were less than 3.6, and accuracy (relative error) was better than 5.3%. The limits of detection and quantification of diclofenac were 25 and 75 ng/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of diclofenac in healthy Turkish volunteers who had been given 50 mg diclofenac.     

Determination of the enantiomeric purity of amphetamine after derivatization with Sanger’s reagent (2,4-dinitrofluorobenzene [DNFB]) by simultaneous dual circular dichroism and ultraviolet spectroscopy

Determination of Se in biological materials was attempted by microwave-induced plasma mass spectrometry (MIP-MS). (1) Serum samples were available after 10 times dilution with 0.5% nitric acid solution containing 0.1% Triton X-100. When oxygen gas was inserted into the plasma gas (nitrogen) in order to improve the combustion, the sensitivity was reduced to 45%. The detection limit of this method was 0.5 ng/mL. (2) Standard reference materials on commercial base were used to evaluate the accuracy of the Se determination by MIP-MS after microwave digestion. In samples like bovine liver and human hair with Se concentrations of more than 0.7 μg/g, the standard curve method after internal standard (IS) correction was acceptable. This procedure was unsuitable for samples with low Se concentrations such as milk powder (certified value of Se 0.11 μg/g), or plant leaf samples. (3) Instead of IS correction, the peak height of the spectrum was used for calculations from the matrix matched calibration curve. The results of all materials were close to the certified values, even at 25 ng/g. The detection limit of the MIP-MS with microwave digestion and IS correction was 0.05 ng/mL in standard solutions. The detection limit of the peak height method was 0.1 ng/mL and was estimated to be < 20 ng/g in plant materials. Received: 25 September 1998 / Revised: 15 February 1999 / Accepted: 18 February 1999     

Quantitation of unbound sunitinib and its metabolite N-desethyl sunitinib (SU12662) in human plasma by equilibrium dialysis and liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study

A rapid, selective, and sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous determination of unbound sunitinib and its active metabolite N‐desethyl sunitinib in plasma. Plasma and post‐dialysis buffer samples were extracted using a liquid–liquid extraction procedure with acetonitrile–n‐butylchloride (1:4, v/v). Chromatographic separation was achieved on a Waters X‐Terra® MS RP₁₈ column with a mobile phase consisting of acetonitrile and water (60:40, v/v) containing formic acid (0.1%, v/v) using an isocratic run, at a flow‐rate of 0.2 mL/min. Analytes were detected by electrospray tandem mass spectrometry in the selective reaction monitoring mode. Linear calibration curves were generated over the ranges 0.1–100 and 0.02–5 ng/mL for sunitinib and 0.2–200 and 0.04–10 ng/mL for N‐desethyl sunitinib in plasma and in phosphate‐buffered solution, respectively. The values for both within‐day and between‐day precision and accuracy were well within the generally accepted criteria for analytical methods. The analytical range was sufficient to determine the unbound and total concentrations of both analytes. The method was applied for measurement unbound concentrations in addition to total concentrations of sunitinib and its metabolite in plasma of a cancer patient receiving 50 mg daily dose. Copyright © 2012 John Wiley & Sons, Ltd.     

Simple method for the determination of rosiglitazone in human plasma using a commercially available internal standard

To the best of our knowledge, bioanalytical methods to determine rosiglitazone in human plasma reported in literature use internal standards that are not commercially available. Our purpose was to develop a simple method for the determination of rosiglitazone in plasma employing a commercially available internal standard (IS). After the addition of celecoxib (IS), plasma (0.25 mL) samples were extracted into ethyl acetate. The residue after evaporation of the organic layer was dissolved in 750 microL of mobile phase and 50 microL was injected on to HPLC. The separation was achieved using a Hichrom KR 100, 250 x 4.6 mm C(18) with a mobile phase composition potassium dihydrogen phosphate buffer (0.01 m, pH 6.5):acetonitrile:methanol (40:50:10, v/v/v). The flow-rate of the mobile phase was set at 1 mL/min. The column eluate was monitored by fluorescence detector set at an excitation wavelength of 247 nm and emission wavelength of 367 nm. Linear relationships (r(2) > 0.99) were observed between the peak area ratio rosiglitazone to IS vs rosiglitazone concentrations across the concentration range 5-1000 ng/mL. The intra-run precision (%RSD) and accuracy (%Dev) in the measurement of rosiglitazone were <+/-10.69 and <-12.35%, respectively across the QC levels (50-1000 ng/mL). The extraction efficiency was >80% for both rosiglitazone and IS from human plasma. The lower limit of quantitation of the assay was 5 ng/mL. In summary, the methodology for rosiglitazone measurement in plasma was simple, sensitive and employed a commercially available IS.     

Automated determination of verapamil and norverapamil in human plasma with on-line coupling of dialysis to high-performance liquid chromatography and fluorometric detection

A fully automated method for the simultaneous determination of verapamil and its main metabolite norverapamil in human plasma is described. This method is based on on-line sample preparation using dialysis followed by clean-up and enrichment of the dialysate on a precolumn and subsequent HPLC analysis with fluorometric detection. All sample handling operations were performed automatically by a sample processor equipped with a robotic arm (ASTED system). The plasma samples were dialysed on a cellulose acetate membrane (cut-off: 15 kD) and the dialysate was purified and enriched on a short pre-column filled with cyanopropyl silica. Before starting dialysis, this trace enrichment column (TEC) was first conditioned with the HPLC mobile phase and then with pH 3.0 acetate buffer. 370 μl of plasma sample spiked with the internal standard (gallopamil) were dialysed in the static-pulsed mode. The solution at the donor side was pH 3.0 acetate buffer containing Triton X-100 while the acceptor solution was made of the same acetate buffer. When dialysis was discontinued, the analytes were desorbed from the TEC by the HPLC mobile phase and transferred to the C₁₈ analytical column by means of a switching valve. This mobile phase consisted of a mixture of acetonitrile, pH 3.0 acetate buffer and 2-aminoheptane. The influence of different parameters of the dialysis process on the recovery of verapamil and norverapamil has been studied. The effect of the volume, the aspirating and dispensing flow-rates of the dialysis solution has been investigated. The recoveries of verapamil and norverapamil in plasma were close to 75% and the limits of quantification were 5 ng/ml for both analytes. The method was found to be linear in the concentration range from 5 to 500 ng/ml (r²: 0.9996 for both analytes). The intra-day and inter-day reproducibilities at a concentration of 100 ng/ml were 2.3% and 5.6% for verapamil and 1.7% and 5.1% for norverapamil, respectively.     

HPLC analysis and pharmacokinetic study of quercitrin and isoquercitrin in rat plasma after administration of Hypericum japonicum thunb. extract

A simple HPLC method was developed for determination of quercitrin and isoquercitrin in rat plasma. Reversed-phase HPLC was employed for the quantitative analysis using kaempferol-3-O-beta-D-glucopyranoside-7-O-alpha-L-rhamnoside as an internal standard. Following extraction from the plasma samples with ethyl acetate-isopropanol (95:5, v/v), these two compounds were successfully separated on a Luna C(18) column (250 x 4.6 mm, 5 microm) with isocratic elution of acetonitrile-0.5% aqueous acetic acid (17:83, v/v) as the mobile phase. The flow-rate was set at 1 mL/min and the eluent was detected at 350 nm for both quercitrin and isoquercitrin. The method was linear over the studied ranges of 50-6000 and 50-5000 ng/mL for quercitrin and isoquercitrin, respectively. The intra- and inter-day precisions of the analysis were better than 13.1 and 13.2%, respectively. The lower limits of quantitation for quercitrin and isoquercitrin in plasma were both of 50 ng/mL. The mean extraction recoveries were 73 and 61% for quercitrin and isoquercitrin, respectively. The validated method was successfully applied to pharmacokinetic studies of the two analytes in rat plasma after the oral administration of Hypericum japonicum thunb. ethanol extract.     

Quantitation of clobazam in human plasma using high-performance liquid chromatography.

A rapid and simple reversed-phase high-performance liquid chromatographic (HPLC) method for the determination of clobazam concentrations in human blood samples is developed and validated. Solid-phase column extraction is performed to clean up blood samples before running the analytical HPLC system. The chromatography is isocratic with a mobile phase consisting of acetonitrile (20%, v/v), methanol (23%, v/v), and 0.1 M potassium hydrogen phosphate buffer (pH 3.6; 57%, v/v) at a constant flow rate of 2 mL/min. Clobazam is detected at 226 nm. Chromatography is completed within less than 25 min. The recovery rate is greater than 95% and linear over a wide range of drug concentrations. The intra-assay coefficient of variation percentage varies between 4.3 and 12. This method is used for therapeutic drug monitoring in patients undergoing antiepileptic therapy with clobazam. Plasma levels of clobazam ranged from 21 to 663 ng/mL. Other antiepileptic compounds, such as clonazepam and phenobarbital, did not interfere with the detection of clobazam.     

A simple and sensitive assay for the quantitative analysis of paclitaxel and metabolites in human plasma using liquid chromatography/tandem mass spectrometry

A sensitive and specific LC-MS/MS assay for the determination of paclitaxel and its 3'p- and 6-alpha-hydroxy metabolites is presented. A 200 microL plasma aliquot was spiked with a 13C6-labeled paclitaxel internal standard and extracted with 1.0 mL tert-butylmethylether. Dried extracts were reconstituted in 0.1 M ammonium acetate-acetonitrile (1:1, v/v) and 25 microL volumes were injected onto the HPLC system. Separation was performed on a 150 x 2.1 mm C18 column using an alkaline eluent (10 mm ammonium hydroxide-methanol, 30:70, v/v). Detection was performed by positive ion electrospray followed by tandem mass spectrometry. The assay quantifies a range for paclitaxel from 0.25 to 1000 ng/mL and metabolites from 0.25 to 100 ng/mL using 200 microL human plasma samples. Validation results demonstrate that paclitaxel and metabolite concentrations can be accurately and precisely quantified in human plasma. This assay is now used to support clinical pharmacologic studies with paclitaxel.     

Determination of coenzyme Q10 in human seminal plasma by high-performance liquid chromatography and its clinical application

A high-performance liquid chromatographic (HPLC) method for the analysis of coenzyme Q10 (CoQ10) in human seminal plasma was developed and applied to investigate its clinical significance as a reference index relating to oxidative stress and infertile status of spermatozoa. After precipitation of proteins in seminal plasma with methanol, CoQ10 and coenzyme Q9 (CoQ9; internal standard) were extracted with hexane. The supernatant after centrifugation was evaporated to dryness with nitrogen at 45 degrees C. The residue was re-dissolved in isopropanol. HPLC separation of the sample solution was performed on a Lichrospher C(18) column with a mobile phase composed of isopropanol-methanol-tetrahydrofuran in the ratio of 55:39:6 (v/v/v) at a flow rate of 1.0 mL/min. Under the chromatographic conditions described, the CoQ10 and CoQ9 had retention times of approximately 5.83 and 4.97 min, respectively. The peaks were detected at UV 275 nm. Good separation and detectability of CoQ10 in human seminal plasma were obtained. The method was linear in the range 0.01-10.00 microg/mL. The relative standard deviations within- and between-assay for CoQ10 analysis were 0.85 and 1.86%, respectively. The average recoveries were 94.1-99.0% for the human seminal plasma samples. The CoQ10 levels in seminal plasma of 195 patients and 23 control subjects were studied. CoQ10 concentrations in the two populations were: 37.1 +/- 12.2 ng/mL in the fertile group and 48.5 +/- 20.4 ng/mL in the infertile group. The large difference (p < 0.01) between the fertile and infertile populations is evident.     

Pharmacokinetic and tissue distribution of paclitaxel in rabbits assayed by LC‐UV after intravenous administration of its novel liposomal formulation

A simple, rapid and sensitive LC‐UV method was developed and validated for the determination of paclitaxel (PTX) in rabbit plasma and tissues. A 2 mL aliquot of acetonitrile and 10 μL ammonium acetate (pH 5.0, 6 m ) as extraction agents were used to markedly increase the extraction recoveries and greatly reduce the endogenous substances. The separation was achieved on a C₁₈ column at 30 °C using an acetonitrile–ammonium acetate buffer (pH 5.0, 0.02 m ; 55:45, v/v) at a flow rate of 1.0 mL/min; UV detection was used at 227 nm. Good linearity was obtained between 0.025 and 10,000 µg/mL for plasma and between 0.025–200,000 µg/g for tissue samples (r > 0.999). The limit of detection was 6 ng/mL in plasma, 8 ng/g in heart and 12.5 ng/g in other tissues. The limit of quantitation was 25 ng/mL in plasma and heart, 125 ng/g in other tissues. The intra‐ and inter‐day assays of precision and accuracy for all bio‐samples ranged from 1.38 to 9.60% and from 83.6 to 114.5%, respectively. The extraction recoveries ranged from 70.1 to 109.5%. Samples were stable during three freeze–thaw cycles or stored in a freezer at ?20 °C for 30 days. The assay method was successfully applied to a study of the pharmacokinetics and tissue distribution of novel PTX lung targeting liposomes. Copyright © 2013 John Wiley & Sons, Ltd.     

Highly sensitive determination and validation of gabapentin in pharmaceutical preparations by HPLC with 4-fluoro-7-nitrobenzofurazan derivatization and fluorescence detection

A sensitive HPLC method with pre-column fluorescence derivatization using 4-Fluoro-7-Nitrobenzofurazan (NBD-F) has been developed for the determination of gabapentin in pharmaceutical preparations. The method is based on the derivatization of gabapentin with (NBD-F) in borate buffer of pH 9.5 to yield a yellow, fluorescent product. The HPLC separation was achieved on a Inertsil C(18) column (250 mm × 4.6 mm) using a mobile phase of methanol water (80:20, v/v) solvent system at 1.2 mL/min flow rate. Mexiletine was used as the internal standard. The fluorometric detector was operated at 458 nm (excitation) and 521 nm (emission). The assay was linear over the concentration range of 5 50 ng/mL. The method was validated for specificity, linearity, limit of detection, limit of quantification, precision, accuracy, robustness. Moreover, the method was found to be sensitive with a low limit of detection (0.85 ng/mL) and limit of quantitation (2.55 ng/mL). The results of the developed procedure for gabapentin content in capsules were compared with those by the official method (USP 32). Statistical analysis by t- and F-tests, showed no significant difference at 95 confidence level between the two proposed methods.     

Development of a method for the determination of danofloxacin in plasma by HPLC with fluorescence detection

A simple and sensitive HPLC method has been developed for the determination of danofloxacin (DAN) in plasma. Sample preparations were carried out by adding phosphate buffer (pH 7.4, 0.1 M), followed by extraction with trichloromethane. DAN and the internal standard, sarafloxacin (SAR), were separated on a reversed-phase column, and eluted with aqueous solution-acetonitrile (80:20 v/v). The fluorescence of the column effluent was monitored at lambda(ex) = 338 and lambda(em) = 425 nm. The retention times were 2.80 and 4. 40 min for DAN and SAR, respectively. The method was shown to be linear from 1 to 1500 ng/mL (r(2) = 0.999). The detection and quantitation limit were 1 and 5 ng/mL, respectively. Mean recovery was determined as 80% by the analysis of plasma standards containing 150, 750 and 1500 ng/mL. Inter- and intra-assay precisions were 4.0% and 2.4%, respectively.     

Determination of memantine in plasma and vitreous humour by HPLC with precolumn derivatization and fluorescence detection

A new HPLC procedure with precolumn derivatization and rimantadine as the internal standard for determining memantine, a candidate agent for the treatment of glaucoma in plasma and vitreous humour, has been developed and validated. Precolumn derivatization was performed with 9-fluorenylmethyl-chloroformate-chloride (FMOC-Cl) as the derivatization reagent and followed by a liquid-liquid extraction with n-hexane. Optimal conditions for derivatization were an FMOC-Cl concentration of 1.5 mM, a reaction time of 20 min, the temperature at 30°C, the borate buffer pH 8.5, and a borate buffer-acetonitrile ratio of 1:1. The derivatives were analyzed by isocratic HPLC with the fluorescence detector λex 260 nm λem 315 nm on a Novapack C(18) reversed-phase column with a mobile phase of acetonitrile-water (73:27, v/v), 40°C, and a flow rate of 1.2 mL/min. The linear range was 10-1000 ng/mL with a quantification limit of ～ 10 ng/mL for both types of samples. This analytical method may be suitable for using in ocular availability studies.     

Development and validation of HPLC method for imiquimod determination in skin penetration studies

A simple, rapid and sensitive analytical procedure for the measurement of imiquimod in skin samples after in vitro penetration studies has been developed and validated. In vitro penetration studies were carried out in Franz diffusion cells with porcine skin. Tape stripping technique was used to separate the stratum corneum (SC) from the viable epidermis and dermis. Imiquimod was extracted from skin samples using a 7:3 (v/v) methanol:acetate buffer (100 mM, pH 4.0) solution and ultrasonication. Imiquimod was analyzed by HPLC using C(8) column and UV detection at 242 nm. The mobile phase used was acetonitrile:acetate buffer (pH 4.0, 100 mM):diethylamine (30:69.85:0.15, v/v) with flow rate 1 mL/min. Imiquimod eluted at 4.1 min and the running time was limited to 6.0 min. The procedure was linear across the following concentration ranges: 100-2500 ng/mL for both SC and tape-stripped skin and 20-800 ng/mL for receptor solution. Intra-day and inter-day accuracy and precision values were lower than 20% at the limit of quantitation. The recovery values ranged from 80 to 100%. The method is adequate to assay imiquimod from skin samples, enabling the determination of the cutaneous penetration profile of imiquimod by in vitro studies.     

Determination of the enantiomeric purity of amphetamine after derivatization with Sanger’s reagent (2,4-dinitrofluorobenzene [DNFB]) by simultaneous dual circular dichroism and ultraviolet spectroscopy

Determination of Se in biological materials was attempted by microwave-induced plasma mass spectrometry (MIP-MS). (1) Serum samples were available after 10 times dilution with 0.5% nitric acid solution containing 0.1% Triton X-100. When oxygen gas was inserted into the plasma gas (nitrogen) in order to improve the combustion, the sensitivity was reduced to 45%. The detection limit of this method was 0.5 ng/mL. (2) Standard reference materials on commercial base were used to evaluate the accuracy of the Se determination by MIP-MS after microwave digestion. In samples like bovine liver and human hair with Se concentrations of more than 0.7 μg/g, the standard curve method after internal standard (IS) correction was acceptable. This procedure was unsuitable for samples with low Se concentrations such as milk powder (certified value of Se 0.11 μg/g), or plant leaf samples. (3) Instead of IS correction, the peak height of the spectrum was used for calculations from the matrix matched calibration curve. The results of all materials were close to the certified values, even at 25 ng/g. The detection limit of the MIP-MS with microwave digestion and IS correction was 0.05 ng/mL in standard solutions. The detection limit of the peak height method was 0.1 ng/mL and was estimated to be < 20 ng/g in plant materials.