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1.
A multiresidue method has been developed for the simultaneous determination of sulfadiazine, sulfathiazole, sulfapyridine,
sulfamerazine, sulfamethoxydiazine, sulfamethylthiazole, sulfamethazine, sulfamonomethoxine, sulfamethoxypyridazine, sulfisoxazole,
sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline in natural animal casings by HPLC after solid-phase extraction. The
sulfonamides were extracted with acetonitrile and the extract cleaned up with an Oasis MCX SPE cartridge prior to analysis.
Separation was on a ZOBAX Eclipse XDB-C8 column using gradient elution with acetonitrile/methanol/0.1% acetic acid. The effect of separation conditions on chromatographic
behavior and recovery has been studied. Calibration graphs were linear with very good correlation coefficients (r = 0.9983−0.9996) in the concentration range from 0.02 to 1 μg mL−1. The limits of quantitation (LOQ) for the 13 sulfonamides were in the range of 1.5–2.2 μg kg−1. Decision limits (CCα) and detection capabilities (CCβ) were in the range of 105.2–111.0 and 113.0–120.2 μg kg−1, respectively. The recovery for casings spiked with 1.5–100 μg kg−1 ranged from 65.2 to 85.9%. The relative standard deviations (RSDs) of the sulfonamides for six measurements at 100 μg kg−1 were from 2.2 to 7.7%. The applicability of the method to the analysis of salted swine casings, salted sheep casings and
dry casing samples was demonstrated. 相似文献
2.
Fumonisins B1 (FB1) and fumonisin B2 (FB2) are the main members of a family of mycotoxins produced by Fusarium verticillioides, Fusarium proliferatum, and other fungi species of the section Liseola. The present work shows the results of comparative studies using two different procedures for the analysis of fumonisins
in maize and maize-based samples. The studied analytical methods involve extraction with methanol/water, dilution with PBS,
and clean-up through immunoaffinity columns. Two reagents (o-phthaldialdehyde and naphthalene-2,3-dicarboxaldehyde) were studied for formation of fluorescent derivatives. The separation
and identification were carried out by high-performance liquid chromatography with fluorescence detection. The optimized method
for analysis of fumonisins in maize involved extraction with methanol/water (80:20), clean-up with an immunoaffinity column,
and derivatization with naphthalene-2,3-dicarboxaldehyde (NDA). The limit of detection was 20 μg kg−1 for FB1 and 15 μg kg−1 for FB2. Recoveries of FB1 and FB2 ranged from 79% to 99.6% for maize fortified at 150 μg kg−1 and 200 μg kg−1, respectively, with within-day RSDs of 3.0 and 2.7%. The proposed method was applied to 31 samples, and the presence of fumonisins
was found in 14 samples at concentrations ranging from 113 to 2,026 μg kg−1. The estimated daily intake of fumonisins was 0.14 μg kg−1 body weight per day. 相似文献
3.
Summary A high-performance liquid chromatographic method, with 9-anthryldiazomethane as derivatizing agent, has been developed for
the simultaneous determination ofN-carbamoyl aspartate andl-dihydroorotate in serum. Sample preparation for 1 mL serum was by simple liquid-liquid extraction and then derivatization.
The compounds were separated on a Luna C18(2) column by use of a gradient prepared from acetonitrile and 10 mM sodium acetate
buffer, pH 6.0, and fluorimetric detection was performed at excitation and emission wavelengths of 365 nm and 412 nm, respectively.
The response was found to be linearly dependent on concentration between 0.8 and 60 μg mL−1 forl-dihydrooratate and between 0.9 and 90 μg mL−1 forN-carbamoyl aspartate; the mean recovery rates were 50 and 51%, respectively. The limits of detection and quantification were
0.33 μg mL−1 and 0.6 μg mL−1, respectively, forl-dihydroorotate and 0.4 μg mL−1 and 0.7 μg mL−1 forN-carbamoyl aspartate. This method can be used to assess accumulation ofN-carbamoyl aspartate andl-dihydroorotate in body fluids in situations where cellular pyrimidine de novo synthesis is impaired. 相似文献
4.
Koryagina NL Savelieva EI Khlebnikova NS Goncharov NV Jenkins RO Radilov AS 《Analytical and bioanalytical chemistry》2006,386(5):1395-1400
A novel procedure has been developed for determination of fluoroacetic acid (FAA) in water and biological samples. It involves
ethylation of FAA with ethanol in the presence of sulfuric acid, solid-phase microextraction of the ethyl fluoroacetate formed,
and subsequent analysis by GC-FID or by GC-MS in selected-ion-monitoring mode. The detection limits for FAA in water, blood
plasma, and organ homogenates are 0.001 μg mL−1, 0.01 μg mL−1, and 0.01 μg g−1, respectively. The determination error at concentrations close to the detection limit was less than 50%. For analysis of
biological samples, the approach has the advantages of overcoming the matrix effect and protecting the GC and GC-MS systems
from contamination. Application of the approach to determination of FAA in blood plasma and organ tissues of animals poisoned
with sodium fluoroacetate reveals substantial differences between the dynamics of FAA accumulation and clearance in rabbits
and rats. 相似文献
5.
A fully automated method using direct immersion solid-phase microextraction (DI-SPME) and headspace on-fiber silylation for
simultaneous determinations of exogenous endocrine-disrupting chemicals (EDCs) and endogenous steroid hormones in environmental
aqueous and biological samples by gas chromatography–mass spectrometry (GC-MS) was developed and compared to a previously
reported manual method. Three EDCs and five endocrine steroid hormones were selected to evaluate this method. The extraction
and derivatization time, ion strength, pH, incubation temperature, sample volume, and extraction solvent were optimized. Satisfactory
results in pure water were obtained in terms of linearity of calibration curve (R
2=0.9932–1.0000), dynamic range (3 orders of magnitude), precision (4–9% RSD), as well as LOD (0.001–0.124 μg L−1) and LOQ (0.004–0.413 μg L−1), respectively. These results were similar to those obtained using a manual method, and moreover, the precision was improved.
This new automated method has been applied to the determinations of target compounds in real samples used in our previous
study on a manual SPME method. Exogenous octylphenol (OP), technical grade nonylphenol (t-NP), and diethylstilbestrol (DES) were at 0.13, 5.03, and 0.02 μg L−1 in river water and 3.76, 13.25, and 0.10 μg L−1 in fish serum, respectively. Natural steroid hormones estrone (E1), 17β-estradiol (E2), and testosterone (T) were at 0.19, 0.11, and 6.22 μg L−1 in river water; and in female fish serum E1, E2, and pregnenolone (PREG) were at 1.37, 1.95, and 6.25 μg L−1, respectively. These results were confirmed by the manual method. The developed fully automated SPME and on-fiber silylation
procedures showed satisfactory applications in environmental analysis and the performances show improved precision and a reduced
analysis time compared to the manual method. 相似文献
6.
A high-performance liquid chromatography–UV method for determining DCJW concentration in rat plasma was developed. The method
described was applied to a pharmacokinetics study of intramuscular injection in rats. The plasma samples were deproteinized
with acetonitrile in a one-step extraction. The HPLC assay was carried out using a VP-ODS column and the mobile phase consisting
of acetonitrile–water (80:20, v/v) was used at a flow rate of 1.0 mL min−1 for the effective eluting DCJW. The detection of the analyte peak area was achieved by setting a UV detector at 314 nm with
no interfering plasma peak. The method was fully validated with the following validation parameters: linearity range 0.06–10 μg mL−1 (r > 0.999); absolute recoveries of DCJW were 97.44–103.46% from rat plasma; limit of quantification, 0.06 μg mL−1 and limit of detection, 0.02 μg mL−1. The method was further used to determine the concentration–time profiles of DCJW in the rat plasma following intramuscular
injection of DCJW solution at a dose of 1.2 mg kg−1. Maximum plasma concentration (C
max) and area under the plasma concentration–time curve (AUC) for DCJW were 140.20 ng mL−1 and 2405.28 ng h mL−1. 相似文献
7.
Summary Two procedures, based on large-volume injection with a programmed-temperature vaporizer (PTV), have been developed for the
determination of several triazine and organophosphorus pesticides. The use of PTV for injection in gas chromatography (GC)
has enabled the introduction of up to 200 μL sample extract into the GC, thus increasing the sensitivity of the method. PTV
injection has been combined off-line with two different microextraction procedures—liquid-liquid partition and solid-phase
extraction.
A simple and rapid off-line liquid-liquid microextraction procedure (5 mL water/1 mL methyltert-butyl ether) was applied to surface water samples spiked at levels between 0.01 and 5μg L−1. Recoveries of the overall procedure were >80% and the precision was better than 15%. Detection limits were <30 ngL−1 from 200-μL injections in GC-NPD analysis of triazines and GC-FPD analysis of organophosphorus pesticides. Off-line automated
solid-phase extraction with C18 cartridges has been applied to water samples (50 mL) spiked at 0.01, 0.1 and 1 μg L−1. The overall procedure was satisfactory (recoveries >80% and coefficients of variation <12%) and the limits of detection
ranged from 1 to 9 ng L−1.
Finally, several surface water samples were anlysed, and triazine herbicides were detected at concentrations of approx. 0.1–0.2
μg L−1. The results were similar to those obtained by conventional solvent extraction then GC-MSD after splitless injection of 2
μL. 相似文献
8.
Capitán-Vallvey LF Valencia MC Arana Nicolás E García-Jiménez JF 《Analytical and bioanalytical chemistry》2006,385(2):385-391
An integrated solid-phase spectrophotometry–FIA method is proposed for simultaneous determination of the mixture of saccharin
(1,2-benzisothiazol-3(2H)-one-1,1-dioxide; E-954) (SA) and aspartame (N-l-α-aspartyl-l-phenylalanine-1-methyl ester; E-951) (AS). The procedure is based on on-line preconcentration of AS on a C18 silica gel minicolumn and separation from SA, followed by measurement, at λ=210 nm, of the absorbance of SA which is transiently retained on the adsorbent Sephadex G-25 placed in the flow-through cell
of a monochannel FIA setup using pH 3.0 orthophosphoric acid–dihydrogen phosphate buffer, 3.75×10–3 mol L−1, as carrier. Subsequent desorption of AS with methanol enables its determination at λ=205 nm. With a sampling frequency of 10 h−1, the applicable concentration range, the detection limit, and the relative standard deviation were from 1.0 to 200.0 μg mL−1, 0.30 μg mL−1, and 1.0% (80 μg mL−1, n=10), respectively, for SA and from 10.0 to 200.0 μg mL−1, 1.4 μg mL−1, and 1.6% (100 μg mL−1, n=10) for AS. The method was used to determine the amounts of aspartame and saccharin in sweets and drinks. Recovery was always
between 99 and 101%. The method enabled satisfactory determination of blends of SA and AS in low-calorie and dietary products
and the results were compared with those from an HPLC reference method. 相似文献
9.
Popp M Hann S Mentler A Fuerhacker M Stingeder G Koellensperger G 《Analytical and bioanalytical chemistry》2008,391(2):695-699
A novel method employing high-performance cation chromatography in combination with inductively coupled plasma dynamic reaction
cell mass spectrometry (ICP–DRC–MS) for the simultaneous determination of the herbicide glyphosate (N-phosphonomethylglycine) and its main metabolite aminomethyl phosphonic acid (AMPA) is presented. P was measured as 31P16O+ using oxygen as reaction gas. For monitoring the stringent target value of 0.1 μg L−1 for glyphosate, applicable for drinking and surface water within the EU, a two-step enrichment procedure employing Chelex
100 and AG1-X8 resins was applied prior to HPIC–ICP–MS analysis. The presented approach was validated for surface water, revealing
concentrations of 0.67 μg L−1 glyphosate and 2.8 μg L−1 AMPA in selected Austrian river water samples. Moreover, investigations at three waste water-treatment plants showed that
elimination of the compounds at the present concentration levels was not straightforward. On the contrary, all investigated
plant effluents showed significant amounts of both compounds. Concentration levels ranged from 0.5–2 μg L−1 and 4–14 μg L−1 for glyphosate and AMPA, respectively. 相似文献
10.
A new high-performance liquid chromatography assay was developed for the determination of minocycline in plasma and brain.
A solid–liquid extraction procedure was coupled with a reversed-phase HPLC system. The system requires a mobile phase consisting
of acetonitrile:water:perchloric acid (26:74:0.25, v/v/v) adjusted to pH 2.5 with 5 M sodium hydroxide for elution through a RP8 column (250 × 3.0 mm, i.d.) with UV detection set
at 350 nm. The method proved to be accurate, precise (RSD < 20%) and linear between 0.15–20 μg mL−1 in plasma and 1–20 μg mg−1 in brain. The method was successfully applied to a blood-brain barrier minocycline transport study. 相似文献
11.
Simultaneous determination of six major ergot alkaloids and their epimers in cereals and foodstuffs by LC–MS–MS 总被引:1,自引:0,他引:1
This paper describes a new and rapid method for accurate quantification of the six ergot alkaloids, ergometrine, ergotamine,
ergosine, ergocristine, ergocryptine, and ergocornine, by liquid chromatography–tandem mass spectrometry (LC–MS–MS). The six
ergot alkaloids studied have been defined by the European Food Safety Authority (EFSA) as among the most common and physiologically
active ones. In addition, the method enables the quantification of the corresponding six epimers (ergo-inines) of these ergot alkaloids. This is of considerable importance in terms of the differences in toxicity of the isomeric forms.
The method involves extraction under alkaline conditions using a mixture of acetonitrile and ammonium carbonate buffer followed
by a rapid clean-up using dispersive solid-phase extraction with PSA (primary secondary amine) and a short chromatographic
LC-run (21 min) with subsequent MS–MS detection. The method was developed and validated using ten different cereal and food
samples. The major strength of the new method compared with previously published techniques is the simplicity of the clean-up
procedure and the short analysis time. The limits of quantification were 0.17 to 2.78 μg kg−1 depending on the analyte and matrix. Recovery values for the 12 ergot alkaloids spiked into ten different matrices at levels
of 5, 50, and 100 μg kg−1 were between 69 and 105% for 85 of 90 recovery measurements made over six days. Measurement uncertainty values were highly
satisfactory. At a concentration level of 5 μg kg−1 the expanded measurement uncertainty ranged from ±0.56 to ±1.49 μg kg−1, at a concentration level of 100 μg kg−1 the expanded measurement uncertainty ranged from ±8.9 to ±20 μg kg−1. Both LOQs and measurement uncertainties were dependent on the analyte but almost independent of the matrix. The method performance
was satisfactory when tested in a mini-intercomparison study between three laboratories from three different countries.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO2) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic
diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol)
(TX). Under static conditions phenol was quantitatively extracted onto TX-SiO2 in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO2 for phenol is 2.4 mg g−1 with distribution coefficients up to 3.4 × 104 mL g−1; corresponding data for 1-naphthol are 1.5 mg g−1 and 3 × 103 mL g−1. The distribution coefficient does not change significantly for solution volumes of 0.025–0.5 L and adsorbent mass less than
0.03 g; 1–90 μg analyte can be easily eluted by 1–3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol
and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A
540) and phenol concentration (C) in water was found according to the equation A
540 = (6 ± 1) × 10−2 + (0.9 ± 0.1)C (μmol L−1) with a detection range from 1 × 10−8 mol L−1 (0.9 μL g−1) to 2 × 10−7 mol L−1 (19 μL g−1), a limit of quantification of 1 μL g−1 (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric
method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical
analysis. The detection limit of 1-naphthol with this method is 6 μL g−1 while the quantification limit is 20 μL g−1. A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one
to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08–3.2 mL g−1. 相似文献
13.
Kiran R. Patil Vipul P. Rane Jaiprakash N. Sangshetti Devanand B. Shinde 《Chromatographia》2008,67(7-8):575-582
A simple, rapid, and precise method is developed for the quantitative simultaneous estimation of telmisartan and ramipril
in combined pharmaceutical dosage form. A chromatographic separation of the two drugs was achieved with an ACE 5 C18, 25-cm analytical column using buffer–acetonitrile (55:45 v/v). The buffer used in mobile phase contains 0.1 M sodium perchlorate monohydrate in double distilled water pH adjusted 3.0
with trifluoroacetic acid. The instrumental settings are flow rate of 1.5 mL min−1, column temperature at 30 °C, and detector wavelength of 215 nm using a photodiode array detector. The resolution between
ramipril and telmisartan were found to be more than 5. Theoretical plates for ramipril and telmisartan were 13,022 and 6,629.
Tailing factor for ramipril and telmisartan was 0.94 and 0.98. Telmisartan, ramipril and their combination drug product were
exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the stressed samples were analysed by the
proposed method. Peak homogeneity data of telmisartan and ramipril is obtained using photodiode array detector, in the stressed
sample chromatograms, demonstrated the specificity of the method for their estimation in presence of degradants. The described
method shows excellent linearity over a range of 20–400 μg mL−1 for telmisartan and 2.5–50 μg mL−1 for ramipril. The correlation coefficient for telmisartan and ramipril are 1. The relative standard deviation for six measurements
in two sets of each drug in tablets was always less than 2%. The proposed method was found to be suitable and accurate for
quantitative determination and the stability study of telmisartan and ramipril in pharmaceutical preparations. 相似文献
14.
A. M. Qandil B. M. Tashtoush B. M. Al-Taani S. M. Al-Nabulsi F. Al-Zogoul 《Chromatographia》2008,67(3-4):287-291
A simple, rapid and selective RP-HPLC method was developed and validated for the determination of ketorolac and five piperazinylalkyl
ester prodrugs. A binary isocratic mobile phase composed of a mixture of 65:35 (v/v) 0.02 M phosphate buffer (pH 5.4) and acetonitrile was used on a C18 column (125 × 4 mm, 5 μm). The injection volume was 25 μL and the detection wavelength was 314 nm and the flow rate was 1.5 mL min−1. The method exhibited excellent linearity with R
2 of no less than 0.999 and intra-assay and inter-assay precision that were less than the maximum amount allowed according
to Horwitz equation. The accuracy was found to be within the allowed ±15%. The limits of detection for the analytes were between
0.060 and 0.220 μg mL−1 and the limits of quantification were between 0.183 and 0.667 μg mL−1. This method was used successfully for the study of the solubility, stability and partition coefficients of piperazinylalkyl
ester prodrugs of ketorolac. 相似文献
15.
A rapid and inexpensive method for simultaneous quantification of terbumeton (TER), and its major potential metabolites (TED;
terbumeton-desethyl, TOH; terbumeton-2-hydroxy and TID; terbumeton-deisopropyl) in soil bulk water (SBW) samples is proposed.
The analytical method involves extraction–concentration from SBW samples using a graphitized carbon black (GCB) cartridge
followed by their separation–detection by reversed-phase high-performance liquid chromatography analysis using a C18 column and a diode array detector. A mobile phase of acetonitrile−0.005 mol L−1 phosphate buffer (pH 7.0) (35:65, v/v) at a flow rate of 0.8 mL min−1 in isocratic elution mode has been used. After optimization of the extraction and separation conditions, this method can be
used for the simultaneous determination of investigated compounds in the range of the international limits of 0.1 μg L−1. For TER the detection limit was 0.009 μg L−1 and it was 0.100, 0.550, and 0.480 μg L−1 for TED, TOH, and TID, respectively. The recoveries of TER, TED, TOH, and TID from SBW samples, measured at three levels of
concentration range, were found to be between 48.0 and 102.0%. The intra-day precision measured by relative standard deviation
(RSD) was always lower than 9.0%. 相似文献
16.
Continuous disposal of endocrine-disrupting compounds (EDCs) into the environment can lead to serious human health problems
and can affect plants and aquatic organisms. The determination of EDCs in water has become an increasingly important activity
due to our increased knowledge about their toxicities, even at low concentration. The EDCs in water samples from the reclaimed
water plant of Tianjin, northern China, were identified by gas chromatography (GC)–mass spectrometry (MS). Important and contrasting
EDCs including estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), 4-tert-octylphenol (OP), 4-nonylphenol (NP),
bisphenol A (BPA), di-n-butyl phthalate (DnBP), diisobutyl phthalate (DIBP), and di(2-ethylhexyl)phthalate (DEHP) were selected as the target compounds.
Concentrations of steroid hormones, alkylphenolic compounds and phthalates ranged from below the limit of detection (LOD)
to 8.1 ng L−1, from <LOD to 14.2 ng L−1, and from 1.00 μg L−1 to 23.8 μg L−1, respectively. The average removal efficiencies for target EDCs varied from 30% to 82%. These results indicate that environmental
endocrine disrupting compounds are not completely removed during reclaimed water treatment and may be carried over into the
general aquatic environment. 相似文献
17.
Tribalat L Paisse O Dessalces G Grenier-Loustalot MF 《Analytical and bioanalytical chemistry》2006,386(7-8):2161-2168
In the framework of developing analyses for exogenous contaminants in food matrices such as honey, we have compared data obtained
by high-performance liquid chromatography coupled with mass spectrometry (LC–MS) to those provided by high-performance liquid
chromatography and tandem mass spectrometry (LC–MS–MS). Initial results obtained with LC–MS showed that the technique lacked
selectivity, which is why the method was validated by LC–MS–MS. This method involves a solid-phase extraction (SPE) of nitrofuran
metabolites and nitrofuran parent drugs, a derivatization by 2-nitrobenzaldehyde for 17 h, and finally a clean-up by SPE.
The data obtained show that the limits of detection varied between 0.2 and 0.6 μg kg−1 for the metabolites and between 1 and 2 μg kg−1 for nitrofuran parent drugs. The method was applied to different flower honeys. The results showed that nitrofurans (used
as antibiotics) are consistently present in this matrix, the predominant compound being furazolidone.
Figure Working bees 相似文献
18.
Jorge L. Guzmán Mar Leticia López Martínez Pedro L. López de Alba Nancy Ornelas Soto Víctor Cerdà Martín 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):433-439
A multisyringe flow injection analysis method for the determination of uranium in water samples was developed. The methodology
was based on the complexation reaction of uranium with arsenazo (III) at pH 2.0. Uranium concentrations were spectrophotometrically
detected at 649 nm using a light emitting diode. Under the optimized conditions, a linear dynamic range from 0.1 to 4.0 μg mL−1, a 3σ detection limit of 0.04 μg mL−1, and a 10σ quantification limit of 0.10 μg mL−1 were obtained. The reproducibility (%) at 0.5, 2.5, and 4.0 μg mL−1 was 2.5, 0.9, and 0.6%, respectively (n = 10). The interference effect of some ions was tested. The proposed method was successfully applied to the determination
of uranium in water samples. 相似文献
19.
Guanidinoacetate methyltransferase deficiency is a recently discovered inborn defect of creatine biosynthesis which reduces
serum creatinine concentrations to as low as 0.58 μg mL−1 (or 0.00058 μg mL−1 after 1,000-fold dilution). To measure ultra trace levels of creatinine in diluted samples, molecularly imprinted solid-phase
extraction (MISPE) and molecularly imprinted polymer (MIP) sensor techniques have been found to be inadequate. A combination
of these techniques (i.e. MISPE hyphenated with use of an MIP-sensor), reported in this paper, has been found to be highly
suitable for direct assay of creatinine in highly diluted human blood serum without complicated pretreatment of the sample.
The proposed technique has the potential to enhance the sensitivity of creatinine measurement from μg mL−1 to ng mL−1 in highly dilute aqueous samples in which the concentrations of interfering constituents are reduced to negligible levels.
In this work the sensitivity to creatinine was found to be improved compared with that of the MIP-sensor method alone (limit
of detection, LOD, 0.00149 μg mL−1). After preconcentration by MISPE and use of the sensor the detection limit for creatinine was as low as 0.00003 μg mL−1 (RSD = 0.94%, S/N = 3; 50-fold preconcentration factor) in aqueous samples. 相似文献
20.
A simple, rapid, and precise reversed-phase high-performance liquid chromatographic method has been developed for simultaneous determination of losartan potassium, ramipril, and hydrochlorothiazide. The three drugs were separated on a 150 mm × 4.6 mm i.d., 5 μm particle, Cosmosil C18 column. The mobile phase was 0.025 m sodium perchlorate–acetonitrile, 62:38 (v/v), containing 0.1% heptanesulphonic acid, pH adjusted to 2.85 with orthophosphoric acid, at a flow rate of 1.0 mL min−1. UV detection was performed at 215 nm. The method was validated for linearity, accuracy, precision, and limit of quantitation. Linearity, accuracy, and precision were acceptable in the ranges 35–65 μg mL−1 for losartan, 1.75–3.25 μg mL−1 for ramipril, and 8.75–16.25 μg mL−1 for hydrochlorothiazide. 相似文献