Journal of Chromatography B (v.860, #1)

A simple and sensitive high-performance liquid chromatographic method was developed for the simultaneous determination of dihydromyricetin (1) and myricetin (2) in rat plasma after orally administrating the decoction of Ampelopsis grossedentata. Plasma samples were acidified with 0.375% phosphoric acid and extracted with ethyl acetate. Analysis of the extract was performed on reversed-phase C18 column with a gradient eluent composed of acetonitrile and 0.04% phosphoric acid. The flow rate was kept at 1 ml/min and the detection wavelength was set at 290 and 370 nm for 1 and 2, respectively. The calibration curves were linear in the range of 0.247–4.114 μg/ml and 0.150–2.501 μg/ml for 1 and 2, respectively. The intra-day and inter-day precisions were better than 4.9 and 6.2%, respectively. The limits of detection (LOD) for 1 and 2 in plasma were 21.600 and 52.530 ng/ml, and the limits of quantification (LOQ) were 0.247 and 0.150 μg/ml, respectively. The mean recoveries for 1 and 2 were 92.0 and 93.3%, respectively. The accuracy and precision were well within the acceptable range and R.S.D. of measured rat samples was less than 7.5%. This validated method has been successfully applied in the pharmacokinetics study of dihydromyricetin and myricetin in vivo after orally administrating the decoction of A. grossedentata to rats.
Keywords: Ampelopsis grossedentata; Pharmacokinetics; HPLC-DAD; Dihydromyricetin; Myricetin;

A simple, sensitive, and specific high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method for the analysis of the bile acid profile has been developed. Fifteen bile acids, including free and conjugated bile acids, were separated and detected by HPLC–MS/MS. The MS detection was performed by electrospray ionization (ESI) in negative ion mode. Quantification was achieved in multiple reaction monitoring (MRM) mode with external standard curve methods. Total analysis time was 15 min for one sample including re-equilibration time of the column. The assay was linear in the range 0.02–100.0 μmol/L with correlation coefficients of standard curves for all bile acids better than 0.999. The detection limits ranged from 0.001 to 0.006 μmol/L for different bile acids. The precisions for each bile acid were CVs < 3.8% for within-day and CVs < 6.1% for between-day. The average recoveries for all bile acids studied were in the range of 86–110.0%. The developed method was applied to the analysis of clinic samples consisting of 53 women with healthy pregnancies and 43 women with intrahepatic cholestasis of pregnancy (ICP). The results revealed that the bile acid profile was markedly different between women with ICP and women with healthy pregnancies.
Keywords: Bile acid profile; HPLC–MS/MS; Serum; External standard calibration;

A sensitive and selective ion-pair liquid chromatography–tandem mass spectrometric method (IP-LC–MS/MS) for the simultaneous determination of amodiaquine (AQ) and its active metabolite, N-desethylamodiaquine (AQm), in human blood has been developed and validated. Pentafluoropropionic acid (PFPA) was applied as ion-pairing reagent in reversed-phase chromatographic separation. The effects of PFPA concentrations and the volume fraction of acetonitrile in the mobile phase on the retention of analytes were investigated on a Venusil MP-C18 column, and the mobile phase was finally optimized as acetonitrile:water (23:77, v/v) with 0.0667% PFPA in the aqueous phase. The results proved that PFPA as an ion-pairing reagent could provide desirable chromatographic performance in the IP-LC–MS/MS determination of 4-aminoquinoline compounds. Blood samples were protein precipitated with acetonitrile using hydroxychloroquine (OHCQ) as the internal standard. The detection was carried out in multiple reaction monitoring (MRM) mode via positive atmospheric pressure chemical ionization (APCI) interface. The lower limits of quantification were established at 0.150 and 1.50 ng/mL for AQ and AQm, respectively. The validated IP-LC–MS/MS method was applied to a clinical pharmacokinetic study of AQ and AQm in human blood after an oral administration of 600 mg AQ hydrochloride (459 mg base).
Keywords: Amodiaquine; N-desethylamodiaquine; Pentafluoropropionic acid; Ion-pair liquid chromatography–tandem mass spectrometry; Pharmacokinetics;

Analytical method validation for the evaluation of cutaneous occupational exposure to different chemical classes of pesticides by Angela Simonelli; Pascale Basilicata; Nadia Miraglia; Loredana Castiglia; Rossella Guadagni; Antonio Acampora; Nicola Sannolo (26-33).
In occupational exposure to pesticides, validated methodologies are available only in regards to homogeneous chemical classes of substances and the inhaling exposure, neglecting the cutaneous one that, especially in agriculture, represents an important route of absorption. An analytical methodology for the simultaneous quantification of different chemical classes of pesticides by using pads as environmental matrix and GC–MS/SIM as detection method was developed and validated. The extraction step of analytes from pads was optimized by comparing analytes recovery percentages obtained with different extraction solvents. High recoveries were obtained with ether and, above all, with acetonitrile. Validation experiments following the Food and Drug Administration Guidelines were carried out.
Keywords: Cutaneous exposure; Analytical method validation; Pesticides; Pads; Selected ion monitoring;

Validation of a sensitive LC–MS assay for quantification of glyburide and its metabolite 4-transhydroxy glyburide in plasma and urine: An OPRU Network study by Suresh Babu Naraharisetti; Brian J. Kirby; Mary F. Hebert; Thomas R. Easterling; Jashvant D. Unadkat (34-41).
Glyburide (glibenclamide, INN), a second generation sulfonylurea is widely used in the treatment of gestational diabetes mellitus (GDM). None of the previously reported analytical methods provide adequate sensitivity for the expected sub-nanogram/mL maternal and umbilical cord plasma concentrations of glyburide during pregnancy. We developed and validated a sensitive and low sample volume liquid chromatographic–mass spectrometric (LC–MS) method for simultaneous determination of glyburide (GLY) and its metabolite, 4-transhydroxy glyburide (M1) in human plasma (0.5 mL) or urine (0.1 mL). The limits of quantitation (LOQ) for GLY and M1 in plasma were 0.25 and 0.40 ng/mL, respectively whereas it was 1.06 ng/mL for M1 in urine. As measured by quality control samples, precision (% coefficient of variation) of the assay was <15% whereas the accuracy (% deviation from expected) ranged from −10.1 to 14.3%. We found that the GLY metabolite, M1 is excreted in the urine as the glucuronide-conjugate.
Keywords: Glyburide; Metabolites; Liquid chromatography–mass spectrometry; β-Glucuronidase; Gestational diabetes mellitus; Plasma; Umbilical cord plasma; Urine;

A validated method for the determination of triethylenetetramine, a selective copper-chelator currently undergoing clinical trials for the treatment of diabetic heart failure, and its two major metabolites, N 1-acetyltriethylenetetramine and N 1,N 10-diacetyltriethylenetetramine in human serum using HPLC is reported. The method used 9-flouorenylmethylchloroformate chloride to label all three analytes. The fluorescence labeled analytes were then separated chromatographically using a reversed phase C18 column under a gradient elution program and detected spectrofluorometrically at 317 nm with excitation at 263 nm. Application of the method is demonstrated by pharmacokinetic measurement in one healthy volunteer taking the drug orally.
Keywords: HPLC; FMOC; TETA; LC–MS; Diabetic heart failure;

The levels of estrogens and/or their metabolites play important roles in carcinogenesis, reproductive function, and sexual development during perinatal and adolescence periods. The main purpose of this report was to investigate the applicability of high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) with electrospray ionization (ESI) and/or atmospheric pressure chemical ionization (APCI) for simultaneous detection of estrone (E1) and its six metabolites. Both positive and negative ionization modes in ESI and APCI were used to evaluate the signal responses of seven target analytes. Among the seven target analytes, five analytes, E1, 16α-hydroxyestrone, 2-methoxyestrone, 4-methoxyestrone, and 2-hydroxyestrone-3-methyl, produced signals with the best signal-to-noise (S/N) ratios in positive APCI-MS/MS mode, while the other two analytes, 2-hydroxyestrone and 4-hydroxyestrone, yielded the best S/N ratios in negative ESI-MS/MS mode. Based on the results of the evaluation, HPLC–APCI-MS/MS with switching between positive and negative modes was recommended for simultaneous detection of E1 and its six metabolites. The proposed analytical scheme was successfully applied in the analysis of cell culture medium of Human liver carcinoma cells treated with varying amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Keywords: Estrogen; Estrone; Metabolite; Electrospray ionization; Atmospheric pressure chemical ionization;

Adenosine triphosphate (ATP) is an important high-energy compound widely used in biological and therapeutic fields. It can be produced by phosphorylation of adenosine monophosphate (AMP) with microbial cells in industrial scale and the effective isolation of ATP from microbial fermentation broth is a challenging work. In this work, we develop a novel one-step method to directly separate ATP from fermentation broth of Saccharomyces cerevisiae by anion-exchange chromatography using supermacroporous cryogel. The cryogel bed with tertiary amine groups was prepared by grafting N,N-dimethylaminoethyl methacrylate (DMAEMA) monomer chains onto the matrix of a polyacrylamide-based cryogel in a glass column and its properties of liquid dispersion, water permeability, porosity as well as the ligand density were measured. Chromatographic separation of ATP from the fermentation broth by the cryogel was carried out using deionised water and 0.01 M HCl as running buffer, respectively. The breakthrough characteristics and elution performance in the cryogel bed were revealed and analyzed. The purities of the obtained ATP were analyzed quantitatively by high performance liquid chromatography (HPLC). The maximal purity of ATP by the one-step separation method was 95.5% using 0.01 M HCl as running buffer in this work. The corresponding chromatographic behaviors were investigated and analyzed.
Keywords: Cryogel; Anion-exchange; Adenosine triphosphate; Purification; Adsorption; Elution;

Polyethyleneimine phosphate and citrate systems act like pseudo polyampholytes as a starting method to isolate pepsin by Alejandra Manzur; Darío Spelzini; Beatriz Farruggia; Diana Romanini; Guillermo Picó (63-68).
The aqueous solution behaviour of polyethyleneimine (a cationic synthetic polymer) in the presence of anions (such as citrate and phosphate) was studied by means of turbidimetry. The variation of the absorbance at 420 nm of dilute mixture with pH, the polymer concentration and the ionic strength were examined. The mixture of polyethyleneinine citrate or polyethyleneinine phosphate behaves as a pseudo polyampholyte with an isoelectric point of 5.5 and 6.2 for phosphate and citrate respectively and a precipitation pH range between 3.5 and 8.0. Pepsin was completely precipitated with the polymer anion complex within this pH interval. Citrate showed a better precipitation effect than phosphate did. The precipitate was reversibly dissolved in NaCl (for concentrations higher than 0.2 M) and pepsin kept its biological activity. Studies of pepsin thermal stability (by differential scanning calorimetry) revealed that the polyethyleneimine presence increased the enzyme denaturation temperature. The circular dichroism spectrum of pepsin showed a non-significant loss of secondary and tertiary enzyme structure by the polyethyleneimine. However, the polymer presence increased the biological activity of pepsin.
Keywords: Pepsin; Polyethyleneimine; Precipitation; Polyelectrolyte; Polymer;

Simultaneous analysis of lysine, N ɛ-carboxymethyllysine and lysinoalanine from proteins by Lourdes Bosch; Maria Luz Sanz; Antonia Montilla; Amparo Alegría; Rosaura Farré; María Dolores del Castillo (69-77).
Protein quality was assayed by simultaneous measurement of lysine (Lys), carboxymethyllysine (CML) and lysinoalanine (LAL). GC-FID analysis of N-tert-butyl dimethylsilyl (tBDMSi) derivatives of these amino acids was undertaken. tBDMSi derivates were separated on a CP-SIL 5CB commercially fused silica capillary column (25 m × 0.25 mm i.d., 0.25 μm film thickness) employing a thermal gradient programmed from 200 to 300 °C. The identity of tBDMSi derivatives of Lys, CML and LAL was established by GC–MS while FID detection was employed for quantification. Analytical parameters such as linearity (lysine 350–4200 μM, LAL 3–81 μM, CML 16–172 μM), precision (1–13% variation coefficients), accuracy (85–108% average recovery) and limits of detection (lysine 0.4 mg/100 g protein, LAL 5.0 mg/100 g protein, CML 3.4 mg/100 g protein) and quantification (lysine 1.4 mg/100 g protein, LAL 15.2 mg/100 g protein, CML 11.2 mg/100 g protein) were determined for validation of the analytical approach. Model systems and real foods have been studied. Kinetic of CML formation from different food proteins (BSA, soy protein, casein and gluten) was performed employing model systems. Carboxymethylation rate depended on the source of protein. Maillard reaction progressed to advanced stages damaging the protein quality of stored infant foods, soy drinks, boiled eggs and dry powdered crepes. CML values ranged from 62 to 440 mg/100 g protein were measured. LAL was also formed during boiling eggs (21–68 mg/100 g protein) indicating additional damage by crosslinking reaction. In agreement, lysine content was affected by both food processing and storage.
Keywords: Gas chromatography; Lysine; Lysinoalanine; N ɛ-Carboxymethyllysine; Protein;

The analysis of biomarkers from exhaled breath condensate (EBC) is a non-invasive but challenging method for the detection of pulmonary diseases. The amino acids l-proline (Pro) and l-tyrosine (Tyr) are precursors for two important metabolites, trans-l-4-hydroxyproline (trans-l-4-hydroxypyrrolidin-2-carboxylic acid, t-Hyp) and nitrotyrosine (NT). Whereas t-Hyp is supposed to be a biomarker for lung fibrosis, NT is a promising biomarker for inflammation in airway diseases. Analysis of EBC requires extremely sensitive methods, because the epithelial lining fluid of the lung and upper airway is highly diluted in EBC. The high intra- and interindividual variation of this dilution implicates additional problems for sample collection and the interpretation of EBC results. Hence, our aim was to work out a method that would compensate for these possible dilution effects. We have developed a new, reliable and very sensitive method for the simultaneous determination of Pro, t-Hyp, Tyr and NT from EBC. Except for t-Hyp, we used labelled internal standards (IS) l-proline 13C5, 15N (Pro 13C5), l-tyrosine-13C9 (Tyr 13C9), 13C9-3-nitrotyrosine (NT13C9), IS for t-Hyp was cis-4-hydroxy-l-proline, which were added to the samples before they were lyophilised for concentration. For the separation of the analytes we used hydrophilic interaction liquid chromatography (HILIC), coupled to tandem-mass-spectrometry (MS/MS). The limit of detection (LOD) was 0.5 μg/l for Pro and Tyr and 5 ng/l for t-Hyp and NT. The relative standard deviation (RSD) of the precision from day to day was between 2.6 and 8.0% at spiked concentrations between 4 and 25 μg/l for Pro and between 4.2 and 7.3% for Tyr. The RSD of the precision from day to day was between 7.5 and 13.2% at spiked concentrations between 40 and 250 ng/l for t-Hyp and between 3.5 and 8.2% for NT. The method was established using 27 healthy subjects with a median age of 46 years. Concentrations ranged from 2.8 to 51.9 μg/l for Pro, from <5 to 516.5 ng/l for t-Hyp, from 2.4 to 99.1 for Tyr and for NT concentration ranged between <5 and 1686.5 ng/l.
Keywords: Proline; Hydroxyproline; Tyrosine; Nitrotyrosine; HILIC; LC/MS; ZIC®-HILIC column; EBC; Biomarkers; Pulmonary diseases; Standardisation parameter;

A GC–MS method for the simultaneous determination of hexanal, heptanal, octanal, nonanal and decanal in exhaled breath was established and validated. The aldehydes were derivatized on PDMS/DVB fibres using O-2,2,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA) as the headspace derivatization reagent. The resultant oximes were quantified by GC–MS in selected ion monitoring (SIM) mode. The method provides detection limits of 0.01–0.03 nM for the aldehydes, with a linear response in the concentration range 0.002–20 nM. Within-day precision values for the five aldehydes at 0.02–0.04 nM and 0.2–0.4 nM were in the ranges: 3–9% and 3–8%, respectively; the corresponding between-day precision values were 11–22% and 10–24%. Exhaled breath samples could be stored at −20 °C for 48 h.
Keywords: Breath analysis; Aldehydes; Lipid peroxidation; GC–MS; Solid-phase microextraction;

Liquid chromatography method for simultaneous analysis of amino acids and biogenic amines in biological fluids with simultaneous gradient of pH and acetonitrile by Valentin Lozanov; Bistra Benkova; Lyudmila Mateva; Stefan Petrov; Elenko Popov; Chavdar Slavov; Vanio Mitev (92-97).
A liquid chromatography method for simultaneous analysis of amino acids, polyamines, catecholeamines and metanephrines in human body fluids after derivatization with 9-fluorenylmethyloxycarbonyl chloride was developed. The chromatographic behavior of analytes at different pH of mobile phase was studied. Successful baseline resolution of all analyzed compounds was achieved using simultaneous gradient of pH and organic modifier in reverse phase mode of HPLC within 36 min. The repeatability of the proposed procedure in respect of retention time and peak area, expressed as RSD, ranges from 0.06 to 1.64% and 0.4 to 7.6%, respectively. The method linearity in the range of 1–200 μM for amino acids and in the range of 0.1–20 μM for polyamines, catecholeamines and metanephrines was found to be with correlation coefficients higher than 0.994. The limit of quantification (LOQ) was assessed to be in the range of 2.6–10 pmol for amino acids and 2–4 pmol for polyamines, catecholeamines and metanephrines.
Keywords: Liquid chromatography; Amino acids; Polyamines; Catecholeamines; Metanephrines; Fmoc;

Partition features and renaturation enhancement of chymosin in aqueous two-phase systems by Georgina Reh; Dario Spelzini; Gisela Tubío; Guillermo Picó; Beatriz Farruggia (98-105).
Aqueous two-phase systems of polyethylene glycol (molecular mass 1450, 3350 and 6000)–phosphate and polyethylen-polypropilen oxide (molecular mass 8400)–maltodextrin systems were used in order to study the partition features of recombinant chymosin from inclusion bodies. These systems in the presence of 8 M urea were used for the solubilization of inclusion bodies containing recombinant chymosin and for the oxidative renaturation of this protein. Recombinant chymosin showed to be partitioned in favour of the top phase in all studied systems with a partition coefficient between 4 and 6. The recovery of the chymosin biological activity was 32% in the polyethylen-polypropilen oxide, while in the polyethylene glycol–phosphate the recovery was 50–59%. The results indicate that the liquid–liquid extraction would be an adequate tool able to isolate and concentrate chymosin from inclusion bodies with a yield of biological activity higher than that obtained from the standard method (43%).
Keywords: Chymosin; Maltodextrin; Polyethylene glycol; Polyoxidethylene; Partition; Inclusion bodies;

Quantification of 22 phthalate metabolites in human urine by Manori J. Silva; Ella Samandar; James L. Preau; John A. Reidy; Larry L. Needham; Antonia M. Calafat (106-112).
Phthalates are ubiquitous industrial chemicals with high potential for human exposure. Validated analytical methods to measure trace concentrations of phthalate metabolites in humans are essential for assessing exposure to phthalates. Previously, we developed a sensitive and accurate automated analytical method for measuring up to 16 phthalate metabolites in human urine by using on-line solid phase extraction coupled with isotope dilution–high performance liquid chromatography (HPLC)–electrospray ionization-tandem mass spectrometry. To include the measurement of seven additional analytes, including oxidative metabolites of diisononyl and diisodecyl phthalates, two chemicals used extensively in numerous consumer products, we used a novel nontraditional HPLC solvent gradient program. With this approach, we achieved adequate resolution and sensitivity for all 22 analytes with limits of detection in the low ng/mL range, without increasing the analytical run time. The method also has high accuracy with automatic recovery correction, high precision, and excellent sample throughput with minimal matrix effects. Although it is possible to measure these 22 phthalate metabolites with adequate precision and accuracy at sub-parts-per-billion levels, additional information, including toxicokinetic data, is needed to demonstrate the usefulness of these phthalate metabolites for exposure assessment purposes.
Keywords: Reverse HPLC gradient; Phthalate metabolites; Phthalates; Biomonitoring; Exposure assessment; Diisodecyl phthalate; Diisononyl phthalate; Phthalate analysis;

A sensitive, specific and accurate LC–MS/MS method was developed for simultaneous determination of icariin, icariside II and osthole in rat plasma. With carbamazepine as the internal standard, plasma samples were prepared by protein precipitation with acetonitrile. Analysis was carried out on an ACQUITY UPLC™ BEH C18 column with a linear gradient and 0.1% aqueous acetic acid and acetonitrile were used as mobile phase. Detection was performed by means of electrospray ionization mass spectrometry in positive ion mode with multiple reaction monitoring. Linear calibration curves of icariin, icariside II and osthole were obtained over the concentration ranges of 2.00–200, 2.00–200 and 2.00–500 ng/ml, respectively. The intra- and inter-day precisions were within 8.0% and 14%, and the accuracy was from −6.0% to 9.0%. The method was successfully applied to pharmacokinetic studies of icariin, icariside II and osthole in rats after oral administration of Gushudan extract.
Keywords: Icariin; Icariside II; Osthole; Gushudan; LC–MS/MS; Pharmacokinetics;

Separation and identification of plasma short-chain acylcarnitine isomers by HPLC/MS/MS for the differential diagnosis of fatty acid oxidation defects and organic acidemias by Isaac Ferrer; Pedro Ruiz-Sala; Yolanda Vicente; Begoña Merinero; Celia Pérez-Cerdá; Magdalena Ugarte (121-126).
This paper reports a new, high-performance liquid chromatography/tandem mass spectrometry method for the separation and identification of human plasma short-chain acylcarnitine isomers. This simple, rapid procedure involves the use of a single sample previously shown to contain elevated acylcarnitine concentrations by flow injection analysis, and can separate two C4, three C5, two C5:1 and four C5-OH acylcarnitine isomers, thus permitting the differential diagnosis of certain fatty acid oxidation defects and organic acidemias.
Keywords: Acylcarnitine isomers; Tandem mass spectrometry; Fatty acid oxidation defects; Isovaleryl-CoA dehydrogenase; 3-Methylcrotonyl-CoA carboxylase; β-Ketothiolase; 3-Hydroxy-3-methylglutaryl-CoA lyase; Pivaloylcarnitine;

Microemulsion electrokinetic chromatography for the separation of arctiin and arctigenin in Fructus Arctii and its herbal preparations by Wenjuan Lü; Yonglei Chen; Yuxia Zhang; Xiuping Ding; Hongli Chen; Mancang Liu (127-133).
A microemulsion electrokinetic chromatography method was used to separate arctiin and arctigenin in Fructus Arctii and its herbal preparations. The separation of arctiin and arctigenin was performed using a 1-butanol–SDS–ethyl acetate–water microemulsion in 10 mM sodium tetraborate buffer. The analytes were baseline-resolved within 4 min. In the concentration range 5–500 μg/mL, the calibration curves reveal linear relationships between the peak area for each analyte and its concentration (correlation coefficients: 0.9993 for arctiin and 0.9998 for arctigenin). The method was applied to the analysis of arctiin and arctigenin in herbal preparations, and the recoveries were 98.7–103.1% for arctiin and 97.6–103.2% for arctigenin, respectively.
Keywords: Microemulsion electrokinetic chromatography; Fructus Arctii; Arctiin; Arctigenin;

Plasma phospholipids metabolic profile of chronic glomerulonephritis was investigated using high performance liquid chromatography/mass spectrometry (LC/MS) and principal component analysis. The plasma samples of 18 patients with chronic glomerulonephritis, 17 patients with chronic renal failure (CRF) without renal replacement therapy and 18 healthy persons were collected and analyzed. It was found that combination of the LC/MS technique with PCA can be successfully applied to phospholipid profile analysis. The results showed that primary chronic glomerulonephritis and CRF had phospholipids metabolic abnormality. Nineteen phospholipid species were identified as possible biomarkers in plasma samples of chronic glomerulonephritis and chronic renal failure. Moreover, the identification of the molecular structure of the potential phospholipid markers was obtained by ESI-MS/MS experiment. It suggests that phospholipids can be used as potential biomarkers on the progress of primary chronic glomerulonephritis.
Keywords: Phospholipids; Chronic glomerulonephritis; High performance liquid chromatography; Mass spectrometry;

Improved high-performance liquid chromatographic detection of paclitaxel in patient's plasma using solid-phase extraction, and semi-micro-bore C18 separation and UV detection by Manabu Suno; Takashi Ono; Shinya Iida; Noriko Umetsu; Ko-ichi Ohtaki; Takehiro Yamada; Toshio Awaya; Machiko Satomi; Yoshikazu Tasaki; Keiko Shimizu; Kazuo Matsubara (141-144).
Although a number of analytical methods for taxanes have been published, none of them are sufficiently suitable for use in a medical setting. In this study, we established an improved analytical HPLC/UV detection method using a Sep-Pak C18 cartridge for extraction and a semi-micro-bore column for separation. This method employed here reduced chromatographic background signals, and allowed a more sensitive analysis of taxanes in human blood sample. The recovery of taxanes after the solid-phase extraction procedure was over 90%. Chromatographic separation of paclitaxel and docetaxel was achieved within 30 min with no interference peak by a semi-micro-bore column, packed either with C18 (Wakosil 5C18 RS) or pentafluorophenyl (Curosil/Taxol) materials. The method was reproducible with coefficients of variation less than 6%. This analytical procedure was simple and sensitive with lower quantification limit of 3 ng/ml. The improved sensitivity achieved by the popular HPLC/UV apparatus, which is available in hospitals, would vouch safer and more efficient therapy with taxane.
Keywords: Paclitaxel; Docetaxel; HPLC/UV; Semi-micro-bore column; Sep-Pak C18; Therapeutic drug monitoring;