Determination of propiverine and its metabolites in rat samples by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometric (LC-MS-MS) method was developed and validated for the determination of the anticholinergic and antimuscarinc drug propiverine and eight of its metabolites in serum, urine, faeces and different tissue samples of rats. Samples containing propiverine and its metabolites in serum and urine and in the supernatants of faeces and tissue homogenates were extracted and cleaned up using an automated solid phase extraction (SPE) method. An external calibration was used. The analytes were measured employing the multiple reaction monitoring mode (MRM). A sufficient response over the range of 10-1000 ng/ml was demonstrated. The lower limit of quantification of the nine substances was 10 ng/ml. The presented method is suitable for pharmacokinetic or toxicokinetic studies. To look for additional unknown metabolites, the LC-MS-MS system operated in the precursor ion mode using typical product ions of propiverine and of its metabolites. With the help of the chromatographic behaviour and typical fragment ions of the unknown metabolites, it was possible to elucidate their structure. Five until now unknown metabolites were found in the urine and faeces samples. However, without reference substances, a quantification of these analytes was not possible.     

Quantification of the xenoestrogens 4-tert.-octylphenol and bisphenol A in water and in fish tissue based on microwave assisted extraction, solid-phase extraction and liquid chromatography-mass spectrometry

Extraction methods were developed for quantification of the xenoestrogens 4-tert.-octylphenol (tOP) and bisphenol A (BPA) in water and in liver and muscle tissue from the rainbow trout (Oncorhynchus mykiss). The extraction of tOP and BPA from tissue samples was carried out using microwave-assisted solvent extraction (MASE) followed by solid-phase extraction (SPE). Water samples were extracted using only SPE. For the quantification of tOP and BPA, liquid chromatography mass spectrometry (LC-MS) equipped with an atmospheric pressure chemical ionisation interface (APCI) was applied. The combined methods for tissue extraction allow the use of small sample amounts of liver or muscle (typically 1 g), low volumes of solvent (20 ml), and short extraction times (25 min). Limits of quantification of tOP in tissue samples were found to be approximately 10 ng/g in muscle and 50 ng/g in liver (both based on 1 g of fresh tissue). The corresponding values for BPA were approximately 50 ng/g in both muscle and liver tissue. In water, the limit of quantification for tOP and BPA was approximately 0.1 microg/l (based on 100 ml sample size).     

HPLC/MS测定动物组织及尿样中的β-兴奋剂

采用微量化样品前处理技术，以固相萃取为净化方法．电喷雾正离子多反应监测方式建立了尿样及动物组织中β-兴奋剂残留量的液相色谱-串联质谱联用测定法。检测的定量限在0．15～0．6ng／g，线性范围均大于10^3，线性方程的相关系数大于0．999，组织样品和尿样的回收率大于70％．     

Analysis of 5-hydroxymethylfurfural in foods by gas chromatography-mass spectrometry

A new, simple and selective method for the analysis of 5-hydroxymethylfurfural (HMF) in foods by gas chromatography coupled to mass spectrometry (GC-MS) is proposed. Several derivatising procedures based on the formation of an HMF silylated derivative using different reagents were studied. Among the derivatising reagents examined, N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) provided the best derivatisation yield. Sample clean-up was also optimised, using either liquid-liquid extraction with dichloromethane or solid-phase extraction (SPE) with several commercially available cartridges, and the best results were obtained using ENV+ cartridges. Quality parameters such as day-to-day and run-to-run precision (RSD<10%), linearity (between 25 and 700 ng g(-1)) and detection limit (6 ng g(-1)) were established. This method was successfully applied to the analysis of HMF content in several Spanish food samples from a local market, such as jam, honey, orange juice and bakery products.     

Quantification of clenbuterol in equine plasma,urine and tissue by liquid chromatography coupled on-line with quadrupole time-of-flight mass spectrometry

Clenbuterol (CBL) is a potent beta(2)-adrenoceptor agonist used for the management of respiratory disorders in the horse. The detection and quantification of CBL can pose a problem due to its potency, the relatively low dose administered to the horse, its slow clearance and low plasma concentrations. Thus, a sensitive method for the quantification and confirmation of CBL in racehorses is required to study its distribution and elimination. A sensitive and fast method was developed for quantification and confirmation of the presence of CBL in equine plasma, urine and tissue samples. The method involved liquid-liquid extraction (LLE), separation by liquid chromatography (LC) on a short cyano column, and pseudo multiple reaction monitoring (pseudo-MRM) by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS). At very low concentrations (picograms of CBL/mL), LLE produced better extraction efficiency and calibration curves than solid-phase extraction (SPE). The operating parameters for electrospray QTOF and yield of the product ion in MRM were optimized to enhance sensitivity for the detection and quantification of CBL. The quantification range of the method was 0.013-10 ng of CBL/mL plasma, 0.05-20 ng/0.1 mL of urine, and 0.025-10 ng/g tissue. The detection limit of the method was 13 pg/mL of plasma, 50 pg/0.1 mL of urine, and 25 pg/g of tissue. The method was successfully applied to the analysis of CBL in plasma, urine and various tissue samples, and in pharmacokinetic (PK) studies of CBL in the horse. CBL was quantified for 96 h in plasma and 288 h in urine post-administration of CLB (1.6 micro g/kg, 2 x daily x 7 days). This method is useful for the detection and quantification of very low concentrations of CBL in urine, plasma and tissue samples.     

Quantification of the new triketone herbicides, sulcotrione and mesotrione, and other important herbicides and metabolites, at the ng/l level in surface waters using liquid chromatography-tandem mass spectrometry

The LC/ESI/MSMS method allows the trace quantification (ng/l) of the new triketone herbicides, i.e. sulcotrione and mesotrione, and important herbicides and metabolites, in natural waters. Solid phase extraction (SPE) for sample enrichment is performed with OASIS (recoveries 94-112% for parent herbicides). Neutral and acidic compounds were analyzed separately with ESI in positive and negative mode, respectively. Quantification limits varied between 0.5 and 10 ng/l. The acidic herbicides detection was improved by a neutralizing post-column addition solution. The influence of ion suppression on quantification is discussed in detail. It is shown that we could overcome this problem and achieve reliable quantification using isotope labeled internal standards (ILIS) for every single analyte. The methods performance is illustrated with samples from a lake depth profile.     

Development of a multi-residue method for the determination of organic micropollutants in water, sediment and mussels using gas chromatography-tandem mass spectrometry

This study describes the development of a multiresidue method based on gas chromatography-electron ionization-tandem mass spectrometry (GC-EI-MS/MS) for the detection of sixteen polycyclic aromatic hydrocarbons (PAHs), five phthalate esters (PEs), seven polychlorinated biphenyls (PCBs), six polybrominated diphenyl ethers (PBDEs), six alkylphenols (APs), three organochlorined pesticides and their isomers or degradation products (OCPs) and bisphenol A in seawater, river water, wastewater treatment plant (WWTP) effluents, sediments and mussels. Solid phase extraction (SPE) was used for the extraction of target analytes in aqueous samples, and ultrasound assisted extraction for solid samples. GC-EI-MS/MS acquisition conditions in selected reaction monitoring (SRM) using two transitions per compound were optimized. In this way, quantification and unequivocal identification of organic micropollutants were performed in compliance with the Decision 2002/657/EC. Good linearity responses with coefficients of determination higher than 0.99 were obtained. Methodological detection limits (MDLs) in seawater ranged from 0.1 to 6 ng L(-1); in river water from 0.1 to 4.8 ng L(-1); in WWTP effluents from 1 to 75 ng L(-1); in sediments from 1 to 150 ng g(-1) and in mussels from 1 to 125 ng g(-1). MDLs and recovery yields were compared with other published methods and similarities or even improvements were achieved. The optimized method was applied to analyze five samples from each matrix collected in coastal areas, showing its potential use for marine pollution monitoring.     

Multi-residue analysis of penicillin residues in porcine tissue using matrix solid phase dispersion.

The aim of this study was to develop a multi-residue method for the analysis of penicillins in animal tissue. Matrix solid phase dispersion (MSPD) was employed to extract the residues and the extracts were then cleaned-up by C18 solid phase extraction (SPE). Pre-column derivatisation using acetic anhydride and 1,2,4-triazole in the presence of mercuric chloride was employed to allow detection in 325 nm. Gradient elution was required to elute amoxicillin, ampicillin, penicillin G, cloxacillin and dicloxacillin derivatives from a C18 reversed phase column using phosphate buffer-acetonitrile mobile phase. The developed method had a limit of detection of 20 ng g-1 and had recoveries in the range 40-90% for the 5 drugs in samples fortified at 40 and 200 ng g-1; the maximum residue limits (MRLs) for these drugs were in the range of 50-300 ng g-1 (ppb).     

Simultaneous ultra-high-pressure liquid chromatography–tandem mass spectrometry determination of amphetamine and amphetamine-like stimulants,cocaine and its metabolites,and a cannabis metabolite in surface water and urban wastewater

An ultra-high-pressure liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method has been developed for the simultaneous quantification and confirmation of 11 basic/acidic illicit drugs and relevant metabolites in surface and urban wastewater at ng/L levels. The sample pre-treatment consisted of a solid-phase extraction using Oasis MCX cartridges. Analyte deuterated compounds were used as surrogate internal standards (except for norbenzoylecgonine and norcocaine) to compensate for possible errors resulting from matrix effects and those associated to the sample preparation procedure. After SPE enrichment, the selected drugs were separated within 6 min under UHPLC optimized conditions. To efficiently combine UHPLC with MS/MS, a fast-acquisition triple quadrupole mass analyzer (TQD from Waters) in positive-ion mode (ESI+) was used. The excellent selectivity and sensitivity of the TQD analyzer in selected reaction monitoring mode allowed quantification and reliable identification at the LOQ levels. Satisfactory recoveries (70–120%) and precision (RSD < 20%) were obtained for most compounds in different types of water samples, spiked at two concentration levels [limit of quantification (LOQ) and 10LOQ]. Thus, surface water was spiked at 30 ng/L and 300 ng/L (amphetamine and amphetamine-like stimulants), 10 ng/L and 100 ng/L (cocaine and its metabolites), 300 ng/L and 3000 ng/L (tetrahydrocannabinol-COOH). Recovery experiments in effluent and influent wastewater were performed at spiking levels of three and fifteen times higher than the levels spiked in surface water, respectively. The validated method was applied to urban wastewater samples (influent and effluent). The acquisition of three selected reaction monitoring transitions per analyte allowed positive findings to be confirmed by accomplishment of ion ratios between the quantification transition and two additional specific confirmation transitions. In general, drug consumption increased in the weekends and during an important musical event. The highest concentration levels were 27.5 μg/L and 10.5 μg/L, which corresponded to 3,4-methylenedioxymethamphetamine (MDMA, or ecstasy) and to benzoylecgonine (a cocaine metabolite), respectively. The wastewater treatment plants showed good removal efficiency (>99%) for low levels of illicit drugs in water, but some difficulties were observed when high drug levels were present in wastewaters.     

Determination of thyroid hormones and their metabolites in tissue using SPE UPLC-tandem MS

A solid‐phase liquid chromatography tandem mass spectrometry (SPE LC‐MS/MS) method was developed to determine thyroid hormones and their metabolites in tissue samples. The separation was achieved using reversed‐phase ultra‐performance liquid chromatography (UPLC); the mass spectrometric detection was achieved by positive electrospray ionization and multiple reaction monitoring. Prior to the UPLC separation a sample cleanup with a cation exchange was performed. ¹³ C₆ labeled internal standards were used for the thyroid hormones and their metabolites. The method was linear over a range from 0.23 to 90 nmol/L for thyroxine and from 0.23 to 9 nmol/L for the metabolites. The lower limit of quantification ranged from 0.98 to 1.73 pg on column. Intra‐ and total assay variation were <10 and <15%, respectively. This method enables us to link thyroid hormone tissue concentrations to local iodothyronine deiodinase expressions, which will enhance our understanding of the regulation of thyroid hormone metabolism on the tissue level. Copyright © 2011 John Wiley & Sons, Ltd.     

Solid-phase extraction and liquid chromatography--mass spectrometry for the determination of free fatty acids in shellfish

A novel analytical protocol for the determination of free fatty acids (FFAs; saturated, monounsaturated and polyunsaturated) in shellfish using electrospray ionisation and liquid chromatography-mass spectrometry (LC-MS) is described. Total lipids were extracted from four commercially important shellfish species using chloroform-methanol in a modification of the traditionally used Bligh and Dyer method. FFAs were recovered from lipidic shellfish extracts by solid-phase extraction (SPE) on an aminopropyl-silica column using a 98:2 v/v diethyl ether (DEE)-acetic acid solution. Ether extracts containing the FFAs were evaporated and reconstituted in 70:30 v/v methanol-chloroform before analysis by LC-MS. The limits of quantification (LOQs) of the method ranged from 60 to 560 microgg(-1) wet weight depending on the different FFAs determined with selected ion monitoring (SIM). Results demonstrate that LC-MS is well suited for identification and quantification of FFAs in shellfish and negates the use of sample derivatisation required in gas chromatographic analysis.     

The use of liquid chromatography/mass spectrometry for quantitative analysis of oxycodone, oxymorphone and noroxycodone in Ringer solution, rat plasma and rat brain tissue

Sensitive and reproducible methods for the determination of oxycodone, oxymorphone and noroxycodone in Ringer solution, rat plasma and rat brain tissue by liquid chromatography/mass spectrometry are described. Deuterated analogs of the substances were used as internal standards. Samples in Ringer solution were analyzed by direct injection of 10 microL Ringer solution diluted by an equal volume of water. The limit of quantification was 0.5 ng/mL and the method was linear in the range of 0.5-150 ng/mL for all substances. To analyze oxycodone and oxymorphone in rat plasma, 50 microL of plasma were precipitated with acetonitrile, and the supernatant was directly injected onto the column. To analyze oxycodone, oxymorphone and noroxycodone in rat plasma, 100 microL of rat plasma were subjected to a C18 solid-phase extraction (SPE) procedure, before reconstituting in mobile phase and injection onto the column. For both methods the limit of quantification in rat plasma was 0.5 ng/mL and the methods were linear in the range of 0.5-250 ng/mL for all substances. To analyze the content of oxycodone, oxymorphone and noroxycodone in rat brain tissue, 100 microL of the brain homogenate supernatant were subjected to a C18 SPE procedure. The limit of quantification of oxycodone was 20 ng/g brain, and for oxymorphone and noroxycodone 4 ng/g brain, and the method was linear in the range of 20-1000 ng/g brain for oxycodone and 4-1000 ng/g brain for oxymorphone and noroxycodone. All methods utilized a mobile phase of 5 mM ammonium acetate in 45% acetonitrile, and a SB-CN column was used for separation. The total run time of all methods was 9 min. The intra-day precision and accuracy were <11.3% and <+/-14.9%, respectively, and the inter-day precision and accuracy were <14.9% and <+/-6.5%, respectively, for all the concentrations and matrices described.     

Measurement of perchlorate in water by use of an 18O-enriched isotopic standard and ion chromatography with mass spectrometric detection

A novel analytical method has been developed for the determination of 4-tert.-octylphenol (OP) and 4-nonylphenol (NP) in laboratory animal feed samples, which involves stir bar sorptive extraction (SBSE) followed by liquid desorption (LD) and column-switching liquid chromatography-mass spectrometry (CS-LC-MS) with solid-phase extraction (SPE). The method required correction by stable isotopically labeled surrogate standards, deuterium 4-tert.-octylphenol (OP-d) and [2H5] 4-(1-methyl)octylphenol (m-OP-d5). A feed sample was homogenized with methanol by ultrasonication. After centrifugation, the supernatant was subjected to extraction for 120 min at room temperature (25 degrees C) using a stir bar coated with polydimethylsiloxane. After the extraction, the analyte was desorbed from the stir bar by LD using acetonitrile. Then, the liquid sample was analyzed by CS-LC-MS with SPE. The average recoveries from laboratory feed samples spiked with OP and NP at 20 ng g(-1) were 99.5 and 103.8%, respectively, with correction using the added surrogate standards. The limits of quantification were 1 ng g(-1) for OP and 5 ng g(-1) for NP in feed sample. The measurement of OP and NP in commercial laboratory animal feed samples resulted in the detection of sub ng g(-1) NP     

同位素内标稀释液相色谱-串联质谱法测定鱼贝类组织中残留的环丙氟哌酸

建立了不同鱼贝类肌肉组织中以氘代同位素为内标测定环丙氟哌酸残留量的液相色谱-串联质谱(LC-MS/MS)方法。样品加入内标环丙氟哌酸-D8和磷酸盐缓冲溶液(pH 7.0)后进行匀质并用乙腈超声提取,经正己烷脱脂后采用Waters Oasis MAX小柱净化,在Cloversil-C18柱上,以乙腈-0.05%三氟醋酸(体积比为25∶75)为流动相,采用多反应监测(MRM)模式,液相色谱-电喷雾质谱法测定。根据环丙氟哌酸和氘代内标物的定量离子质量色谱图的峰面积比值,采用内标法定量。结果表明,环丙氟哌酸和内标的定量离子峰面积比值与环丙氟哌酸浓度在0.1～50.0 μg/kg范围内呈现良好的线性关系,相关系数为0.9991,方法的定量检测限为0.1 μg/kg,回收率为92.5%～98.1%,相对标准偏差(RSD)小于4.3%。将该方法用于市场上10种鱼和贝类样品的检测,结果表明该法具有灵敏、准确的优点,完全满足残留分析的确证检测要求。     

Simultaneous solid-phase extraction of acidic, neutral and basic pharmaceuticals from aqueous samples at ambient (neutral) pH and their determination by gas chromatography-mass spectrometry

Seven polymeric solid-phase extraction (SPE) sorbents were evaluated with regard to their ability to extract acidic, neutral and basic pharmaceuticals and estrogens simultaneously from water at neutral pH. Highest recoveries (70-100%) for the majority of the analytes were obtained with styrene-methacrylate and styrene-N-vinylpyrrolidone co-polymers. The latter one (Oasis HLB) was chosen for further refinement of an extraction method for the quantitative determination of acidic and neutral drugs in surface water samples at detection limits below 1 ng/l. A sequential elution protocol was applied for clean-up and separation of the extracted analytes into fractions suitable for further compound specific processing. The neutral analytes as well as the acidic compounds after derivatisation were quantified by GC-MS. Caffeine, ibuprofen, its metabolites and diclofenac were detected in river water samples in the 1-100 ng/l range.     

Sensitive determination of acidic drugs and triclosan in surface and wastewater by ion-pair reverse-phase liquid chromatography/tandem mass spectrometry

A new method is presented for the determination of 12 acidic pharmaceuticals (non-steroidal anti-inflammatory drugs and bezafibrate), including two metabolites from aqueous samples, together with triclosan as a personal care product. Ion-pair liquid chromatography (IP-LC) with electrospray ionisation tandem mass spectrometry (ESI-MS) in the negative ion mode was employed. The ion-pairing agent (tri-n-butylamine) increased the signal intensity for all acidic analytes and detection limits of 6-200 ng/L were obtained by multiple reaction monitoring. This allows analysis of wastewater samples by direct injection into the LC/MS system without the need for a preceding enrichment step. When combined with a solid-phase extraction (SPE) step, limits of quantification between 0.15 and 11 ng/L were obtained from 100-mL sample volumes, which is adequate for most applications. The occurrence of matrix effects was studied and standard addition was required for reliable quantification after SPE from wastewater. The method was finally applied to surface and wastewaters, with analyte concentrations ranging from below the detection limit up to 5.5 microg/L.     

Perry G. Wang (Ed.): Monolithic chromatography and its modern applications

Organic micropollutants such as pharmaceuticals, perfluorinated compounds (PFCs), and pesticides, are important environmental contaminants. To obtain more information regarding their presence in marine organisms, an increasing demand exists for reliable analytical methods for quantification of these micropollutants in biotic matrices. Therefore, we developed extraction procedures and new analytical methods for the quantification of 14 pesticides, 10 PFCs, and 11 pharmaceuticals in tissue of marine organisms, namely blue mussels (Mytilus edulis). This paper presents these optimized analytical procedures and their application to M. edulis, deployed at five stations in the Belgian coastal zone. The methods consisted of a pressurized liquid extraction and solid-phase extraction (SPE) followed by ultra high-performance liquid chromatography coupled to triple quadrupole mass spectrometry for pharmaceuticals and pesticides, and of a liquid extraction using acetonitrile and SPE, followed by liquid chromatography coupled to time-of-flight mass spectrometry for PFCs. The limits of quantification of the three newly optimized analytical procedures in M. edulis tissue varied between 0.1 and 10 ng g(-1), and satisfactory linearities (≥0.98) and recoveries (90-106%) were obtained. Application of these methods to M. edulis revealed the presence of five pharmaceuticals, two PFCs, and seven pesticides at levels up to 490, 5, and 60 ng g(-1), respectively. The most prevalent micropollutants were salicylic acid, paracetamol, perfluorooctane sulfonate, chloridazon, and dichlorvos.     

A highly sensitive liquid chromatography tandem mass spectrometry method for simultaneous quantification of midazolam, 1'-hydroxymidazolam and 4-hydroxymidazolam in human plasma

A highly sensitive liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of midazolam and its major metabolites 1'-hydroxymidazolam and 4-hydroxymidazolam in human plasma was developed and validated. Stable isotope-labeled midazolam-D(4) and 1'-hydroxymidazolam-D(4) were used as internal standards. Compounds were extracted from 0.5 mL plasma by liquid-liquid extraction with ethyl acetate-heptane (1:4). Chromatography was achieved using a Sunfire C(18) column. The mobile phase was a gradient with 10 m m formic acid in Milli-Q water and methanol at a flow rate of 0.3 mL/min. Total run time was 10 min. Detection was performed using a tandem mass spectrometer with positive electrospray ionization. Calibration curves were linear over the range of 0.10-50.0 ng/mL for midazolam and 0.025-25.0 ng/mL for both metabolites. For all compounds the lower limit of quantification was 0.10 ng/mL. Imprecision was assessed according to the NCCLS EP5-T guideline and was below 10% for all compounds. Mean recoveries were between 94 and 109% for midazolam and its metabolites. The validated method was successfully applied in a pharmacokinetic study investigating in vivo CYP3A-activity in a large cohort of renal allograft recipients using sub-therapeutic doses of midazolam as a drug-probe.     

LC-MS determination of linear alkylbenzene sulfonates and their carboxylic degradation products in influent and effluent water samples and sludges from sewage-treatment plants

Linear alkylbenzene sulfonates (LAS) have been determined in samples of the influent and the effluent, and in the sludge, from sewage-treatment plants (STP). LAS and sulfophenyl carboxylate compounds (SPC) were isolated by solid-phase extraction (SPE) with the polymeric phase Isolute ENV, then determined by liquid chromatography-electrospray mass spectrometry (LC-ESI-MS). The method enabled unequivocal identification of C10-C13 LAS by monitoring the ion at m/z 183 and the base peak corresponding to the [M-H]- ion. Average recoveries varied from 77-93% and the linear range of the method varied from 0.2 to 10 microg L(-1), with a limit of detection ranging from 10 ng L(-1) to 1.5 microg L(-1) when 200 mL waste water were preconcentrated. For sewage sludge, recoveries varied from 58 to 90% and the linear range was between 0.2 and 100 microg L(-1), with a detection limit ranging from 0.4 to 120 microg kg(-1) when 2.5 g sewage sludge was extracted. Unequivocal identification and determination of some metabolites of the LAS, the sulfophenyl carboxylate compounds (SPC), was achieved by monitoring [M-H]- ions.     

高效液相色谱-串联质谱法同时测定人尿液中7种邻苯二甲酸酯代谢物

建立了同时检测人尿液中7种邻苯二甲酸酯代谢物的高效液相色谱-串联三重四极杆质谱法。尿液经酶水解后,采用萃取柱净化,以2%(v/v)甲酸甲醇溶液为洗脱剂,经苯基柱分离,以0.1%(v/v)乙酸水溶液和0.1%(v/v)乙酸乙腈溶液为流动相进行梯度洗脱,采用电喷雾离子源负离子模式和多反应监测模式采集信号,用同位素内标法进行定量分析。尿液中7种邻苯二甲酸酯代谢物在0.2~200.0 μg/L范围内定量离子的相对峰面积比值与质量浓度均呈良好线性关系(r≥0.99976);检出限(LOD)为13.43~80.21 ng/L,定量限为44.77~267.37 ng/L; 3个水平的加标回收率为88.8%~108.9%,日内和日间精密度均不大于17.05%。该方法可同时准确、灵敏、简便地测定人尿液中7种邻苯二甲酸酯代谢物的暴露水平。