Screening for inherited metabolic diseases using gas chromatography–tandem mass spectrometry (GC–MS/MS) in Sichuan,China

The aim of this study was to retrospectively diagnose and confirm inherited metabolic diseases (IMD), from a small population of IMD high‐risk patients, with the aid of gas chromatography–tandem mass spectrometry (GC–MS/MS), technologies yet to be popularized in Sichuan, China. Using GC–MS/MS coupled with clinical diagnosis, we retrospectively analyzed samples of dried blood spots and urine specimen from 183 IMD high‐risk infant patients, who visited the West China Second Hospital of Sichuan University between June 2013 and October 2015. Four out of 183 IMD high‐risk infant patients were finally diagnosed to be IMD positive, among which two patients were identified with phenylketonuria, one with maple syrup urine disease, and 1 with methylmalonic academia. Restrictive diets and other symptomatic treatments were employed to treat the confirmed infant patients whose conditions are still under tracking and there are zero cases of death so far. GC–MS/MS was found to be an efficient and reliable way to detect IMD. It is necessary to apply GC–MS/MS, in addition to other clinical approaches, for diagnosing candidate IMD patients so that the confirmed patients can get medical intervention and timely treatment.     

Analysis of emerging organic contaminants in poultry manure by gas chromatography–tandem mass spectrometry

A multiresidue method was developed for the determination of 19 emerging organic contaminants (pharmaceutical drugs, personal care products, and bisphenol A) in poultry manure. Lyophilized samples of manure were extracted by ultrasound‐assisted matrix solid‐phase dispersion and the extracts were analyzed by gas chromatography with tandem mass spectrometry after derivatization. Analysis of spiked poultry manure samples, at levels ranging from 25 to 150 ng/g, gave satisfactory recovery results for all the compounds, with values from 67 to 106%. The developed procedure provided detection limits that ranged from 0.9 to 2.2 ng/g. Finally, the validated method was applied to poultry manure samples collected from 23 poultry farms in Spain. Salicylic acid was found in most of the samples analyzed at levels up to 2501 ng/g, whereas, methyl paraben, orthophenylphenol, ibuprofen, paracetamol, and carbamazepine were detected at levels up to 250 ng/g. Composting of manure showed an important decrease in the levels of the detected contaminants.     

Fabric phase sorptive extraction for the determination of 17 multiclass fungicides in environmental water by gas chromatography‐tandem mass spectrometry

A rapid environmental pollution screening and monitoring workflow based on fabric phase sorptive extraction‐gas chromatography‐tandem mass spectrometry (FPSE‐GC‐MS/MS) is proposed for the first time for the analysis of 17 widespread used fungicides (metalaxyl, cyprodinil, tolylfluanid, procymidone, folpet, fludioxonil, myclobutanil, kresoxim methyl, iprovalicarb, benalaxyl, trifloxystrobin, fenhexamid, tebuconazole, iprodione, pyraclostrobin, azoxystrobin and dimethomorph) in environmental waters. The most critical parameters affecting FPSE, such as sample volume, matrix pH, desorption solvent and time, and ionic strength were optimized by statistical design of experiment to obtain the highest extraction efficiency. Under the optimized conditions, the proposed FPSE‐GC‐MS/MS method was validated in terms of linearity, repeatability, reproducibility, accuracy and precision. To assess matrix effects, recovery studies were performed employing different water matrices including ultrapure, fountain, river, spring, and tap water at 4 different concentration levels (0.1, 0.5, 1 and 5 µg/L). Recoveries were quantitative with values ranging between 70–115%, and relative standard deviation values lower than 14%. Limits of quantification were at the low ng/L for all the target fungicides. Finally, the validated FPSE‐GC‐MS/MS method was applied to real water samples, revealing the presence of 11 out of the 17 target fungicides.     

Development and validation of a liquid chromatography–tandem mass spectrometry method for the determination of febuxostat in human plasma

A rapid and sensitive analytical method based on liquid chromatography coupled to tandem mass spectrometry detection with positive ion electrospray ionization was developed for the determination of febuxostat in human plasma using d₇‐febuxostat as the internal standard (IS). A simple protein precipitation was performed using acetonitrile. The analyte and IS were subjected to chromatographic analysis on a Capcell PAK C₁₈ column (4.6 × 100 mm, 5 µm) using acetonitrile–5 mm ammonium acetate–formic acid (85:15:0.015, v/v/v) as the mobile phase at a flow rate of 0.6 mL/min. An Agilent 6460 electrospray tandem mass spectrometer was operated in the multiple reaction monitoring mode. The precursor‐to‐product ion transitions m/z 317 → m/z 261 (febuxsotat) and m/z 324 → m/z (261 + 262) (d₇‐febuxostat, IS) were used for quantitation. The results were linear over the studied range (10.0–5000 ng/mL), and the total analysis time for each chromatograph was 3 min. The intra‐ and inter‐day precisions were less than 7.9 and 7.2%, respectively, and the accuracy was within ±4.2%. No evidence of analyte instability in human plasma was observed storage at ?20°C for 31 days. This method was successfully applied in the determination of febuxostat concentrations in plasma samples from healthy Chinese volunteers. Copyright © 2012 John Wiley & Sons, Ltd.     

Combination of liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry for the detection of 21 anabolic steroid residues in bovine urine

For the detection of anabolic steroid residues in bovine urine, a highly sensitive liquid chromatographic/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method was developed using both positive and negative ionization. For four compounds the ESI mode was not sensitive enough and gas chromatographic/mass spectrometric GC/MS detection was therefore still necessary as a complementary method. The sample clean-up consisted of solid-phase extraction (SPE) on a C(18) column followed by enzymatic hydrolysis and a second solid-phase extraction on a combination of a C(18) and a NH(2) column. After this last SPE clean-up, the eluate was split into two equal aliquots. One aliquot was further purified and after derivatization used for GC/MS analysis. The other aliquot was analyzed with LC/MS/MS in both ESI+ and ESI- modes. The method was validated according to the European Commission Decision 2002/657/EC. Decision limits (CCalpha) were between 0.16 and 1 ng ml(-1) for the compounds detected with the LC/MS/MS method. The developed method is used in routine analysis in our laboratory.     

Quantification of homoegonol in rat plasma using liquid chromatography–tandem mass spectrometry and its pharmacokinetics application

Homoegonol is a biologically active neolignan isolated from Styrax species with cytotoxic, antimicrobial, anti‐inflammatory and anti‐asthma activities. For the quantification of homoegonol in rat plasma, a selective and sensitive liquid chromatography–tandem mass spectrometric method was developed and validated for the first time using protein precipitation with methanol as a sample clean‐up procedure. The analytes were separated in an Atlantis dC₁₈ column using a gradient elution of methanol and 0.1% formic acid, and mass‐to‐charge ratios were determined in selective reaction monitoring mode using tandem mass spectrometry with m/z 343.12 > 296.97 for homoegonol and m/z 517.30 > 282.90 for udenafil (internal standard). The standard curve was linear over the concentration ranges of 1 ? 500 ng/mL using a 30 μL rat plasma sample. The coefficient of variation and relative error for intra‐ and inter‐assay at four quality control levels were 3.9–10.0 and ‐3.3–2.7%, respectively. The overall recovery of homoegonol from rat plasma using protein precipitation was 99.7 ± 7.7%. The pharmacokinetics parameters of homoegonol were dose‐independent after both intravenous (1, 2.5 and 5 mg/kg doses) and oral (5, 10 and 20 mg/kg doses) administration in male Sprague–Dawley rats. Copyright © 2014 John Wiley & Sons, Ltd.     

Rapid method for the confirmatory analysis of chrysoidine in aquaculture products by ultra‐performance liquid chromatography–tandem mass spectrometry

A sensitive and fast method for the quantification of the illegal dye chrysoidine in aquaculture products with ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) is presented. Muscle tissues were made alkaline with sodium hydroxide and extracted with ethyl acetate. After evaporation and subsequent defatting with n‐hexane, extracts were directly injected onto the UPLC‐column. Chromatography was performed on a C₁₈ column using 0.1% formic acid in water and an acetonitrile gradient within 6 min. Mass spectrometric analysis was performed in the positive electrospray MS/MS mode. The limit of quantification was 0.25 ng/g, which was 30 times lower than the only previously published method with gas chromatographic detection. A complete validation according to the scientific literature and as defined by the European Union was performed. The applicability of the method was shown in the analysis of more than 50 unknown samples in the framework of a monitoring program. Copyright © 2010 John Wiley & Sons, Ltd.     

Development and validation of dried blood spots technique for quantitative determination of topiramate using liquid chromatography–tandem mass spectrometry

An LC‐MS/MS method for determination of the anti‐epileptic drug topiramate (TPM) in dried blood spot (DBS) samples was developed and validated. DBS samples were prepared by spotting 30 μL of spiked whole blood onto FTA^TM DMPK‐C cards and drying for at least 3 h. Six‐millimetre punched spots were then extracted by using a mixture of methanol and water (90:10, v/v) with deuterated internal standard (topiramate‐d₁₂). The extracted samples were injected into a liquid chromatograph equipped with a tandem mass spectrometric detector. Negative ions were monitored in the selected reaction monitoring mode and transitions m/z 338.2 → 78.1 and m/z 350.3 → 78.1 were used for the quantitative evaluation of TPM and internal standard, respectively. The results obtained from validation were statistically evaluated according to the requirements of the European Medicines Agency and US Food and Drug Administration regulatory guidelines. The linearity of the method was checked within a concentration range from 10 to 2000 ng/mL. The validation results indicate that the method is accurate, precise, sensitive, selective and reproducible. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of pesticides in dried minor tropical fruits from Colombia using the Quick,Easy, Cheap,Effective, Rugged,and Safe method‐gas chromatography–tandem mass spectrometry

The AOAC 2007.1 quick, easy, cheap, effective, rugged, and safe official method, together with gas chromatography coupled to a triple quadrupole mass spectrometer was applied for the analysis of 38 multiclass pesticides from dried fruits typically cultivated and exported from Colombia: uchuva (Physalis peruviana), lulo (Solanum quitoense), guanabana (Anona muricata), and pitahaya (Hylocereus undatus). The whole method was validated in terms of matrix‐matched calibration, matrix effect, and recovery using atrazine‐d₅ as internal standard, triphenylphosphate for quality control of the injection, and a proper mixture of analytes protectants. Matrix‐matched calibration data were found satisfactory for all pesticides and dried fruits, reporting R² values above 0.99. Matrix effect values evidenced the existence of such effect in most cases. The applied procedure gave satisfactory recovery percentages (70–120%) and relative standard deviation values (< 20%) for 92% of the 456 combinations pesticide/fruit studied (spiked levels of 25, 200, and 400 µg/kg). Finally, 20 real dried fruit samples were analyzed and residues of tebuconazole were found in two samples of uchuva at a concentration below the lowest calibration level of the method for one of them and at 10.8 ± 1.6 µg/kg for the other, being below or similar to the general maximum residue level established for monitoring purposes in food applications.     

Multiresidue analysis of 74 pesticides in fruits and vegetables by liquid chromatography–electrospray–tandem mass spectrometry

A multiresidue method is described for the determination of 74 pesticides commonly used in crop protection including mainly carbamate, conazole, benzimidazole and pyrimidine fungicides and insecticides. Pesticides residues are extracted from the samples with ethyl acetate. No additional clean-up steps are necessary. Analysis is performed by liquid chromatography–electrospray ionization–tandem mass spectrometry. The method has been validated for various fruits and vegetables matrices. Good sensitivity and selectivity of the method are obtained with limits of quantification of 0.01 mg/kg in almost all cases. Recoveries, RSD and accuracy values of the method fulfilled the criteria of validation commonly admitted. The method was applied very satisfactorily to routine analysis as a complement to traditional GC method. More than 2500 fruits and vegetables samples have been controlled, as a part of the pesticide monitoring program of the “Service de Protection de la Consommation” in Geneva. Quality control systems applied during the assays have demonstrated very good performances and stability with time.     

Indirect hydrogen analysis by gas chromatography coupled to mass spectrometry (GC–MS)

Gas chromatography (GC) is an analytical tool very useful to investigate the composition of gaseous mixtures. The different gases are separated by specific columns but, if hydrogen (H₂) is present in the sample, its detection can be performed by a thermal conductivity detector or a helium ionization detector. Indeed, coupled to GC, no other detector can perform this detection except the expensive atomic emission detector. Based on the detection and analysis of H₂ isotopes by low‐pressure chemical ionization mass spectrometry (MS), a new method for H₂ detection by GC coupled to MS with an electron ionization ion source and a quadrupole analyser is presented. The presence of H₂ in a gaseous mixture could easily be put in evidence by the monitoring of the molecular ion of the protonated carrier gas. Copyright © 2013 John Wiley & Sons, Ltd.     

Relationships between structure,ionization profile and sensitivity of exogenous anabolic steroids under electrospray ionization and analysis in human urine using liquid chromatography–tandem mass spectrometry

The relationships between the ionization profile, sensitivity, and structures of 64 exogenous anabolic steroids (groups I–IV) was investigated under electrospray ionization (ESI) conditions. The target analytes were ionized as [M + H]⁺ or [M + H–nH₂O]⁺ in the positive mode, and these ions were used as precursor ions for selected reaction monitoring analysis. The collision energy and Q3 ions were optimized based on the sensitivity and selectivity. The limits of detection (LODs) were 0.05–20 ng/mL for the 64 steroids. The LODs for 38 compounds, 14 compounds and 12 compounds were in the range of 0.05–1, 2–5 and 10–20 ng/mL, respectively. Steroids including the conjugated keto‐functional group at C3 showed good proton affinity and stability, and generated the [M + H]⁺ ion as the most abundant precursor ion. In addition, the LODs of steroids using the [M + H]⁺ ion as the precursor ion were mostly distributed at low concentrations. In contrast, steroids containing conjugated/unconjugated hydroxyl functional groups at C3 generated [M + H ? H₂O]⁺ or [M + H ? 2H₂O]⁺ ions, and these steroids showed relatively high LODs owing to poor stability and multiple ion formation. An LC‐MS/MS method based on the present ionization profile was developed and validated for the determination of 78 steroids (groups I–V) in human urine. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous determination of isomeric substituted anilines by imidization with benzaldehyde and gas chromatography–mass spectrometry

The chromatographic separation of several isomeric anilines is a challenging issue. Herein, a simple method for the simultaneous determination of four groups of isomeric primary aromatic amines, including chloroanilines, methylanilines, methoxylanilines, and dimethylanilines, was presented. In this method, all of the 15 primary aromatic amines were easily transformed into the corresponding imine derivative by treatment with benzaldehyde under mild conditions. The formed isomeric imine derivatives were completely separated on a commercial capillary gas chromatography column. The effects of several derivatization parameters were investigated and optimized. Linearity in the optimized method ranged from 0.050 to 50 μg/mL with the squared correlation coefficients (R²) between 0.9981 and 0.9999. Reasonable reproducibility was obtained, with the intraday relative standard deviation (N = 5) ranging from 0.89 to 4.57% and interday relative standard deviation ranging from 2.26 to 7.69% at the concentration of 5.0 μg/mL. The developed method has been successfully applied to determine these isomeric aromatic amines in real samples.     

Dynamic changes of metabolite accumulation in Scrophulariae Radix based on liquid chromatography–tandem mass spectrometry combined with multivariate statistical analysis

Scrophulariae Radix is one of the most popular traditional Chinese medicines. The harvesting time of Scrophulariae Radix is closely related to the quality of products in this traditional Chinese medicine. The goal of the study is to analyze the dynamic changes of metabolite accumulation in Scrophulariae Radix. The difference of constituents in Scrophulariae Radix harvested at different times was analyzed by liquid chromatography with triple quadrupole‐time of flight tandem mass spectrometry coupled with principal component analysis and partial least‐square discriminant analysis. According to the accurate mass of molecular and product ions provided by triple quadrupole‐time of flight tandem mass spectrometry, a total of 30 differential constituents were identified. Furthermore, the contents of ten index differential constituents in Scrophulariae Radix were simultaneously determined by liquid chromatography coupled with triple quadrupole‐linear ion trap tandem mass spectrometry. Gray relational analysis was performed to evaluate the samples harvested at different times according to the contents of ten constituents. All of the results demonstrated that the quality of Scrophulariae Radix collected at traditional harvest time was better. This study will provide the basic information for revealing the dynamic change law of metabolite accumulation of Scrophulariae Radix and exploring its quality forming mechanism.     

Phospholipid profiling of 57 soybean (Glycine max) varieties by high‐performance liquid chromatography–tandem mass spectrometry and principal component analysis to classify Korean soybean germplasm

Phospholipids (PLs) in 57 varieties of soybeans were profiled by high‐performance liquid chromatography–electrospray ionization‐tandem mass spectrometry and principal component analysis (PCA) to discriminate PL‐rich soybeans. The PL calibration curves showed linearity with correlation coefficients >0.9964. The recoveries at 5 mg/L spiked level ranged from 72.8 to 86.7% and those at 12.5 mg/L from 78.2 to 85.1%. The repeatability at a 5 mg/L spiked level ranged from 2.5 to 7.0% and those at 12.5 mg/L from 1.2 to 3.9%. The average total PL content in the 57 soybean varieties was about 35.3 mg/kg. The total PL content was the highest in Aodaiz (35, 48.7 ± 1.4 mg/kg) and the lowest in Poongsannamul (56, 16.0 ± 0.7 mg/kg). The PCA showed that RS‐78sun (42), Gyeongsang #1 (3) and Aodaiz (35) are the most improved varieties of the investigated 57 varieties from the viewpoint of PL content. Copyright © 2012 John Wiley & Sons, Ltd.     

Multi‐residue analysis of 44 pharmaceutical compounds in environmental water samples by solid‐phase extraction coupled to liquid chromatography‐tandem mass spectrometry

A solid‐phase extraction combined with a liquid chromatography‐tandem mass spectrometry analysis has been developed and validated for the simultaneous determination of 44 pharmaceuticals belonging to different therapeutic classes (i.e., antibiotics, anti‐inflammatories, cardiovascular agents, hormones, neuroleptics, and anxiolytics) in water samples. The sample preparation was optimized by studying target compounds retrieval after the following processes: i) water filtration, ii) solid phase extraction using Waters Oasis HLB cartridges at various pH, and iii) several evaporation techniques. The method was then validated by the analysis of spiked estuarine waters and wastewaters before and after treatment. Analytical performances were evaluated in terms of linearity, accuracy, precision, detection, and quantification limits. Recoveries of the pharmaceuticals were acceptable, instrumental detection limits varied between 0.001 and 25 pg injected and method quantification limits ranged from 0.01 to 30.3 ng/L. The precision of the method, calculated as relative standard deviation, ranged from 0.3 to 49.4%. This procedure has been successfully applied to the determination of the target analytes in estuarine waters and wastewaters. Eight of these 44 pharmaceuticals were detected in estuarine water, while 26 of them were detected in wastewater effluent. As expected, the highest values of occurrence and concentration were found in wastewater influent.     

Development and validation of a hydrophilic interaction chromatography–tandem mass spectrometry for quantification of nicotine and its metabolites in human maternal and cord sera

A selective and sensitive HILIC‐MS/MS method for the simultaneous quantification of nicotine and its metabolites in human maternal and cord sera was developed and validated. After solid‐phase extraction, LC separation was achieved on a hydrophilic interaction chromatography. The validated method is capable of selective identification as well as accurate and sensitive quantification. Analyte recovery ranged from 86.2 to 107.7% and intra‐ and inter‐day assay precision were less than 15% relative standard deviation. This sensitive HILIC‐MS/MS method can be used to determine nicotine and its metabolic profile in smokers. This validated method is useful for the determination of nicotine and its metabolites in human serum in future studies of the effects of nicotine exposure on neonatal outcome. Copyright © 2010 John Wiley & Sons, Ltd.     

Liquid chromatography‐tandem mass spectrometry method for determination of Sirolimus coated drug eluting nano porous carbon stents

Liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method has proved to powerful research tool due to its sensitivity, high selectivity, and high throughput efficiency..Sirolimus was extracted from plasma by two‐step extraction procedure using chloroform as extracting solvent. Signal intensity was high using ESI⁺ source provided for the quantitation of samples. Chromatographic separation was performed on phenomenax C‐18 column (250 × 4.60 mm 5microns).Mobile phase contains acetonitrile, water (80; 20 v/v) + 0.1% acetic acid, flow rate 1 mL/min.The retention time of Sirolimus 8.4 min, the total run time10 min. Linearity correlation coefficients (r²) curve was 0.997183.calibraction range 10–1000 ng/mL. The UV detection of Sirolimus was at 278(277.78) nm. Sirolimus coated drug eluting stents, MRM (Multiple reaction monitoring) transition of Sirolimus m/z 936.83–208.84 was selected to obtain maximum sensitivity. LC/MS/MS results exhibited consistency in drug content on the stent surface. In‐vitro release kinetic indicated the release of Sirolimus in 41 days from the date of implanted. Drug release was found at the first day, burst release was observed at 7^th day of implantation. This study involved pharmacological coating of stents, based on the notion that sustained systemic local delivery of anti‐proliferative agents. LC‐MS/MS method has been successfully used in the pharmacokinetic analysis of Sirolimus coated drug eluting stents. Copyright © 2009 John Wiley & Sons, Ltd.     

Investigation of sarin(Se) reactivity against human plasma proteins using liquid chromatography–tandem mass spectrometry

Electron ionization mass spectrum of sarin(Se) was interpreted in compare of sarin MS spectrum. Inhibition of butyrylcholinesterase of human plasma by sarin and sarin(Se) was determined spectrophotometrically using modified Ellman method. It appeared that after incubation with sarin and sarin(Se), cholinesterase inhibition were 93% and 83%, respectively. Sarin, sarin(Se), and sarin(Se)‐d₇ were spiked into a vial containing human plasma, and albumin adduct metabolites were identified using liquid chromatography–tandem mass spectrometry. The experiments show that these agents are attached to tyrosine on albumin in human blood. Corresponding deuterated adducts were used to confirm the proposed mechanisms for the formation of the fragments in mass spectrometry experiments.     

Simultaneous quantification of atenolol and chlorthalidone in human plasma by ultra‐performance liquid chromatography–tandem mass spectrometry

A simple, sensitive and reproducible ultra‐performance liquid chromatography–tandem mass spectrometry method has been developed for the simultaneous determination of atenolol, a β‐adrenergic receptor‐blocker and chlorthalidone, a monosulfonamyl diuretic in human plasma, using atenolol‐d7 and chlorthalidone‐d4 as the internal standards (ISs). Following solid‐phase extraction on Phenomenex Strata‐X cartridges using 100 μL human plasma sample, the analytes and ISs were separated on an Acquity UPLC BEH C₁₈ (50 mm × 2.1 mm, 1.7 µm) column using a mobile phase consisting of 0.1% formic acid–acetonitrile (25:75, v/v). A tandem mass spectrometer equipped with electrospray ionization was used as a detector in the positive ionization mode for both analytes. The linear concentration range was established as 0.50–500 ng/mL for atenolol and 0.25–150 ng/mL for chlorthalidone. Extraction recoveries were within 95–103% and ion suppression/enhancement, expressed as IS‐normalized matrix factors, ranged from 0.95 to 1.06 for both the analytes. Intra‐batch and inter‐batch precision (CV) and accuracy values were 2.37–5.91 and 96.1–103.2%, respectively. Stability of analytes in plasma was evaluated under different conditions, such as bench‐top, freeze–thaw, dry and wet extract and long‐term. The developed method was superior to the existing methods for the simultaneous determination of atenolol and chlorthalidone in human plasma with respect to the sensitivity, chromatographic analysis time and plasma volume for processing. Further, it was successfully applied to support a bioequivalence study of 50 mg atenolol + 12.5 mg chlorthalidone in 28 healthy Indian subjects. Copyright © 2015 John Wiley & Sons, Ltd.