Ultra-performance Liquid Chromatography-mass Spectrometry Method Research Articles

Ultra-performance liquid chromatography-mass spectrometry methods for the determination of the residual quantities of ramipril and hydrochlorothiazide for controlling the cleaning of equipment

Monitoring the completeness of equipment cleaning is essential to prevent cross-contamination of medicinal products. Therefore, it is necessary to develop fast and sensitive methods for studying residual quantities of active ingredients on the surfaces of technological equipment. The aim of the work was to develop and validate analytical methods for the determination of ramipril and hydrochlorothiazide in wash waters by ultra-performance liquid chromatography–mass spectrometry method. Materials and methods. In the study, standard samples of ramipril (USP RS) and hydrochlorothiazide (USP RS), as well as class A reagents, were used. Samples were analysed on a liquid chromatograph with an MS detector (Agilent 6420 and Waters Xevo TQD ACQUITY). We used the Kinetex C18 column (2.1 mm × 30 mm × 1.7 μm); mobile phase – 0.1% formic acid solution in deionised water – Acetonitrile (ratio 73:27 for the determination of ramipril and 91.5:8.5 for the determination of hydrochlorothiazide); mobile phase rate of 0.4 mL/min for the determination of ramipril and 0.35 mL/min for the determination of hydrochlorothiazide; column temperature 45 °C for the determination of ramipril and 40 °C for the determination of hydrochlorothiazide, ionisation mode - electric spray in positive mode; The detection parameters are the mode of registration of the daughter ion 417 → 234 m/z for the determination of ramipril and 298 → 281 m/z for the determination of hydrochlorothiazide. Results and discussion. Methods for the determination of ramipril and hydrochlorothiazide in wash waters by ultra-performance liquid chromatography–mass spectrometry have been developed. The developed methods have sufficient linearity, correctness and precision. The sensitivity of the techniques was confirmed at the level of 0.0026 μg/ml. The techniques can be used in the concentration range of 0.0026 – 0.0255 μg/ml Conclusions. Analytical methods for determining ramipril and hydrochlorothiazide in wash waters have been developed and validated.

Metabolomics analysis of patients with Schistosoma japonicum infection based on UPLC-MS method

BackgroundSchistosomiasis is still one of the most serious parasitic diseases. Evidence showed that the metabolite profile in serum can potentially act as a marker for parasitic disease diagnosis and evaluate disease progression and prognosis. However, the serum metabolome in patients with Schistosoma japonicum infection is not well defined. In this study, we investigated the metabolite profiles of patients with chronic and with advanced S. japonicum infection.MethodsThe sera of 33 chronic S. japonicum patients, 15 patients with advanced schistosomiasis and 17 healthy volunteers were collected. Samples were extracted for metabolites and analyzed with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS).ResultsWe observed significant differences in metabolite profiles in positive and negative ion modes between patients with advanced and chronic S. japonicum infection. In patients with chronic S. japonicum infection, 199 metabolites were significantly upregulated while 207 metabolites were downregulated in advanced infection. These differential metabolites were mainly concentrated in steroid hormone biosynthesis, cholesterol metabolism and bile secretion pathways. We also found that certain bile acid levels were significantly upregulated in the progression from chronic to advanced S. japonicum infection. In receiver operator characteristic (ROC) analysis, we identified three metabolites with area under the curve (AUC) > 0.8, including glycocholic (GCA), glycochenodeoxycholate (GCDCA) and taurochenodeoxycholic acid (TCDCA) concentrated in cholesterol metabolism, biliary secretion and primary bile acid biosynthesis.ConclusionsThis study provides evidence that GCA, GCDCA and TCDCA can potentially act as novel metabolite biomarkers to distinguish patients in different stages of S. japonicum infection. This study will contribute to the understanding of the metabolite mechanisms of the transition from chronic to advanced S. japonicum infection, although more studies are needed to validate this potential role and explore the underlying mechanisms.Graphical

An eco-friendly ultra-performance liquid chromatography-mass spectrometry method for quantification of rivaroxaban and ticagrelor in rat plasma: grapefruit interactions.

Aim: An eco-friendly ultra-performance liquid chromatography-tandem mass spectrometry method was developed to study the pharmacokinetics of rivaroxaban and ticagrelor in rat plasma, utilizing moxifloxacin as an internal standard. The food-drug interaction between grapefruit juice and these drugs was also investigated. Methods: Liquid-liquid extraction was used. A nonporous stationary phase Agilent® Poroshell 120EC C18 column was used with methanol: 0.1% aqueous formic acid (95:5 v/v) as a mobile phase. The detection was performed in multiple reaction monitoring mode using positive electrospray ionization. The method's validation was conducted in accordance with US FDA and European Medicines Agency guidelines. Results & conclusion: Grapefruit juice should be ingested with caution in patients treated with antithrombotic medications as it may increase their plasma concentration, inducing bleeding, and requires close clinical monitoring.

Screening and identification of anti-acetylcholinesterase ingredients from Tianzhi granule based on ultrafiltration combined with ultra-performance liquid chromatography-mass spectrometry and in silico analysis

Ethnopharmacological relevanceTianzhi granule (TZG) is a traditional Chinese formula that is widely used for the treatment of vascular dementia (VaD). Aim of the studyTo discover the herbs in TZG possessing acetylcholinesterase (AChE) inhibitory activity and to screen the anti-acetylcholinesterase ingredients from active herbs. Materials and methodsIn vitro AChE inhibitory activity assay of eleven herbal extracts was conducted. An ultrafiltration combined with ultra-performance liquid chromatography-mass spectrometry method was established to screen and identify the anti-acetylcholinesterase ingredients from active extracts. In addition, in vitro AChE inhibitory activity assay and molecular docking were adopted for further investigation. Moreover, ultra-performance liquid chromatography-mass spectrometry was performed for the content determination of active compounds in TZG. ResultsThree herbs in TZG showed significant AChE inhibitory activity. A total of thirteen active ingredients were screened out and identified, and all of these compounds were present in TZG. Five available commercial standards presented moderate AChE inhibitory activity, and all of which have a relatively high content in TZG. ConclusionA number of herbs and compounds with acetylcholinesterase inhibitory activity were found in TZG, which provided a scientific basis for the material basis and quality control research of TZG.

Simultaneous Determination of Alogliptin, Linagliptin, Saxagliptin, and Sitagliptin in Bulk Drug and Formulation by UPLC Q-TOF-MS

Background: A simple and sensitive Ultra Performance Liquid Chromatography-Mass Spectrometry method was developed and validated to measure the concentrations of Alogliptin (ALO), Linagliptin (LIN), Saxagliptin (SAX), and Sitagliptin (SIT) using Pioglitazone (PIO) as an internal standard. Methods: Chromatographic separation of six gliptins was achieved on a C-18 column (100×2.1 mm, 2.7 μm) using a mobile phase consisting of formic acid in water, 0.1%v/v: acetonitrile in gradient elution. Electrospray ionization (ESI) source was operated in the positive ion mode. Targeted MS/MS mode on a QTOF MS was used to quantify the drug utilizing the transitions of 340.1(m/z), 473.2 (m/z), 316.2 (m/z), 408.1 (m/z), and 357.1 (m/z) for ALO, LIN, SAX, SIT and PIO respectively. Results: As per ICH Q2R1 guidelines, a detailed validation of the method was carried out and the standard curves were found to be linear over the concentration ranges of 1516.0-4548.1 ng mL-1, 519.8- 1559.4 ng mL-1, 1531.4-4594.3 ng mL-1and 1519.6-4558.8 ng mL-1 for ALO, LIN, SAX and SIT respectively. Precision and accuracy results were within the acceptable limits. The mean recovery was found to be 98.8 _ 0.76 % (GEM), 102.2 _ 1.59 % (LIN), 95.3 _ 2.74 % (SAX) and 99.2 _ 1.75 % (SIT) respectively. Conclusions: The optimized validated UPLC QTOF-MS/MS method offered the advantage of shorter analytical times and higher sensitivity and selectivity. The optimized method is suitable for application in quantitative analysis of pharmaceutical dosage forms for QC laboratory.

Development of Ultra-Performance Liquid Chromatography-Mass Spectrometry Method for Simultaneous Determination of Three Cationic Dyes in Environmental Samples.

Lower dye concentrations and the presence of several dyes along with other matrices in environmental samples restrict their determination. Herein, a highly sensitive and rapid ultra-performance tandem mass spectrometric method was developed for simultaneous determination of cationic dyes, namely methylene blue (MB), rhodamine B (RB) and crystal violet (CV), in environmental samples. To preconcentrate environmental samples, solid-phase extraction cartridges were developed by using hydrogen peroxide modified pistachio shell biomass (MPSB). The surface morphological and chemical functionalities of MPSB were well characterized. The developed method was validated considering different validation parameters. In terms of accuracy and precision, the %RSD for all three dyes at all four concentration points was found to be between 1.26 and 2.76, while the accuracy reported in terms of the recovery was found to be 98.02%-101.70%. The recovery was found to be in the range of 98.11% to 99.55%. The real sample analysis shows that MB, RB, and CV were found in the ranges of 0.39–5.56, 0.32–1.92 and 0.27–4.36 μg/mL, respectively.

Development and Validation of a Rapid and Sensitive Method for the Simultaneous Estimation of Gemigliptin and Teneligliptin in Bulk and Dosage Forms by Using Liquid Chromatography-tandem Mass Spectrometry

Background: A simple and sensitive ultra-performance liquid chromatography-mass spectrometry method was developed and validated to measure the concentrations of gemigliptin (GEM) and teneligliptin (TEN) using pioglitazone (PIO) as an internal standard. Methods: Chromatographic separation of two gliptins was achieved on a C-18 (100 mm X 2.1 mm, 2.7 μm) column using a mobile phase consisting of formic acid in water (0.1 % v/ v): acetonitrile in gradient elution. Electrospray ionization (ESI) source was operated in positive mode (ionization). Targeted MS-MS mode on a quadrupole time of flight (Q-TOF) mass spectrometer was used to quantify the drugs utilizing the mass transitions of 490.1 (m/z), 427.2 (m/z) and 357.1 (m/z) for GEM, TEN and PIO, respectively. Results: As per ICH Q2R1 guidelines, a detailed validation of the method was carried out and the standard curves were found to be linear between the concentration ranges of 509.8-1529.4 ng mL-1 and 510.6-1531.7 ng mL-1 for GEM and TEN, respectively. Precision and accuracy results were found to be within the acceptable limits. The mean recovery was found to be 98.8± 0.76 % (GEM) and 98.6 ±0.98 % (TEN), respectively. Conclusions: The optimized validated UPLC-QTOF (MS-MS) method offered the advantage of shorter analytical times and higher sensitivity and selectivity to the nanogram level.

Colostral and mature breast milk protein compositional determinants in Qingdao, Wuhan and Hohhot: maternal food culture, vaginal delivery and neonatal gender.

Breast milk proteins are essential to infants as they provide nutrition and protection. This study evaluated multiple factors that might influence breast milk proteins to identify the determinants that lead to inter-individual and longitudinal differences. Five major breast milk proteins (β-casein, α-lactalbumin, lactoferrin, serum albumin and κ-casein) from breast milk samples collected from 55 mothers in three cities (Hohhot, Wuhan and Qingdao) in China were analyzed using a validated ultraperformance liquid chromatography-mass spectrometry method. Various factors were statistically evaluated for their associations with breast milk proteins: mother's age, parity, delivery mode, infant gender and infant birthweight. Although decreased in concentrations, the proportions of β-casein and α-lactalbumin increased from colostrum (33.8% and 26.8%) to mature milk (40.3% and 31.6%), respectively. Mothers of older age were found to produce a lower concentration of total protein. Compared with vaginal delivery, caesarean section was associated with lower concentrations of κ-casein, lactoferrin and β-casein in mature milk. Infant gender influenced breast milk proteins in colostrum: mothers who delivered a girl tended to produce more κ-casein, lactoferrin and total protein. Furthermore, regional differences were found, and mothers from Hohhot produced significantly higher concentrations of α-lactalbumin and lactoferrin than those from Qingdao and Wuhan. This regional difference might be linked to the different dietary patterns of these mothers among cities. Our study deepens the understanding of breast milk protein dynamics in Chinese population and provides evidence on potential determinants, which can serve as guidance for infant nutrition optimization.

In vivo microdialysis with ultra performance liquid chromatography-mass spectrometry for analysis of tetramethylpyrazine and its interaction with borneol in rat brain and blood.

Tetramethylpyrazine (TMP) has been widely used in the treatment of ischemic cerebrovascular disease. However, the mechanism of TMP and how to increase its bioavailability need to be further explored. In our study, an in vivo microdialysis sampling technique coupled with ultra-performance liquid chromatography-mass spectrometry method was developed to investigate the pharmacokinetic properties of TMP and its interaction with different doses of borneol (BO) in rats. Linearity of TMP in brain and blood dialysates exhibited good linear relationships over the concentration range of 0.991-555.14 ng/mL. The specificity, linearity, accuracy, precision, matrix effect and stability were within acceptable ranges. The results demonstrated that BO had a marked impact on the pharmacokinetic properties of TMP. After co-administration, the areas under the concentration-time curve (AUC) of TMP in brain and blood were significantly increased. Meanwhile, the peak concentration of TMP in brain was also enhanced. The AUCBrain /AUCBlood of TMP, increased from 44% to 56 and 60.8% after co-administration with BO (15 and 30 mg/kg). The pharmacodynamic results showed that TMP co-administration with BO enhanced the cerebral blood flow during the period of ischemia and reduced the infarct volume. Overall, it might be an effective way to treat stroke to use TMP co-administered with BO.

Comparative pharmacokinetics of acteoside from total glycoside extracted from leaves of Rehmannia and Dihuangye total glycoside capsule in normal and diabetic nephropathy rats.

Rehmannia glutinosa Libosch (RG), is officially listed in the Chinese Pharmacopoeia and is widely used in China. In this paper, a sensitive and rapid ultra-performance liquid chromatography-mass spectrometry method including multiple-reaction monitoring mode was developed and applied to study the pharmacokinetic effect of acteoside from total glycoside extracted from the leaves of Rehmannia (TLR) and Dihuangye total glycoside capsule (DTG) in normal and diabetic nephropathy rats. The diabetic nephropathy rat model was induced by intraperitoneal injection of a small dose of streptozotocin and high-fat diet and plus 5% glucose drinking water. Samples of plasma of rats were obtained at different times after rats were administered TLR (7.2 g/kg) and DTG (360 mg/kg). After deproteinization by acetonitrile, the concentrations of acteoside in rats at different time points were detected by UPLC-TQ-MS method and pharmacokinetics parameters were calculated using DAS 3.2.8 software. A good linearity of acteoside was shown in the range of 8.51-3404.8 ng/m L (r2 = 0.9987). The mean extraction recovery of analyte was in the range of 63.55-79.49%, and the intra- and inter-day RSD values were <8.8%. Compared with the normal group, the maximum plasma concentration, AUC0-t , AUC0-∞ and apparent plasma clearance corresponding dose in model group rats decreased significantly. After rats were administered TLR and DTG, the acteoside reached the maximum plasma concentration at about 15 min. The method proved to be simple, rapid and specific, and to be suitable for the determination of acteoside in plasma of diabetic nephropathy rats and pharmacokinetic study.

Mass Spectrometric Characterization of an Acid-Labile Adduct Formed with 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and Albumin in Humans.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogenic heterocyclic aromatic amine formed during the high-temperature cooking of meats. The cytochrome P450-mediated N-hydroxylation of the exocyclic amine group of PhIP produces 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine, an electrophilic metabolite that forms adducts with DNA and proteins. Previous studies conducted by our laboratory showed that the reaction of N-oxidized PhIP metabolites with human albumin in vitro primarily occurs at the Cys34 residue, to produce an acid-labile linked sulfinamide adduct. On the basis of these findings, we developed a sensitive ultraperformance liquid chromatography-mass spectrometry method to measure acid-labile albumin-PhIP adducts in human volunteers administered a dietary-relevant dose of 14C-labeled PhIP [Dingley, K. H., et al. (1999) Cancer Epidemiol., Biomarkers Prev. 8, 507-512]. Mild acid treatment of albumin (0.1 N HCl, 37 °C for 1 h) or proteolytic digestion with Pronase [50 mM ammonium bicarbonate buffer (pH 8.5) at 37 °C for 18 h] released similar amounts of covalently bound PhIP, which was characterized by multistage scanning and quantified by Orbitrap mass spectrometry. The amount of [14C]PhIP recovered by acid treatment of albumin 24 h following dosing accounted for 7.2-21.3% of the [14C]PhIP bound to albumin based on accelerator mass spectrometry measurements. 2-Amino-1-methyl-6-(5-hydroxy)phenylimidazo[4,5-b]pyridine, a hydrolysis product of the Cys34 S-N linked sulfenamide adduct of PhIP, was not detected in either acid-treated or protease-treated samples. These findings suggest that a portion of the PhIP bound to albumin in vivo probably occurs as an acid-labile sulfinamide adduct formed at the Cys34 residue.

Survey on fungi contamination and natural occurrence of mycotoxins in 94 corn feed ingredients collected from China

Objective: To investigate fungi contamination and the natural occurrence of mycotoxins in corn feed ingredients collected from China. Methods: A total of 94 corn feed ingredient samples were collected from 8 Chinese provinces(i.e., Anhui, Hebei, Heilongjiang, Jilin, Jiangsu, Liaoning, Inner Mongolia, and Shandong)in February 2014. A tandem ultra-performance liquid chromatographymass spectrometry method was used for simultaneous detection of twelve kinds of mycotoxins, including aflatoxin(AF), type A and type B tricothecenes, and zearalenone(ZEN). Contaminated fungi were also identified and counted. Results: AF was detected in 36.2%(34/94)of samples; the concentration of AFB1 was the highest in the four AFs with the range: 0.3~181.3 μg/kg; and then followed by AFB2(range: 1.0-74.3 μg/kg). There were 7 samples(7.5%)with AFB1 concentrations higher than the tolerance limit of 50 μg/kg. The concentration of type A tricothecenes in all samples was lower(0.1-10.5 μg/kg). DON had the most serious contamination than other kind of type B tricothecenes(range: 0.7-606.6 μg/kg; median: 66.3 μg/kg). The DON concentration in all samples was below the tolerance limit of 1 000 μg/kg. ZEN was detected in 76.6%(72/ 94)of samples(median: 36.9 μg/kg), with 3 samples having ZEN concentrations higher than the tolerance limit of 500 μg/kg. The survey on fungi contamination showed that all samples were contaminated by fungi(range: 5.0-1.4×105 CFU/g). There were 18 and 3 samples with quantities of fungi higher than the tolerance and forbidden limits, respectively. The Aspergillus, Penicillium, Fusarium, Trichoderma and Mucor genuses were the predominant fungi in corn feed ingredients, with detection rates of 71.3%(67), 60.6%(57), 71.3%(67), 27.7%(26), and 24.5%(23), respectively. The detection rate of Fusarium moniliforme, 73.4%(69/94)was higher than that of Aspergillus flavus, 41.5%(39/94). Conclusion: In this survey, the corn feed ingredients were not seriously contaminated by AF and type A tricothecenes but mainly contaminated by type B trichothecenes, including DON and its derivatives, as well as ZEN. They were also contaminated by fungi such as Aspergillus, Penicillium, and Fusarium.

In Vitro Characterization of the Human Liver Microsomal Kinetics and Reaction Phenotyping of Olanzapine Metabolism.

Olanzapine (OLZ) is an atypical antipsychotic used in the treatment of schizophrenia and related psychoses. The metabolism of OLZ is complex and incompletely characterized. This study aimed to elucidate the enzymes and pathways involved in the metabolism of OLZ and to determine the kinetics of OLZ oxidation and glucuronidation by human liver microsomes, recombinant cytochrome P450 (rP450) enzymes, and recombinant UDP-glucuronosyltransferase (rUGT) enzymes. An ultra-performance liquid chromatography-mass spectrometry method was developed and validated to quantify OLZ, its four oxidative metabolites (N-desmethyl-OLZ, 2-hydroxymethyl-OLZ, 7-hydroxy-OLZ, and OLZ-N-oxide), and two N-glucuronides (OLZ-10-N-glucuronide and OLZ-4'-N-glucuronide). Consistent with previous reports, UGT1A4, CYP1A2, and flavin-containing monooxygenase 3 play major roles in catalyzing the formation of OLZ-10-N-glucuronide, 7-hydroxy-OLZ, and OLZ-N-oxide, respectively. In addition, a previously uncharacterized major contribution of CYP2C8 to OLZ-N-demethylation was demonstrated. The kinetics of OLZ metabolite formation (Km and Vmax) by human liver microsomes, rP450 enzymes, and rUGT enzymes were characterized in the presence of bovine serum albumin [2% (w/v)]. Consistent with the known effect of bovine serum albumin on CYP1A2, CYP2C8, and UGT1A4 activities, Km values reported here are lower than previously reported values for OLZ metabolic pathways. In addition to CYP1A2-mediated OLZ-N-demethylation, these results suggest that other P450 enzymes, particularly CYP2C8, contribute significantly to oxidative OLZ metabolism through catalysis of OLZ-N-demethylation.

The use of library identification and common fragments for the identification of corticosteroids in forensic samples

The detection of corticosteroids and sex steroids in samples with no content indication, which are confiscated for forensic investigation, is a challenge in doping analysis. A screening method based on the identification of androgens, estrogens, gestagens, and their esters by means of a mass spectral library, along with a fast ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method, was recently developed in our lab for the analysis of dietary supplements. However, for forensic investigations, it is important to extend the scope of the method to corticosteroids in various matrices. Therefore, 36 corticosteroids were added to the mass spectral library, and the sample preparation step was modified so that androgens, gestagens, corticosteroids, and their esters could be analyzed with only one injection with the UPLC-MS method. A complementary tool to the existing library identification was found in the extraction of common fragment ions out of the full scan data obtained for the library search. The fragment ion with m/z 147 was found to be a good marker for the detection of steroids. Extra confirmation was obtained from the fragment ions with m/z 135 (for all steroids) and 237 (specific for corticosteroids) or from the fragment ions with m/z 77, 91, and 105. The effectiveness of this approach was evaluated on some samples previously screened for forensic investigation with thin-layer chromatography and confirmed with a targeted gas chromatography-mass spectrometry method. This study shows that the combination of the library identification and the common fragment ions approach can be a valuable tool in the detection of steroids without defining any target at the start of the analysis.

Determination of acrylamide in food by gas and liquid chromatography-mass spectrometry

Acrylamide in food was determined by gas chromatography - mass spectrometry (GC-MS) after bromination of acrylamide and underivatized acrylamide was quantified by ultra performance liquid chromatography -mass spectrometry (UPLC-MS). Two different sample preparation methods were used and optimised. The GC-MS method was used for various food matrices like breads, potato crisps, potato crackers, french fries. The UPLC-MS method was used for analysis of coffee. The limit of detection and limit of quantification for acrylamide were 7 µg.kg-1 and 20 µg.kg-1 by GC-MS, 9 µg.kg-1 and 30 µg.kg-1 by UPLC-MS. For both methods the reproducibility, given as relative standard deviation was &lt; 5% , and the recovery was close to 100 %.

Urinary Excretion Study of Coenzyme Q10 in Rats by Ultra-Performance Liquid Chromatography-Mass Spectrometry

A method based on ultra-performance liquid chromatography mass spectrometry (UPLC-MS) applying atmospheric pressure chemical ionization in the positive ion mode is developed for the determination of coenzyme Q10 (CoQ10) in rat urine. The assay involves the extraction of crude urine, fast liquid chromatography on a Waters Acquity UPLC BEH C18 column (1.7 microm, 1.0 x 50 mm), and selected ion monitoring detection using mass transition. The calibration range is found to be 0.05-25 microg/mL, with the lower limit of quantitation of 0.05 microg/mL. Intra- and inter-day precision (relative standard deviation) for CoQ10 in rat urine range from 0.7% to 15%, and accuracy expressed in recovery rates in urine is between 83% and 118%. The recovery of this method is found to be between 80% and 95% at three concentrations. The total cumulative recovery of CoQ10 is 1.16 +/- 1.05% (percentage of dose intake, n = 4) from rat urine collected over 30 h after oral administration of the drug. The UPLC-MS method described allows the quick determination of CoQ10 in rat urine with good precision and accuracy. It is suitable for further excretion studies of CoQ10 in animals.

Simultaneous determination of benzo[ a]pyrene and eight of its metabolites in Fundulus heteroclitus bile using ultra-performance liquid chromatography with mass spectrometry

A sensitive and fast method was developed to quantitate the carcinogenic polycyclic aromatic hydrocarbon benzo[ a]pyrene (BaP) and eight of its oxidized metabolites by ultra-performance liquid chromatography (UPLC) coupling with mass spectrometry (MS). The UPLC method, using an acetonitrile:water gradient as a mobile phase, provided baseline separation of the BaP metabolites including three BaP diones. Linearity of detection was in the range of 0.2–5.0 ng/μL, and limits of detection (LOD) were lower than 0.01 ng/μL for BaP and all of the metabolites except BaP tetrol. In order to test this method in environmentally relevant samples, we exposed the small fish Fundulus heteroclitus to BaP and quantitated biliary BaP metabolites. Extraction recovery of all compounds varied from 65.4 ± 21.3% to 92.4 ± 3.0%. In exposed fish bile, the BaP diones, BaP-7,8-dihydrodiol, and 3-hydroxy BaP metabolites predominated, existing mainly as glucuronic acid conjugates. This UPLC–MS method will be useful for further defining the roles of cytochrome P450s with both in vivo and in vitro models in the understanding of the mechanisms of metabolic activation and detoxification of BaP.

Development of an ultra-performance liquid chromatography–mass spectrometry method for the detection of lipophilic marine toxins

A rapid method for the detection of marine toxins was developed using an ultra-performance liquid chromatography (UPLC) system coupled to a latest generation mass spectrometry (MS) system. The analysis of 21 lipophilic marine toxins was achieved on an Acquity C18 column using a water–acetonitrile gradient with a cycle time of 6.6 min, reducing analysis time by more than a factor two compared to HPLC while maintaining peak resolution. Linear ranges, limits of detection and limits of quantification were established for okadaic acid (OA), pectenotoxin-2, azaspiracid-1 (AZA1), yessotoxin, gymnodimine and 13-desmethylspirolide C. The method was found to be accurate when using a triplicate methanolic extraction. Matrix effects were assessed by standard addition of OA and AZA1 in extracts of raw and heat-treated flesh of mussels and oysters. For the analysis of AZA1, the UPLC–MS method was always prone to signal suppression, while for OA analysis signal suppression was observed in extracts of raw shellfish flesh and signal enhancement in extracts of heat-treated flesh. Matrix effects occurring in the method presented are diminished compared to previous studies.