Rapid Resolution Liquid Chromatography-tandem Mass Research Articles

Assessment of carbonic anhydrase 3 as a marker for meat authenticity and performance of LC-MS/MS for pork content

In recent years, food fraud is a global issue that has raised wide public concern. Mass spectrometry techniques have a significant advantage of qualitatively and quantitatively analyzing food authenticity, especially for highly processed meat products. In this work, a simple and specific, rapid resolution liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed and validated for the determination of pork content in processed meat products according to internal standard (ISTD) method. To improve the efficiency of sample preparation, simplified bead-beating and enzymolysis process were investigated. In contrast with different heat-stable and specific porcine-peptides, EPITVSSDQMAK, GGPLTAAYR, HDPSLLPWTASYDPGSAK from Carbonic anhydrase 3 proved to have an excellent quantitative ability, thus obtaining good linear relationship and satisfactory recovery. This method was successfully applied to different types of meat products, thus demonstrating that complex mixtures of pork content can be accurately quantified.

Development of an LC-MS/MS method for quantitative analysis of Chlorogenic acid in human plasma and its application to a pharmacokinetic study in Chinese patients with advanced solid tumor

A simple and specific, rapid resolution liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was developed and validated for determination of chlorogenic acid in human plasma using neochlorogenic acid as the internal standard. Plasma samples were precipitated with methanol and separated on a Zorbax C18 column (50 × 2.1 mm, i.d. 1.8 μm) at a flow rate of 0.4 mL/min using a gradient mobile phase of methanol-water containing 0.1% formic acid (v/v). The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring in negative ESI mode. The method was fully validated over the concentration range of 10–2000 ng/mL. The indicators of inter- and intra-day precision (RSD%) were all within 10.7%, and the accuracy (RE%) was ranged from -3.0% to 10.6%. Moreover, we evaluated this bioanalytical method by re-analysis of incurred samples as an additional measure of assay reproducibility. This method was successfully applied to pharmacokinetic study of CGA in Chinese subjects with advanced solid tumor after intramuscular injection administration of Chlorogenic acid for injection (CAFI).

Microdialysis combined with RRLC–MS/MS for the pharmacokinetics of two major alkaloids of Bi qi capsule and the potential roles of P-gp and BCRP on their penetration

Bi qi capsule (BQC) is a traditional Chinese medicine prescription that is clinically used for the treatment of rheumatoid arthritis. Strychnine and brucine, as two typical kinds of alkaloids, are the primary active and neurotoxic constituents of BQC. In this study, a sensitive and reliable rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) quantitative method was used to determine the concentrations of brucine and strychnine in rat brain and blood dialysates. The blood-brain barrier (BBB) penetration of free brucine and strychnine and their pharmacokinetic characteristics were investigated by the validated RRLC-MS/MS method coupled with in vivo microdialysis for the first time. The dialysate brain-blood AUC ratios of brucine were 0.098, 0.44 and 0.40 respectively at 0.4, 0.8 and 1.6 g kg−1 doses of BQC, and the dialysate brain-blood AUC ratios of strychnine were 0.20, 1.25 and 2.06 respectively at 0.4, 0.8 and 1.6 g kg−1 doses of BQC. The high brain-blood AUC ratios of brucine and strychnine were observed in medium and high dose groups of BQC. In addition, the effects of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) on brucine and strychnine across BBB were also studied using the above method as well as molecular docking. The results prompted that brucine was the substrate of P-gp, and strychnine might be the inhibitor of P-gp. Brucine and strychnine showed high brain penetration, so it is very important to well control the clinic dosage of BQC and manufactory quality for avoiding the side effects and obtaining good therapeutic efficacy. Our study could be further used in investigating BBB penetration for other drugs caused neurotoxicity.

Quality Control of the Fuzi Lizhong Pill Through Simultaneous Determination of 16 Major Bioactive Constituents by RRLC-MS-MS.

Fuzi Lizhong pill (FLP) is used to treat gastritis, and the monarch drug of it is Aconiti Lateralis Radix Praeparata (Fuzi, aconite roots) which is a toxic herbal medicine. To better control the safety and quality of FLP, an effective method to analyze the contents of 16 toxic and bioactive components using rapid resolution liquid chromatography-tandem triple-quadrupole mass spectrometer was established. The 16 constituents included aconine, mesaconine, hypaconitine, benzoylaconine, benzoylmesaconine, benzoylhypaconine, adenosine, liquiritin, liquiritigenin, glycyrrhizic acid, isoliquiritigenin, 6-gingerol, atractylenolide III, atractylenolide I, atractylenolide II and glycyrrhetic acid. Ideal separation was performed using gradient elution in 13 min by optimized conditions. All the isomerides were isolated to baseline. The improved method with a polarity switch in contiguous time segments could analyze the five types of components, including polar and nonpolar compounds, without decreasing sensitivity. The proposed method was fully validated. The results revealed that contents of six alkaloids from Fuzi were significantly different among the samples. Using the established method and multivariate statistical method, the quality consistency of two dosage forms of FLP from different companies were analyzed. The optimized method could be used for the quality control of FLP and investigate index compound variation between two dosage forms.

Antibiotics in Crab Ponds of Lake Guchenghu Basin, China: Occurrence, Temporal Variations, and Ecological Risks

Antibiotics are widely used in aquaculture, however, this often results in undesirable ecological effects. To evaluate the occurrence, temporal variations, and ecological risk of antibiotics in five crab ponds of Lake Guchenghu Basin, China, 44 antibiotics from nine classes were analyzed by rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS). Twelve antibiotics belonging to six classes were detected in the aqueous phase of five crab ponds, among which sulfonamides and macrolides were the predominant classes, and six compounds (sulfamonomethoxine, sulfadiazine, trimethoprim, erythromycin-H2O, monensin, and florfenicol) were frequently detected at high concentrations. In general, the antibiotic levels varied between different crab ponds, with the average concentrations ranging from 122 to 1440 ng/L. The antibiotic concentrations in crab ponds exhibited obvious seasonal variations, with the highest concentration and detection frequency detected in summer. Multivariate analysis showed that antibiotic concentrations were significantly correlated with environmental variables, such as total organic carbon, phosphate, ammonia nitrogen, and pH. Sulfadiazine, clarithromycin, erythromycin-H2O, and ciprofloxacin posed a high risk to algae, while the mixture of antibiotics could pose a high risk to aquatic organisms in the crab ponds. Overall, the usage of antibiotics in farming ponds should be comprehensively investigated and controlled to preserve a healthy aquaculture ecosystem.

Pharmacokinetic Comparisons of Typical Constituents in Curcumae Rhizoma and Vinegar-Processed Curcumae Rhizoma after Oral Administration to Rats.

The Raw Curcumae Rhizoma (R-CR), included in the Chinese Pharmacopoeia Edition 2015, is a well-known Chinese herbal medicine. However, the vinegar-processed Curcumae Rhizoma (V-CR) is used more widely than R-CR. The pharmacokinetics comparison of R-CR and V-CR after oral administration to rats is poorly understood. A novel method, rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS) coupled with a sensitive, specific, and convenient microdialysis sampling method, free from endogenous interference was developed in this research. The extracts of R-CR and V-CR were administered orally to each group of rats. The blood and liver microdialysis probes were positioned within the jugular vein toward the right atrium and the median lobe near the center of the liver, respectively. Then, a double-peak phenomenon was observed in the concentration-time curves of curdione in R-CR group, while it was not observed in V-CR group. The liver-to-blood distribution ratio of curdione in V-CR group increased significantly (P < 0.05) compared to that of R-CR group. However, compared with V-CR group, the pharmacokinetic parameters of curcumol exhibited no statistically significant differences from those of R-CR group. These results indicate that vinegar-processed procedure has influence on the pharmacokinetic process of Curcumae Rhizoma in/ns. RRLC-MS coupled with microdialysis system could be used to evaluate the pharmacokinetics of typical constituents in Curcumae Rhizoma after oral administration.

Occurrence, source analysis and risk assessment of androgens, glucocorticoids and progestagens in the Hailing Bay region, South China Sea

The occurrence and spatial distribution of 40 steroids in the environmental matrices of the Hailing Bay region, South China Sea, were investigated by rapid resolution liquid chromatography–tandem mass spectrometry (RRLC–MS/MS). Seventeen, 14 and 11 of 40 steroids were detected with the concentrations ranging from 0.04 (testosterone) to 40.00ng/L (prednisolone), 1.33 (4-hydroxy-androst-4-ene-17-dione) to 1855ng/L (androsta-1,4-diene-3,17-dione) and <0.19 (androsta-1,4-diene-3,17-dione) to 2.37ng/g (progesterone) in the seawater, the municipal sewage discharged effluent and the sediment samples, respectively. The concentrations and risk quotients (RQs) of the steroids detected in the water samples decreased in the order of municipal sewage discharge site>wharves~aquaculture zones~tourism areas>offshore areas. The distribution of steroids in the marine environment was significantly correlated with the levels of chemical oxygen demand (COD) and ammonium nitrogen (NH4-N). Source analysis indicated that untreated municipal sewage was the main source of steroids in the marine environment. Furthermore, progesterone was found to be a reliable chemical indicator to surrogate different steroids in both the water and sediment phases based on the correlation analysis.

LC–MS/MS determination and pharmacokinetic study of seven flavonoids in rat plasma after oral administration of Cirsium japonicum DC. extract

Ethnopharmacological relevanceCirsium japonicum DC., a Traditional Chinese Medicine, has the curative effect of antihemorrhagic and antitumor. Pharmacological studies prove that the curative effect may relate to the flavonoids. A simple and rapid resolution liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was first developed and validated for the quantification of seven flavonoids including pectolinarin, linarin, pectolinarigenin, hispidulin, diosmetin, acacetin and apigenin in rat plasma after oral administration of Cirsium japonicum DC. extract. Materials and methodsThe chromatographic separation was achieved on a C18 column with gradient elution by using a mixture of 0.1% formic acid aqueous solution and methanol as the mobile phase at a flow rate of 0.8mL/min. A tandem mass spectrometric detection was conducted using multiple-reaction monitoring (MRM) via an electrospray ionization (ESI) source in positive and negative ionization mode simultaneously. Samples were pre-treated by a single-step protein precipitation with methanol, and sulfamethoxazole was used as internal standard (IS). ResultsThe optimized mass transition ion-pairs (m/z) for quantization were 623.4/315.2 for pectolinarin, 593.3/285.1 for linarin, 315.3/300.2 for pectolinarigenin, 301.2/286.2 for hispidulin, 301.2/258.2 for diosmetin, 283.0/267.9 for acacetin, 269.0/117.0 for apigenin and 252.2/155.8 for IS. After oral administration of 6mL/kg Cirsium japonicum DC. extract in rats, the maximum plasma concentration (Cmax) of pectolinarin, linarin, pectolinarigenin, hispidulin, diosmetin, acacetin and apigenin were 876.77±97.34ng/mL, 86.79±1.70ng/mL, 6.13±0.12ng/mL, 32.85±2.50ng/mL, 37.2±2.04ng/mL, 19.02±1.29ng/mL and 148.26±20.63ng/mL, respectively. The time to reach the maximum plasma concentration (Tmax) was 5min for pectolinarin, linarin, pectolinarigenin, hispidulin, diosmetin, acacetin and 360min for apigenin. The intra-day and inter-day precisions (RSD%) for seven compounds were less than 13.16% and 7.77% and the accuracy (RE%) range from −7.92% to 14.77%. ConclusionsThis is the first research on the pharmacokinetic study of bioactive components in rat plasma after oral administration of Cirsium japonicum DC. extract. The results provided a meaningful basis for better understanding the absorption mechanism of Cirsium japonicum DC. and evaluating the clinical application of this herb medicine.

Steroids in marine aquaculture farms surrounding Hailing Island, South China: Occurrence, bioconcentration, and human dietary exposure

The occurrence, bioconcentration, and human dietary exposure via seafood consumption of 24 steroids were investigated by rapid resolution liquid chromatography–tandem mass spectrometry (RRLC–MS/MS) in six typical marine aquaculture farms surrounding Hailing Island, South China. Ten, 9, 10, 15 of 24 steroids were detected at concentrations ranging from <0.1 (testosterone) to 40ng/L (prednisolone), from 0.1 (4-androstene-3,17-dione) to 2.4ng/g (progesterone), from 0.3ng/g (testosterone) to 21.4ng/g (epi-androsterone), and from <0.1 (testosterone) to 560ng/g (cortisol) (wet weight) in the water, sediment, feed and biota samples, respectively. Synthetic steroids (androsta-1,4-diene-3,17-dione, 17α-boldenone, 17β-boldenone, 17β-trenbolone, prednisolone, norgestrel) were detected in the feed samples, clearly demonstrating the illegal use of steroids in the feed. The field bioconcentration factors (BCFs) of steroids calculated in different aquatic organisms ranged from 93.8 to 4000. The estimated daily intakes (EDIs) of androgens, glucocorticoids, and progestagens via consumption of seafood (i.e., shrimps, crabs, mollusks, and fish) for different age groups were in the range of 33.4–134, 2061–8566, and 40.4–155ng/d for children (2–5years), youth (6–18years), and adults (>18years), respectively. Even though no significant risk from dietary exposure arises from individual steroid, elevated risk to humans can result from the occurrence of multiple steroids in the seafood raised in the aquaculture farms, especially for the sensitive populations, such as pregnant women and children.

Determination of 15 sedative residues in mutton by rapid resolution liquid chromatography–tandem mass spectrometry

The use of xenobiotic compounds in animal husbandry has given rise to consumer anxieties regarding residual risk and food safety. Thus, animal tissues have become main samples for residue analysis and food safety for sedatives. In this study, a rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) method was established for the determination of 15 sedatives residues in mutton. After enzymolysis, sedatives residues in mutton were extracted by ammonium hydroxide-acetonitrile (10:90, v/v) and determined by RRLC-MS/MS with quantification by standard curve method. The calibration curves showed good linearity within the concentrations of 0.5-50 µg kg(-1) with the correlation coefficients (r(2)) ranged from 0.9639 to 0.9984. The limits of detection (LODs) and quantification (LOQs) were 0.25-2.5 and 0.5-5 µg kg(-1), respectively. The average recoveries of spikes samples were in the ranges of 74.1-116.8% with relative standard deviations of intra- and inter-day ranged from 2.6% to 11.2% and from 2.1% to 11.4%, respectively. This method is simple, sensitive and accurate in the determination of sedative residues.

QuEChERS-based extraction procedure and rapid resolution liquid chromatography coupled to triple quadrupole mass spectrometry for the determination of nine mycotoxins in cereal-based complementary foods for infants and young children

A rapid method has been developed for the determination of aflatoxins B1, B2, G1 and G2, ochratoxin A, zearalenone, T-2 toxin, deoxynivalenol and fumonisin B1 in cereal-based complementary foods for infants and young children. The mycotoxins were extracted from the samples using a modified QuEChERS-based extraction procedure without any further clean-up step. The separation of the analytes was carried out on an Agilent XDB C18 column (50 mm x 2.1 mm, 1.8 microm) using the mobile phases of acetonitrile and 5 mmol/L ammonium acetate-0.1% (volume percentage) formic acid aqueous solution with gradient elution. The extract was determined by rapid resolution liquid chromatography-tandem mass spectrometry. Matrix-matched calibration was used for the quantification. The proposed method showed good linear correlation with the correlation coefficients all above 0.98. The blank samples were fortified at three levels, and the recoveries ranged from 77.6% to 105.7% with the RSDs from 2.5% to 13.7%. The limits of detection ranged from 0.1 microg/kg to 15.8 microg/kg. The developed method was successfully applied for mycotoxin analysis in 41 samples bought from markets. The method shows advantages in both accuracy and sensitivity, and is suitable for the rapid multi-aflatoxin screening in cereal-based complementary foods for infants and young children.

Direct quantitative analysis of benzodiazepines, metabolites, and analogs in diluted human urine by rapid resolution liquid chromatography–tandem mass spectrometry

Rapid resolution liquid chromatography (RRLC) coupled with triple quadrupole mass spectrometry (QqQ-MS) was developed for direct quantitative analysis of benzodiazepines (BDZs) and their metabolites, as well as BDZ analogs (zopiclone, zolpidem, and zaleplon) in diluted human urine. A perfluorophenyl column packed with sub-2-μm particles and a C8 precolumn were applied to accomplish RRLC analysis with symmetric peak shapes. Urine samples were diluted 10-fold with Milli-Q water prior to autoinjection for direct quantification of 34 target analytes with negligible matrix effect. Gradient elution and dynamic multiple reaction monitoring were used for simultaneous quantitation of 34 BDZs, metabolites, and BDZ analogs. Good recovery was obtained in the range of 80.2–98.5% and the limit of detection ranged from 0.01 ng/mL to 0.5 ng/mL for all 34 target analytes in spiked urine. Moreover, good precision and accuracy were obtained for quantitative determination in diluted urine samples by the proposed RRLC/QqQ-MS method for intra-day/inter-day assays in the ranges of 0.1–8.8%/0.1–8.9% and 91.2–106.1%/89.6–104.6%, respectively. The applicability of this newly developed RRLC/QqQ-MS method was demonstrated by quantitative determination of BDZs, metabolites, and BDZ analogs in various clinical urine samples.

Quantification of lincomycin resistance genes associated with lincomycin residues in waters and soils adjacent to representative swine farms in China

Lincomycin is commonly used on swine farms for growth promotion as well as disease treatment and control. Consequently, lincomycin may accumulate in the environment adjacent to the swine farms in many ways, thereby influencing antibiotic resistance in the environment. Levels of lincomycin-resistance genes and lincomycin residues in water and soil samples collected from multiple sites near wastewater discharge areas were investigated in this study. Sixteen lincomycin-resistance and 16S rRNA genes were detected using real-time PCR. Three genes, lnu(F), erm(A), and erm(B), were detected in all water and soil samples except control samples. Lincomycin residues were determined by rapid resolution liquid chromatography-tandem mass spectrometry, with concentrations detected as high as 9.29 ng/mL in water and 0.97 ng/g in soil. A gradual reduction in the levels of lincomycin-resistance genes and lincomycin residues in the waters and soils were detected from multiple sites along the path of wastewater discharging to the surrounding environment from the swine farms. Significant correlations were found between levels of lincomycin-resistance genes in paired water and soil samples (r = 0.885, p = 0.019), and between lincomycin-resistance genes and lincomycin residues (r = 0.975, p < 0.01). This study emphasized the potential risk of dissemination of lincomycin-resistance genes such as lnu(F), erm(A), and erm(B), associated with lincomycin residues in surrounding environments adjacent to swine farms.

Management of domoic acid monitoring in shellfish from the Catalan coast

Monitoring of amnesic shellfish poisoning (ASP) toxins in shellfish from the Catalan coast started in 2001. No ASP toxins were detected in any of the analyses performed before 2008. On 22 January 2008, domoic acid (DA) was detected in Donax trunculus (0.5mg kg(-1)) and confirmed by rapid resolution liquid chromatography-tandem mass spectrometry (0.6mg kg(-1)). A total of 974 shellfish samples were analyzed from January 2008 to December 2011, covering all the Catalan production areas and the most important marketed species. DA was detected in 23.8% of the samples and was recorded every month in all areas and all species, except Ostrea edulis, although the percentage of samples with DA and DA content varied widely among samples. DA exceeded the regulatory level of 20mg kg(-1) twice: in Callista chione sampled on February 2008 and in D. trunculus sampled on April 2010. DA content in Bolinus brandaris appeared constant and close to 4.5mg kg(-1) for months in 2009. Mytilus galloprovincialis, Crassostrea gigas, and Ruditapes sp. presented very low concentrations of DA in the Ebro Delta bays, despite 113 alert situations according to Pseudo-nitzschia spp. abundances and the high number of shellfish samples analyzed. The origin of DA in Catalan shellfish remains unknown.

Highly sensitive and simultaneous determination of sixteen sulphonamide antibiotics, four acetyled metabolites and trimethoprim in meat by rapid resolution liquid chromatography-tandem mass spectrometry

A novel multiresidue analysis method is developed for highly sensitive and simultaneous determination of 16 sulphonamides (SAs), 4 acetyled metabolites, and trimethoprim in pork and mutton by rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS). The sample was extracted with acetonitrile under ultrasonication incubation, followed by solid phase extraction (SPE). The calibration curves showed good linearity with correlation coefficient (r) more than 0.998. The limit of quantification (LOQ) was 0.35–1.0 μg/kg, which can ensure to detect studied drugs at the maximum residue level (MRL) of 10 μg/kg. The mean recoveries at addition level of 1.0, 5.0 and 50 μg/kg were in the range of 68.3–104% with the relative standard deviation (RSD) of 3.5–9.2%. The intra-day precision (as RSD) for six determinations at 50 μg/kg spiked level within a day was in the range of 4.2–8.9%. The method is sensitive, accurate, convenient and rapid, and can be used for the qualitatively and quantitatively determination of multiresidue of the studied drugs in meat.

Simultaneous determination of human and veterinary antibiotics in various environmental matrices by rapid resolution liquid chromatography–electrospray ionization tandem mass spectrometry

A robust and sensitive analytical method is presented in which 11 classes of antibiotics are simultaneously extracted and determined in surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge. Water samples with different volumes were adjusted to pH 3, added with 0.2g Na2EDTA and then extracted using Oasis hydrophilic–lipophilic balance (HLB) cartridges. Extraction of solid samples was carried out by a combination of ultrasonic and vortex mixing using a mixture of acetonitrile and citric buffer at pH 3 as the extraction solution. The extracts of the solid samples were then cleaned-up by a tandem solid phase extraction (SPE) method using a strong anion exchange cartridge (SAX) and a HLB cartridge, followed by analysis using rapid resolution liquid chromatography–tandem mass spectrometry (RRLC–MS/MS) equipped with electrospray ionization source. Among the 50 target compounds, the recoveries in the range of 50–150% were obtained for 39, 40, 36, 40, 38, 33 and 36 antibiotics in the spiked samples of surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge with three concentrations, respectively. Method quantification limits (MQLs) for the target compounds (except sulfaguanidine and sulfanilamide) were in the range of 0.52–5.88ng/L, 2.36–65.8ng/L, 1.73–20ng/L, 1.42–9.52ng/L, 0.64–6.67ng/g (except bacitracin and cloxacillin), 1.33–17.4ng/g (except salinomycin, narasin, monensin, cloxacillin and novobiocin) and 1.50–28.6ng/g (except salinomycin, narasin, monensin and cloxacillin) in surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge, respectively. The developed analytical method was successfully applied in the determination of target compounds in wastewater and sludge samples from Huiyang wastewater treatment plants, and in ground water, lagoon wastewater, manure and sediment collected from a pig farm, in South China.

Integrated rapid resolution liquid chromatography–tandem mass spectrometric approach for screening and identification of metabolites of the potential anticancer agent 3,6,7-trimethoxyphenanthroindolizidine in rat urine

An integrated approach combining data acquisition using MSE and multi-period product ion scan (mpMS/MS), with high-resolution characteristic extracted ion chromatograms (hcXIC) as a data mining method, was developed for in vivo drug metabolites screening and identification. This approach is illustrated by analyzing metabolites of a potential anticancer agent, 3,6,7-trimethoxyphenanthroindolizidine (CAT) in rat urine based on rapid resolution liquid chromatography combined with tandem mass spectrometry (RRLC–MS/MS). Untargeted full-scan MSE enabled the high-throughput acquisition of potential metabolites, and targeted mpMS/MS contributed to the sensitivity and specificity of the acquisition of molecules of interest. The data processing method hcXIC, based on the structure of CAT, was shown to be highly effective for the metabolite discovery. Through the double-filtering effect of the characteristic ion and accurate mass, conventional extracted ion chromatograms that contained a substantial number of false-positive peaks were simplified into chromatograms essentially free of endogenous interferences. As a result, 21 metabolites were detected in rat urine after oral administration of CAT. Based on the characteristic fragmentation patterns of the phenanthroindolizidine alkaloid, the structures of 9 metabolites were identified. Furthermore, the interpretation of the MS/MS spectra of these metabolites enabled the determination of demethylation position as well as the differentiation between N-oxidized and hydroxylated metabolites.

Steroids in a typical swine farm and their release into the environment

The occurrence and fate of fourteen androgens, four estrogens, five glucocorticoids and five progestagens were investigated by rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) in a typical swine farm with lagoon waste disposal systems, in south China. Nineteen, 22 and 8 of 28 steroids were detected at concentrations ranging from 2.2 ± 0.1 ng/g (androsta-1,4-diene-3,17-dione) to 14,400 ± 394 ng/g (progesterone) in the feces samples, from 6.1 ± 2.3 ng/L (17β-boldenone) to 10,800 ± 3190 ng/L (norgestrel) in the flush water samples, and from 5.0 ± 0.2 ng/g (progesterone) to 225 ± 79.4 ng/g (5α-dihydrotestosterone) in the suspended particles, respectively. By comparing the types and concentrations of steroids in different treatment stages of the lagoon systems, it demonstrated that the lagoon systems used in the farm were not effective method to reduce various steroids in wastewater. Among the thirteen synthetic steroids detected in the swine feces and flush water, only seven (methyl testosterone, 17α-trenbolone, 17β-trenbolone, 17α-ethynyl estradiol, dexamethasone, medroxyprogesterone, and norgestrel) were regarded as the parent/metabolite compounds of animal exogenous usage. According to the estimated masses of steroids from feces and flush water, the excretion of steroids for sows were mainly from feces, but for piglets or barrows, most excreted steroids were through flush water rather than feces. The total daily excreted masses of androgens, estrogens, glucocortcoids and progestagens in the sow feces were in the range of 90.7–6310 μg/d, which were up to a thousand fold of those in the feces of other growth stages indicating that the proportion of sow number in the swine farm directly influenced the total excretion mass of steroids. In addition, two natural steroids 4-androstene-3,17-dione and progesterone were worth notice due to their relatively high concentrations per sow excretion, 277 μg/d and 6380 μg/d, respectively, which are approximately equivalent to the daily excretion of 100 persons. Some steroids were also detected in the well water, vegetable field and receiving stream, and may pose potential high risks to some sensitive organisms in the receiving environment.

Determination of ginsenosides Rb1, Rb2, and Rb3 in rat plasma by a rapid and sensitive liquid chromatography tandem mass spectrometry method: Application in a pharmacokinetic study

A sensitive rapid resolution liquid chromatography-tandem mass spectrometry method was developed to determine the pharmacokinetics of ginsenoside Rb(1), Rb(2), and Rb(3) in rats, after oral administration (50mg/kg) and intravenous administration (10mg/kg) of Rb(1), Rb(2), and Rb(3), respectively. The plasma samples were extracted by saturated N-butanol with Rg(2) as internal standard. Chromatographic separation was performed on a Zorbax SB-C18 column (50 mm × 4.6 mm, 1.8 μm) with a mobile phase consisting of methanol and 1mM ammonium formate (74:26, v/v). Multiple reaction monitoring mode was performed using the fragmentation transitions of m/z 1107.7→m/z 178.9, m/z 1077.7→m/z 148.6, and m/z 1077.7→m/z 783.4 for Rb(1), Rb(2), and Rb(3), respectively. Calibration curves were recovered over a concentration range of 20-1000 ng/ml for Rb(1) and Rb(2), and 50-2500 ng/ml for Rb(3). The limits of detection were 3.0 ng/ml, 4.0 ng/ml, and 6.5 ng/ml. Both intra-day and inter-day variances were less than 15% and the accuracy was within 86-114% for the three ginsenosides. All three ginsenosides had poor oral bioavailability (0.78%, 0.08%, and 0.52% for Rb(1), Rb(2), and Rb(3), respectively). The value of Rb(1) is higher than that of Rb(2) or Rb(3), indicating that ginsenosides with hexose and hydroxyl groups (Rb(1)) could present better pharmacokinetic behaviors than those with pentose groups in the same glycosylation site by oral administration.

Simultaneous Determination of 33 Medicine Residues in Aquatic Products by Rapid Resolution Liquid Chromatography-Tandem Mass Spectrometry

A new approach for the simultaneous determination of five classes residues,tetracyclines,quinolones,sulfoamides,tripmethoprim and triphenylmethane,in aquatic products by rapid resolution liquid chromatography-tandem mass spectrometry(RRLC-MS/MS) was established.Analytes were extracted by Na2EDTA-Mcllvaine buffer and acetonitrile,then defatted using hexane.Electrospray ionization mass spectrometry was operated in the positive mode using dynamic multiple reaction monitoring(DMRM) for the qualitative and quantitative analysis of 33 analytes after the separation on RRLC.The correlation coefficients of linear calibration curves were over 0.99 in the corresponding concentration range.The average recoveries of the 33 analytes ranged from 63.6% to 115.2%,and the relative standard deviation(RSD) in three different concentrations was 4.6%-14.6%.The limit of detection(LOD,S/N≥3) and quantification(LOQ,S/N≥10) were 0.1-2.0 μg/kg and 0.5-5.0 μg/kg,respectively.The method is simple,fast,sensitive and reliable,and is suitable for the determination of residues in aquatic products.