Rapid quantification of fatty acids in plant oils and biological samples by LC-MS.

Analysis of fatty acids (FA) in food and biological samples such as blood is indispensable in modern life sciences. We developed a rapid, sensitive and comprehensive method for the quantification of 41 saturated and unsaturated fatty acids by means of LC-MS. Optimized chromatographic separation of isobaric analytes was carried out on a C8 reversed phase analytical column (100 × 2.1 mm, 2.6 µm core-shell particle) with a total run time of 15 min with back pressure lower than 300 bar. On an old triple quadrupole instrument (3200, AB Sciex), pseudo selected reaction monitoring mode was used for quantification of the poorly fragmenting FA, yielding limits of detection of 5-100 nM. Sample preparation was carried out by removal of phospholipids and triglycerides by solid-phase extraction (non-esterified fatty acids in oils) or saponification in iso-propanol (fatty acyls). This is not only a rapid strategy for quantification of fatty acyls, but allows the direct combination with the LC-MS-based analysis of fatty acid oxidation products (eicosanoids and other oxylipins) from the same sample. The concentrations of fatty acyls determined by means of LC-MS were consistent with those from GC-FID analysis demonstrating the accuracy of the developed method. Moreover, the method shows high precisions with a low intra-day (≤ 10% for almost all fatty acids in plasma and ≤ 15% in oils) and inter-day as well as inter-operator variability (< 20%). The method was successfully applied on human plasma and edible oils. The possibility to quantify non-esterified fatty acids in samples containing an excess of triacylglycerols and phospholipids is a major strength of the described approach allowing to gain new insights in the composition of biological samples.

Rapid differentiation of Ganoderma species by direct ionization mass spectrometry.

In this study, direct ionization mass spectrometry (DI-MS) has been developed for rapid differentiation of Ganoderma (known as Lingzhi in Chinese), a very popular and valuable herbal medicine. Characteristic mass spectra can be generated by DI-MS directly from the raw herbal medicines with the application of a high voltage and solvents. Rapid differentiation of the Ganoderma species that are officially stated in the Chinese pharmacopoeia from easily confused Ganoderma species could be achieved based on this method, as the acquired DI-MS spectra showed that ganoderic acids, the major active components of Ganoderma, could be found only in the official Ganoderma species but not in the confused Ganoderma species. In addition, classification of wild and cultivated Ganoderma and potential differentiation of Ganoderma from different geographical locations could be accomplished based on principal component analysis (PCA) or hierarchical clustering analysis (HCA). The method is rapid, simple and reproducible, and can be further extended to analysis of other herbal medicines.

Pulsed Direct Current Electrospray: Enabling Systematic Analysis of Small Volume Sample by Boosting Sample Economy.

We had developed pulsed direct current electrospray ionization mass spectrometry (pulsed-dc-ESI-MS) for systematically profiling and determining components in small volume sample. Pulsed-dc-ESI utilized constant high voltage to induce the generation of single polarity pulsed electrospray remotely. This method had significantly boosted the sample economy, so as to obtain several minutes MS signal duration from merely picoliter volume sample. The elongated MS signal duration enable us to collect abundant MS(2) information on interested components in a small volume sample for systematical analysis. This method had been successfully applied for single cell metabolomics analysis. We had obtained 2-D profile of metabolites (including exact mass and MS(2) data) from single plant and mammalian cell, concerning 1034 components and 656 components for Allium cepa and HeLa cells, respectively. Further identification had found 162 compounds and 28 different modification groups of 141 saccharides in a single Allium cepa cell, indicating pulsed-dc-ESI a powerful tool for small volume sample systematical analysis.

A rapid and highly specific method to evaluate the presence of pyrrolizidine alkaloids in Borago officinalis seed oil.

Pyrrolizidine alkaloids (PAs) are complex molecules, present in plants as free bases and N-oxides. They are known for their hepatotoxicity, and consequently there is a health risk associated with the use of medicinal herbs that contain PAs. Unfortunately, there is no international regulation of PAs in foods, unlike those for herbs and medicines: in particular, for herbal preparation or herbal extracts, the total PA content must not exceed 1 µg/kg or 1 µg/l, respectively. Borago officinalis seed oil is a source of γ-linolenic acid, and its use is increased in both pharmaceutical and health food industries. Even if studies based on gas chromatography and TLC methods showed that PAs are not co-extracted with oil, the development of a rapid and sensitive method able to evaluate the presence of PAs in commercially available products is surely of interest. The presence of PAs in a commercially available Borago officinalis seed oil was tested either in the oil sample diluted with tetrahydrofuran/methanol (MeOH)/H2 O (85/10/5 v:v:v) or after extraction with MeOH/H2 O (50/50 v:v) solution The samples were analysed by electrospray ionization in positive ion mode and in high mass resolution (60,000) conditions. In both cases to evaluate the effectiveness of the method, spiking experiments were performed adding known amount of two PA standards to the borage seed oil. A limit of detection in the order of 200 ppt was determined for these two compounds, strongly analogous to Borago officinalis seed oil PAs. Consequently, if present, PAs level in Borago officinalis seed oil must lower than 200 ppt.

Tissue distribution profiles of three antiparkinsonian alkaloids from Piper longum L. in rats determined by liquid chromatography-tandem mass spectrometry.

The alkaloids of Piper longum L. (PLA) improved motor dysfunction and dopamine depletion in a rat model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. A rapid, accurate, simple, and high-performance liquid chromatography-mass spectrometry method was developed and fully validated to simultaneously detect three P. longum L. antiparkinsonian alkaloids (piperine (PPR), piperlonguminine (PPL), and Δα,ß-dihydropiperlonguminine (DPPL)) in rat plasma, heart, liver, spleen, lung, kidney, and brain tissues. Rat plasma and tissue homogenates were pretreated with methanol/acetonitrile (1:1, v/v) using a simple protein precipitation method. Chromatographic separation was achieved on a Phenomenex Gemini C18 column (50mm×2.00mm, 5µm) with a gradient mobile phase containing 0.1% (v/v) formic acid in water or acetonitrile. The elution was pumped at a flow rate of 0.4ml/min, and the injection volume was 10µl with a total running time of 4min. The analysis was performed by selected reaction monitoring of the transitions m/z 285.9→201.1, m/z 274.3→209.9, and m/z 276.2→134.9 for PPR, PPL, and DPPL, respectively. All three analytes showed good linearity (R>0.995) in plasma and tissue homogenates, and the lower limit of quantification was 0.20ng/ml. The distribution of PPR, PPL and DPPL in all 7 tissues was examined. The highest concentrations for PPR and PPL were observed in the liver, while the highest DPPL concentration was observed in the kidney. Following oral administration, the highest levels of PPR, PPL and DPPL in different tissues were found at approximately 2h. PPR, PPL and DPPL could cross the blood-brain barrier. The present study provides evidences for that PPR, PPL and DPPL may play roles in improving motor dysfunction and dopamine depletion.

Compound coverage enhancement of electrospray ionization mass spectrometry through the addition of a homemade needle.

The response of many previously low-detectable or undetectable compounds in electrospray ionization mass spectrometry (ESI-MS) has been enhanced by the addition of a simple, homemade needle into the traditional ESI interface. The needle located between the ESI emitter and the ion sweep cone (inlet of the detector) would ionize those neutral gaseous compounds, formed during electrospray, by a corona discharge process. The mobile phases, ESI parameters and positions of the needle were investigated and optimized. Several groups of compounds and herbal extracts were tested using the homemade set-up. Both the results of the flow injection and the hyphenated MS analyses showed significant enhancement effects of our homemade needle. The advantages of the proposed method include low cost, simplicity and practicality.

Determination of cnidilin and its two metabolites in rat bile and stool after oral administration by HPLC/electrospray ionization tandem mass spectrometry.

A simple, fast and sensitive method for the simultaneous determination of cnidilin and its two metabolites (M1 and M2) in rat bile and stool using HPLC coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) has been developed. The sample pretreatment was simple, because methanol was the only additive used for dilution of bile and ultrasound of stool. Pimpinellin was used as internal standard (IS). The separation was performed on a reverse phase C18 column with gradient elution consisting of 0.5‰ aqueous formic acid and methanol (containing 0.5‰ formic acid). The detection was in the multiple-reaction monitoring mode within 7 min. All the analytes were in accordance with the requirement of the validation of the method in vivo (linearity, precision, accuracy, limit of detection and limit of quantification). After oral administrating 24 mg/kg of the prototype drug cnidilin, M1 and M2 were determined in bile within 36 h, and in stool within 60 h. Cnidilin in bile was completely excreted in 24 h, and the main excretive amount of cnidilin was 80% in the first 6 h, but the drug recovery in bile within 24 h was <1.95%. In stool, the main excretive amount of cnidilin was 95.8% in the first 24 h, and the drug recovery within 48 h was lower than 1.48%.

Structural elucidation of molecular species of pacific oyster ether amino phospholipids by normal-phase liquid chromatography/negative-ion electrospray ionization and quadrupole/multiple-stage linear ion-trap mass spectrometry.

Although marine oysters contain abundant amounts of ether-linked aminophospholipids, the structural identification of the various molecular species has not been reported. We developed a normal-phase silica liquid chromatography/negative-ion electrospray ionization/quadrupole multiple-stage linear ion-trap mass spectrometric (NPLC-NI-ESI/Q-TRAP-MS(3)) method for the structural elucidation of ether molecular species of serine and ethanolamine phospholipids from marine oysters. The major advantages of the approach are (i) to avoid incorrect selection of isobaric precursor ions derived from different phospholipid classes in a lipid mixture, and to generate informative and clear MS(n) product ion mass spectra of the species for the identification of the sn-1 plasmanyl or plasmenyl linkages, and (ii) to increase precursor ion intensities by "concentrating" lipid molecules of each phospholipid class for further structural determination of minor molecular species. Employing a combination of NPLC-NI-ESI/MS(3) and NPLC-NI-ESI/MS(2), we elucidated, for the first time, the chemical structures of docosahexaenoyl and eicosapentaenoyl plasmenyl phosphatidylserine (PS) species and differentiated up to six isobaric species of diacyl/alkylacyl/alkenylacyl phosphatidylethanolamine (PE) in the US pacific oysters. The presence of a high content of both omega-3 plasmenyl PS/plasmenyl PE species and multiple isobaric molecular species isomers is the noteworthy characteristic of the marine oyster. The simple and robust NPLC-NI-ESI/MS(n)-based methodology should be particularly valuable in the detailed characterization of marine lipid dietary supplements with respect to omega-3 aminophospholipids.

Dispersive solid-phase extraction cleanup combined with accelerated solvent extraction for the determination of carbamate pesticide residues in Radix Glycyrrhizae samples by UPLC-MS-MS.

Dispersive solid-phase extraction (DSPE) cleanup combined with accelerated solvent extraction (ASE) is described here as a new approach for the extraction of carbamate pesticides in Radix Glycyrrhizae samples prior to UPLC-MS-MS. In the DSPE-ASE method, 15 carbamate pesticides were extracted from Radix Glycyrrhizae samples with acetonitrile by the ASE method at 60 °C with a 5 min heating time and two static cycles. Cleanup of a 1 mL aliquot of the extract by the DSPE method used 20 mg PSA (primary secondary amine), 50 mg Al(2)O(3)-N, and 20 mg GCB (graphitized carbon black) (as cleanup sorbents) under the determined optimum conditions. The linearity of the method was in the range of 10 to 200 ng/mL with correlation coefficients (r(2)) of more than 0.996. The limits of detection were approximately 0.2 to 5.0 µg/kg. The method was successfully used for the analysis of target pesticides in Radix Glycyrrhizae samples. The recoveries of the carbamate pesticides at the spiking levels of 50, 100, and 200 µg/kg ranged from 79.7% to 99.3% with relative standard deviations lower than 10%. This multi-residue analytical method allows for a rapid, efficient, sensitive and reliable determination of target pesticides in Radix Glycyrrhizae and other medicinal herbs.

Direct identification of phenolic constituents in Boldo Folium (Peumus boldus Mol.) infusions by high-performance liquid chromatography with diode array detection and electrospray ionization tandem mass spectrometry.

A very simple and direct method was developed for the qualitative analysis of polyphenols in boldo (Peumus boldus Mol., Monimiaceae) leaves infusions by high-performance liquid chromatography with diode array detection (HPLC-DAD) and electrospray ionization tandem mass spectrometry (HPLC-MS(n)). The phenolic constituents identified in infusions of the crude drug Boldo Folium were mainly proanthocyanidins and flavonol glycosides. In the infusions, 41 compounds were detected in male and 43 compounds in female leaf samples, respectively. Nine quercetin glycosides, eight kaempferol derivatives, nine isorhamnetin glycosides, three phenolic acids, one caffeoylquinic acid glycoside and twenty one proanthocyanidins were identified by HPLC-DAD and ESI-MS for the first time in the crude drug. Isorhamnetin glucosyl-di-rhamnoside was the most abundant flavonol glycoside in the male boldo sample, whereas isorhamnetin di-glucosyl-di-rhamnoside was the main phenolic compound in female boldo leaves infusion. The results suggest that the medicinal properties reported for this popular infusion should be attributed not only to the presence of catechin and boldine but also to several phenolic compounds with known antioxidant activity. The HPLC fingerprint obtained can be useful in the authentication of the crude drug Boldo Folium as well as for qualitative analysis and differentiation of plant populations in the tree distribution range.

Rapid separation and identification of 54 major constituents in Buyang Huanwu decoction by ultra-fast HPLC system coupled with DAD-TOF/MS.

Buyang Huanwu Decoction (BYHWD), is a well-known traditional Chinese preparation consisting of Radix Astragali, Radix Angelicae Sinensis, Rhizoma Ligustici Chuanxiong, Radix paeoniae Rubra, Flos Carthami, Semen Persicae and Lumbricus. An ultra-fast high-performance liquid chromatography (HPLC) method coupled with diode array detection (DAD) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) has been developed for rapid separation and structural identification of constituents in BYHWD. Using an ultra-fast HPLC system with short columns (4.6 x 50 mm, 1.8 microm), the total analysis time for this complex prescription is less than 30 min. With various fragmentor voltages in TOF/MS, accurate mass measurements (less than 5 ppm error) for molecular ions and characteristic fragment ions could represent reliable identification criteria for these compounds. Fifty-four major constituents from BYHWD sample, including four C-glycosyl quinochalcones, four flavonoid O-glycosides, sixteen isoflavones, six monoterpene glycosides, eight saponins, four organic acids and five amino acids, were identified or tentatively characterized based on their retention times, DAD and TOF/MS data. All the compounds were further assigned in the seven individual crude drugs. In conclusion, the ultra-fast HPLC with DAD-TOF/MS is a highly useful and efficient technique to separate and identify constituents in complex matrices of herbal medicines or preparations.

Detection and characterization of synthetic steroidal and non-steroidal anti-inflammatory drugs in Indian ayurvedic/herbal products using LC-MS/TOF.

It is claimed that ayurvedic/herbal healthcare products (AHPs) are safe because of their natural origin. However, several reports exist of adulteration of AHPs with synthetic drugs. In this study, a generalized strategy was developed using LC-MS/TOF for the detection and verification of steroidal and anti-inflammatory drugs in 58 AHPs collected from various parts of India. The strategy involved recording of mass spectral information for standard drugs-including ionization mode (ESI/APCI - ve or + ve), mass spectrum, accurate mass, identification of qualifier fragments (two), extracted ion chromatograms (EICs), isotopic pattern and determination of UV max (nm)-through UV-PDA studies. Adulteration was then detected in AHPs primarily through comparison of EICs at accurate m/z for molecular ion peaks and R(T) matching with the standard. It was confirmed by spiking with the standards, and matching mass spectrum, accurate mass, R(T) of qualifier fragments, isotopic pattern and UV spectrum of the standards with the adulterant peaks in AHPs. Dexamethasone and diclofenac were detected as adulterants in ten AHPs whereas one AHP tested positive for piroxicam and another for dexamethasone. All the adulterated products were sold by the healthcare practitioners, while no product marketed by manufacturers or chemist shops had this problem. The study showed that LC-MS/TOF-based screening could be used as a rapid approach to monitor adulteration of steroids and anti-inflammatory drugs in AHPs.

An acylated flavonol glycoside and hydrolysable tannins from Callistemon lanceolatus flowers and leaves.

INTRODUCTION: Callistemon lanceolatus DC. (Myrtaceae) is a plant rich in polyphenols, and is used as anticough, antibronchitis and insecticide in folk medicine. Because of the biological importance of plant polyphenols, particularly tannins, a phytochemical study was of interest to investigate the constitutive poyphenols in the extracts of flowers and leaves. OBJECTIVE: To avoid time-consuming methodology for isolation of a complex mixture of known metabolites, HPLC-ESI/MS was employed for fast picking up of the new compounds followed by identification of the structures with UV and one- and two-dimensional NMR. METHODOLOGY: Flowers and leaves were separately extracted with hot aqueous methanol under reflux (70 degrees C). Pre-isolation of the total extracts was achieved through column chromatographic fractionation on polyamide with water-methanol for gradient elution. The main fractions were purified using repeated column chromatography on cellulose and/or Sephadex LH-20 with suitable eluents. HPLC-ESI/MS analyses were carried out in the single ion monitoring (SIM) and negative ion modes. The pure compounds in methanol-water (1:1) were analysed by direct infusion ESI/MS. Final structure elucidation was obtained by one- and two-dimensional NMR. RESULTS: Two new metabolites namely quercetin 3-O-beta-D-glucuronopyranoside n-butyl ester (1) and n-butylgallate 4-O-(2',6'-di-O-galloyl)-beta-D-glucopyranoside (4) along with nine known ones were identified from the aqueous methanol extracts of flowers and leaves. CONCLUSION: The study has shown that Callistemon lanceolatus is rich in polyphenols. HPLC-ESI/MS may be used, in negative ion mode, as an efficient and rapid analytical tool for investigating complex plant extracts.

Amino acid profiling in plant cell cultures: an inter-laboratory comparison of CE-MS and GC-MS.

A CE-MS method for metabolic profiling of amino acids was developed and used in an integrated functional genomics project to study the response of Medicago truncatula liquid suspension cell cultures to stress. This project required the analysis of more than 500 root cell culture extracts. The CE-MS method profiled 20 biologically important amino acids. The CE-MS method required no sample derivatization prior to injection and used minimal sample preparation. The method is described in terms of CE and MS operational parameters, reproducibility of migration times and response ratios, sample preparation, sample throughput, and reliability. This method was then compared with a previously published report that used GC-MS metabolic profiling for the same tissues. The data reveal a high level of similarity between the CE-MS and GC-MS amino acid profiling methods, thus supporting these as complementary technologies for metabolomics. We conclude that CE-MS is a valid alternative to GC-MS for targeted profiling of metabolites, such as amino acids, and possesses some significant advantages over GC-MS.