Polyphenolic combinations quantification through ABTS•+ radical cations accumulation kinetics measurement

It has been a challenging task of analytical chemistry to qualitatively and quantitatively analyze the diverse compounds in the complex mixture. Liquid chromatography-mass spectroscopy (LC-MS), especially, ultra-high performance liquid chromatography (UPLC) coupled with high resolution mass spectrometry (HRMS), is a powerful tool for the analysis of complex samples. UPLC can greatly enhance the ability and efficiency of chromatographic separation. On the other hand, HRMS can provide more precise molecular weight and can thus improve the reliability and accuracy of qualitative and quantitative analysis. In this paper, we summarized the application of LC-MS technology to analysis of small molecule compounds in typical complex mixtures (urine, blood, cell metabolites and natural product extracts), concentrating on sample preparation, data acquisition, data (pre)processing, qualitative and quantitative analysis, multivariate analysis. Furthermore, technical challenges and developments in the analysis of complex samples by LC-MS were summarized and prospected.

Rapid computerized identification of compounds in complex biological mixtures by gas chromatography—mass spectrometry

Lysimachia christinae Hance was commonly used in Oriental medicine for treating the hepatitis virus, cholecystitis and cholagogic efficiency. According to the previous study, it possesses high antioxidant and anti-inflammatory activity. Simultaneous determination analytical method of isolated eight compounds, cynaroside (1), 2-(3,4-dimethoxyphenyl) ethyl O-α-L-arabinopyranosyl-(1→2)-O-[6-deoxy-α-L-mannopyranosyl-(1→3)] β-D-glucopyranoside (2), stearylester ricinoleic acid (3), (E)-4-(3,4-dimethoxyphenyl) but-3-en-1-yl palmitate (4), 2-hydroxy-24-methoxy-4-tetracosenoic acid (5), 2-hydroxy-24-propoxy-4-tetracosenoic acid (6), β-sitosterol (7), and androst-16-ene-3,6-diol (8) were established by using HPLC-DAD. This HPLC analysis was detected on a Dionex C18 column (5 μm, 120 Å, 4.6 mm × 150 mm) at 25℃. The mobile phase consisted of 0.1% trifluoroacetic acid and acetonitrile at a flow rate of 1 mL/min. Validation of the method was assessed by linearity, precision and accuracy test. Calibration curve was good at r² 0.9998. Limits of detection (LOD) ranged from 0.19 to 8.18 g/ml and Limits of quantification (LOQ) ranged from 0.19 to 24.80 g/ml. The relative standard deviations (RSD) values of precision test, intra- and inter- day, were less than 0.99% and 1.0%. The accuracy test results ranged from 98.81% to 106.49% and RSD values were less than 0.95%. These results showed that the HPLC-DAD method was very reliable and accurate for the quantity analysis of eight compounds in L. christinae extract for quality control.

Objective To assess the precision and accuracy of bone mineral measurement utilizing spectral CT imaging with a European Spine Phantom (ESP).Methods Within the ESP named Num.145,there are three orderly vertebral bodies which were marked by L1 with Hydroxyapatite(HAP)of 50.0 mg/cm3,L2 with HAP of 100.0 mg/cm3,and L3 with HAP of 200.0 mg/cm3.The ESP was scanned by using gemstone spectral imaging (GSI) model ten times.Using GSI viewer,measurements of HAP-water concentration and HAP-fat concentration were done.The precision and accuracy of each parameter were evaluated by the results of relative standard deviation (RSD) and relative error (RE),respectively.The difference between each parameter with the real value was evaluated statistically by one-sample t test.The differences among the three vertebral bodies' same parameter were evaluated statistically by paired t test.Results The results of HAP-water concentration in L1,L2,L3 were (54.5 ±4.2),(113.3 ± 2.7) and (219.7 ± 7.7) mg/cm3,each of which was significantly higher than the real value(t values were 3.400,15.874 and 8.155,P＜0.01).And,the RSD values were 7.67％,2.34％ and 3.48％;the RE values were 5.3％,12.9％ and 9.8％.The results of HAP-fat concentration in L1,L2,L3 were (91.9±4.0),(149.5±2.5) and (254.2±7.2) mg/cm3,each of which was significantly higher than the real value(t values were 33.489,62.399 and 23.578,P＜0.01).And the RSD values were 4.31％,1.68％ and 2.86％; the RE values were 81.0％,49.1％ and 27.0％.In every vertebral body,the result of HAP-water concentration was significantly lower than the result of HAP-fat concentration (P＜0.01).Conclusions By utilizing spectral CT imaging,the precision and accuracy of bone mineral measurement were poor.Therefore,this method is not applicable for clinical measurement. Key words: Bone mineral density ; Tomography,X-ray computed; Comparative study

Simultaneous trace determination of acidic non-steroidal anti-inflammatory drugs in purified water, tap water, juice, soda and energy drink by hollow fiber-based liquid-phase microextraction and ultra-high pressure liquid chromatography coupled to tandem mass spectrometry

Arsenic (As) and As-containing compounds have a wide array of applications in medicine, industry, and agriculture and has been associated with adverse health outcomes. In support of studies investigating the toxicity and toxicokinetic behavior of arsenic compounds, we developed and validated a high-resolution sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) method to quantitate total arsenic in Sprague-Dawley (SD) rat plasma and heart. Primary matrix standard curves prepared in male SD rat plasma were linear (r ≥ 0.999) over the range of 5 to 1250 ng As/mL plasma with accuracy determined as relative error (RE) was ≤ ±20% at the lower limit of quantitation (LLOQ) of 5 ng/mL and ≤ ±15% for all other concentrations. The method limit of detection (LOD) was 0.728 ng/mL plasma. Mean extraction recovery was 96.7%, with a relative standard deviation (RSD) of 4.0%. The method demonstrated acceptable inter- (≤ ±7.3% RE and ≤ 8.0% RSD) and intra-day (≤ ±14.9% RE and ≤ 6.8% RSD) accuracy and precision. Method selectivity was ≤ 20% of the response for the LLOQ. Method performance was also evaluated in SD rat heart by preparing QC samples in heart homogenate and quantifying using plasma calibration curve. The mean RE value was −3.8% and the RSD value was 3.4% demonstrating that the method is suitable for quantitation of arsenic in rat heart.

An integral strategy toward the rapid identification of analogous nontarget compounds from complex mixtures

This paper describes the x‐ray fluorescence determination of major and minor elements in ferrotitanium, ferroniobium and ferrovanadium. Samples preparation was accomplished using two different procedures: compressed pellets and fusion beads. Calibration graphs were prepared by mixing two ferroalloys of each of the considered types in different proportions. These ferroalloys were selected from industrial batches, providing the most varied composition available in order to cover as completely as possible the ranges of composition listed in ISO specifications. Total reproducibility tests, incorporating sample preparation and measurement, were performed using six samples prepared with the ferroalloys having the highest alloying grade. The relative standard deviation (RSD) values referred to the major element in Fe–Ti, Fe–Nb and Fe–V were 0.20, 0.17 and 0.21%, respectively, when using compressed pellets, and 0.16, 0.14 and 0.13% when using fusion beads. As regards the minor elements, the RSD values were in all cases below 5% for compressed pellets and below 3% for fused beads. The criterion applied to test the agreement of the two methods showed that the difference between the results provided by both samples preparation systems may be explained in terms of random errors. Accuracy was checked by analysing Certified Reference Materials of each of the types of ferroalloys studied. Copyright © 2002 John Wiley & Sons, Ltd.

A specific and reliable ultra-performance liquid chromatography-diode array detection method has been developed and validated for the quantitative assessment of a traditional Oriental herbal formulation, Samhwangsasim-tang (SST). A Halo reversed-phase amide column (2.7 µm, 4.6 × 150 mm) was used to separate marker compounds; detection was conducted by ultraviolet absorbance at 250 nm. The column temperature was maintained at 45°C. A mobile phase consisting of acetonitrile (A) and 0.1% trifluoroacetic acid in water (B) was found to be suitable for the separation, at a flow rate of 1.8 mL/min with gradient elution. Linearity, specificity, precision and recovery were calculated to validate the method and instrumentation. Under the described conditions, all marker compounds (rhaponticin, berberine, palmatine, baicalin, baicalein and wogonin) were collected within 25 min. All calibration curves of components showed good linearity (correlation coefficient > 0.9996). The limit of detection and limit of quantification ranged from 0.08-3.05 and 0.23-8.12 µg/mL, respectively. The relative standard deviation (RSD) and repeatability values of intra-day and inter-day precision were less than 2.30, 2.99 and 1.82%, respectively. In the recovery test, the accuracy ranged from 97.56-103.30% with RSD values less than 2.63%. The developed method was simple, specific, sensitive, accurate, precise and reproducible for the quantification of the active chemical constituents of SST. The simultaneous analysis of the contents of marker compounds in different SST samples prepared by different extraction procedures and different commercial products was successfully evaluated.

In this study, major phytochemical compounds of Vaccinium bracteatum Thunb. (VB) aqueous leaf extract were isolated and analyzed using a HPLC-based method, followed by method validation in accordance with the International Conference on Harmonisation (ICH) guidelines for drug development. Five major compounds were isolated in VB extract. Apart from vaccinoside, which had been the only compound isolated in VB extract to date, vanillic acid and protocatechuic acid were isolated for the first time. Isolation of orientin and isoorientin in the VB extract helped validate the reverse-phase analytical method. A new simple and rapid high-performance liquid chromatography (HPLC)-based method was developed for the validation of orientin and isoorientin in VB extract and was determinated according to the ICH guidelines. The analytical method was validated through a Waters Alliance HPLC System containing an e2695 separation module and a 2998 photodiode array (PDA) detector. The VB extract and solutions of orientin and isoorientin were analyzed using a reverse-phase Eclipse XDB-C18 column (4.6 × 250 mm ID, 5 µm, Waters), which was maintained at 30 °C. A mobile phase of methanol and 0.01% formic acid in water was used at a flow rate of 1.0 mL/min to achieve gradient elution. The linearity of the orientin and isoorientin was excellent results (R2 ≥ 0.9999) in the concentration range of 1.0–50.0 μg/mL. Precision values ranged 98.55–101.70% and 98.70–101.18%, respectively. The intra-day and inter-day relative standard deviation (RSD) values of the orientin and isoorientin were all <2.0%. The average recoveries of orientin ranged 98.30–101.57%, whereas isoorientin ranged 97.81–102.14% with RSD values <2.0%. Quantitative analysis found that VB extract contained 2.90 mg/g of orientin and 3.45 mg/g of isoorientin.

A high performance liquid chromatographic method with diode array detection (DAD) was established for simultaneous determination of ten aromatic acids in five Siwu series decoctions (Xiongqiong decoction, Siwu decoction, Taohongsiwu decoction, Xiangfusiwu decoction, and Shaofuzhuyu decoction) and related 16 crude herbs. These ten compounds were analyzed simultaneously with a SunFire C18 column (4.6 mm × 250 mm, 5 µm) by gradient elution using 0.5% aqueous acetate acid (v/v)-methanol as the mobile phase; the flow rate was 1.0 mL/min. The sample was detected with DAD at 230, 254, and 323 nm and the column was maintained at 25°C. All the compounds showed good linearity (r2 > 0.9998) in the range of the test concentration. The precisions were evaluated by intra-day and inter-day tests, and relative standard deviation (RSD) values were reported within the range of 0.23–2.28% and 0.26–2.79%. The recovery studies for the quantified compounds were observed over the range of 94.8% and 104.6% with RSD values less than 3.29%. The validated method was successfully applied for the simultaneous determination of the aromatic acids contents in five formulae and 16 crude herbs, and some aromatic acids were identified for the first time in these crude herbs. The results also indicated that the contents of some aromatic acids varied greatly in different decocting process. This research provided some experimental data reference for clinical application of the relative herbs, and it could enhance the study of the compatibility rule of traditional Chinese medicine.

Potentiometric determination of some 1,4-benzodiazepines in pharmaceutical preparations and biological samples

In the environmental and pharmacological sciences, it is important to selectively detect chlorine- and bromine-containing compounds in complex mixtures. Currently, a new technique called microwave-induced plasma/chemical reaction interface mass spectrometry (MIP/CRIMS) is being used as a selective detector of elements and stable isotopes. This technique, which involves post-column reactions (a reaction interface), includes a low-pressure microwave-induced helium plasma (MIP) to which a reaction gas is added. Effluents of a chromatographic column that enter this reaction interface are converted into small stable neutrals. The mass spectra of these neutrals will identify and quantify the elements and isotopes of interest. Once the retention times of the peaks of interest are obtained, their full mass spectra can be acquired by repeating the experiment with the MIP off. This method combines the sensitivity of a halogen specific detector with the compound identification of mass spectrometry. In this study, SO2 has been found highly effective as a reaction gas for selective detection of chlorine- and bromine-containing compounds using GC/MIP/CRIMS. Detection limits of 10 pg and 1 ng, and dynamic range of at least four and two orders of magnitude, were achieved for chlorine- and bromine-containing compounds, respectively. The selective detection of chlorinated compounds in complex mixtures is demonstrated by using a mixture of non-chlorinated compounds and polychlorinated biphenyls, and by selective detection of triclopyr (a chlorinated herbicide) in extracts of leaves of garden bean (Phaseolus vulgaris var. Topcrop).

Characterization and quantification of the triterpenoids in different parts of Xanthoceras sorbifolia by HPLC–ESI-MS

Robotic written silver ink on photographic paper for detection of thiram residues in fruits