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A simple, fast, sensitive, and reproducible isocratic liquid chromatography-mass spectrometry (LC-MS) method coupled with an atmospheric pressure chemical ionization (APCI) interface for simultaneous separation and determination ofL-arginine (ARG) and its methylated metabolites,N-monomethyl-L-arginine (MMA),N G,N G-dimethylarginine (asymmetric dimethyl arginine, ADMA), andN G,N' G-dimethylarginine (symmetric dimethyl arginine, SDMA), in human plasma is presented. Sample pretreatment is not required other than deproteinization with 5-sulfosalicylic acid (5-SSA). Satisfactory chromatographic separation was achieved on a 2.0×150-mm Shimadzu VP-ODS column by using a mobile phase consisting of water/acetonitrile (90/10, v/v) containing 0.5% trifluoroacetic acid (TFA). Positive selective ion monitoring (SIM) mode was chosen for quantification of each analyte. The positively protonated molecular ions [M+H]+ of ARG, MMA, ADMA, and SDMA were monitored atm/z175, 189, 203, and 203, respectively.L-Homoarginine was used as the internal standard (IS) for the assay. The limits of quantification (LOQs) were found to be 1.0 µmol L-1 for ARG, and 0.2 µmol L-1 for MMA, ADMA, and SDMA. The inter-assay precision and accuracy were in the range of 1.8-4.9% and -3.0-5.0%, respectively. The intra-assay precision and accuracy were in the order of 1.7-4.6 and -2.6-4.0%, respectively. The recoveries were between 90.0 and 106.6%. The levels of ARG, MMA, ADMA, and SDMA in human plasma were also determined using the developed method. [ABSTRACT FROM AUTHOR]

Gas chromatography-mass spectrometry and multivariate curve resolution were applied to the differential analysis of the volatile components in Agrimonia eupatoria specimens from different plant parts. After extracted with water distillation method, the volatile components in Agrimonia eupatoria from leaves and roots were detected by GC-MS. Then the qualitative and quantitative analysis of the volatile components in the main root of Agrimonia eupatoria was completed with the help of subwindow factor analysis resolving two-dimensional original data into mass spectra and chromatograms. 68 of 87 separated constituents in the total ion chromatogram of the volatile components were identified and quantified, accounting for about 87.03% of the total content. Then, the common peaks in leaf were extracted with orthogonal projection resolution method. Among the components determined, there were 52 components coexisting in the studied samples although the relative content of each component showed difference to some extent. The results showed a fair consistency in their GC-MS fingerprint. It was the first time to apply orthogonal projection method to compare different plant parts of Agrimonia eupatoria, and it reduced the burden of qualitative analysis as well as the subjectivity. The obtained results proved the combined approach powerful for the analysis of complex Agrimonia eupatoria samples. The developed method can be used to further study and quality control of Agrimonia eupatoria.

Objective: HPLC-ESI-MS to establish a method for simultaneous determination of adenosine and cordycepin in Cordyceps sinensis and C. militarris., Method: HPLC-ESI-MS method. An electrospray ionization (ESI) interface and selective ion monitoring (SIM) mode were used. The analytical column was a 2.0 mm x 150 mm Shimadzu VP - ODS column and the mobile phase was water (94%), methanol (5%) and formic acid (1%). 2-Chloroadenosine was used as internal standard for this assay., Result: The regression equations and coefficient were Y = 0.134 6X + 0.001 29 (r = 0.998 4) for adenosine, Y = 0.216 4X + 0.021 5 (r = 0.999 1) for cordycepin. The liner range was 0.5 approximately 124.5 microg x mL(-1) and 0.5 approximately 136.5 microg x mL(-1) for adenosine and cordycepin, respectively. The average recoveries of adenosine and cordycepin were 95.8% and 98.1%, respectively., Conclusion: This method is highly sensitive, fast and selective, which can be used for the determination of nucleosides in C. sinensis and its substitutes. This method can also be applied for the quality control of above herbs.