Date Published: August 13, 2012
Author(s): Chee Wei Lim, Siew Hoon Tai, Sheot Harn Chan.
Flow-injection mass spectrometry (FI/MS) represents a powerful analytical tool for the quality assessment of herbal formula in dietary supplements. In this study, we described a scaffold (proof-of-concept) adapted from spectroscopy to quantify Cordyceps sinensis and Ganoderma lucidum in a popular Cordyceps sinensis /Ganoderma lucidum -enriched health beverage by utilizing flow-injection/mass spectrometry/artificial neural network (FI/MS/ANN) model fingerprinting method with feature selection capability. Equal proportion of 0.1% formic acid and methanol (v/v) were used to convert extracts of Cordyceps sinensis and Ganoderma lucidum into their respective ions under positive MS polarity condition. No chromatographic separation was performed. The principal m/z values of Cordyceps sinensis and Ganoderma lucidum were identified as: 104.2, 116.2, 120.2, 175.2, 236.3, 248.3, 266.3, 366.6 and 498.6; 439.7, 469.7, 511.7, 551.6, 623.6, 637.7 and 653.6, respectively. ANN models representing Cordyceps sinensis and Ganoderma lucidum were individually trained and validated using three independent sets of matrix-free and matrix-matched calibration curves at concentration levels of 2, 20, 50, 100, 200 and 400 μg mL-1. Five repeat analyses provided a total of 180 spectra for herbal extracts of Cordyceps sinensis and Ganoderma lucidum. Root-mean-square-deviation (RMSE) were highly satisfactory at <4% for both training and validation models. Correlation coefficient (r2) values of between 0.9994 and 0.9997 were reported. Matrix blanks comprised of complex mixture of Lingzhi fermentation solution and collagen. Recovery assessment was performed over two days using six sets of matrix blank (n = 6) spiked at three concentration levels of approximately 83, 166 and 333 mg kg-1. Extraction using acetonitrile provided good overall recovery range of 92-118%. A quantitation limit of 0.2 mg L-1 was reported for both Cordyceps sinensis and Ganoderma lucidum. Intra-day and inter-day RMSE values of 7% or better were achieved. Application of the scaffold in a high-throughput routine environment would imply a significant reduction in effort and time, since the option of having a model driven analytical solution is now available.
Flow injection mass spectrometry (FI/MS) represents a proven analytical tool for the qualitative and quantitative analyses of chemical residues in complex matrices (Nanita et al. ; Nanita ; Kristiansen et al. ; Nanita et al. ). It has also been successfully applied for qualitative high-throughput metabolite fingerprinting (Enot et al. ; Beckmann et al. ) and screening (Roddy et al. ) in drugs discovery. Owing to the complex compositional variation of food matrices, traditional FI/MS strategy involved the application of a chromatographic step to separate the targeted analyte of interest before detection, thereby generating quantitative or semi quantitative information on individual analytes. Such targeted analyte profiling strategy demands strict control over the chromatographic process to obtain reproducibility (Lisec et al. ). With extended use, it becomes inevitable that chromatographic column undergoes gradual deterioration, thereby contributing toward significant changes in data characteristics such as peak-shape asymmetry after performing high-volume profiling experiments. For a high-throughput routine laboratory with broad analytical base, the cost of ownership (COO) associated with the sustenance of chromatographic accessories therefore presents a steep challenge, amongst others.
The objective of this study was to quantify the amount of (C) and (G) present in a beverage containing complex ingredients of Lingzhi fermentation solution and collagen in minutes without performing chromatographic separation. As a first step, the MS fingerprints for (C) and (G) were obtained as the sum of all the spectra between 0 and 1.0 min, at six levels of concentration (2, 20, 50, 100, 200 and 400 μg mL-1). Next, m/z values that were specific to (C) and (G) were identified.
The authors declare that they have no competing interests.