Pressure Chemical Ionization Mass Research Articles

“Dilute-and-shoot” triple parallel mass spectrometry method for analysis of vitamin D and triacylglycerols in dietary supplements

A method is demonstrated for analysis of vitamin D fortified dietary supplements that eliminates virtually all chemical pretreatment prior to analysis, which is referred to as a "dilute-and-shoot" method. Three mass spectrometers, in parallel, plus a UV detector, an evaporative light-scattering detector (ELSD), and a corona charged aerosol detector (CAD) were used to allow a comparison of six detectors simultaneously. Ultraviolet data were analyzed using internal standard, external standard, and response factor approaches. The contents of gelcaps that contained 2,000 IU (50 μg) vitamin D(3) in rice bran oil, diluted to 100 mL, were analyzed without the need for lengthy saponification and extraction. Vitamin D(3) was analyzed using UV detection, extracted ion chromatograms, selected ion monitoring (SIM) atmospheric pressure chemical ionization mass spectrometry (APCI-MS), and two transitions of multiple reaction monitoring (MRM) APCI-MS. The internal standard, external standard, and response factor methods gave values of 0.5870 ± 0.0045, 0.5893 ± 0.0041, and 0.5889 ± 0.0045 μg/mL, respectively, by UV detection. The values obtained by MS were 0.6117 ± 0.0140, 0.6018 ± 0.0244, and 0.5848 ± 0.0146 μg/mL by SIM and two transitions of MRM, respectively. The triacylglycerols in the oils were analyzed using full-scan APCI-MS, electrospray ionization (ESI) MS, up to MS(4), an ELSD, and a CAD. The method proved to be very sensitive for vitamin D(3), as well as triacylglycerols (TAGs), allowing identification of intact TAGs containing fatty acids up to 28 carbons in length. LC-ESI-MS of glycerin polymers is also demonstrated.

An improved high performance liquid chromatography–photodiode array detection–atmospheric pressure chemical ionization–mass spectrometry method for determination of chlorophylls and their derivatives in freeze-dried and hot-air-dried Rhinacanthus nasutus (L.) Kurz

Rhinacanthus nasutus (L.) Kurz, a traditional Chinese herb possessing antioxidant and anti-cancer activities, has been reported to contain functional components like carotenoids and chlorophylls. However, the variety and amount of chlorophylls remain uncertain. The objectives of this study were to develop a high performance liquid chromatography–photodiode array detection–atmospheric pressure chemical ionization–mass spectrometry (HPLC–DAD–APCI–MS) method for determination of chlorophylls and their derivatives in hot-air-dried and freeze-dried R. nasutus. An Agilent Eclipse XDB-C18 column and a gradient mobile phase composed of methanol/N,N-dimethylformamide (97:3, v/v), acetonitrile and acetone were employed to separate internal standard zinc-phthalocyanine plus 12 cholorophylls and their derivatives within 21min, including chlorophyll a, chlorophyll a′, hydroxychlorophyll a, 15-OH-lactone chlorophyll a, chlorophyll b, chlorophyll b′, hydroxychlorophyll b, pheophytin a, pheophytin a′, hydroxypheophytin a, hydroxypheophytin a′ and pheophytin b in hot-air-dried R. nasutus with flow rate at 1mL/min and detection at 660nm. But, in freeze-dried R. nasutus, only 4 chlorophylls and their derivatives, including chlorophyll a, chlorophyll a′, chlorophyll b and pheophytin a were detected. Zinc-phthalocyanine was found to be an appropriate internal standard to quantify all the chlorophyll compounds. After quantification by HPLC–DAD, both chlorophyll a and pheophytin a were the most abundant in hot-air-dried R. nasutus, while in freeze-dried R. nasutus, chlorophyll a and chlorophyll b dominated.

Rapid analysis of formic acid, acetic acid, and furfural in pretreated wheat straw hydrolysates and ethanol in a bioethanol fermentation using atmospheric pressure chemical ionisation mass spectrometry

Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) offers advantages as a rapid analytical technique for the quantification of three biomass degradation products (acetic acid, formic acid and furfural) within pretreated wheat straw hydrolysates and the analysis of ethanol during fermentation. The data we obtained using APCI-MS correlated significantly with high-performance liquid chromatography analysis whilst offering the analyst minimal sample preparation and faster sample throughput.

Condensed Tannins and Flavonoids from the Forage Legume Sulla (Hedysarum coronarium)

The condensed tannin concentrations and composition and the characterization of the phenolic constituents in the leaves of the forage legume sulla (Hedysarum coronarium), a biennial forage legume found in temperate agricultural regions, were studied. The colorimetric butanol-HCl assay was used for the quantitation of the seasonal condensed tannin concentrations in the leaves of sulla. Fractionation of extracts on Sephadex LH-20 using step elution with aqueous methanol, followed with aqueous acetone or gradient elution with water, aqueous methanol, and aqueous acetone, gave condensed tannin and flavonoid fractions. The chemical characteristics of the purified condensed tannin fractions were studied by acid-catalyzed degradation with benzyl mercaptan and electrospray ionization mass spectrometry (ESI-MS). Thiolysis revealed that epigallocatechin was the major extender unit (15-75%) while gallocatechin was the major terminal unit (50-66%), thus indicating the extractable sulla condensed tannin fraction as the prodelphinidin type. Condensed tannin oligomers to polymers obtained from Sephadex LH-20 gradient fractions ranged between 2.9 and 46 mDP. The homo- and heterogeneous oligomer ions in condensed tannin gradient fractions detected by ESI-MS ranged from 2 to 10 DP and are consistent with the values obtained by thiolysis (2.9-6.9 DP). Lower molecular weight phenolics, including flavonoids and phenolic acids, were characterized by liquid chromatography atmospheric pressure chemical ionization mass spectrometry (LC-APCI/MS) and ESI/MS/MS on a linear ion trap. The flavonoids extracted with aqueous acetone and methanol from sulla leaves and identified included kaempferol, rutin, quercetin-7-O-α-L-rhamnosyl-3-O-glucosylrhamnoside, quercetin-3-O-α-L-rhamnosyl-7-O-glucoside, kaempferol-3-O-β-D-glucoside-dirhamnoside, genistein-7-O-β-D-glucosyl-6″-O-malonate, formononetin-7-O-β-D-glucoside-6″-O-malonate, and afrormosin and the phenolic acid chlorogenic acid.

Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography/mass spectrometry and gas chromatography/flame ionization detection

Fatty acid (FA) and triacylglycerol (TG) composition of natural oils and fats intake in the diet has a strong influence on the human health and chronic diseases. In this work, non-aqueous reversed-phase (NARP) and silver-ion high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection and gas chromatography with flame-ionization detection (GC/FID) and mass spectrometry detection are used for the characterization of FA and TG composition in complex samples of animal fats from fallow deer, red deer, sheep, moufflon, wild boar, cock, duck and rabbit. The FA composition of samples is determined based on the GC/FID analysis of FA methyl esters. In total, 81 FAs of different acyl chain length, double bond (DB) number, branched/linear, cis-/ trans- and DB positional isomers are identified. TGs in animal fats contain mainly monounsaturated and saturated FAs. High amounts of branched and trans-FAs are observed in the samples of ruminants. In NARP mode, individual TG species are separated including the separation of trans- and branched TGs. Silver-ion mode provides the separation of TG regioisomers, which enables the determination of their ratios. Great differences in the preference of unsaturated and saturated FAs in the sn-2 position on the glycerol skeleton are observed among individual animal fats. Unsaturated FAs are preferentially occupied in the sn-2 position in all animal samples except for wild boar with the strong preference of saturated FAs in the sn-2 position.

Differentiation of various kinds of Fructus schisandrae by surface desorption atmospheric pressure chemical ionization mass spectrometry combined with Principal Component Analysis

Various kinds of Fructus schisandrae were studied by surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS) without any sample pretreatment. The volatile components in F. schisandrae were detected in the ambient environment and the analytical time for each sample was only 30 s. F. schisandrae are produced mainly in 5 different geographical regions (Elunchun, Mudanjiang, Tonghua, Tieling and Shangluo), and they could be successfully differentiated according to their chemical markers by Principal Component Analysis (PCA). A total of 8 components which gave more contribution for PCA analysis were unambiguously identified by comparison of the MS 2 data of chemical markers to the data of reference compounds as reported in the literature. Similarly, wild grown and cultivatable species of F. schisandrae were well separated by the above-mentioned method. In addition, raw and processed cultivatable F. schisandrae (steamed by water, alcohol, vinegar, or honey, and fried by honey) were found to be clustered at different location, respectively. Furthermore, the clustered degree of differently processed products was correlated with their clinical effects. Our results demonstrated that DAPCI-MS in combination with PCA was a feasible technique for high-throughput differentiation of various kinds of F. schisandrae. It is also possible that DAPCI-MS could become a powerful technology in the studies of traditional Chinese medicine studies and in situ analysis of Chinese herbs.

Simultaneous determination of tryptophan, kynurenine, kynurenic and xanthurenic acids in honey by liquid chromatography with diode array, fluorescence and tandem mass spectrometry detection

A liquid chromatography method using diode array-fluorescence detection and atmospheric pressure chemical ionization mass spectrometry (LC-DAD-FLD and LC–APCI-MS/MS) was developed to quantify the levels of tryptophan (TRP), kynurenine (KYN), kynurenic (KYNA) and xanthurenic (XA) acids in honey. This procedure involved isolating the compounds of interest via solid-phase extraction (SPE) with mixed-mode polymeric cartridges. Chromatographic separation of the analytes was performed in isocratic mode on a Synergi 4μ Hydro-RP 80Å (150 × 4.60 mm i.d.) analytical column at 30 °C. The mobile phase of 20 mM ammonium formate (pH 4) and methanol was passed at a flow rate of 0.5 mL/min. In replicate sets of spiked honey samples, the average analyte recoveries ranged from 60 to 98% for TRP, 55 to 120% for KYN, 65 to 106.5 for KYNA and 56 to 114% for XA. Detection limits ranged from 4 to 36 μg/kg for LC-DAD-FLD to 0.2 and 1.0 μg/kg for LC–APCI-MS/MS. A strong matrix effect was found when MS/MS was employed, necessitating calibration using the standard addition method on matrix-matched standards for each honey type. The method was used to quantify each of the compounds of interest in 17 honey samples of distinct botanical origins.

Carbon disulfide reagent allows the characterization of nonpolar analytes by atmospheric pressure chemical ionization mass spectrometry

While atmospheric pressure ionization methodologies have revolutionized the mass spectrometric analysis of nonvolatile analytes, limitations native to the chemistry of these methodologies hinder or entirely inhibit the analysis of certain analytes, specifically, many nonpolar compounds. Examination of various analytes, including asphaltene and lignin model compounds as well as saturated hydrocarbons, demonstrates that atmospheric pressure chemical ionization (APCI) using CS(2) as the reagent produces an abundant and stable molecular ion (M(+•)) for all model compounds studied, with the exception of completely saturated aliphatic hydrocarbons and the two amino acids tested, arginine and phenylalanine. This reagent substantially broadens the applicability of mass spectrometry to nonvolatile nonpolar analytes and also facilitates the examination of radical cation chemistry by mass spectrometry.

LC/MS analysis of stratum corneum lipids: ceramide profiling and discovery

Ceramides (CERs) in the upper layer of the skin, the stratum corneum (SC), play a key role in the skin barrier function. In human SC, the literature currently reports 11 CER subclasses that have been identified. In this paper, a novel quick and robust LC/MS method is presented that allows the separation and analysis of all known human SC CER subclasses using only limited sample preparation. Besides all 11 known and identified subclasses, a 3D multi-mass chromatogram shows the presence of other lipid subclasses. Using LC/MS/MS with an ion trap (IT) system, a Fourier transform-ion cyclotron resonance system, and a triple quadrupole system, we were able to identify one of these lipid subclasses as a new CER subclass: the ester-linked ω-hydroxy fatty acid with a dihydrosphingosine base (CER [EOdS]). Besides the identification of a new CER subclass, this paper also describes the applicability and robustness of the developed LC/MS method by analyzing three (biological) SC samples: SC from human dermatomed skin, human SC obtained by tape stripping, and SC from full-thickness skin explants. All three biological samples showed all known CER subclasses and slight differences were observed in CER profile.

Lipidomic profiling of biological tissues using off-line two-dimensional high-performance liquid chromatography–mass spectrometry

Lipids are important components in all biological tissues having many essential roles associated with the proper function of the organism. Their analysis in the biological tissues and body fluids is a challenging task due to the extreme sample complexity of polar lipids and to their amphiphilic character. In this work, we describe a new method for the characterization of the lipid composition in various tissues, using off-line two-dimensional coupling of hydrophilic interaction liquid chromatography (HILIC) and reversed-phase (RP) high-performance liquid chromatography coupled to electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) mass spectrometry. In the first dimension the total lipid extracts are fractioned using HILIC into individual lipid classes. In total, 19 lipid classes (+3 regioisomeric pairs) that cover a wide range of polarities are separated in one analytical run, which is the highest number of analyzed lipid classes reported so far. The lysophospholipid regioisomers are also separated in HILIC mode followed by the identification based on the characteristic ESI mass spectra. The collected fractions of the various lipid classes are further separated in the RP mode, which offers an excellent resolution of the individual lipid species. Their ESI or APCI mass spectra give correct information on the fatty acid composition and on the individual regioisomeric positions on the glycerol skeleton. Off-line coupling of both modes enables the comprehensive analysis of plant and animal samples as illustrated on the analysis of egg yolk, soya and porcine brain tissues.

Pharmacokinetics of ergosterol in rats using rapid resolution liquid chromatography–atmospheric pressure chemical ionization multi-stage tandem mass spectrometry and rapid resolution liquid chromatography/tandem mass spectrometry

Rapid resolution liquid chromatography/tandem multi-stage mass spectrometry (RRLC–MS n ) and rapid resolution liquid chromatography/tandem mass spectrometry (RRLC/MS/MS) methods were developed for the identification and quantification of ergosterol and its metabolites from rat plasma, urine and faeces. Two metabolites (ERG1 and ERG2) were identified by RRLC/MS n . The concentrations of the ergosterol were determined by RRLC/MS/MS. The separation was performed on an Agilent Zorbax SB-C18 with the mobile phase consisting of methanol and water (containing 0.1% formic acid). The detection was carried out by means of atmospheric pressure chemical ionization mass spectrometry in positive ion mode with multiple reaction monitoring (MRM). Linear calibration curves were obtained in the concentration range of 7–2000, 6–2000 and 8–7500 ng/mL for plasma, urine and faecal homogenate, respectively. The intra- and inter-day precision values (RSD) were below 10%. The method was applied to the pharmacokinetic properties and elimination pathway of ergosterol in rats.

The genus Dracunculus – A source of triacylglycerols containing odd-numbered ω-phenyl fatty acids

Reversed phase liquid chromatography–atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/MS-APCI) was used to identify and quantify triacylglycerols (TAGs) having odd-numbered ω-phenylalkanoic acids from seeds of the flower plant Dracunculus vulgaris, and TAGs from the bacterium Rhodococcus erythropolis prepared by precursor directed biosynthesis from phenylalanine and having the corresponding even-numbered ω-phenylalkanoic acids. Model compounds, which are not commercially available, were prepared by organic synthesis and this allowed us to extend the number of identified natural TAGs to nearly 140 molecular species. Both synthetic and natural compounds containing ω-phenylalkanoic acids were found to have antioxidant and free radical scavenging properties.

Derivatization-independent cholesterol analysis in crude lipid extracts by liquid chromatography/mass spectrometry: Applications to a rabbit model for atherosclerosis

Direct measurement of various sterols in crude lipid extracts in a single experiment from limited biological samples is challenging. Current mass spectrometry (MS) based approaches usually require chemical derivatization before subjecting to MS analysis. Here, we present a derivatization-independent method for analyzing various sterols, including cholesterol and its congeners, using liquid chromatography and atmospheric pressure chemical ionization mass spectrometry. Based on the specific tandem mass spectrometry pattern of cholesterol, multiple reaction monitoring (MRM) transitions were used to quantify free cholesterol and its fatty acyl esters. Several cholesterol oxidation products could also be measured using the upfront liquid chromatography separation and specific MRM transitions. The method was validated alongside established enzymatic assays in measuring total cholesterol. As a proof of concept, we analyzed plasma sterols in rabbits administrated with a high cholesterol diet (HCD) which is a classical atherosclerotic model. Free cholesterol, cholesterol esters, 7-hydroxycholesterol, and 7-ketocholesterol were elevated in plasma of rabbits on HCD. This method could also serve as an excellent tool for quantitative analysis of other sterols such as ergosterol and sitosterol in other organisms beside mammalian. In Saccharomyces cerevisiae, our results indicated dramatic increases of the ratio of ergosterol esters to free ergosterol in both yeh2Δ and tgl1Δ cells, which are consistent with the function of the respective enzymes.

Phantom Ring‐Closing Condensation Polymerization: Towards Antibacterial Oligoguanidines

The first example of phantom ring-closing condensation polymerization for the synthesis of oligoguanidines is presented. A new oligoguanidine with a ring structure was achieved in one step by the condensation reaction of a triamine, like diethylenetriamine, with guanidine hydrochloride. The condensation reaction proceeded by selective ring-closure towards the formation of five-membered rings in the oligomer backbone. The resulting polymer repeat unit structure was different from the starting monomers (phantom polymer) and was formed by elimination of three molecules of ammonia per repeat unit. The inter-, intra-, and inter-molecular reaction sequences led to the new structure as proved by different spectroscopic techniques (atmospheric pressure chemical-ionization mass spectrometry, and one-dimensional and two-dimensional homo- and heteronuclear correlation NMR experiments) as well as supported by quantum chemical investigations. Preliminary results regarding antibacterial use of the resulting oligoguanidine were also promising and showed its effect within 15-30 min as an antibacterial material.

‘Dilute‐and‐Shoot’ Method for Vitamin D Analysis in Dietary Supplement Capsules

Three methods are demonstrated for a complete analysis of vitamin D and triacylglycerols (TAGs) in fortified dietary supplements that virtually eliminates all chemical pretreatment prior to analysis. Three mass spectrometers, in parallel, plus a UV detector, an evaporative light scattering detector (ELSD), and a corona charged aerosol detector (CAD), were used simultaneously. The contents of gelcaps labeled as containing 1000 IU (25 mcg) vitamin D3 in safflower oil and 2000 IU (50 mcg) vitamin D3 in rice bran oil were analyzed without the need for lengthy saponification and extraction. Three to five gelcaps were analyzed using vitamin D2 as an internal standard. Vitamin D3 was analyzed using UV detection, selected ion monitoring (SIM) atmospheric pressure chemical ionization mass spectrometry (APCI‐MS), and two transitions of multiple reaction monitoring (MRM) APCI‐MS. TAGs in the oils were analyzed using full‐scan APCI‐MS, electrospray ionization (ESI) MS, up to MS4, plus two auxiliary detectors‐‐‐the ELSD and CAD. TAGs containing fatty acids up to 28 carbons in length were identified. The vitamin D contents of the gelcaps exceeded label values, and additional chromatographic peaks appeared when the source of vitamin D3 was fish oil (safflower oil gelcap) versus synthetic vitamin D3 (rice bran oil gelcap).

Highly sensitive, quick and simple quantification method for mono and disaccharides in aqueous media using liquid chromatography–atmospheric pressure chemical ionization–mass spectrometry (LC–APCI–MS)

A highly sensitive, rapid LC–APCI–MS method for identification and quantification of mono and disaccharides in simple or complex aqueous phase has been developed. This original method is easy to use, no derivation and no post-column injection are needed. The separation is performed with a hydrophilic amino interaction (HILIC) column allowing high-throughput analysis with analysis times of 15 min for monosaccharides to 22 min for disaccharides. The development of the method carried out with 9 standard saccharides allowed to point out a dynamic range from 0.1–25.6 to 1–256 μg mL −1 depending on the considered sugar. Next, the method was validated on saccharides at known concentrations in water and on 2 real samples: orange juice and aqueous phase obtained after enzymatic hydrolysis of sunflower seeds.

Variation in aroma release between panellists consuming different types of confectionary

ABSTRACTVariation in in vivo volatile release was studied using atmospheric pressure chemical ionization–mass spectrometry. The extent of variation in in vivo flavour release was related to the partitioning behaviour of the compound. Compounds with highest air/water partition coefficients (Kaw) showed more variation in release than those with low Kaw values. Sample matrix components (such as lipid) have the potential to influence the air/product partition coefficient. If they reduce the partition coefficient they can reduce the variation in volatile release. Variation in release was assessed for menthone from a series of five different sample types. Chewing gum gave the most consistent release, which was attributed to the consistency of chewing in oral processing and volatile delivery. The least consistent release intensity was associated with the boiled sweet, which may have resulted in substantial variation in oral processing and hence volatile delivery. A study of a panel of 50 people showed that there were strong correlations in the intensity of volatile release across sample types. Panellists who released high concentrations of volatiles into their breath from one sample type would typically do so for another. Equally, panellists who released lower amounts from one sample type would also release less from others. Some differences in the intensity of aroma release were observed between sample types. These appear to be related to textural differences between samples, which would affect oral processing. Copyright © 2011 John Wiley & Sons, Ltd.

Mass Spectrometric Detection of Cholesterol Oxidation in Bovine Sperm1

We report on the presence and formation of cholesterol oxidation products (oxysterols) in bovine sperm. Although cholesterol is the most abundant molecule in the membrane of mammalian cells and is easily oxidized, this is the first report on cholesterol oxidation in sperm membranes as investigated by state-of-the-art liquid chromatographic and mass spectrometric methods. First, oxysterols are already present in fresh semen samples, showing that lipid peroxidation is part of normal sperm physiology. After chromatographic separation (by high-performance liquid chromatography), the detected oxysterol species were identified with atmospheric pressure chemical ionization mass spectrometry in multiple-reaction-monitoring mode that enabled detection in a broad and linear concentration range (0.05-100 pmol for each oxysterol species detected). Second, exposure of living sperm cells to oxidative stress does not result in the same level and composition of oxysterol species compared with oxidative stress imposed on reconstituted vesicles from protein-free sperm lipid extracts. This suggests that living sperm cells protect themselves against elevated oxysterol formation. Third, sperm capacitation induces the formation of oxysterols, and these formed oxysterols are almost completely depleted from the sperm surface by albumin. Fourth, and most importantly, capacitation after freezing/thawing of sperm fails to induce both the formation of oxysterols and the subsequent albumin-dependent depletion of oxysterols from the sperm surface. The possible physiological relevance of capacitation-dependent oxysterol formation and depletion at the sperm surface as well as the omission of this after freezing/thawing semen is discussed.

Enantiomeric separation of asymmetric triacylglycerol by recycle high-performance liquid chromatography with chiral column

In our previous studies, we employed recycle HPLC for the separation of triacylglycerol (TAG)-positional isomers (PIs). In this study, a recycle HPLC system equipped with a polysaccharide-based chiral column was applied to the enantiomeric separation of some asymmetric TAGs having straight-chain C16–C18 acyl residues. As a result, 1,2-dipalmitoyl-3-oleoyl- rac-glycerol ( rac-PPO), 1,2-dioleoyl-3-palmitoyl- rac-glycerol ( rac-OOP), and 1,2-dipalmitoyl-3-linoleoyl- rac-glycerol ( rac-PPL) were resolved into their respective enantiomers. However, neither 1,2-dioleoyl-3-linoleoyl- rac-glycerol ( rac-OOL), consisting of only unsaturated fatty acids, nor 1,2-dipalmitoyl-3-stearoyl- rac-glycerol ( rac-PPS), consisting of only saturated fatty acids, was resolved. These results suggest that the asymmetric TAGs, used in this study, having both a palmitic acid moiety and an oleic acid (or a linoleic acid) moiety at the sn-1 or sn-3 positions are resolved by the chiral column. This new chiral separation method can be used in combination with atmospheric pressure chemical ionization mass spectrometry to determine the sn-OOP/ sn-POO ratio in palm oil. This method is applicable for the chiral separation of asymmetric TAGs in palm oil.

Differentiation of human kidney stones induced by melamine and uric acid using surface desorption atmospheric pressure chemical ionization mass spectrometry

Clinically obtained human kidney stones of different pathogenesis were dissolved in acetic acid/methanol solutions and then rapidly analyzed by surface desorption atmospheric pressure chemical ionization mass spectrometry (SDAPCI-MS) without any desalination treatment. The mass spectral fingerprints of six groups of kidney stone samples were rapidly recorded in the mass range of m/z 50-400. A set of ten melamine-induced kidney stone samples and nine uric acid derived kidney stone samples were successfully differentiated from other groups by principal component analysis of SDAPCI-MS fingerprints upon positive-ion detection mode. In contrast, the mass spectra recorded using negative-ion detection mode did not give enough information to differentiate those stone samples. The results showed that in addition to the melamine, the chemical compounds enwrapped in the melamine-induced kidney stone samples differed from other kidney stone samples, providing useful hints for studying on the formation mechanisms of melamine-induced kidney stones. This study also provides useful information on establishing a MS-based platform for rapid analysis of the melamine-induced human kidney stones at molecular levels.