Rapid analysis of trace pollutants using laser mass spectrometry

Organic pollution has been gaining more and more attention.Yet,at present the determination of virtually all of them,including polycyclic aromatic carbons (PAHs),the largest single class of chemical carcinogens known today,is made via pre-purification and pre-concentration.The major problems are complexity and time-consuming,thus,no ideal real-time on-line monitoring can be done.Laser mass spectrometry combines UV spectroscopy and time-of-flight mass spectrometry (TOF-MS) through resonance-enhanced multiphoton ionization (REMPI).It is characteristic of high sensitivity,high selectivity and rapidity.In this paper,after its principles,a small mobile laser mass spectrometer,in which a mini-excimer (KrF,248 nm) laser was used,is introduced.Real-time analysis of vehicle exhaust gas was made using this instrument,and the results showed some advantages over traditional methods:multicomponent detection,including benzene,toluene,xylene,C3-benzene,naphthalene,and methyl-naphthalene; high sensitivity (100 ppb);high time-resolution (0.1 s);and no need for pre-purification or pre-concentration of samples.

Study on Testing the Composition of Indoor Air Pollution to Benzene Series by Laser Mass Spectrometry

This paper reports some experimental detecting results of pollutants in the atmosphere by means of laser mass spectrometry. For toluene as calibration gas, the calibration procedure was also given. Benzene, toluene and xylene were discovered in testing indoor atmosphere resulting from dope in the course of fitment. Meanwhile, it is noticeable that the concentration of various harmful elements is obviously decreasing as timegoeson.

The isolation and identification of apolipoprotein C-I in hormone-refractory prostate cancer using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry

Androgens play a central role in prostate cancer pathogenesis, and hence most of the patients respond to androgen deprivation therapies. However, patients tend to relapse with aggressive prostate cancer, which has been termed as hormone refractory. To identify the proteins that mediate progression to the hormone-refractory state, we used protein-chip technology for mass profiling of patients＇ sera. This study included 16 patients with metastatic hormone-refractory prostate cancer who were initially treated with androgen deprivation therapy. Serum samples were collected from each patient at five time points： point A, pre-treatment; point B, at the nadir of the prostate- specific antigen （PSA） level; point C, PSA failure; point D, the early hormone-refractory phase; and point E, the late hormone-refractory phase. Using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, we performed protein mass profiling of the patients＇ sera and identified a 6 640-Da peak that increased with disease progression. Target proteins were partially purified, and by amino acid sequencing the peak was identified as a fragment of apolipoprotein C-I （ApoC-I）. Serum ApoC-I protein levels increased with disease progression. On immunohistochemical analysis, the ApoC-i protein was found localized to the cytoplasm of the hormone-refractory cancer cells. In this study, we showed an increase in serum ApoC-I protein levels in prostate cancer patients during their progression to the hormone-refractory state, which suggests that ApoC-I protein is related to progression of prostate cancer. However, as the exact role of ApoC-I in prostate cancer pathogenesis is unclear, further research is required.

Analysis of Single Nucleotide Polymorphism in Human Paraoxonase 1 Gene(Q192R) with Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

Introduction Single nucleotide polymorphisms （SNPs） are the most abundant DNA markers in the human genome occurring at a frequency of one in every 500--1000 nucleotides. A variety of methods have been used for the analysis of single nucleotide polymorphisms, including restriction fragment length polymorphism （RFLP）, direct sequencing by using laser-induced fluorescence detectionTM, fluorescence energy transfer, MALDI-TOF MS combined with primer extension or invasive cleavage, and fluorescence polarization. During the past two decades, mass spectrometry has become a very popular tool in the analysis of biomolecules and is perfectly suited to the analysis of single nucleotide polymorphisms （SNPs） due to its speed, low cost, and accuracy. In this work, we used MALDI TOF mass spectrometry to detect the fragments of restriction endonuclease hydrolysis of PCR products flanking a SNP located at paraoxonase 1（Q192R）. Compared with electrophoresis, this method requires less time of analysis and possess a higher accuracy.

A novel sample preparation method of matrix-assisted laser desorption/ionization time of flight mass spectrometry for polystyrene

A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and signal intensity of mass spectra were improved. The mechanism was also analyzed.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry traces the geographical source of Biomphalaria pfeifferi and Bulinus forskali,involved in schistosomiasis transmission

Background Freshwater snails of the genera Bulinus spp.,Biomphalaria spp.,and Oncomelania spp.are the main intermediate hosts of human and animal schistosomiasis.Identification of these snails has long been based on mor-phological and/or genomic criteria,which have their limitations.These limitations include a lack of precision for the morphological tool and cost and time for the DNA-based approach.Recently,Matrix-Assisted Laser Desorp-tion/lonization Time-Of-Flight(MALDI-TOF)mass spectrometry,a new tool used which is routinely in clinical microbi-ology,has emerged in the field of malacology for the identification of freshwater snails.This study aimed to evaluate the ability of MALDI-TOF MS to identify Biomphalaria pfeifferi and Bulinus forskali snail populations according to their geographicalorigin.Methods This study was conducted on 101 Bi.pfeifferi and 81 Bu.forskali snails collected in three distinct geo-graphical areas of Senegal(the North-East,South-East and central part of the country),and supplemented with wild and laboratory strains.Specimens which had previously been morphologically described were identified by MALDl-TOF MS[identification log score values(LSV)≥1.7],after an initial blind test using the pre-existing database.After DNA-based identification,new reference spectra of Bi.pfeiferi(n=10)and Bu.forskali(n=5)from the geographical areas were added to the MALDI-TOF spectral database.The final blind test against this updated database was per-formed to assess identification at the geographic source level.Results MALDI-TOF MS correctly identified 92.1%of 101 Bi.pfeifferi snails and 98.8%of 81 Bu.forskali snails.At the final blind test,88%of 166 specimens were correctly identified according to both their species and sampling site,with LSVs ranging from 1.74 to 2.70.The geographical source was adequately identified in 90.1%of 91 Bi.pfeifferi and 85.3%of 75 Bu.forskalii samples.Conclusions Our findings demonstrate that MALDI-TOF MS can identify and differentiate snail populations according to geographical origin.It outperforms the current DNA-based approaches in discriminating laboratory from wild strains.This inexpensive high-throughput approach is likely to further revolutionise epidemiological studies in areas which are endemic for schistosomiasis.

Mass spectrometry-based serum peptide profiling in hepatocellular carcinoma with bone metastasis

AIM: To investigate the potential of serum peptides as a diagnostic tool for hepatocellular carcinoma (HCC) with bone metastasis.

Identification of serum biomarkers for diagnosing stage Ⅰ lung adenocarcinoma by MALDI-TOF mass spectrometry

Objective To identify specific biomarkers that could improve early diagnosis of lung adenocarcinoma using matrix-assisted laser desorption/ionization (MALDI) technology. Methods Serum samples were isolated from 17 patients with stage Ⅰ lung adenocarcinoma and 17 age-and sex-matched healthy controls,and the serum proteomic profiles were obtained by matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry. Results Compared with healthy control group,two highly expressed potential biomarkers were identified with the relative molecular weights of 6 631.64 Da and 4 964.21 Da. The two best novel protein peaks were automatically chosen for the system training and the development of the constructed model. The constructed model was then used to test an independent set of masked serum samples from 15 lung adenocarcinoma patients and 22 healthy individuals. The analysis yielded a sensitivity of 93.3%,and a specificity of 95.5%. Conclusion These results suggest that MALDI-TOF-MS ProteinChip technology is a quick,convenient,and high-output analyzing method that is capable of selecting several relatively potential biomarkers from the serum of lung adenocarcinoma patients and may have a clinical value in the future,and will provide clues to identifying new serologic biomarkers of lung adenocarcinoma.

Establishment and Preliminary Application of Two dimensional Electrophoresis and Mass Spectrometry in Ovary Study

Objective To apply two-dimensional electrophoresis and mass spectrometry in the ovary proteome researchMethods Protein extractions from mouse ovaries were run in IPGphor isoelectric focus system with 11 cm and 24 cm IPG strips respectively (pH 3～10, 0.3 mm thick), then the protein spots were identified by mass spectrometry.Results The ovary protein exactions separated by two-dimensional electrophoresis have got high resolution, and identifing protein by mass spectrometry was highly efficient and facilitly. These two techniques should facilitate further investigation of female reproduction proteome research.Conclusion These two rapid high resolutions and efficient techniques have a variety of applications foreground in female reproduction proteome pattern research.

Elemental Quantitative Distribution and Statistical Analysis on Cross Section of Stainless Steel Sheet by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

An innovative application of laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） technique in illustrating elemental distributions on stainless steel sheets was presented. The technique proved to be a systematic and accurate ap- proach in producing visual images or maps of elemental distributions at cross-sectional surface of a stainless steel sheet. Two stain- less steel sheets served as research objects： 3 mm×l 300 mm hot-rolled stainless steel plate and 1 mm×l 260 mm cold-rolled plate. The cross-sectional surfaces of the two samples at 1/4 position along the width direction were scanned （raster area -44 mm2 and 11 mm2） with a focused laser beam （wavelength 213 nm, diameter of laser crater 100 μm, and laser power 1.6 mJ） in a laser abla- tion chamber. The laser ablation system was coupled to a quadrupole ICP-MS, which made the detection of ion intensities of 27A1＋, 44Ca＋, 47Ti-, 55Mn＋ and 56Fe＋ within an area of interest possible. One-dimensional （ID） content line distribution maps and two- dimensional （2D） contour maps for specific positions or areas were plotted to indicate the element distribution of a target area with high accuracy. Statistic method was used to analyze the acquired data by calculating median contents, maximum segregation, sta- tistic segregation and content-frequency distribution.

Mg/Ca,Ba/Ca,and S/Ca ratios as environmental and growth proxies for bivalve shells from the Haima cold seep,South China Sea

Bivalve shell fossils,cemented by authigenic carbonates,are widely spread in the Haima cold seep,Qiongdongnan Basin of the South China Sea(SCS).In this study,we examined an element profile of Gigantidas platifrons in the Haima cold seeps at a water depth of 1381 m.Based on the scanning electron microscope(SEM)analyses,the prismatic layer and nacreous layer were identified,which are characterized by prismatic structure and stratified structure,respectively.In addition,the profile can be subdivided into two parts:altered and unaltered zones.Laser inductively coupled plasma mass spectrometry(LA-ICP-MS)mapping shows that the element concentrations of the altered zones were influenced by the authigenic carbonate rocks,whereas the element concentrations of unaltered zones remain stable.In-situ X-ray diffraction(XRD)analyses show that the mineral constituent of the prismatic layer is mainly composed of aragonite.Along with the growth profile,Mg/Ca ratios of unaltered zones have minor variations,ranging 0.72-0.97 mmol/mol(mean=0.87 mmol/mol),with estimated temperatures of 3.8-4.1℃,indicating that the temperature of the surrounding seawater remains constant and agree with the measured data of 3.9℃which was conducted by a conductivity-temperature-depth system(CTD).The minor variations of Ba/Ca ratios(0.01-0.06 mmol/mol;mean=0.04 mmol/mol)indicate a relatively stabilized salinity of the surrounding seawater.S/Ca ratios show large variations of 0.04-4.15 mmol/mol(mean=1.37 mmol/mol).S/Ca ratios have regular variations which generally correspond to the variations of the Mg/Ca ratios,highlighting that the S/Ca ratios of bivalve shells show the potential to reflect the growth rate of the Gigantides.However,further studies should be carried out on the understanding of the links between the S/Ca ratios and seepage intensity of cold-seep fluids.

Nocardia cyriacigeorgica infection in a patient with repeated fever and CD4+T cell deficiency:A case report

BACKGROUND Nocardia pneumonia shares similar imaging and clinical features with pulmonary tuberculosis and lung neoplasms,but the treatment and anti-infective medication are completely different.Here,we report a case of pulmonary nocardiosis caused by Nocardia cyriacigeorgica(N.cyriacigeorgica),which was misdiagnosed as community-acquired pneumonia(CAP)with repeated fever.CASE SUMMARY A 55-year-old female was diagnosed with community-acquired pneumonia in the local hospital because of repeated fever and chest pain for two months.After the anti-infection treatment failed in the local hospital,the patient came to our hospital for further treatment.Enhanced computed tomography showed multiple patchy,nodular and strip-shaped high-density shadows in both lungs.A routine haematological examination was performed and showed abnormalities in CD19+B cells and CD4+T cells.Positive acid-fast bifurcating filaments and branching gram-positive rods were observed in the bronchoalveolar lavage fluid of the patient under an oil microscope,which was identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry as N.cyriacigeorgica.The patient’s condition quickly improved after taking 0.96 g compound sulfamethoxazole tablets three times a day.CONCLUSION The antibiotic treatment of Nocardia pneumonia is different from that of common CAP.Attention should be given to the pathogenic examination results of patients with recurrent fever.Nocardia pneumonia is an opportunistic infection.Patients with CD4+T-cell deficiency should be aware of Nocardia infection.

Surface-assisted laser desorption/ionization mass spectrometry for drug and metabolite analysis

Surface-assisted laser desorption/ionization mass spectrometry(SALDI-MS)uses inorganic nanomaterials as matrixes to facilitate desorption and ionization of analytes.Compared with the traditional matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)technique,SALDI-MS has the advantages of less interference in the low mass range,better reproducibility and higher salt tolerance.It is highly suitable for the analysis of small molecule compounds.In recent years,researchers have developed a range of nanomaterials that are successfully applied to the field of small molecule drug and metabolite analysis including drug screening and quantification,drug delivery,metabolite profiling,biomarker discovery and so forth.This review summarizes the latest progress of SALDI-MS matrix materials such as metal-based,carbon-based,silica-based nanomaterials and organic framework nanomaterials and their applications.In addition,our perspective of SALDI-MS technology is also discussed for further advancement.

Determination of persistent organic pollutants by gas chromatography/laser multiphoton ionization/time-of-flight mass spectrometry

An authentic mixture of polychlorinated biphenyls was measured using a short wide-bore capillary column for the group separation of major components present in an actual sample of Kanechlor. The limits of detection were improved by ca. 2 fold in comparison with those obtained using a conventional capillary column, since the retention time was reduced and the amount of analytes introduced into the mass spectrometer per unit time could be increased. On the other hand, surface-water and sediment samples containing polycyclic aromatic hydrocarbons （PAHs） were collected from the river located in the vicinity of a waste water treatment plant. Even acenaphthylene, a minor component of the mixture could be measured for the sediment sample, and the concentra- tions were determined for several heavy PAHs. As demonstrated, a technique involving laser multiphoton ionization/time-of-flight mass spectrometry was useful as a sensitive and selective analytical tool for the trace analysis of persistent organic pollutants in an environmental sample.

Detection of Sialylated N-Linked Glycans by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Native and methyl-esterified sialylated glycans were analyzed with 2,4,6-trihydroxyacetophenone（THAP）and 2,5-dihydroxybenzoic acid（DHB）as matrix by a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer（MALDI-TOF MS）.High quality negative-ion spectra of commercial sialylated glycan were obtained with THAP as matrix.Detection limit of the glycan was less than 0.1 pmol.After methyl esterification of sialic acid（SA）residue,sialylated glycans were detected sensitively in the positive-ion mode using DHB as matrix.Neutral and sialylated glycans from the mixture of asialofetuin and fetuin were methylesterified and simultaneously recognized in one manipulation.Methyl esterification of SA residue offers a convenient and sensitive way to identify the structure of N-linked glycans for glycan profiling.

笼内金属富勒烯的合成与分析

自1985年,Smalley等人首次在飞行时间质谱仪中检测到C60以来[1],富勒烯碳原子族的研究便不断深入,最初发现的激光蒸发含稀土化合物的石墨只能得到微量的金属富勒烯,仅限于质谱检测,直到1990年,Kratschmer等人采用石墨电子弧放电首次得到宏观量的富勒烯[2],才使得富勒烯研究进入了实质性的研究阶段.……

MALDI-TOF-MS法对重组人内皮抑素蛋白分子质量测定

肿瘤的生长依赖于血管的生成,新生血管不仅为肿瘤生长提供必需的营养物质,而且为肿瘤细胞扩散提供了重要的途径[1].1997年哈佛大学的O'Reilly等[2]发现了一种内源性新血管生成抑制因子内皮抑素(Endostatin),显示出特异抑制激活的血管内皮细胞增殖和肿瘤新血管生成的生物学活性,其抗肿瘤作用具有高效、低毒、无耐药性的优点.……

Bacterial flora concurrent with Helicobacter pylori in the stomach of patients with upper gastrointestinal diseases

AIM： To investigate the non-He/icobacterpy/ori （H. pylori） bacterial flora concurrent with H. pylori infection.METHODS： A total of 103 gastric biopsy specimens from H. pylori positive patients were selected for bacterial culture. All the non-H, pylori bacterial isolates were identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry （MALDI-TOF MS）.RESULTS： A total of 201 non-H, pyiori bacterial isolates were cultivated from 67 （65.0%） of the 103 gastric samples, including 153 isolates identified successfully at species level and 48 at genus level by MALDI-TOF MS. The dominant species were Streptococcus, Neisseria, Rothla and Staphylococcus, which differed fromthe predominantly acid resistant species reported previously in healthy volunteers. The prevalence of non-H. pylori bacteria was higher in non-ulcer dyspepsia group than in gastric ulcer group （100% vs 42.9%, P 〈 0.001）. Six bacterial species with urease activity （Staphylococcus epidermidis, Staphylococcus warneri, Staphylococcus capitis, Staphylococcus aureus, Brevibacteriurn spp. and Klebsiella pneumoniae） were also isolated.CONCLUSION： There is a high prevalence of the non-H, pylori bacteria concurrent with H. pylori infection, and the non-H, pylori bacteria may also play important as-yet-undiscovered roles in the pathogenesis of stomach disorders.

Proteiomic patterns for endometrial cancer using SELDI-TOF-MS

Serum samples from endometrial cancer (EC) patients and healthy females were analyzed using surface-enhanced laser desorption-ionization time-of-flight mass spectrometry (SELDI-TOF-MS) to discover the potential diagnostic biomarker for detection of EC. A preliminary training set of spectra derived from 40 EC patients and 30 healthy women were used to develop a proteomic model that effectively discriminated cancer patients from healthy women. The training set had a specificity of 100% and sensitivity of 92.5% in the EC detection. A blind test set, including 20 new cancer cases and 10 healthy women, was used to validate the sensitivity and specificity of this multivariate model, which had a corresponding results of 60% in specificity and 75% in sensitivity, respectively. The combination of SELDI-TOF-MS with bioinformatics tools could help find new biomarkers and establish the detection of EC with high sensitivity and specificity.

Diagnostic model of saliva protein finger print analysis of patients with gastric cancer

AIM:To explore the method for early diagnosis of gastric cancer by screening the expression spectrum of saliva protein in gastric cancer patients using mass spectrometry for proteomics.METHODS:Proportional peptide mass fingerprints were obtained by analysis based on proteomics matrix-assisted laser desorption ionization time-of-flight/mass spectrometry.A diagnosis model was established using weak cation exchange magnetic beads to test saliva specimens from gastric cancer patients and healthy subjects.RESULTS:Significant differences were observed in the mass to charge ratio(m/z) peaks of four proteins(1472.78 Da,2936.49 Da,6556.81 Da and 7081.17 Da) between gastric cancer patients and healthy subjects.CONCLUSION:The finger print mass spectrum of saliva protein in patients with gastric cancer can be established using gastric cancer proteomics.A diagnostic model for distinguishing protein expression mass spectra of gastric cancer from non-gastric-cancer saliva can be established according to the different expression of proteins 1472.78 Da,2936.49 Da,6556.81 Da and 7081.17 Da.The method for early diagnosis of gastric cancer is of certain value for screening special biological markers.