Paper spray ionization mass spectrometry: Study of a method for fast-screening analysis of pesticides in fruits and vegetables

New faster and simpler methods for determination of pesticides in agricultural products are necessary as requirements for food safety are becoming increasingly stringent. One possibility is to introduce a fast, easy and low-cost screening method before liquid chromatography mass spectrometry analyses. We hereby present a systematic proof of concept study of paper spray mass spectrometry method for pesticide detection as a screening method. Two sampling approaches – wiping the surface with paper and applying the sample homogenate directly on the paper – were used. The wiping method was more extensively studied for imazalil and thiabendazole originally present in oranges. For homogenized samples three matrices – oranges, tomatoes and grapes – and five pesticides of different chemical nature and polarity – thiabendazole, aldicarb, imazalil, methomyl and methiocarb – were chosen. It has been shown that limits of detection below maximum residue levels can be achieved for both methods (e.g. imazalil and thiabendazole detection limits were found to be lower than 5 mg/kg). The methods are therefore suitable for fast screening of samples. Moreover, the wiping method was also applied for 11 samples – oranges, grapefruits, lemons, limes, mandarins, tomatoes, apples, pears, strawberries, grapes and sweet peppers – from the local supermarket to screen for different pesticides. Three positive samples for thiabendazole and imazalil and one positive sample for imazalil were found.     

Thermal degradation kinetics of lutein, β-carotene and β-cryptoxanthin in virgin olive oils

A first-order kinetic mechanism is appropriate for describing the thermal degradation of lutein, β-carotene (β-c) and β-cryptoxanthin (β-cry) in virgin olive oils (VOO). Competitive and parallel reactions occur with lutein that yield reactions of isomerization and subsequent degradation to colorless products. β-c and β-cry thermal degradation reaction was only studied as a total degradation reaction to products. The thermal stability varies among carotenoids and was greater for lutein than β-c and β-cry but being affected significantly by changes in their geometric configuration. A true kinetic compensation effect exists in lutein, β-c and β-cry degradation reactions. The isokinetic study compared kinetic and thermodynamic parameters (TP) determined in the three VOO matrices of different pigment content (high, medium, and low), and found that the oily medium did not significantly affect the reaction mechanisms. Consequently, TP can be extrapolated to any type of VOO matrix yielding a mathematical model that predicts the carotenoid degradation and (Z)-lutein isomer formation in VOO with time, and depending on temperature.     

Identification of potential bioactive peptides generated by simulated gastrointestinal digestion of soybean seeds and soy milk proteins

In this work, the bioactive peptides produced during in vitro gastrointestinal digestion of soybean seeds and soy milk were investigated. The analysis was performed on extracted protein samples from soybean seeds and milk or directly on untreated soy milk. Proteins samples were subjected to simulated gastrointestinal digestion and then analyzed by nano-liquid chromatography coupled to tandem mass spectrometry for peptide sequencing. The identified peptides were 1173 in soybean seed samples, 1364 in untreated soy milk samples and 1422 in soy milk samples in which proteins were extracted by precipitation. The peptide identifications were then employed to search specific databases and look for the presence of bioactive peptides in the investigated samples, either with known biological activity or with potential antimicrobial activity. Results pointed out that soybean proteins underwent an extensive degradation process during gastrointestinal digestion and generated a large number of bioactive peptides, some with established activity, some with predicted antimicrobial activity. Finally, the supernatants collected after protein precipitation with acetone from both soybean seeds and soy milk were also analyzed to evaluate the presence of peptides produced by the action of endogenous proteases. Likely, peptides found in soy milk samples could be formed during food processing.     

评价基质辅助激光解析电离飞行时间质谱对葡萄球菌属的鉴定能力

目的评价基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)在临床鉴定常见葡萄球菌属的能力。方法采用MALDI-TOF MS对2011-2013年收集的151株葡萄球菌属进行分析比较;对鉴定结果不一致的菌株,用16SrRNA测序方法进行最后鉴定,评价MALDI-TOF MS的鉴定能力。结果 151株葡萄球菌属用MALDI-TOF MS与VITEK-2鉴定结果一致的有135株,符合率为89.4%,两种鉴定方法对39株金黄色葡萄球菌、34株表皮葡萄球菌及1株施氏葡萄球菌的鉴定符合率为100.0%;对16株结果不一致的随即用16SrRNA作进一步分析,其中15株鉴定结果与MALDI-TOF MS结果一致,MALDI-TOF MS与16SrRNA测序法对葡萄球菌属的鉴定能力符合率更高。结论与传统的VITEK-2鉴定方法比较,MALOT-TOF MS具有简便、快速、敏感、准确等优点,可用于葡萄球菌属的鉴定。     

基质辅助激光解吸电离飞行时间质谱在鉴定儿童血流感染少见苍白杆菌的应用及耐药情况分析

目的 快速鉴定和分析儿童血流感染少见苍白杆菌及其耐药情况分析。 方法 收集某儿童医院儿童血流感染的临床标本中分离的苍白杆菌26株,运用基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,MALDI-TOF MS)技术,对其进行检测,并结合测序结果分析确定菌株;根据药敏实验结果,用PCR法分析其耐药情况。 结果 26株实验菌株最后通过MALDI-TOF MS和16S rRNA基因测序技术,有25株被鉴定为解糖精假苍白杆菌,药敏结果显示它们对哌啦西林/他唑巴坦、喹诺酮类、氨基糖苷类和复方新诺明的耐药率为0.0%。而对氨曲南耐药率为100.0%,其他β-内酰胺类抗菌药物有不同的耐药率。AmpC和AmpR耐药基因检测均为阴性。 结论 MALDI-TOF MS能够快速鉴定临床少见苍白杆菌,儿童血流感染的解糖精假苍白杆菌不产头孢菌素酶,结合药敏分析结果及儿童用药特点,建议使用哌啦西林/他唑巴坦。     

基质辅助激光解析/电离飞行时间质谱法和表面等离子谐振法在HPV分型检测中的应用比较

目的:评价比较基质辅助激光解析/电离飞行时间质谱法(MALDI-TOF-MS)和表面等离子谐振法(SPR)在人乳头瘤病毒(HPV)分型检测中的应用。方法:两种方法对30种不同型别HPV L1基因分型国家参考品和129份经液基薄层细胞检测的样本分别进行检测和评价。结果:MALDI-TOF-MS法和SPR法检测参考品具有100%的一致性。采用测序法确定129份样本中有93份为HPV阳性,36份为HPV阴性。高危型样本的分型准确率MALDITOF-MS法为100%(77/77),SPR为94.8%(73/77);MALDI-TOF-MS法HPV分型检测的敏感率为88.2%(82/93)、特异性为88.9%(32/36),与SPR法的灵敏率和特异性相当。结论:MALDI-TOF-MS在HPV分型检测中具有较好的灵敏性和特异性,与SPR法一致。     

Profiling gangliosides from milk products and other biological membranes using LC/MS

Gangliosides are an important class of glycosphingolipids involved in numerous biological processes such as neuronal development, host–pathogen interactions and gastrointestinal health. Due to the highly heterogeneous nature and relatively low abundance of gangliosides, characterization of gangliosides in biological membranes is challenging. Existing methods for ganglioside analysis are quite time consuming and require expensive high resolution mass spectrometers. A rapid method combining reversed phase chromatography and mass spectrometry was developed using a triple-quadrupole mass spectrometer operating in multiple reaction monitoring mode. The ganglioside species were separated with a Poroshell 120 EC-C18 column and analysed under the negative ion mode. This method allows a sensitive, specific, and quantitative assay for profiling gangliosides. The method is developed for analysis of gangliosides in the milk fat globule membrane of whole milk and applied to other biological membranes. Application includes the cellular membrane of prostate cancer cells. In summary, the method allows various biological membranes to be screened for over 600 gangliosides from 12 classes (GM1, GM2, GM3, GM4, GD1, GD2, GD3, GD4, GT1, GT2, GT3, and GT4) in less than three hours. In summary, expressed as % of relative amounts: 1.5% GM3, 80.2% GD3, 14.4% GT3, 1.5% GM1, 2.4% GD1 were observed in whole milk; 2.5% GD1, 88.2% GD3, 2.5% GM1, 2.2% GM3, 0.2% GT2, 4.2% GT3 were observed in buttermilk and 10.6% GD1, 55.6% GD3, 1.6% GM1, 12.2% GM3, 19.2% GT3, 0.9% GT4 were observed in colostrum.     

两种菌体前处理方法对MALDI-TOF MS鉴定临床分离菌效果的影响

目的评价2种不同前处理方法对基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ ionization time of flight mass spectrometry,MALDI-TOF MS)鉴定临床分离菌效果的影响。 方法收集临床菌株43株,划线传代后,分别使用提取法和抹板法对微生物样本进行前处理,然后用MALDI-TOF MS鉴定比较两种处理方法的准确率和蛋白指纹图谱特征。 结果以16S rRNA/ITS RNA测序结果为参考标准,待测菌株经提取法处理后,MALDI-TOF MS鉴定革兰阳性菌、革兰阴性菌和真菌的种水平准确率分别为93.8%、100.0%和30.8%,待测菌株经抹板法处理后,MALDI-TOF MS鉴定革兰阳性菌、革兰阴性菌和真菌的种水平准确率分别为75.0%、100%和7.7%。提取法处理菌株后得到的蛋白指纹图谱中特征峰更多,信噪比更高,蛋白指纹图谱重现性更好。 结论推荐采用提取法为MALDI-TOF MS鉴定的常规前处理方法,其对建立标准的微生物检测流程,提高质谱鉴定的正确率,有重要价值。     

应用基质辅助激光解吸附电离飞行时间质谱分析宫颈鳞癌早期浸润蛋白质

目的探讨基质辅助激光解吸附电离飞行时间质谱(matrix assisted laser desorption ionization ti me of flight mass spectrometry,MALDI-TOF-MS)对宫颈鳞癌(squamous carcinoma of thecervix,SCC)组织切片直接分析,获取宫颈鳞癌早期浸润的分子标志物的有效性。方法利用超微量点样枪将化学基质直接点样到宫颈鳞癌组织切片上,然后利用基质辅助激光解吸附电离飞行时间质谱直接扫描宫颈鳞癌组织切片,分析宫颈鳞癌组织蛋白质分子。结果获得的25种蛋白质质谱峰强度比较,差异有显著意义(P<0.05)。其中7种差异蛋白质有分类意义,其质/核(M/Z)分别为:m/z3433,m/z4786,m/z10092,m/z10835,m/z15114,m/z15854和m/z16345。差异蛋白质m/z3433,m/z15114,m/z15854在宫颈鳞癌鳞状上皮组织高度表达,可作为宫颈鳞癌早期诊断的标志蛋白;差异蛋白质m/z16345在宫颈鳞癌的间质组织高度表达,可作为宫颈鳞癌早期间质浸润和扩散诊断的标志蛋白。结论利用基质辅助激光解吸附电离飞行时间质谱技术成功获取一组差异蛋白质。该差异蛋白组可望作为宫颈鳞癌早期诊断的标志蛋白。     

Levels of lipochromes and other bioactives in virgin olive oil from new olive germplasm

The composition of virgin olive oils from three new olive cultivars, such as Arno, Tevere and Basento, has been investigated in this work. Our attention was focused on chlorophylls, carotenes, xanthophylls and other major bioactives, as well as on some analytical indices related to functionality, quality and typicality of the new products. Our analytical study showed how the new oil kinds, especially Arno oil, had an interesting qualitative-quantitative composition of the pigment fraction. Pheophytin a (within the chlorophyll subfraction) and lutein (within the carotenoid subfraction) were found to be the major natural pigments occurring in the new products. Interesting were also the concentrations of biophenols, tocopherols, and tocotrienols detected in the three new oil varieties, as well as the values of the remarkable ratio fatty acids ω₆/fatty acids ω₃ and biophenols/polyunsaturated fatty acids (PUFA) (and those of the analytical variables endurance and susceptibility to autoxidation). The chemometric analyses showed how different multivariate methods were effective in discriminating between oil varieties. Thus, these chemometrics can effectively be used for traceability or authentication of the new products. We concluded how the three new olive cultivars can actually lead to new advances in the olive growing sector.     

Actinotignum schaalii血流感染1例及病原体鉴定报告

 Actinotignum schaalii是一种新型致病菌，可导致尿路感染和侵袭性感染。2022年贵黔国际总医院收治1例急性尿潴留患者血培养标本，采用基质辅助激光解吸电离飞行时间质谱（MALDI-TOF-MS）技术鉴定结果为Actinotignum schaalii，为兼性厌氧的革兰阳性球杆菌。该病例为国内首次血培养检出Actinotignum schaalii，该患者使用头孢他啶5 d后，感染症状明显减轻，感染指标恢复正常，患者未诉发热等不适，遂出院。结合国内外相关文献，探讨Actinotignum schaalii的临床特征、鉴定及治疗。     

Identification and quantification of polyphenolic compounds in ten pear cultivars by UPLC-PDA-Q/TOF-MS

The aim of this study was to identify and compare phenolic acids, flavan-3-ols and procyanidins, flavonol glycosides, flavones and hydroquinones in different cultivars of pear. Pear fruits (Pyrus communis L.) of ten cultivars (‘Bonkreta Williamsa’, ‘Carola’, ‘Dicolor’, ‘Faworytka’, ‘Hortensia’, ‘Konferencja’, ‘Lukasówka’, ‘Nojabrska’, ‘Radana’ and ‘Uta’) were used in this study. Sixty-five phenolic compounds, including 26 phenolic acids, 22 flavan-3-ols and procyanidins, 15 flavonols, 1 flavone, and 1 hydroquinone, were determined in the examined samples using the ultra-performance liquid chromatography photodiode detector-quadrupole/time of flight-mass spectrometry (UPLC-PDA-Q/TOF-MS) method. Major differences were found in the phenolic profiles of investigated cultivars. The ‘Radana’ cultivar exhibited the highest total phenolics content (894.9 mg/kg FW) and was characterized by the highest concentration of phenolic acids (503.1 mg/kg FW) and arbutin (70.8 mg/kg FW).     

Comparison of fatty acids, vitamin E and physicochemical properties of Canarium odontophyllum Miq. (dabai), olive and palm oils

Canarium odontophyllum Miq. fruit (dabai) is an important food and oil resource for the native people in Sarawak, Malaysia. However, there is little information regarding their oil composition. In this paper, fatty acid compositions, vitamin E contents and physicochemical properties of dabai pulp and kernel oils were studied. These parameters were compared with commercial olive and palm oils. The content of total saturated fatty acid was found to be 44.4% in dabai pulp, kernel (60.8%), palm oil (47.9%) and olive (25.5%) oils. Palmitic, myristic, oleic and linoleic acids were detected in dabai pulp oil (36.1, 5.8, 41.5 and 11.8%) dabai kernel oil (46.4, 9.3, 35.1 and 2.8%), palm oil (33.8, 9.2, 39.7 and 10.9%) and olive oil (9.9, 12.9, 64.4 and 5.1%). Vitamin E was not detected in the dabai pulp oil, while palm oil had the highest vitamin E content, followed by dabai kernel oil and olive oil. In addition, the physicochemical characteristics of dabai oils show better quality than the studied commercial oils. The present study also showed that dabai pulp and kernel oils have good fatty acid composition and a high potential to be developed into healthy cooking oils.     

A pilot survey of 2- and 3-monochloropropanediol and glycidol fatty acid esters in foods on the Canadian market 2011–2013

We are presenting data on the occurrence of 2- and 3-MCPD esters and glycidol esters (MCPDEs and GEs) in more than 100 different edible fats, oils, and related products containing fats/oils, such as cookies and cooking sprays. Most of these products were purchased from retail stores in Ottawa, Canada between 2011 and 2013 in duplicate, thus allowing for evaluation of temporal trends. GEs and MCPDEs were determined by stable isotope dilution analysis using glycidol-d₅ labelled standards by LC–MS/MS in APCI mode and GC–MS in SIM mode after derivation with cyclohexanone, respectively. Unprocessed oils did not contain detectable levels of GEs or MCPDEs or contained them in trace amounts. The exception was palm oil, which contained 100–550 ng/g MCPDEs. GEs and MCPDEs content was highly variable in processed oils/fats, reaching 10.6 and 17.1 μg/g (expressed as glycidol and MCPDs equivalents, respectively). Walnut, rice bran, grape seed oils and palm oil shortening were found to have the highest levels of MCPDEs and GEs. Levels in cookies also varied greatly from 5 to 339 ng/g, expressed as glycidol equivalents and from 29 to 510 ng/g expressed as MCPD equivalents.     

MALDI-TOF MS对临床常见真菌鉴定准确性的Meta分析

目的评价基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)鉴定临床常见真菌的准确性,为临床真菌感染的诊断及治疗提供依据。方法计算机检索各据库,查找MALDI-TOF MS检测真菌准确性的文献,对纳入的文献进行质量评价和数据提取,采用QUADAS-2工具对纳入文献的偏倚风险进行评价,运用Meta-Disc1.4软件进行Meta分析,比较不同菌株来源、菌种、参考方法、使用仪器各亚组的诊断效能。结果共纳入文献26篇,9 708株真菌,基本涵盖了临床常见酵母菌属及丝状真菌属。Meta分析结果显示,MALDI-TOF MS鉴定真菌合并灵敏度[95%置信区间(95%CI)]为0.97(0.97～0.97),合并特异度(95%CI)为0.85(0.81～0.88),合并阳性似然比(95%CI)为5.60(4.55～6.90),合并阴性似然比(95%CI)为0.02(0.01～0.04),诊断比值比(95%CI)为282.40(149.50～533.46),汇总受试者工作特征曲线下面积为0.9078。亚组分析结果显示,MALDI-TOF MS技术对临床酵母菌属及丝状真菌属的鉴定,不受菌株来源、仪器品牌等因素影响,均具有很好的鉴定效果。结论MALDI-TOF MS对临床常见真菌鉴定的准确性高,适合在临床广泛推广应用。     

MALDI-TOF MS在液体培养分枝杆菌菌种鉴定中的研究

目的研究基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)对液体培养分枝杆菌菌种鉴定的能力。方法回顾性收集本院2017年10月-2018年10月液体培养分离到的结核分枝杆菌40株,非结核分枝杆菌85株,采用MALDI-TOF MS菌种鉴定,与传统生化鉴定方法和16S r DNA测序结果进行比较,以测序结果为金标准分析MALDITOF MS对分枝杆菌菌种鉴定的准确性,评价其应用价值。结果测序结果46株为结核分枝杆菌,40株符合初筛结果,另有6株初筛非结核菌株鉴定为结核分枝杆菌,78株为非结核分枝杆菌,1株奴卡菌。MALDI-TOF MS从46株结核分枝杆菌中正确鉴定出44株,正确鉴定率为95.65%;78株非结核分枝杆菌中,69株正确鉴定,1株奴卡菌正确鉴定,NTM正确鉴定率为88.46%(69/78);奴卡菌鉴定率为100.00%(1/1),另对常见堪萨斯分枝杆菌、脓肿分枝杆菌等非结核分枝杆菌均能正确鉴定。结论MALDI-TOF MS对液体培养分枝杆菌具有较高鉴定率,是一种快速、简便准确的鉴定方法,在临床应用中具有重要价值。     

Evaluation of fatty acid and mineral content of Tanzanian seeds and oils

Fatty acids (FA) and micronutrients are required for normal growth and development. Deficiency in FA and micronutrients is prevalent in several African countries. The objective of this study was to determine mineral and FA composition of seeds and oils available to residents of Rudewa-Mbuyuni village in Tanzania. Samples were analyzed for FA and mineral composition by gas chromatography mass spectrometry (GC/MS) and, inductively coupled plasma (ICP) emission spectroscopy, respectively. Linoleic acid (LA) and alpha-linolenic acid (ALA) were higher in sunflower (Helianthus sp) oil, 252 mg/g and 0.58 mg/g, and pumpkin seeds (Cucurbita pepo), 126 mg/g and 0.17 mg/g, respectively. Pumpkin seeds contained 9170 mg/kg of potassium, 115 mg/kg of iron and 62 mg/kg of zinc, which are important cofactors for FA metabolism. Pumpkin seeds and sunflower oil are dietary sources of essential FA (EFA) that could be incorporated into Tanzanian diets, especially where there is a high prevalence of growth stunting, cognitive impairment, and EFA deficiency, such as in Rudewa-Mbuyuni. Since the sunflowers and pumpkin analyzed in this study are widely distributed throughout Africa, these data may be beneficial to various regions where EFA and mineral deficiencies are common.     

Direct atomic absorption spectrometry determination of arsenic,cadmium, copper,manganese, lead and zinc in vegetable oil and fat samples with graphite filter furnace atomizer

The article presents the results of optimization of operation parameters, investigation of analytical characteristics and the abilities of a graphite filter-furnace (FF) atomizer for the direct electrothermal atomic absorption spectroscopy (ET AAS) determination of trace amounts of Mn, As, Pb, Cu, Cd and Zn in some vegetable oils and fats. The effect of pyrolysis and atomization temperatures of the graphite FF atomizer on atomic absorbance values of the listed elements at their evaporation from some organic solutions in the presence of a Pd-Mg chemical modifier (CM) was investigated. For the ET AAS determination of As, Pb, Cd and Zn with Pd-Mg CM, the temperature of the graphite FF atomizer for the pyrolysis step can be raised by 250–350 °C. This mode allows to eliminate the background absorption, to increase the sensitivity of the elements to be analyzed and to enhance the total content of vegetable oils or fats in organic solutions up to 0.5 g mL⁻¹. The obtained limits of quantification for Mn, As, Pb, Cu, Cd and Zn were 0.002, 0.004, 0.004, 0.002, 0.0008, 0.0004 mg kg⁻¹, respectively. The relative standard deviation (RSD) varied between ∼3 and 8% and the time of one element determination did not exceed ∼3–5 min. The reliability of the proposed method was checked using the reference method. A paired Student's t-test showed no significant difference between the results obtained by both methods on a 95% confidence level.     

凝胶渗透色谱和固相萃取净化气相色谱-负化学源-质谱测定羊肠衣中的氯霉素残留量

目的：建立羊肠衣中氯霉素残留含量的分析方法。方法：羊肠衣样品用乙酸乙酯提取,凝胶渗透色谱和固相萃取净化,净化后的提取物用BSTFA＋TMCS衍生化,气相色谱-负化学源-质谱法（GC-NC I-MS）选择离子定量检测,内标法定量,间位氯霉素为内标物。结果：5个添加水平的平均回收率在78.3%～106.0%之间,相对标准偏差在1.1%～10.3%之间。检出限（LOD）为0.1μg/kg,测定低限（LOQ）为0.3μg/kg。结论：该法简便省时,自动化程度高,可以满足欧盟委员会决议2002/657/EC和2003/181/EC的要求。     

利用MALDI-TOF MS特异质量峰对耐碳青霉烯类肺炎克雷伯菌同源性的快速分型

目的利用基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)筛选耐碳青霉烯类肺炎克雷伯菌(CRKP)的特异质量峰,并根据特异质量峰对CRKP进行快速同源性分析。方法选取某院微生物实验室已进行多位点序列分型(MLST)的CRKP 76株,52株用于方法的建立,24株用于方法的验证。设置5个不同的特异峰挑选标准,按照不同的标准筛选各ST型特异质量峰,依据筛选的特异质量峰对CRKP进行分型,将与MLST结果符合率最高的标准确定为最佳标准。依据最佳标准筛选出的特异峰对24株CRKP进行分型,验证特异峰质量分型方法的准确性,并与质谱仪软件中的主成分分析(PCA)和核心图谱(MSP)聚类分析进行比较。结果按照标准2[(1)信噪比(S/N)≥4,(2)S/N比值≥1.5,(3)变异系数(CV)≤40%],52株CRKP中共筛选出45个特异质量峰,利用特异质量峰对29株CRKP进行分型,与MLST符合率最高,达82.8%,确定为最佳标准。按照此标准筛选出的特异质量峰对另外24株CRKP进行分型,与MLST符合率达83.3%。而PCA聚类分析与MLST的符合率仅为66.7%,MSP聚类分析与MLST一致性较差,没有明显符合ST型的分组趋势。结论利用MALDI-TOF MS筛选出不同ST型别CRKP的特异质量峰,可用于CRKP的快速同源性分析,为暴发流行的监测和医院感染的控制提供依据。