Dipartimento di Chimica, Università della Calabria, Via Pietro Bucci Cubo 12/C, I-87030 Arcavacata di Rende, CS, Italy.
Anal Chim Acta. 2012 Oct 17;747:58-66. doi: 10.1016/j.aca.2012.08.016. Epub 2012 Aug 23.
A new analytical approach is exploited in the assay of selenium speciation in selenized and not selenium enriched potatoes based on the widely available solid-phase microextraction (SPME) coupled to-GC-triple quadrupole mass spectrometry (SPME-GC-QqQ MS) method. The assay of selenomethionine (SeMet) and selenomethylselenocysteine (SeMeSeCys) in potatoes here reported provides clues to the effectiveness of SPME technique combined with gas chromatography-tandem mass spectrometry, which could be of general use. For the exploitation of the GC method, the selected analytes were converted into their N(O,S)-alkoxycarbonyl alkyl esters derivatives by direct treatment with alkyl chloroformate in aqueous extracts. The performance of five SPME fibers and three chloroformates were tested in univariate mode and the best results were obtained using the divinylbenzene/carboxen/polydimethylsiloxane fiber and propylchloroformate. The variables affecting the efficiency of SPME analysis were optimized by the multivariate approach of design of experiment (DoE) and, in particular, a central composite design (CCD) was applied. Tandem mass spectrometry in selected reaction monitoring (SRM) has allowed the elimination of matrix interferences, providing reconstructed chromatograms with well-resolved peaks and the achievement of very satisfactory detection and quantification limits. Both precision and recovery of the proposed protocol tested at concentration of 8 and 40 μg kg(-1) (dry matter), offered values ranging from 82.3 to 116.3% and from 8.5 to 13.1% for recovery and precision, respectively. The application of the method to commercial samples of selenized and not selenium enriched potatoes proved that the Se fertilization increases significantly the concentration of these bioavailable selenoamino acids.
一种新的分析方法被用于硒形态分析，该方法基于广泛应用的固相微萃取（SPME）结合气相色谱-三重四极杆质谱（SPME-GC-QqQ MS），用于硒代蛋氨酸（SeMet）和硒代甲基硒代半胱氨酸（SeMeSeCys）的测定。这里报道的马铃薯中硒代蛋氨酸和硒代甲基硒代半胱氨酸的测定为 SPME 技术与气相色谱-串联质谱相结合的有效性提供了线索，这种方法可能具有普遍性。为了开发 GC 方法，选择的分析物通过在水提取物中直接用烷基氯甲酸酯处理，转化为它们的 N（O，S）-烷氧基羰基烷基酯衍生物。在单变量模式下测试了五种 SPME 纤维和三种氯甲酸酯，使用二乙烯基苯/羧基/聚二甲基硅氧烷纤维和丙基氯甲酸酯获得了最佳结果。通过实验设计（DoE）的多变量方法优化了影响 SPME 分析效率的变量，特别是应用了中心组合设计（CCD）。选择反应监测（SRM）中的串联质谱允许消除基质干扰，提供具有良好分辨率峰的重建色谱图，并实现非常令人满意的检测和定量限。在 8 和 40μgkg(-1)（干物质）浓度下测试的建议方案的精密度和回收率提供了 82.3%至 116.3%和 8.5%至 13.1%的回收率和精密度范围。该方法应用于硒代和非硒代马铃薯的商业样品，证明了 Se 施肥显著增加了这些生物可利用的硒代氨基酸的浓度。
