Ammazzini Sara, Onor Massimo, Pagliano Enea, Mester Zoltán, Campanella Beatrice, Pitzalis Emanuela, Bramanti Emilia, D'Ulivo Alessandro
C.N.R., Institute of Chemistry of Organometallic Compounds, UOS of Pisa, Via Moruzzi, 1, 56124 Pisa, Italy; University of Pisa, Department of Chemistry and Industrial Chemistry, Via Risorgimento, 35, 56125 Pisa, Italy.
C.N.R., Institute of Chemistry of Organometallic Compounds, UOS of Pisa, Via Moruzzi, 1, 56124 Pisa, Italy.
J Chromatogr A. 2015 Jun 26;1400:124-30. doi: 10.1016/j.chroma.2015.04.040. Epub 2015 Apr 28.
A novel method for the determination of salivary thiocyanate is presented. Thiocyanate was converted into ethyl thiocyanate by single-step aqueous derivatization based on triethyloxonium tetrafluoroborate and measured by gas chromatography-mass spectrometry (15 min runtime). The ethyl thiocyanate derivative is volatile and can be sampled from the headspace. The derivatization chemistry proposed allows for separation of the analyte from saliva matrix whose introduction in the measurement system is avoided. Quantitation of the analyte was obtained by isotope dilution, employing a (13)C-enriched thiocyanate as internal standard. Technical details and fundamental aspects of derivatization chemistry and calibration strategy are presented. The method was validated by comparison with a standard method based on ion chromatography. The two independent methodologies produced results in agreement within 3%. Also a three level spike recovery test was carried out for validation purpose and quantitative recoveries were attained. The method is fast, simple, safe, and sensitive. Measurement of a 1 mL volume 50 ng/g of thiocyanate standard produced a signal-to-noise ratio of 250 for the analytical peak. This method is therefore suitable for ultra-trace determination of thiocyanate (low part-per-billion range). For the application described the full detection potential of the method was not required and the sample preparation presented has been designed for quantitation of saliva samples containing 1-400 μg/g of thiocyanate with a combined standard uncertainty of 2% relative for saliva samples containing 25 μg/g of thiocyanate. This method was applied for the determination of thiocyanate in human saliva samples.
本文提出了一种测定唾液中硫氰酸盐的新方法。基于四氟硼酸三乙氧鎓，通过单步水相衍生将硫氰酸盐转化为乙基硫氰酸盐，并采用气相色谱 - 质谱联用仪进行测定（运行时间15分钟）。乙基硫氰酸盐衍生物具有挥发性，可从顶空取样。所提出的衍生化学方法能够将分析物与唾液基质分离，避免了唾液基质进入测量系统。采用富集了(13)C的硫氰酸盐作为内标，通过同位素稀释法对分析物进行定量。文中介绍了衍生化学方法和校准策略的技术细节及基本方面。通过与基于离子色谱的标准方法进行比较，对该方法进行了验证。两种独立的方法所得结果在3%以内一致。此外，还进行了三级加标回收试验以进行验证，实现了定量回收。该方法快速、简便、安全且灵敏。对1 mL体积、浓度为50 ng/g的硫氰酸盐标准品进行测量，分析峰的信噪比为250。因此，该方法适用于硫氰酸盐的超痕量测定（低十亿分率范围）。对于所述应用，并不需要该方法的全部检测潜力，所提出的样品制备方法旨在对含有1 - 400 μg/g硫氰酸盐的唾液样品进行定量，对于含有25 μg/g硫氰酸盐的唾液样品，合成标准不确定度为2%相对值。该方法已应用于人体唾液样品中硫氰酸盐的测定。
