顶空-气相色谱法分析水中的挥发性苯系物

文献名： Structural, morphological and optical properties of Bi NPs obtained by laser ablation and their selective detection of L-cysteine 作者： Ramon Gabriel Teixeira Rosaa, Celso de Araujo Duartea , Wido Herwig Schreinera, Ney Pereira Mattoso Filhoa, Arandi Ginane Bezerra Jr.b, Andersson Barisonc, Fernanda Maria Marins Ocamposc a Departamento de Física, Universidade Federal do Paraná Centro Politécnico, CP 19044, 81531-990 Curitiba (PR), Brazil b Departamento Acadêmico de Física, Universidade Tecnológica Federal do Paraná, 80230-901 Curitiba (PR), Brazil c Departamento de Química, Universidade Federal do Paraná Centro Politécnico, CP 19081, 81531-990 Curitiba (PR), Brazil 摘要：In the present work we show the results of the investigation of the properties of bismuth nanoparticles (NPs) obtained by the laser ablation in water. The samples were characterized by various techniques: UV/vis spectroscopy, dynamic light scattering, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, nuclear magnetic resonance and zeta potential. The NPs were metallic and surface oxidated, exhibiting absorption peak at 257 nm due to the surface plasmon resonance. The interaction between the NPs and various amino acids was studied and revealed a selective sensibility to cysteine on a range of concentration from 80 to 720 μM, which we attribute to a dimerization of cysteine to cystine probably complexed to the nanoparticle surface by electrostatic interactions, leading to the modification of the NP absorption spectrum. 关键词：Bismuth; Nanoparticles; Laser ablation; Cysteine

抗氧化剂是指能防止或延缓食品氧化，提高食品的稳定性和延长贮存期的食品添加剂。GB5009.32-2016《食品安全国家标准 食品中9种抗氧化剂的测定》中采用GPC和C18小柱对食品中9种抗氧化剂进行前处理，该方法回收率低，测试结果不稳定。安谱实验优化了实验方法，用CNW Poly-Sery PSD SPE小柱进行前处理，克服了国标方法的缺点，方法简单，9种抗氧化剂的回收率均在90%以上。

当称量仪器用于与质量控制相关的测量时，校准是必须定期执行的关键操作之一。国际上有许多标准规范都有这方面的要求，例如ISO9001、GMP法规以及与食品安全相关的一些标准。然而关于校准的定义、实施和校准的具体操作在全球范围内并没有一个完全统一的标准。在此，我们首先需要了解一下什么是校准，以及与调整和检定的区别。

超纯水机在后期使用中会因各种因素导致设备性能下降，所以为了确保延长设备的使用寿命，日常使用时就应该注意设备的维护和保养，那么导致超纯水机性能下降的因素有哪些呢?