Traviesa-Alvarez J M, Costa-Fernández J M, Pereiro R, Sanz-Medel A
Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain.
Anal Chim Acta. 2007 Apr 18;589(1):51-8. doi: 10.1016/j.aca.2007.02.063. Epub 2007 Mar 3.
A fast and simple flow-through optosensor was designed and characterized for the direct screening of four tetracycline (TCC) antibiotics (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in water and bovine milk samples. The proposed optosensor provides rapid binary yes/no overall responses, being appropriate for the screening of this family of antibiotics above or below a pre-set concentration threshold. The experimental set-up is based on a flow-injection manifold coupled on-line to a phosphorescence detector. Aliquots of the samples are pretreated with Eu(III) to form room temperature phosphorescent metal chelates and injected in the flow manifold. Those chelates are then on-line retained on a conventional flow-cell (packed with polymeric Amberlite XAD-4 particles) which is placed inside the cell holder of the phosphorimeter. After the emission is registered, the antibiotic-metal complexes are eluted from the packed resin with 1M HCl (for milk samples a second regeneration step, using methanol, should be performed). A sample throughput of about 20 samples per hour was obtained. Optimum experimental conditions include a pH 9, a Eu(III) concentration of 2 x 10(-4) M and 8 mM sodium sulphite as chemical deoxygenant. The phosphorescence emitted by the europium-TCC complexes was measured at 394 and 617 nm for excitation and emission wavelengths, respectively. The unreliability region, given by the probability of false positives and false negatives, respectively (set at 5% in both cases) was in the range between 0.2 and 11.6 nM for detection of tetracyclines in water samples (at a cut-off level of 4 nM) and in the range between 165 and 238 nM for detection of tetracyclines in milk (cut-off level fixed at the normative EU level of 200 nM). Finally, the applicability of the proposed screening optosensor was tested for the reliable control of tetracyclines in contaminated and uncontaminated water and milk samples.
设计并表征了一种快速简便的流通式光传感器，用于直接筛查水和牛奶样品中的四种四环素（TCC）抗生素（四环素、土霉素、金霉素和强力霉素）。所提出的光传感器提供快速的二元是/否总体响应，适用于筛查高于或低于预设浓度阈值的此类抗生素。实验装置基于与磷光检测器在线耦合的流动注射歧管。将样品等分试样用Eu(III)预处理以形成室温磷光金属螯合物，然后注入流动歧管。然后将这些螯合物在线保留在置于磷光计样品池架内的传统流通池（填充有聚合物Amberlite XAD - 4颗粒）中。记录发射后，用1M HCl从填充树脂中洗脱抗生素 - 金属络合物（对于牛奶样品，应使用甲醇进行第二步再生）。每小时获得约20个样品的分析通量。最佳实验条件包括pH 9、2×10(-4) M的Eu(III)浓度和8 mM亚硫酸钠作为化学脱氧剂。铕 - TCC络合物发出的磷光分别在394 nm和617 nm处测量激发和发射波长。假阳性和假阴性概率分别给出的不可靠区域（两种情况均设定为5%），对于水样中四环素的检测（截止水平为4 nM）在0.2至11.6 nM范围内，对于牛奶中四环素的检测（截止水平固定在欧盟标准水平200 nM）在165至238 nM范围内。最后，测试了所提出的筛查光传感器在受污染和未受污染的水和牛奶样品中对四环素进行可靠控制的适用性。
