三维荧光结合二阶校正快速测定水中酚类

酚类化合物在冶金、炼油、机械制造、医药、农药和油漆等工业有广泛的应用,但酚类化合物具有毒性,若不加以处理将会对环境造成污染。水是生命之源,水环境中酚类化合物检测显得尤为重要。三维荧光光谱分析法具有灵敏度高、检测速度快、预处理方便和痕量检测等特点,二阶校正分析法可以在混合物中分辨出感兴趣的成分。采用三维荧光光谱结合二阶校正方法对水环境中酚类化合物进行测定。实验选用间甲酚和间苯二酚作为被测物质,配置添加干扰物和不添加干扰物两类样本,通过FLS920稳态荧光光谱仪测得8个校正样本和8个预测样本的三维荧光光谱数据,并对其进行数据预处理,扣除原始光谱中所包含的散射干扰,并对原始光谱数据进行激发/发射校正,然后采用db3小波函数生成的小波包对光谱数据进行数据压缩,去除光谱数据中的冗余信息,其中压缩分数达到91.67%,恢复分数达到96.62%。然后分别采用平行因子分析(PARAFAC)和自加权交替三线性分解(SWATLD)两种二阶校正方法对预处理后的光谱数据进行定性和定量分析。根据核一致分析法结合残差判别分析法的分析结果,设定未添加干扰物样品组分数为2,添加干扰物样品组分数为3。定性分析结果显示,无论有无添加干扰物,两种二阶校正法都能准确的分辨出样本中的间甲酚和间苯二酚,其中间甲酚的荧光峰位置为λem=298 nm/λex=274 nm;间苯二酚的荧光峰位置为λem=304 nm/λex=275 nm。定量分析结果显示,用PARAFAC算法测定不添加干扰物的样本时,对间甲酚和间苯二酚浓度的平均回收率分别达到了93.37%±4.92%和95.19%±5.25%;测定添加干扰物样本时,对间甲酚和间苯二酚浓度的平均回收率达到92.09%±2.64%和97.08%±5.26%。用SWATLD算法测定不添加干扰物样本时,对间甲酚和间苯二酚浓度的平均回收率分别达到了93.11%±4.73%和96.80%±5.04%;测定添加干扰物样本时,对间甲酚和间苯二酚浓度的平均回收率达到97.30%±4.52%和96.92%±5.61%,且两种二阶校正方法得出的预测样本均方差(RMSEP)均小于0.03 mg·L-1。实验结果表明,在荧光光谱峰位置相近、光谱严重重叠且有干扰物的情况下, PARAFAC和SWATLD两种二阶校正算法都能对水溶液中的酚类化合物进行快速、准确地测定。

Rapid Determination of Phenol in Water by Three-Dimensional Fluorescence Combined with Second-Order Calibration

Phenolic compounds are widely used in metallurgy, oil refining, machinery manufacturing, medicine, pesticide and paint industries, but they are toxic, if not treated properly they will pollute environment. Water is the source of life, and the detection of phenols in the water environment is particularly important. Three-dimensional fluorescence spectrometry has the characteristics of highly sensitivity, fast detection speed, convenient pretreatment and tracing detection. The second-order correction method can identify the interesting components in compounds. In this paper, three-dimensional fluorescence spectroscopy will be combined with second-order correction method to test phenols in the water. M-cresol and resorcinol were selected as the tested substances in this experiment, and they were divided into two kinds of samples: adding interference and without interference. The data of three-dimensional fluorescence spectra of eight corrected samples and eight predicted samples were measured by FLS920 steady-state fluorescence spectrometer, and the data above were preprocessed: scattering interference contained in the original spectrum was removed;corrected by the excitation/emission correction. Then, the spectral data were compressed by the wavelet packet generated by db3 wavelet function, and the redundant information in the spectral data was removed through this approach. The compression score achieved 91.67%, and the recovery score achieved 96.62%. Then two second-order calibration methods: parallel factor analysis(PARAFAC) and self-weighted alternating trilinear decomposition(SWATLD) were used to analyse the preprocessed data qualitatively and quantitatively separately. According to the results of consistency analysis combined with residual discriminant analysis, the component number of samples without interference was chose as 2, and the samples with interference was chosen as 3. Qualitative analysis showed that regardless of the existing or inexisting interference, these two second-order calibration methods all could identify m-cresol and resorcinol in samples accurately. The fluorescence peak position of m-cresol and resorcinol were located at λem=298 nm/λex=274 nm and λem=304 nm/λex=275 nm separately. The quantitative analysis results show that the average recovery rate of m-cresol and resorcinol reached 93.37%±4.92% and 95.19%±5.25% respectively by PARAFAC without adding interference and under interference, meanwhile the average recovery rate of m-cresol and resorcinol were 92.09%±2.64% and 97.08%±5.28%. Under the same conditions, when we chose SWATLD, the average recovery rate of m-cresol and resorcinol reached 93.11%±4.73% and 96.80%±5.04% respectively, meanwhile the average recovery rate of m-cresol and resorcinol were 97.30%±4.52% and 96.92%±5.61% respectively. The root mean square error of prediction(RMSEP) of the two methods are all less than 0.03 mg·L-1. The experimental results show that two second-order calibration algorithms: PARAFAC and SWATLD can all quickly and accurately test phenols in water when the fluorescence peaks are contiguous, and the spectra overlap seriously meanwhile there are interference in the compounds.