用数字化实验探究含氟牙膏背后的化学原理

为了说明含氟牙膏刷牙预防龋齿背后的化学原理,用鸡蛋壳代替牙齿设计了数字化实验。利用电导率传感器研究鸡蛋壳存在沉淀溶解平衡,利用压强传感器研究含氟牙膏水泡过的鸡蛋壳具有抗酸性,利用Logger Pro的线性拟合功能得到鸡蛋壳与盐酸反应的速率曲线,说明F-的保护时间有限。并从理论上分析了上述现象产生的原因。     

同时测定牙膏中的单氟磷酸盐与游离氟的研究

采用离子色谱法同时测定了牙膏中游离氟与单氟磷酸盐的含量。结果表明,该法具有简单、准确、快速等特点,可以在牙膏产品检测中推广使用。     

牙膏中氟离子质量分数测定的实验教学探索与实践

在强酸性条件下将牙膏中的氟元素转化为氟离子,进而通过离子色谱法获得牙膏中氟离子质量分数。实验测定了4种牙膏样品中氟离子质量分数,均符合国标要求。通过该实验学生不仅能掌握固相萃取样品前处理方法,还能更好地理解和掌握离子色谱仪的工作原理、操作方法及其定性、定量方法。本实验教学不仅提高了学生的学习兴趣,增强了学生的动手能力,而且还特别培养了学生对仪器的维护与保养意识。     

A Potassium Based Fluorine Containing Bioactive Glass for Use as a Desensitizing Toothpaste

Potassium releasing bioactive glasses (BAGs) may offer improved relief for dentine hypersensitivity compared to conventional sodium containing BAGs by releasing K⁺ ions for nerve desensitization and occluding dentinal tubules to prevent fluid flow within dentinal tubules. Potassium oxide was substituted for sodium oxide on a molar basis in a fluoride containing BAG used in toothpastes for treating dentine hypersensitivity. The BAG powders were then immersed in an artificial saliva at pH 7 and tris buffer and the pH rise and ion release behavior were characterized by ICP-OES and ISE. The potassium and sodium containing BAGs were characterized by XRD, DSC, FTIR and NMR. Both BAGs presented amorphous diffraction patterns and the glass transition temperature of the potassium glass was higher than that of the sodium glass. The ³¹P MAS-NMR spectra indicated a peak at 2.7 ppm corresponding to apatite and a small peak at −103 ppm indicated crystallization to fluorapatite. Both BAGs dissolved and formed apatite at similar rates, although the dissolution of the potassium glass was slightly slower and it released less fluoride as a result of partial nanocrystallization to fluorapatite upon quenching. The potassium release from the potassium ions could potentially result in nerve deactivation when used in toothpastes.     

离子色谱法测定牙膏中可溶性氟含量

采用电导抑制检测器–梯度淋洗离子色谱法测定牙膏中可溶性氟含量。使用Ion Pac AS15(250 mm×4mm)色谱柱,Ion Pac AG15(250 mm×4 mm)保护柱,以氢氧化钾溶液梯度淋洗,采用自循环抑制电导检测的方法对牙膏中游离氟含量进行检测。该方法能够准确地测定牙膏中游离氟含量,线性方程的相关系数在0.996以上,样品的加标回收率为99.6%~103.0%,测定结果的相对标准偏差为0.37%~0.42%(n=6)。该法操作简单,无需使用更多化学试剂,灵敏度高,测定结果准确可靠,能满足牙膏中游离氟含量的测定要求。     

离子色谱法测定牙膏中甘油磷酸根的含量

在D ionex-320离子色谱仪上,采用RFC-30淋洗液自动发生器对牙膏中甘油磷酸根的分离尝试了4根不同的阴离子分析柱(AS11-HC、AS17、AS18和AS19),最终确定了以AS18为分析柱。选用适当的梯度淋洗程序,可在较短的时间内完成对牙膏样品的分析。该方法线性关系良好,相关系数r2=0.999 7,检出限为0.024 mg/L,测定结果的相对标准偏差为1.162%(n=6),加标回收率为98.1%~99.0%。方法灵敏度高,重复性好,简便易行。     

New approach on trace analysis of triclosan in personal care products, biological and environmental matrices

Stir bar sorptive extraction and liquid desorption followed by high performance liquid chromatography with diode array detection (SBSE-LD-LC-DAD) is proposed for the determination of triclosan in personal care products, biological and environmental matrices, which is included in the priority lists, set by several international regulatory organizations. Instrumental conditions and experimental parameters that affecting SBSE-LD efficiency are fully discussed. Throughout systematic assays on 25 mL water samples spiked at the 10.0 μg L⁻¹ level, it had been established that stir bars coated with 126 μL of polydimethylsiloxane, an equilibrium time of 1 h (1000 rpm) and acetonitrile under sonification (60 min) as back-extraction solvent, allowed the best analytical performance to determine triclosan in water matrices. From the data obtained, good recovery and remarkable repeatability were attained, providing experimental average yields (78.5 ± 2.2%), although slightly lower than the theoretical equilibrium (99.7%) described by the octanol–water partition coefficients (K_PDMS/W < K_O/W). The analytical performance proved suitable precision (<3.6%), convenient detection limits (0.1 μg L⁻¹) and excellent linear dynamic range (r² > 0.9992) from 0.4 to 108.0 μg L⁻¹. The application of the present method to determine triclosan in real matrices such as commercial toothpaste, saliva and urban wastewater samples, allowed appropriate selectivity, high sensitivity and accuracy using the standard addition methodology. The proposed method showed to be feasible and sensitive with a low-sample volume requirement to monitor triclosan in personal care products, biological and environmental matrices at the trace level, in compliance with international regulatory directives.     

高效液相色谱法测定牙膏中的氨甲环酸

建立了丹磺酰氯柱前衍生/高效液相色谱测定牙膏中氨甲环酸(TA)的方法。牙膏经甲醇提取、氮吹至干,再用丹磺酰氯进行衍生。衍生物通过X-Bridge C18色谱柱(250 mm×4.6 mm×5μm)分离,以乙腈和0.1%甲酸水溶液为流动相梯度洗脱,在紫外波长250 nm条件下进行定量测定。系统考察了缓冲溶液p H值、衍生温度和衍生时间对氨甲环酸衍生效率的影响。结果表明,在优化实验条件下,氨甲环酸衍生物与基体杂质达到有效分离,在1~425 mg/L范围内线性关系良好,相关系数为0.999 5;在20,200,1 600 mg/kg 3个加标浓度下的回收率为98.7%~102%,相对标准偏差为0.85%~2.5%,方法检出限为2.0 mg/kg。该方法准确、可靠、灵敏度高,适用于各类牙膏中氨甲环酸的测定。     

反相高效液相色谱法测定牙膏中的甘草次酸

 采用反相高效液相色谱法测定了牙膏中的甘草次酸。在ＹＷＧ Ｃ１８（４０ｍｍｉ．ｄ．×２５０ｍｍ,１０μｍ）色谱柱上,以Ｖ（甲醇）∶Ｖ（００１ｍｏｌ／ＬＫＨ２ＰＯ４）＝８５∶１５（ｐＨ３０）的溶液为流动相,流速为１０ｍＬ／ｍｉｎ,紫外检测波长为２５４ｎｍ,室温下检测。甘草次酸用甲醇提取。甘草次酸的平均回收率为９９６１％～１０１６７％,样品测试相对标准偏差为１８５％～３１６％。方法操作简便、快速和准确。     

高效液相色谱法同时测定牙膏及漱口水中的23种致癌染料

建立了同时测定牙膏和漱口水中23种致癌染料的高效液相色谱(HPLC)检测方法。漱口水样品直接以乙醇溶解稀释,牙膏样品烘干后以乙醇超声提取。采用ZORBAX Eclipse XDB-Phenyl(150 mm×4.6 mm×5μm)色谱柱进行分离,以2.5 mmol/L磷酸二氢四丁基铵水溶液(pH 7.5)和甲醇-乙腈(体积比50∶50)为流动相进行梯度洗脱,二极管阵列检测器(DAD)在400、500、600 nm波长下检测,外标法定量。结果表明,23种致癌染料在32 min内完成色谱分离,在相应的质量浓度范围内线性良好,相关系数(r2)均不小于0.9991,检出限(LOD)和定量下限(LOQ)分别为0.06~0.66 mg/L和0.18~1.98 mg/L。以阴性牙膏和漱口水为样品基质,23种致癌染料在3个加标水平下的平均回收率分别为91.2%~104%和92.0%~103%,相对标准偏差(RSD,n=6)分别为2.5%~5.8%和2.3%~5.5%。对239个牙膏和88个漱口水样品进行检测,1个牙膏样品中检出碱性紫3。该方法灵敏度高,精密度好,准确度高,适用于牙膏和漱口水中致癌染料的测定,可为牙膏和漱口水的质量安全监控提供参考。