The Application Of Modern Analytical Technique In Trace Analysis

"Trace Elements" generally refers to samples less than 0.01%, such as active ingredients in drugs, drugs or toxins pollutants in environment, metal ion contamination in drugs. The concentration of these substances is low, but the physiological activity is strong. In addition, high accumulation accured gives toxic effect to human body. These problems, people paid more and more attention, have become the focuses of their research. However, it is difficult to analyze trace substances with conventional analytical methods, such as high-performance liquid chromatography, UV spectroscopy. The main method to solve the problem is to improve the sensitivity of analytical methods or develop more sensitive methods. However, it is difficult to detect some of substances which are below pg level, even if sensitive method is performed (such as MS, etc.). Therefore, appropriate sample pre-treatment method to enrich trace substances is introduced to solve this problem. New sample pre-treatment techniques provide new analytical tools to analyze substances which are difficult to monitor (such as substances with low ionization efficiency by MS detection).In this project, a sensitive method has been developed to solve the difficulty in the detection of zoledronic acid. Phosphorusmolybdenum heteropoly acid-rhodamin B produced high RRS, and greatly improved the sensitivity. The detection limit was 1.55ng/ml. The parameters affecting the reaction such as sulfuric acid concentration, potassium persulfate concentration, ammonium molybdate concentration, Rhodamine B concentration, as well as the boiling time, reaction temperature, reaction time were investigated. The method was successfully applied for the determination of zoledronic acid infusion solution. A GF-AAS was established for the determination of aluminum in zoledronic acid injection, and the resource of aluminum in zoledronic acid injection was discussed. The background interference was eliminated by Zeeman background correction. The sensitivity of the method was improved by optimizing the drying, ashing, atomization temperature and time, as well as choice of base modifier. The detection limit was 0.14ng/ml. The method supports direct analysis without digestion and was successfully applied to explore the sources of aluminum in zoledronic acid injection. Another job established in our project is to show the application of Hollow fiber liquid-phase micro-extraction. Hollow fiber liquid-phase micro-extraction, a new enrichment and purified pre-treatment technique, has been applied for the analysis of trace substances in environmental water. Compared with the reported sample preparation techniques, the proposed method seems to be more preferred for its high enrichment, cost effectiveness, minimization of organic waste, and absence of memory effect. Meanwhile, it earned many merits such as extraction and concentration in one set, outstanding purification, no cross-contamination and suitable for various analytes in different matrix. Under optimizing conditions, the enrichment efficiency was 300 and the detection limit was 0.1ng/ml.PART 1 Determination of Trace Zoledronic Acid by Resonance Rayleigh Scattering MethodObjective: To establish a sensitive, fast and simple resonance Rayleigh scattering method for the determination of trace zoledronic acid.Methods: In acid medium, ammonium molybdate of 0.25 mg/ml and inorganic phosphorus which is produced from 1 ml sample solution reacting with KPs of 1% for 10 min, reacts with rhodamin B of 7×10-6 mol/L to form an associated complex of phosphorusmolybdenum heteropoly acid- rhodamin B. The RRS(I) of complex was detected atλex=λem=370 nm with slit width of 5 nm. The same procedure was carried out to measure the blank signal(I0). Sample concentration was calculated by the enhancement of RRS (ΔI= I﹣I0).Results: Under the optimized conditions, the enhancement of RRS (ΔI) is proportional to the concentration of zoledronic acid in solution. The linear relationship was obtained in the range of 6.25 to 100ng/ml. The limit of detection is 1.55 ng/ml with RSD 2.1% and the recovery was 100~101%. Phosphate, phosphate and other coexistence substance (metal ion and mineral acid radical ion) did not interfere the determination of zoledronic acid.Conclusion: A simple and rapid RRS method for the determination of zoledronic acid has been developed. Compared with traditional molybdenum blue spectrophotometry method, it is 500 times more sensitive with limit of detection at 1.55 ng/ml. It provides a new method for the determination of zoledronic acid. The method was successfully applied to the quality control of zoledronic acid infusion solution.PART 2 Pollution of Aluminium in Zoledronic Acid Injection by Graphite Furnace Atomic Absorption SpectrometryObjective: A graphite furnace atomic absorption spectrometry was established for the study of the source of aluminium and the pollution in zoledronic acid injection.Methods: Sample solution of 100μl, adding 50μl 5 mg/ml of magnesium nitrate, diluted to 2.5 ml with 1% nitric acid, and then injected directly into the graphite furnace. Pyrolysis coating graphite tube and aluminium hollow cathode lamp with wavelength of 309.3 nm and lamp current of 10 mA were employed. 80℃and 220℃for drying, 700℃and 1200℃for ashing, 2600℃for atomizing were optimized for temperature program. The aluminium ion in zoledronic acid injection was determined directly by graphite furnace atomic absorption spectrometry with polarized Zeeman background correction.Results: Matrix effect in zoledronic acid injection was cut down in this condition. There was a good linear relationship in the concentration range of 4.00~20.0 ng/ml (r = 0.9995). The detection limit was 0.14 ng/ml, the relative standard deviation were 99% ~104%, and the RSD were 2.7% ~3.5%. The result of zoledronic acid injection of 30 days showed that concentration of aluminium increased with increasing the staying time.Conclusion: A graphite furnace atomic absorption spectrometry was established for the determination of aluminium in zoledronic acid injection. The method was sensitive with the detection limit of 0.14ng/ml. The sample was injected directly instead of complex digestive process. Basal modifier added can reduce the effects of the sample substrate effectively. The result of zoledronic acid injection stability test showed that aluminum ions came from ampoule.PART 3 Enrichment and determination of trace estradiol in environmental water samples by hollow fiber liquid phase microextraction prior to high performance liquid chromatographyObjective: A novel and simple cleanup procedure, based on hollow-fiber liquid-phase microextraction (HF-LPME) is described here, and HPLC-UV was used for the determination of trace estradiol in environmental water samples.Methods: For HF-LPME, the polyvinylidene difluoride hollow fiber membrane was used. N-octyl alcohol was used as n-octyl alcohol. The n-octyl alcohol was injected into the fiber of 11 cm. Then, the two ends of the fiber were enveloped, and then were introduced into a 140ml glass bottle with screw cap. The extraction was performed by agitation at 500 rpm at 25℃for 60 min. After that, 100μl methanol was slowly flushed through the lumen. The whole elution solution was evaporated to dryness at 90℃under nitrogen gas. To the dried sample, 100μl methanol was added before HPLC analysis. The analysis was performed on a KROMASIL C18 column (150 mm×4.6 mm, 5μm), with the mobile phase of methanol-water (75:25) at 25℃and detected at 280nm using UV detector. The flow rate was 1 ml/min.Results: Under the optimized experimental conditions, the enrichment factor was 300. The proposed method was found to be linear in the concentration 1-1000ng/ml for estradiol and the limit of detection for an S/N = 3 was 0.1ng/ml. The recovery of esdradiol was 97.5% ~120.5% with RSD of 4.7% ~7.3%.Conclusion: A hollow-fiber liquid-phase microextraction has been established for the analysis of estradiol. It takes a serial of advantages over liquid-liquid extraction such as high sensitivity with high enrichment factor of 300. Compared with the reported sample preparation techniques, such as solid phase extraction and solid phase microextraction , the proposed method seems to be more preferred for its cost effectiveness, minimization of organic waste, absence of memory effect, accuraty and reliability. It provides a new reliable means for the analysis of estradiol.