Investigation On Chemiluminescence Analysis And Related Chemometric Methods

Chemiluminescence (CL) analysis has been widely used in many fields due to its attracting features including high sensitivity, low detection limit, wide linear dynamic range and inexpensive instruments. However, the relatively poor selectivity of the CL method itself limits its direct application to the analysis of analyte in complicated sample. Great efforts were made to overcome this shortcoming and the most common used way is that the CL method was combined with some separation techniques such as high performance liquid chromatography, gas chromatography and capillary electrophoresis. The CL systems used as postcolumn detectors have also met their problems: e.g., liquid chromatography needs the eluent, which often is a mixture of organic solvent and salts, and this eluent is always incompatible with the CL condition so as to decrease CL signal; in order to provide highly efficient collection of the CL, a CL cell must be specially designed, but such a cell is not commercially available. Furthermore, these methods required relatively complicated and expensive instruments. So, it is one of the most urgent and significant works to improve selectivity of the CL method.In recent years, the use of some analytical techniques combined with multivariate calibration methods such as principal component regression (PCR), partial least squares (PLS), artificial neural network (ANN) and kalman filter (KF) can be considered a promising, faster, direct and relatively less expensive alternative for the multicomponent analysis of mixture. In this kind of situation, where the direct determination of an analyte is difficult due to the presence of one or several other constituents, instead of eliminating the interfering species, e.g., by a separation procedure, the use of multivariate calibration makes possible the quantification of these interferences along with the analyte. Application of multivariate calibration methods of chemometrics in CL analysis is very significant for simultaneous determination of mulitcomponents in complicated samples. The development of a new CL method that allows simultaneous determination without previous separation of mulitcomponents is a relevant subject of research.This thesis includes two parts. Part one is a review, which reports the development of CL and chemometrics during 2000 and 2007.Part two is research report. First, the sensitivity and the selectivity of old CL system were improved and the new CL system was discovered, and the corresponding compounds were determined with flow injection CL method. Also, multivariate calibration methods are started to apply to the analysis of the analytical data obtained in all the instrumentations. In this work, the new approaches for detection of some drugs were exploited by application of multivariate calibration methods in CL analysis. The research results obtained in the thesis are listed as follows:Part I Investigation of new CL system and improvement old sensitivity of CL system combined with flow injection techniqueFlow injection analysis (FIA) is now well established as a powerful sample handling method for analysis in laboratory, which is compatible with a wide range of detection systems. In its most basic form, it is a convenient means of delivering samples to detector in a controlled and reproducible manner. The combination of FIA with CL detection is becoming increasingly important in various fields because of high sensitivity, wide linear dynamic range, reproducibility, simplicity and rapidity.1. CL of peracetic acid in alkaline medium and its application to dihydralazine sulfate determinationThe CL of peracetic acid (PAA) in alkaline medium is very weak but is strongly enhanced after the addition of dihydralazine sulfate (DHZS). Based on this phenomenon, a simple, rapid and highly sensitive flow-injection CL method for the determination of DHZS was developed. The CL emission was linearly related to the DHZS concentration in the range 20-4000 ng/mL with a detection limit (3σ) of 1.2 ng/mL. As a preliminary application, the proposed method has been successfully applied to the determination of DHZS in pharmaceutical preparations, and the recovery of DHZS in human urine was between 96.5% and 102.2%. A detailed CL mechanism was proposed and singlet molecular oxygen (¹O₂) was suggested to be produced in the CL reaction process.2. Investigation of CL behavior of flavonoids with Cerium (IV)-Rhodamine B systemThe CL behavior of five major flavonoid types in cerium (IV)-rhodamine B system was investigated by flow-injection. Strong CL was observed when cerium (IV) reacted with rhodamine B in sulfuric acid medium in the presence of flavonoids. This reaction system has been established as a simple, rapid and highly sensitive flow injection CL analysis for quercetin and kaempferol, and their detection limit (3σ) were 2.7 and 0.22 nmol/L, respectively. The method was successfully applied to the determination of quercetin in the hydrolysate of rutin and compared well with the high performance liquid chromatography (HPLC) method. From a comparison of several related flavonoids, it was concluded that only flavonoids that contain a free 3-hydroxyl and 2, 3-double bond in conjugation with 4-oxo function could produce a relatively strong CL emission.3. Sensitive determination of nanogram levels of diacerein in a pharmaceutical formulation by flow injection CL analysisA simple, sensitive and inexpensive flow injection CL method for the determination of diacerein was proposed. It was based on the greatly enhancive effect of diacerein on the CL reaction between luminol and hydrogen peroxide in alkaline medium. The enhanced CL intensity was linear with the concentration of diacerein over the range 1.0-500 ng/mL with a detection limit (3σ) of 0.2 ng/mL. This simple method has been successfully applied for the determination of diacerein in a pharmaceutical formulation without interference from its potential impurities. The degradation of diacerein was also investigated briefly.4. CL determination of sodium new houttuyfonate in pharmaceutical preparations based on Tween 80 - rhodamine B systemStrong CL emission was observed when sodium new houttuyfonate (SNH) was mixed with Tween 80 in sulfuric acid medium in the presence of rhodamine B. Baseon this phenomenon, a sensitive flow injection-CL method for the determination ofSNH was developed. Under the optimum conditions, the CL emission is linearly withSNH concentration in the range 8.0 - 4000 ng/mL, with a detection limit of 2.7 ng/mL(3σ). As a preliminary application, the proposed method was successfully applied tothe determination of SNH in pharmaceutical preparations. The possible CLmechanism was also discussed in this paper.Part II Applications of multivariate calibration methods of chemometrics in CLanalysis1. Simultaneous determination of captopril and hydrochlorothiazide by time-resolvedCL with artificial neural network calibrationThe combined use of chemometrics and CL measurements, obtained with the aid of the stopped-fiow mixing technique, allowed the development of a simple time-resolved CL method for the simultaneous determination of captopril (CPL) and hydrochlorothiazide (HCT). The stopped-flow technique in a continuous-flow system was employed in this work in order to emphasize the kinetic differences between the two analytes in cerium (IV)-rhodamine 6G CL system. The mixed CL signal was monitored and recorded on the whole process of continuous-flow/stopped-flow, and the obtained data were processed by the chemometric approach of artificial neural network. The relative prediction error (RPE) of CPL and HCT is 5.9% and 8.7%, respectively. The proposed method was successfully applied to the simultaneous determination of CPL and HCT in a Compound pharmaceutical formulation.2. Simultaneous determination of rutin and quercetin by flow injection CL with nonlinear partial least squares calibrationA fast and highly efficient flow injection CL method is proposed for simultaneous determination of rutin and quercetin with nonlinear partial least squares (NL-PLS) calibration. The method is based on the fact that both rutin and quercetin can enhance the CL of luminol-K₃Fe(CN)₆/K₄Fe(CN)₆ reaction, and that their kinetic characteristics are different. The mixed CL kinetic curves of rutin and quercetin were measured and recorded every 0.05 second at a flow rate of 1.67 mL/min, and the obtained data were processed chemometrically by use of two kinds of NL-PLS models, polynomial inner relations PLS and spline inner relations PLS. The proposed method is simple, rapid and was successfully applied to the simultaneous determination of both analytes in Chinese traditional drug, Flos Sophorae buds, and compared well with the high performance liquid chromatography (HPLC) method.3. Simultaneous determination of glucose and fructose in food samples using flow injection CL method with the aid of partial least squares.In this paper, a simple flow injection CL system is developed for simultaneous determination of glucose and fructose in binary mixtures of reducing sugars without previous separation. This method is based on the different kinetics of the individual sugar in the oxidation reaction with periodate. The known KIO₄-pyrogallol CL system was used to measure the kinetic data of the system. The CL intensity was measured and recorded every second from 1 to 450 s. The data obtained were processed chemometrically by use of partial least squares. The relative standard errors of prediction for two analytes were less than 5%. The proposed method was successfully applied to the simultaneous determination of the two sugars in food samples.