| Since the1990s, resonance Rayleigh scattering (RRS) and resonance non-linearscattering (RNLS) technique as a new analytical method, has received much attentiondue to its sensitivity, selectivity, stability, low-cost, simplicity, environmental friendly,etc. Some researcher considered that chromophores aggregated on biologicalmacromolecular or ions of opposite charge form to ion-association complex byelectrostatic attraction, hydrophobic force and charge transfer effect, which not onlycaused the resonance Rayleigh scattering (RRS), second-order scattering (SOS) andfrequency doubling scattering (FDS) intensities greatly enhanced, but also changed itsspectral characteristics. Based on this, the technology has been widely used for theresearch and analysis of biological macromolecules (nucleic acids and proteins), tracemetal ions, dyes, surfactants and drug in practical samples. In this paper, we take somedyes and surfactant as resonance probe, employing RRS, SOS, FDS methods to built aseries of analysis system for detecting trace amounts of cobalt, silver, lanthanum, andcerium. The contents were as follows:1. Resonance Rayleigh scattering and resonance non-linear scattering methods forthe determination trace amounts of cobalt with Co(Ⅱ)-ARS-CPB systemIn pH5.4HAc-NaAc buffer solution, Cobalt chloride (CoCl2) could react withalizarin red S(ARS) and cetylpyridinium bromide(CPB) to form ternary ion associationby electrostatic attraction and hydrophobic force. It resulted in the significantenhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS)and frequency doubling scattering (FDS) intensities. The maximum scatteringwavelength (λex/λem) of RRS, SOS, FDS were located at380nm/380nm,290nm/580nm,578nm/289nm, respectively. The intensities of three scattering signal (ΔIRRS, ΔISOSandΔIFDS) were directly proportional to the concentration of cobalt in the range of0.128～19.2μg/mL for RRS,0.64～33.28μg/mL for SOS and0.64～35.84μg/mL for FDS.Meanwhile, the system had high sensitivity and the detection limits (3σ) were0.015μg/mL (RRS),0.044μg/mL (SOS) and0.052μg/mL (FDS), respectively. Besides,the optimum reaction conditions and the influence of coexisting substances for the RRSintensity were investigated, it demonstrated that this method had a good selectivity, lessreagent consumption and easy operation and applied for the determination of traceamount of cobalt in vitamin B12with pleased results, the sample recovery was between 100.78%and104.08%.2. Investigation and application of Ag(I)-XO-CPB system by resonance Rayleighscattering and resonance non-linear scatteringIn pH5.0C6H8O7-Na3C6H5O7buffer solution, positively charged cetylpyridiniumbromide (CPB) and negatively charged xylenol orange (XO) could react with silvernitrate to form ternary ion-association complex, which caused the resonance Rayleighscattering (RRS), second-order scattering (SOS) and frequency double scattering (FDS)intensities dramatically enhanced. The largest scattering wavelength (λex/λem) of RRS,SOS, FDS were located at467nm/467nm,340nm/680nm,680nm/340nm, respectively.Furthermore, the spectrum characteristics, influence factors and reaction mechanismhave also been investigated minutely. It was revealed that SOS and FDS spectra havesome similarity, and the enhancement of scattering intensities (ΔIRRS，ΔISOSand ΔIFDS)showed a good relationship with the concentration of silver in a certain range. Thelinear range of three methods were2.6～19.5μg/mL (RRS),6.5～91.0μg/mL (SOS),6.5～91.0μg/mL (FDS), and the detection limits (3σ) were0.0126μg/mL for RRS,0.1167μg/mL for SOS and0.1222μg/mL for FDS, respectively. Moreover, the systemalso displayed favourable reproducibility, stability and selectivity, and were successfullyapplied to the determination of trace amounts of silver in actual water samples andsynthetic samples with satisfactory results.3. Determination trace amounts of lanthanum by resonance Rayleigh scattering,second-order scattering and frequency double scattering methods based on theLa(III)-CGR-CPB systemA novel method for the determination of scruple amounts of lanthanum inenvironmental water samples by resonance Rayleigh scattering (RRS), second-orderscattering (SOS) and frequency double scattering (FDS) have been established based onthe formation of La(III)-CGR-CPB ternary ion-association complex. It was discoveredthat in pH3.4H3PO4reaction medium, lanthanum nitrate could react with congo red(CGR) to form1:1complex anion, which further combined with cetylpyridiniumbromide (CPB) to form a heavier molecular weight, larger molecular volume andstronger hydrophobic effect of ternary ion-association complex by electrostaticattraction and hydrophobic force. As a result, the RRS, SOS, FDS intensities enhancedrapidly, and their maximum wavelength (λex/λem) were located at467nm/467nm,289nm/578nm,540nm/270nm, respectively. Under the optimal conditions, therelationship between the scattering intensity and lanthanum concentration was investigated. The results evidenced that the enhancement of three scattering intensities(ΔIRRS，ΔISOSand ΔIFDS) was linear with lanthanum concentration in the range of1.296～10.692μg/mL (RRS),0.972～5.508μg/mL (SOS),0.972～6.156μg/mL (FDS),respectively, and the detection limits (3σ) were0.0143μg/mL for RRS,0.0101μg/mL forSOS,0.0123μg/mL for FDS. Moreover, it was compared with the RRS spectrum andUV absorption spectrum found that the maximum scattering peak of theLa(III)-CGR-CPB ternary ion-association complex was just located in its UV absorptionband, which indicated that the increase of scattering intensity was caused by resonancedue to the scattering frequency was equal to the absorption frequency. Besides, thesystem exhibited an excellent anti-interference ability and stability, it was triumphantlyapplied to the determination of lanthanum in environmental water samples, therecoveries got by standard addition method were in the range of97.28%～102.89%.4. Investigation and application of Ce(Ⅲ)-CGR-BSA system by resonance Rayleighscattering and resonance non-linear scatteringIn pH7.6NH3·H2O buffer solution, the interaction of cerium nitrate with congo red(CGR) and bovine serum albumin (BSA) was studied by resonance Rayleigh scattering(RRS) and resonance nonlinear scattering (RNLS) methods. The results showed thatRRS, SOS, FDS intensities of single or two-two mixed solution were rather weak in thewhole scanning wavelength range. However, after cerium nitrate combined with CGRand BSA to form ternary ion-association complex by electrostatic attraction, causing theincrease of particle volume, molecular weight and hydrophobic effect, which not onlyresulted in the new RRS spectra appeared, but also brought about the remarkableenhancement of RRS, SOS, FDS intensities. The three maximum scattering peaks werelocated at278.6nm，543.6nm,390.6nm, respectively, and the enhancement of scatteringintensities (ΔIRRS， ΔISOSand ΔIFDS) showed a good relationship with ceriumconcentration in the range of2.5～12.5μg/mL. The detection limits (3σ) were0.0426μg/μg/mL for RRS,0.1139μg/mL for SOS and0.4419μg/mL for FDS. Amongthem, RRS method has the highest detection sensitivity. Thus, the optimum reactionconditions and the influence of coexisting substances were investigated by RRS method.The results indicated that the method has good selectivity and operability. Based on theabove research, a sensitive, rapid and simple method for the determination of ceriumhas been established. It was applied for detecting trace amounts of cerium in syntheticsamples and water samples with pleased results. |
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