Organotin analysis

WEN (2000) Speciated organotin analysis for the Women s Environmental Network. Prepared by Scientific Analysis Laboratories Ltd for the Women s Environmental Network,... 

LC-tandem MS was recently used for polymer/additive characterisation. In cases of soft ionisation processes (e.g. ESI, APCI, etc.), MS/MS is often necessary to confirm the ionic species. QITMS has the potential to improve the detection limits for organotin analysis compared to QMS. HPLC-UV and LC-API-MS/MS have been employed for the characterisation of the products of photodegradation of benzotriazole-based UV absorbers (Tinuvin P/328/900) under mild conditions [642]. Among the photoproducts identified... 

Simon, S., Bueno, M., Lespes, G., Mench, M., and Potin-Gautier, M., Extraction procedure for organotin analysis in plant matrices optimization and application, Talanta, 57, 31-43, 2002. 

The main criterion for the detector is that it gives a response specifically for tin, rather than the compound. This is because of the detection limits required for environmental analysis, which are not attainable with non-specific detectors. The most popular detection methods for organotin analysis are FPD using a tin selective filter, MS, MIP-AES, and ICP-MS. Recently, HPLC-MS methods based on atmospheric ionization including electrospray, ion spray, or chemical ionization have been used to detect the organotin species. These methods have the advantage that molecular information concerning the analyte is available, rather than just atomic information. 

Several forms of LC have been used for the separation of organotins. These techniques offer a simple, direct separation, which does not require derivati-zation of the species. The main disadvantages are the lower resolution available with LC and the limitations on detectors that can be coupled to LC for organotin analysis. Ultraviolet detection is not appropriate due to its very poor sensitivity for tin however, fluorimetry has been successfully employed. The recent development of the two hyphenated techniques of LC-MS and LC-ICP-MS has provided two sensitive and selective detectors available for LC speciation. 

GC offers excellent chromatographic resolution and can be coupled to a range of appropriate detectors for organotin detection such as MS, ICP-MS, atomic emission (AED), AAS, and flame photometric detectors (FPD). The main problem with GC is the low volatility of all organotin species except in the tetra-organotin forms. This means that a derivatization step is required prior to GC analysis. This typically involves alkylation of the sample. GC columns, which have been employed for organotin analysis are typically nonpolar PDMS fused silica columns such as HP-1 or the 5% phenyl equivalents such as HP-5. 

AES with a microwave-induced plasma has been a popular technique for organotin analysis allowing very selective detection by utilization of specific Sn emission wavelengths such as 326, 303, or 271 nm. However, the detector can require high maintenance, which can be a drawback for routine use. 

LC-MS has been used for organotin analysis, though its application is much less wide spread than ICP-MS. It offers the advantage of providing structural information because of the soft ionization processes employed in the atmospheric pressure interfaces, and molecular ions (or their adducts) are generally observed for organotin species. 

The terminal dUTP nick end labeling assay (TUNEL reaction) and electrophoretic analysis of DNA/organotin(IV) mixtures allowed the investigation of DNA fragmentation. 

Funk et al. have used a low-pressure mercury lamp without filter to liberate inorganic tin ions from thin-layer chromatographically separated organotin compounds these were then reacted with 3-hydroxyflavone to yield blue fluorescent chromatogram zones on a yellow fluorescent background [22]. Quantitative analysis was also possible here (XoK = 405 nm, Xji = 436 nm, monochromatic filter). After treatment of the chromatogram with Triton X-100 (fluorescence amplification by a factor of 5) the detection limits for various organotin compoimds were between 200 and 500 pg (calculated as tin). 

Inductively coupled plasma mass spectrometry was applied to the analysis of six organotin compounds (chlorides of dimethyl-, dibutyl-, trimethyl-, tributyl-, diphenyl-, and triphenyltin). Detection hmits for the six organotins ranged from 24 to 51 pg as tin the dynamic range was over lO, from 1 pg/1 to 10 mg/1 (Inoue Kawabata, 1993). 

The BUSES model has been run for each of the organotins under consideration. This involved developing use patterns for each compound, together with appropriate emission factors (based on the results presented above) and data on the properties of each of the compounds. The data upon which the analysis is based are the usage of each compound by application. More details on the method can be found in the source document (EC, 2003). Regional PECs for fresh water are summarized in Table 16. 

Mesch KA, Kugele TG (1992) Use of organotin stabilizers — Risk assessment analysis. Journal of Vinyl Technology, 14 131-134. 

Bayona JM (1995) Development of supercritical fluid extraction procedures for the determination of organotin compounds in sediment. In Quevauviller Ph, Maier EA, and Griepink B, eds. Quality assurance for environmental analysis, pp 465-487. Elsevier, Amsterdam. 

Morabito R, Chiavarini S, and Cremisini C (1995) Speciation of organotin compotmds in environmental samples by GS-MS. In Qltevauviller Ph, Maier EA and Griepink B, eds. Quality Assurance for Environmental Analysis, pp 437-462. Elsevier, Amsterdam. 

Progress in the field of polymer/additive analysis in the last three decades can best be illustrated by an old recipe for the direct determination of organotin stabilisers in PVC [142] ... 

SEC-RI/UV has also been used to analyse some 26 thioorganotin compounds, organotin carboxylates and chlorides, essentially PVC stabilisers, and some of their main by-products and related compounds (thioesters and dithioesters, n-alkanes) [803]. Not all organotin chlorides were stable in the adopted analysis conditions. N, Ai -ethylene-bis-stearamide and -oleamide in common plastics (ABS, SAN, PUR, LDPE, PA6.6) can be analysed by SEC after derivatisation with trifluo-roacetic anhydride. SEC analysis of fatty alcohol ethoxy-lates (FAE), used as nonionic surfactants, has also been described [759]. 

Applications Since the introduction of commercial GC-MIP-AES systems, organometallic analysis can be performed routinely, e.g. for speciation of organotin compounds used as PVC stabilisers [356], The hyphenated GC-AED technique can be used to improve the efficiency of additive analysis. While on the one hand... 

Crompton [21] has reviewed the use of electrochemical methods in the determination of phenolic and amine antioxidants, organic peroxides, organotin heat stabilisers, metallic stearates and some inorganic anions (such as bromide, iodide and thiocyanate) in the 1950s/1960s (Table 8.75). The electrochemical detector is generally operated in tandem with a universal, nonselective detector, so that a more general sample analysis can be obtained than is possible with the electrochemical detector alone. 

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