Werner Butte

Critical considerations on the analysis and bioaccumulation of musk xylene and other synthetic nitro musks in fish

Abstract Several analytical methods for the residue analysis of musk xylene (MX), musk ketone (MK), and other nitro musks in fish are presented and discussed. In particular because of a publication about a fast and simple analysis without any clean-up procedure, the necessity of a thorough clean-up of fatcontaining samples is emphasized. In addition, the present knowledge about the high bioconcentration of these lipophilic pollutants in fish is summarized. In a long-term bioconcentration study we found in rainbow trouts bioconcentration factors (BCF) on a wet weight basis (BCF w ) of MX from 4,200 to 5,100 while the BCF values on a lipid basis (BCF L ) ranged from 115,000 to 122,000. These BCF values of MX are in good agreement with the BCF values calculated from the noctanol/water partition coefficient (log K OW = 4.90) using the Quantitative Structure-Activity Relationship (QSAR). A published study with extremely low bioconcentration factors of MX is critically discussed.

Initiation of Radical Chain Reactions of Thiol Compounds and Alkenes without any Added Initiator: Thiol‐Catalyzed cis/trans Isomerization of Methyl Oleate

A kinetic study of the dodecanethiol-catalyzed cis/trans isomerization of methyl oleate (cis-2) without added initiator was performed by focusing on the initiation of the radical chain reaction. The reaction orders of the rate of isomerization were 2 and 0.5 for 1 and cis-2, respectively, and an overall kinetic isotope effect k(H)/k(D) of 2.8 was found. The initiation was shown to be a complex reaction. The electron-donor/-acceptor (EDA) complex of dodecanethiol (1) and cis-2 formed in a pre-equilibrium reacts with thiol 1 to give a stearyl and a sulfuranyl radical through molecule-assisted homolysis (MAH) of the sulfur-hydrogen bond. Fragmentation of the latter gives the thiyl radical, which catalyzes the cis/trans isomerization. A computational study of the EDA complex, MAH reaction, and the sulfuranyl radical calculated that the activation energy of the isomerization was in good agreement with the experimental result of E(A)=82 kJ  M(-1). Overall, the results may explain that the thermal generation of thiyl radicals without any initiator is responsible for many well-known thermally initiated addition reactions of thiol compounds to alkenes and their respective polymerizations and for the low shelf-life stability of cis-unsaturated thiol compounds and of mixtures of alkenes and thiol compounds.

Photocatalytic degradation of reduction products of 2,4,6-trinitrotoluene (TNT)

The photocatalytic degradation of 2-amino-4,6-dinitro, 4-amino-2,6-dinitro-, 2,6-diamino-4-nitro- and 2,4-diamino-6-nitrotoluene in water was studied in the presence of hydrogen peroxide/ferrous ions. Transformation rates were controlled by the number of amino or nitro groups and by the structure of the molecules, i.e. diaminonitrotoluenes were transformed faster than monoaminodinitrotoluenes. On the other hand, compounds with an amino group para to the methyl group were degraded more rapidly than those with an ortho amino group. Besides photooxidation of the methyl group, deamination and cleavage of nitro groups was observed. The main degradation product identified by GC/MS was benzaldehyde.

Organochlorine pesticides and polychlorinated biphenyls in human milk during lactation

Abstract Organochlorine residue levels were determined in human milk samples of 5 women. The contaminants analyzed were: α-, β-, and δ-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), p,p′-DDT, p,p′-DDE, and polychlorinated biphenyls (PCBs). The variation of residue levels in human milk during lactation was investigated for each woman individually. Month-mix samples composed of weekly collected breast milk samples were analyzed over a lactation period between 5 and 9 months. No essential changes in organochlorine residue levels in human milk occurred over the lactation periods investigated; the concentration remained either relatively constant or showed fluctuations with no observable trend.

Photochemical degradation of nitrated musk compounds

Abstract The kinetics of the photochemical degradation of the nitromusk compounds musk xylene (MX), musk tibeten (MT), musk ketone (MK), musk ambrette (MA) and musk moscene (MM) in water was evaluated. The kinetics were of pseudo-first order. Different transformation pathways are discussed, nitromusks with two nitro-groups next to the tert. alkyl-group, i.e. MX, MK and MT undergo intra molecular reactions, whereas for MA and MM inter molecular reactions are favoured.

Calculation of bioconcentration factors from kinetic data by non-linear iterative least-squares regression analysis using a programmable minicalculator

Abstract A program to fit theoretically modelled uptake and clearance periods of the bioconcentration of chemicals to experimental data using a programmable pocket calculator with thermal printer is reported. The bioconcentration factor (BCF) is calculated from the ratio of uptake and clearance rate constants. Because of the impossibility to linearize the kinetic equations an iterative nonlinear GAUSS-NEWTON least-squares fit has been applied for the pocket calculator programm ACCUTI-59, which calculates from a set of start parameters the best values for uptake and clearance rate constants, BCF, and the standard errors as well as the sum of squared deviations. A listing of the program is given.