TY - JOUR
T1 - New strategies for the determination of phenylurea pesticides by gas chromatography with hot splitless inlet systems
AU - Gennaro, Maria Carla
AU - Marengo, Emilio
AU - Gianotti, Valentina
AU - Maurino, Valter
N1 - Funding Information:
The authors gratefully acknowledge financial support by CNR (Consiglio Nazionale delle Ricerche, Roma) and MURST (Ministero dell’Università e della Ricerca Scientifica e Tecnologica, Roma).
PY - 2001/2/23
Y1 - 2001/2/23
N2 - Direct gas chromatographic methods to analyse phenylurea pesticides are discouraged by the thermal instability of these compounds, that in conventional hot splitless inlet systems leads to extensive and irreproducible formation of isocyanates and amines. However a careful control of the operating conditions, like the inlet temperature, the pressure and the presence of suitable chemical additives (as acetic acid, low-molecular-mass amines, organic anhydrides) can either: (i) minimise the thermal decomposition enabling the direct GC-MS analysis of phenylureas, or (ii) lead to reproducible conversion to isocyanates. Experimental design was employed to study the effect of the experimental variables on the thermal transformation of phenylurea pesticides in splitless inlet system. Two strategies were alternatively optimised: (i) the minimisation of degradation reactions to increase the signal of phenylureas; (ii) the maximisation of the degradation to isocyanates that are in turn determined. The maximal yields in isocyanate were obtained with high inlet temperatures, low carrier flows in the injection phase and the presence of acetic anhydride. By contrast, the use of relatively low inlet temperatures, high carrier flows during the injection and the presence of an amine maximise the response of the parent compounds.
AB - Direct gas chromatographic methods to analyse phenylurea pesticides are discouraged by the thermal instability of these compounds, that in conventional hot splitless inlet systems leads to extensive and irreproducible formation of isocyanates and amines. However a careful control of the operating conditions, like the inlet temperature, the pressure and the presence of suitable chemical additives (as acetic acid, low-molecular-mass amines, organic anhydrides) can either: (i) minimise the thermal decomposition enabling the direct GC-MS analysis of phenylureas, or (ii) lead to reproducible conversion to isocyanates. Experimental design was employed to study the effect of the experimental variables on the thermal transformation of phenylurea pesticides in splitless inlet system. Two strategies were alternatively optimised: (i) the minimisation of degradation reactions to increase the signal of phenylureas; (ii) the maximisation of the degradation to isocyanates that are in turn determined. The maximal yields in isocyanate were obtained with high inlet temperatures, low carrier flows in the injection phase and the presence of acetic anhydride. By contrast, the use of relatively low inlet temperatures, high carrier flows during the injection and the presence of an amine maximise the response of the parent compounds.
KW - Experimental design
KW - Injection methods
KW - Pesticides
KW - Phenylureas
UR - http://www.scopus.com/inward/record.url?scp=0035937016&partnerID=8YFLogxK
U2 - 10.1016/S0021-9673(00)01182-1
DO - 10.1016/S0021-9673(00)01182-1
M3 - Article
SN - 0021-9673
VL - 910
SP - 79
EP - 86
JO - Journal of Chromatography A
JF - Journal of Chromatography A
IS - 1
ER -