DIRECT DETERMINATION OF METAMITRON IN SURFACE-WATER BY LARGE SAMPLE VOLUME INJECTION

For a number of applications, e.g., monitoring of surface water quality, trace components which can be detected at levels of 0.1-1 ng do not need preconcentration. However, the determination of these components is usually performed after liquid-liquid or solid-phase extraction, which is time consuming. Injection of the sample directly into the separation system not only saves time (allowing higher sample throughputs), but is also uncomplicated and thus automatable. Metamitron was determined by direct injection of (surface) water samples onto an analytical C-18 column. With a 2-ml loop injection, the detection limit was 0.15-mu-g/l in surface water. No significant peak broadening compared with a 20-mu-l loop injection was observed. The linearity of the method was satisfactory (r2 = 0.9985) and the relative standard deviation for seven replicate 2-ml injections at 2-mu-g/l was 3%. The total analysis time was only 10 min.