2 F A S T - L C Concepts for Automated Pesticide Analysis
Downloaded by GEORGETOWN UNIV on June 4, 2018 | https://pubs.acs.org Publication Date: October 30, 1980 | doi: 10.1021/bk-1980-0136.ch002
DONALD A. BURNS Technicon Industrial
Systems, 511 Benedict Ave.,
Tarrytown,
NY 10591
The planet earth, fortunately for us, is blessed with conditions for "life as we know it" in the form of two kingdoms: animals and plants. One of these animals, man, doesn't always approve of everything else that grows, so he takes positive action to limit the growth of some organisms by creating large machines which spew forth mists of chemicals called pesticides. Since these toxic substances may not disappear from the environment as rapidly as they were dispensed, man is relegated to the laboratory to monitor the residues left in or on the food he plans to eat. Various regulating agencies require ever-increasing numbers of tests at ever-rising costs, so it behooves those who must cope with this situation to study carefully the alternatives. The laboratory director may hire more analytical chemists, or provide more automated instruments for his existing staff. The automation approach nearly always results in higher precision and lower costs per test. One analytical technique especially suited to pesticide analysis is high performance liquid chromatography (HPLC), and one particular version of it is called FAST-LC (an acronym for Fully Automated Sample Treatment for Liquid Chromatography). It is the various aspects of this automated sample treatment which will be considered in this report. Unit Operations Just as a voyage from one point to another consists of many individual steps, so also does an analytical procedure involve many individual operations. These are often referred to as "unit operations", and they may be classified in several ways (eg. obtaining a sample, getting it ready for analysis, the analysis itself, or the detection step for quantitation). The sample may be solid, liquid, or gas, and its pretreatment could include such operations as extraction, filtration, dialysis, distillation, concentration, or even chromatography. The analysis step could be quite direct (as colorimetry often is) or a chromatographic separation may be required prior to detection. If chromatography is employed, it may be necessary to derivatize the 0-8412-05 81 -7/ 80/47-136-015$05.00/0 © 1980 American Chemical Society Harvey et al.; Pesticide Analytical Methodology ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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PESTICIDE
ANALYTICAL
METHODOLOGY
s a m p l e , and t h i s c a n be done e i t h e r b e f o r e o r a f t e r the s e p a r a t i o n on t h e c o l u m n . A n d i n a d d i t i o n t o c o l o r i m e t r y , o t h e r means of d e t e c t i o n are a v a i l a b l e to the a n a l y s t : u l t r a v i o l e t (UV) s p e c t r o p h o t o m e t r y , f l u o r e s c e n c e , electro-chemical, etc. In t h i s r e p o r t i t w i l l be shown how m a n y of these u n i t o p e r a t i o n s c a n be c o m b i n e d i n t o p a r t i a l l y - o r f u l l y - a u t o m a t e d s y s t e m s . A l t h o u g h s e v e r a l types w i l l be d e s c r i b e d , the emphasis w i l l be on H P L C - b a s e d s y s t e m s . A n d t h a t is p r o b a b l y as i t should be, because H P L C i s s t i l l t h e m o s t p o p u l a r a n a l y t i c a l t e c h n i q u e , a c c o r d i n g t o Thomas
