Dry reagent delivery system for field monitors and chemical sensors
thesisposted on 04.06.2013, 13:33 by John M. Lee
There are many methods available for a laboratory analyst to measure the amount of a target analyte within an environmental sample containing a wide variety of other species. However the vast majority of these methods require expensive instrnmentation and the analyst to be trained in its operation and safety procedures. The aim of the following work was to produce a method of analysing environmental pollutants within a complex matrix, without, or with minimal sample pretreatment, using standard colorimetric methods. Results of the analysis would be displayed clearly within a short time and with a high degree of accuracy, selectivity and sensitivity. The tests could be used by an untrained operator and would not contain significant amounts of toxic or irritating chemicals. All the reagents required for the determination and removal of interferences would be contained within the test in the order required by the procedure. The tests would be capable of mass production and would have a shelf life of at least 9 months. TI1e following work describes the research carried out to meet the above criteria. The species of environmental interest investigated are aluminium, silver, molybdenum, sulphur dioxide and nitrogen dioxide. These species were chosen for reasons which will be mentioned in greater depth in the introduction. The tests are, however, not developed with a view to replacing existing instrumental methods, but as means for an operator to determine whether their sample requires further analysis using instrumentaion. TI1e aim of the test result is to provide the operator with the answer to questions such as does my tap water contain more than the recommended limit of aluminium? or does the effiuent from my photographic laboratory contain an amount of silver which could lead to my prosecution?. The operator when given a measurement from the tests, by comparing with a colour chart, for example, 0.1ugml-1, may then decide if they need further analysis using for example, ICP MS techniques. The development of both paper dip tests and a novel soluble polymer reagent delivery system are described, as well as capillary fill and dry reagent tube devices.The successful soluble polymer matrix test (SPMT) is also applied to develop a stripping voltammetric sensor for the detennination of lead in whole blood. It is hoped that the SPMT will negate the need for pretreatment of the blood sample before detennination.