Excel calibration designs

Process analyzers based on a no-moving-parts axial transmissive spectrograph [4,175] design have demonstrated excellent calibration stability when operated in a reasonably stable environment. Analyzers of this type have yielded consistent chemical model results for up to several years without recalibration using robust modeling techniques such as... 

The instrument for measurement of radon with weather parameters and water use was designed, calibrated and used in the field for 1.5 years with excellent results. The power surge and power interruptions were the only limitations on the use of the instrument. The system software was written mostly during the design phase of the project. However, modifications were made in the software to permit better data collection during power interruptions. Battery backup was needed to keep the data during interruptions of our one week studies. 

Microprocessor technology had a great impact on the development of radioisotope instraments. Linearisation of complex calibration curves, compensation for the decay of the radioisotope, and performance of important calibration checks can be handled easily by the microprocessor. In this way, radioisotope instmments of modem design added yet another dimension of reliability and sophistication to their proven excellence. 

We were gratified by the excellent precision that student were able to attain. By the FAA spectroscopy experiment, over 90% of the students had less than five per cent error on their calibration curves. However, we were disappointed and puzzled by the poor results these same students had in their accuracy. Only 40% of the students were within the target of < 10% error on their reference material and over 34% of the students had over 20% error. We suspected that accuracy errors stemmed from the quantitative transfer of a solid and a solution, the only skill unique to the accuracy work. We confirmed our suspicions by designing a laboratory practical to investigate quantitative analysis skills. 

To study catalytic processes of clusters on surfaces with high sensitivity, a newly designed pulsed valve with excellent pulse-to-pulse stability, in combination with absolutely calibrated mass spectrometry, was used to determine turn-over frequencies [75]. 

Faced with dilute samples, proper presentation of the sample and accurate spectrometer calibrations are particularly important. The sample should be mobile rather than bound, deoxygenated, and free of particulates. The removal of particulates by filtration makes a significant improvement to spectral quality. High-resolution solution work usually requires dissolution in a deuterated solvent for instrumental locking. However, excellent spectra can often be obtained in protonated solvents in the presence of a concentrically placed sealed capillary tube containing the deuterated solvent. This approach is unsuitable for intact biological samples where the NMR probe and coil assembly is designed around the specimen. 

Elan software appears to be designed with the assumption that if one is analyzing isotope ratios, the element concentration is plentiful, and the isotopic abundances are not very different. Thus, no option is included for an internal standard, nor for blank subtraction. These would be negligible if the above assumptions were true. For uranium, and especially uranium at urine concentrations, these assumptions are not valid. Therefore, no form of quantitative calibration is selected. Each isotope and element will be acquired as Counting (CPS) Only, so that the internal standard corrected blank counts per second may be calculated and subtracted offline with a program such as Microsoft Excel. 

Exocytotic events from neural cells have also been followed using a microelectrode array system designed for monitoring the effects of dmgs on neurotransmitter release [26]. An excellent detection limit for dopamine (40 nM) and linear calibration over two orders of magnitude were demonstrated. The effects of and l-3,4-dihydroxyphenylalanine concentrations and incubation times on dopamine release were examined. 

---