printed by Techniques for Increasing Productivity in ICP Spectrometry Jerry Dulude, Glass Expansion, Inc., 4 Barlows Landing Rd., Pocasset, MA This paper will examine a number of ways in which the length of the analytical cycle can be reduced without jeopardizing the quality of the results. These include the selection of the ICP-AES configuration, choice of sample introduction components, and software and hardware approaches for shortening or eliminating the rinse step. As both ICP-AES and ICP-MS spectrometers become more and more an integral part of the production laboratory, the emphasis on productivity is enhanced. This paper will examine a number of ways in which the length of the analytical cycle can be reduced without jeopardizing the quality of the results. These include the selection of the ICP-AES configuration, choice of sample introduction components, and software and hardware approaches for shortening or eliminating the rinse step. The Niagara Rapid Rinse Accessory significantly shortens the analysis cycle time of an unattended ICP spectrometer run and as a result achieves higher productivity and faster sample turnaround times. The Niagara begins the rinsing of the nebulizer and spray chamber the instant the sample measurement is completed and continues to rinse until the next sample is ready. Thus the rinse is carried out in the time that is usually wasted waiting for the sample and the rinse solutions to flow from the autosampler to the nebulizer. The Niagara replaces steps 5 and 6 with step 7. The Niagara is controlled by built-in firmware and is triggered by the autosampler. Each kit includes an autosampler kit which has been designed for each of the major autosampler models. Small ID pump tubes at fast speed Small ID capillary tubes Small ID autosampler probe Minimize length of sample tubing The graph below illustrates the stages of analysis for a typical autosampler run on an ICP-AES or ICP-MS spectrometer. Almost all of the stages can be shortened by one means or another. Some of these are dependent upon the specific hardware configuration of the spectrometer and autosampler. Some autosamplers are designed to move faster than others and should be investigated prior to purchase with respect to speed if productivity is an important criterion (stages 1 & 5). For AES spectrometers, particularly, the configuration of the optical and readout systems can significantly affect speed of analysis (stage 4). Dual view (radial and axial) spectrometers take two exposures for each analyses, increasing the integration time. Some chip-based spectrometers must take two exposures to cover the wavelength range of the method. Another aspect to investigate is the readout overhead time which can be significant on various makes and models. This paper will address ways to increase productivity once the spectrometer and autosampler have been procured and installed. BACKGROUND INTRODUCTION Niagara™ Rapid Rinse Accessory CONCLUSIONS Sample cycle for unattended ICP sample analysis AS to sample Smpl fills line Plasma equil Integration AS to rinse Rinse Smpl empties line Effect of Sample Introduction Components Helix O’ring=free Nebulizer fitting EzyFit Zero dead-volume Sample connector Decreasing Dead Volume Faster Flows Software Approaches Fast Pump during Rinse (stages 2, 6, and 7) Double pump speed during the rinse step.Double pump speed during the rinse step. Pump stays in fast mode until the next sample is ready.Pump stays in fast mode until the next sample is ready. Must add 10 to 15 sec. of equilibration time prior to integration.Must add 10 to 15 sec. of equilibration time prior to integration. Reduces cycle time by 5 to 10%Reduces cycle time by 5 to 10% The Helix o’ring-free nebulizer fitting eliminates the o’rings that are a source of dead volume. Likewise, the EzyFit eliminates dead volume in the nebulizer sample port. The entire sample line from the autosampler probe to the nebulizer should be minimized probe to the nebulizer should be minimized in both length and internal diameter. Predictive Rinse Estimate the sample uptake time.Estimate the sample uptake time. Lift the sipper from sample prior to the measurement.Lift the sipper from sample prior to the measurement. Conduct rinse and next sample loading during the previous sampleConduct rinse and next sample loading during the previous sample measurement. measurement. Requires good estimates.Requires good estimates. May not rinse out high concentration samples.May not rinse out high concentration samples. Not compatible with Auto QC Checking.Not compatible with Auto QC Checking. Good for crude assays.Good for crude assays. Intelligent Rinse Determine appropriate rinse based on the last sample.Determine appropriate rinse based on the last sample. If all elements below set point 1: NO RINSEIf all elements below set point 1: NO RINSE If an element exceeds set point 1 but not set point 2: STD RINSEIf an element exceeds set point 1 but not set point 2: STD RINSE If an element exceeds set point 2: MONITOR RINSE SOLNIf an element exceeds set point 2: MONITOR RINSE SOLN UNTIL UNDER SET POINT 1 UNTIL UNDER SET POINT 1 Excellent for high accuracy analyses.Excellent for high accuracy analyses. Little time saving for dirty samples.Little time saving for dirty samples. Sample Mode Rinse Mode BFeZnSeMoCdSnSbTlBi Normal 30s wash 5ppm Solution Blank Uptake = 15sBlank Read delay = 8sBlank Data acq approx = 40sBlank Wash = 30sBlank Total estimated time = 1m33sBlank Total actual time = 1m40s (additional time = autosampler moving etc) BFeZnSeMoCdSnSbTlBi Niagara 10s wash 5ppm Solution Blank Uptake = 15sBlank Read delay = 8sBlank Data acq approx = 40sBlank Wash = 10sBlank Niagara delay = 22sBlank Total estimated time = 1m13s Total actual time = 1m20s (additional time = autosampler moving etc) For greatest productivity for accurate analyses, minimize dead volume on all sample introduction components and combine Niagara with the Fast Pump mode of operation. Niagara achieves 25% reduction in cycle time NORMAL (30-SEC. RINSE) NIAGARA (10 SEC. RINSE) (all results in ppb) Trial performed using Elan 6000 ICP-MS by Gavin Robinson, Hill Laboratories, Hamilton, New Zealand