Into the torch as well as thermostatted optics

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into the torch as well as thermostatted optics facilitate long term stability of the emission signal as seen in the long term stability plot in Figure 2. To run challenging samples, the RF system must be able to rapidly adjust to changes in the plasma conditions. The free running solid state radio frequency (SSRF) generator in the 5110 RV ICP-OES meets these challenges and can handle a wide range of organic samples, from volatile organics such as methanol or gasoline, to semi volatile organics such as kerosene. The benefit of this is that plasma conditions similar to those used for aqueous solutions can be used for organics without the need for high plasma gas flows. In addition, for the analysis of wear metals in kerosene based solvents, like A-Solv, there is no need for Ar/O 2 addition to the auxiliary gas flow or the use of a temperature controlled spray chamber. An Agilent SPS 4 Sample Preparation System was used for automatic sample delivery in combination with a 6 port Advanced Valve System (AVS 6) [2]. The fully integrated AVS 6 utilizes a high speed pump to minimize uptake, and controlled bubble injection to aid with stabilization and washout, offering high throughput and excellent analytical performance for organic sample analysis. The AVS 6 uses a positive displacement pump, requiring little maintenance in comparison to vacuum based pumps. Setup is easy, designed for simple assembly and disassembly, and is robust enough to handle tough samples, making it ideal for oil analysis. The sample introduction system chosen for this analysis was the semi-volatile organics kit comprising of a glass concentric nebulizer, a 1.4 mm id RV torch, solvent resistant tubing, and a double-pass glass cyclonic spray chamber. Instrument operating conditions are listed in Tables 1a and 1b. Fitted background correction was used for all wavelengths, simplifying the method development by eliminating the need to determine off-peak background correction points for each element. Table 1a. Agilent 5110 RV ICP-OES and 6 port Advanced Valve System (AVS 6) operating parameters Parameter Setting Read time (s) 2 Replicates 2 Sample uptake delay (s) 4.5 Stabilization time (s) 6 Rinse time (s) 2 (fast pump: Off) Pump speed (rpm) 12 RF power (kW) 1.30 Aux flow (L/min) 1.0 Plasma flow (L/min) 12.0 Nebulizer flow (L/min) 0.65 AVS 6 settings Loop volume (mL) 0.25 Pump rate: Valve uptake (mL/min) 36.0 Pump rate: Inject (mL/min) 10.0 Bubble injection time (s) 2.5 Pre-emptive rinse time (s) 1.5 Table 1b. Agilent 5110 RV ICP-OES method parameters Parameters Settings Ar/O 2 addition Not required Nebulizer Glass concentric Spray chamber Double Pass Cyclonic Torch Organic 1.4 mm id Sample pump tubing White-white SolvaFlex Waste pump tubing Grey-grey SolventFlex SPS 4 rinse solution Agilent A-Solv ICP solvent Background correction Fitted The wavelengths selected for the analysis are given in Table 2. Wavelengths were selected according to the recommendations of ASTM D5185. Method Detection Limits (MDLs) are also given in Table 2. They are based on three sigma of ten replicate measurements of the

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