Spectra Hardware's uniquely adapted Hydride Generation Unit retrofits to existing DC Plasma Jets with minimal change-over time. Connection between the Generator and the DC Plasma Jet is accomplished by connecting the 5/16" PVC Tubing to the gas outlet of the Phase Separator. (See illustration). The other end attaches to the specially designed Spray Chamber Block Adapter. Remove the Spray Chamber and replace it with this Adapter. The Nebulizer Tubing is removed from the Nebulizer and slipped over the 1/8" I.D. Gray Tubing connected to the rear of the Generator. A Flow Gauge on the front panel is used to control the flow rate of the purge. Nebulizer pressure should be set at 10 psi on the Spectra Jet Supply. The Flow Gauge should be set at 2.5 SCFH. The small 1/16" I.D. Gray Tubing supplies this purge of argon. It is connected to the top of the Phase Separator. The Phase Separator has 1/4"-28 threaded fittings. An adapter is supplied to couple to a 10-32 threaded barbed fitting for both chemistry and purge. The Purge Tube is connected to the top of the Phase Separator (no bend). The one connected to the elbow is the Chemistry Input. 3/8" PVC tubing is supplied for draining. It is connected to the angled arm on the U-Tube Manometer. Drain waste to a plastic container. Be sure not to create a vapor lock in the drain tube. Tubes should fit into the drain bottle just below the neck and never go below the waste level or have kinks along it's length. OPERATION Hydride generation is a technique which utilizes the common property of these elements which form covalent, gaseous hydrides that disassociate at high temp- eratures. As, Se, Te, Sb, Bi Sn (and to a lesser degree Pb and Ge) are volatilized by the addition of Sodium Tetrahydroborate (III) (NABH4) and HCL solution. Other chemistries may be used, but this method is preferred because of faster hydride formation, higher conversion rates, low blank levels, and is simpler to use. After the hydrides are formed, they, along with excess Hydrogen, are passed directly to the plasma using nebulization gas. On ICP Units, hydrides are presented to the central injector tube. DCP Units require the installation of a specially designed chimney located between the two anodes. As, Se, Sb and Ge Samples containing the above mentioned elements in sub-ppm levels can be effectively analyzed to low or sub-ppb levels using hydride generation coupled with Flame AA, ICP, ICP/MS, or DCP Spectrometry. The chemistries involved for all instrumental methods is the same. Operating parameters and uptake rates will have to be tailored for maximum sensitivity for each instrument and analytical technique. The easiest and cleanest chemistry designed for the evolution of hydrogen and metalloid hydrides uses Sodium Tetrahydroborate (Sodium Borohydride) NaBH4 and Hydrochloric Acid (HCl). High concentrations of HCl are used to convert all Arsenic valance states to the As III state and produce gaseous Arsenic Hydride. Lower concentrations of HCl will not convert all As species to the As III, leaving them behind in the waste solution. Se, Sb, and Ge are effectively converted at any HCl concentration level (provided hydrogen gas is being produced). Changing the HCl concentration per element can optimize signal strength for that element. A best multiple element starting concentration set uses a 2% W/V NaBH4 solution stabilized with 0.1 N NaOH. This stock solution has a shelf life of approximately two days. Fresh solutions prior to analysis are recommended. The second solution of HCl has a concentration of approximately 6N. Lower levels (1N HCl) will produce higher signal levels for selenium, but degrade drastically the As signal. Samples should be prepared as normal. Nitric Acid (HNO3) should be avoided if possible. If not, very weak solutions containing less than 1% should be used. All three solutions are brought together in the pumping system using a three stage peristaltic pump. Each solution is pumped individually using approximately the same flow rate (4.5 ml/min.) (blue-blue pump tubing at 60 RPM). Changing flow rates will effect each element's hydride evolution differently. Fine tuning flow rates is recommended for your particular application. Order of mixing starts with individual samples, standards, and blanks combining with HCl at the first mixing Tee just after the peristaltic pump. NaBH4 - NaOH solution is added at the second Tee at the same rate. The final resulting solution is introduced to the reaction vessel via the elbow side arm, filling the vessel's U tube to the drain level. Argon purge gas in introduced to the top of the vessel at approximately 2.5 SCFM. This argon flow is usually taken from the existing nebulizer line. A pressure setting for the incoming argon should not exceed 10 psi. The flow rate for the purge gas is set using the front panel flow gauge. Actual flow rate should be established looking at signal strength and plasma character- istics. Higher flow rates are needed to pierce the plasma in ICPs. Argon is also necessary to remove memory effects of the reaction vessel between samples. OTHER INSTRUMENTATION ICP interconnections are done by teeing the nebulizer supply line connected to the nebulizer. Hydrogen and hydrides actually pass through the nebulizer, but have no aerosol. These gases finally pierce the plasma and reside in the center excit- ation channel. AA applications use the conventional tee cell mounted directly over the burner head. Gases enter the cell allowing the beam from the hollow cathode to pass through them during excitation. In all three analytical methodologies, instrument operation does not change. Peaking, standardization and sampling remains the same. Samples and standards are introduced to the generator instead of a nebulizer and gases are introduced to the source instead of aerosols. Starting concentrations for line identification should not exceed 10 ppm. Typically, standards under 100 ppb should be used for the high points of any calibration curve. Since this methodology uses continuous flow technology, autosampling can be easily implemented. Timing constraints for flushing the vessel and rise time on steady state gas evolution will need to be adjusted. Different elements come off at different rates. Be sure all elements are at a steady rate of formation before analyzing. Continuous flow hydride generation provides a very sensitive multi- element alternative to low level analysis of group IV, V elements. This generic attachment is easily adapted to a wide variety of instrumentation with little or no change in its operation. ANALYSIS OF LEAD