EQUIPMENT

1. Perkin-Elmer Model 4100ZL Atomic Absorption Spectrophotometry
2. Perkin-Elmer AS-71 Autosampler
3. Thallium electrodes discharge lamp
4. Perkin-Elmer System 2 EDL power supply
5. Hamilton Digital Diluter
6. Pyrolitically coated, platform graphite tubes
7. 2 mL sample cups

INSTRUMENT PARAMETERS

1	Wavelength	276.8 nm
2	Slit Width	0.7 nm
3	Slit Height	LOW
4	Signal Type	Zeeman AA
5	Signal Measurement	Peak Height
6	Read Time	5 seconds
7	Read Delay	0 seconds
8	BOC Time	2 seconds
9	Sample Volume	20 micro L
10	Modifier Volume	10 micro L

FURNACE PARAMETERS

STEP	TEMP (°C)	Time (sec)		INT. FLOW
		RAMP	HOLD
1	110	10	25	250
2	130	10	35	250
3	700	5	30	250
4	1600	0	5	0
5	2400	1	2	250

GAS

1. Argon 99.99%

STANDARDS

1. Stock Solutions:
   1. 1000 ppm Thallium: Use certified, Nist traceable Plasma Grade Standard
   2. 100 ppm Thallium: Pipet 10 mL of 1000 ppm thallium standard into a 100 mL volumetric flask. Dilute to volume with deionized water and mix well.
   3. 1 ppm Thallium: Pipet 1 mL of 100 ppm thallium standard into a 100 mL volumetric flask. Dilute to volume with deionized water and mix well.
2. Instrument Calibration Standards
   1. 20, 60, and 100 ppb Thallium - use the following settings on the Hamilton digital diluter to make dilutions of the 1 ppm thallium standard to produce the 60 and 100 ppb thallium standard. Make the 20 ppb thallium standard by diluting the 100 ppb thallium standard.

      Standard Used	Diluter Settings		Final Concentration ppb
      	Diluent	Sample
      100 ppb	32	80	20
      1 ppm	47	30	60
      1 ppm	36	40	100

      Note: This protocol produces 4 mL of the 20 and 100 ppb thallium standard and 5 mL of the 60 ppb thallium standard.

MATRIX MODIFIER REAGENTS

1. Palladium Nitrate: Pd(NO₃)₂
2. Magnesium Nitrate: Mg(NO₃).6H₂O

MATRIX MODIFIER PREPARATION

1. Weigh 0.1083 g palladium nitrate into a 100 mL amber volumetric flask.
2. Add 0.0518 g magnesium nitrate to the 100 mL volumetric flask.
3. Dissolve and dilute to volume with deionized water and mix well.

AUTOSAMPLER LOADING

1. Load the autosampler tray in the following manner:

   Positions 1-34	client samples
   Position 35	matrix modifier
   Position 36	deionized water
   Position 37	20 ppb antimony standard
   Position 38	60 ppb antimony standard
   Position 39	100 ppb antimony standard
   Position 40	quality control sample

PROCEDURE

1. Use the same procedure as given in the lead graphite furnace method p. 125- 127, with the following changes:
   1. Step 2 - change to - Install the thallium electrodes lamp. With the "MOD" button on (green light on), set the power output level to 300 milliamps. Allow the lamp to warm up for 45 minutes. The set current will increase as the lamp warms up. DO NOT READJUST.
   2. Step 6 - change to: Scroll down to and click on "WATER_TL.GEL"
   3. Step 15 - change to: Scroll down to and click on "TL_H2O.IDW"

QUALITY CONTROL

1. If the r value for the calibration curve is less than .990, remake the standards and recalibrate.
2. Analyze the quality control sample before and after the analysis of client samples. Values must be within the control limits established by the supplier of this sample.

REFERENCE

1. Methods for Chemical Analysis of Water and Wastes, 1983, Environmental Protection Agency, Thallium Method 279.2 (Atomic Absorption, furnace technique).