4.1 The sample is collected on a 0.8 µm AA cellulose membrane filter using a flow rate between 1.5 and 2.0 liters per minute. Suggested minimum air volume is 100 liters. A sample blank should also be submitted. (If considerable loose dust is present in the cassette, a clear. filter should be placed over the dust before sealing). 

4.2 The sample cassettes are plugged, sealed with OSHA tape, labeled, and sent to the laboratory for analysis. 

4.3 No storage problems are normally anticipated. Vibration or jolting of samples should be kept to a minimum to avoid dislodging of dust from the filter. 

5.1 Apparatus 

Atomic absorption spectrophotometer equipped with graphite furnace, argon purge system, and deuterium arc background corrector. 

Chart recorder. 

Glassware. 

2 or 3 piece filter cassettes 

AA filters (0.8 µm, cellulose membrane filters 37-mm dia) 

Personal sampling pump (capable of sampling between 1.0 and 2.0 L/pm). 


5.2 Reagents 

HCl, reagent grade 

HNO₃, reagent grade 

A certified aqueous standard such as "SPEX' 1,000 ppm standard follows: 

1,000 ppm Ni solution

Diluting solution: 

Twenty AA filters are ashed with 100 mL concentrated HN0₃ and 100 mL of 1,000 ppm Ni solution to a volume of 20 - 40 mL, diluted to 500 mL with deionized water and 2 mL HCl. 

5.3 Standards Preparation 

Standards are prepared to match the matrix of the samples (filter content acid and nickel concentration) as closely as possible according to the dilution scheme of Table III.
 
The 0.2. 1, 2, 5. 10 and 20 ppm "stock solutions" are made by serial dilution of the 1,000 ppm stock (with deionized water) as

5.4 Sample Preparation 

Note: All Glassware must be rinsed with 1:1 HNO₃ and deionized water prior to use. Conical beakers used for the digestion are refluxed with 1:1 nitric acid and rinsed with deionized water before use. 

Place filter in 125 mL conical  beaker, add 5 ml of 1000 ppm Ni solution and 5 ml concentrated NHO3 and ash to approximately 1-2 ml volume. After sample has cooled, add 2 drops HCl and swirl contents (no additional heating is done).
 
Quantitatively transfer sample to 25 mL volume flask, dilute to volume with deionized water, and mix. Additional dilutions for samples over 2 ppm As are made with the diluting solution.

TABLE II: STOCK SOLUTIONS
STOCK SOL'N		SOL'N USED		M1 USED		M1 FINAL VOL
20 ppm		1000 ppm stock		2		100
10 ppm		100 ppm stock		10		100
5 ppm		100 ppm stock		5		100
2 ppm		100 ppm stock		2		100
1 ppm		10 ppm stock		10		100
0.2 ppm		10 ppm stock		2		100

The diluted stock solutions should be prepared just before using them to prepare the working standards as outlined in Table III. 

When preparing the working standards from the stock solutions, all dilutions are made with the diluting solution.

TABLE III: WORKING STANDARDS
Standard		Stock Sol'n used		mL stock		H1 Final Vol.
0.1 ppm		1.0 ppm		5		50
0.2 ppm		2.0 ppm		5		50
0.5 ppm		5.0 ppm		5		50
1.0 ppm		10.0 ppm		10		100
Wavelength: 214.3 nm				*Tellurium Conditions
Slit 3				Dry= 90T, 50R, 40H, 150F
				Char= 500T, 50R, 30H, 100F
				Atomize= 2000T, Fr. 8H, 15F
				Chart= Range 10
				EDL Power= 9 watts
				(Stds prepared same as As)
				*These are guidelines parameters and may differ from your own.

5.5 Sample Analysis 

The analysis for tellurium is performed using a graphite furnace. 

Instrumental parameters are as follows: 

Atomic absorption unit:		Chart recorder:
EDL wavelength: 214.3 nm		10 mV range
UV mode		20 mm/min speed
slit setting 3		SERVO function
Absorbance function
Repeat mode
D2 Background ON
Temperature programs
Dry:	90° temp
	50 sec ramp time
	40 sec ramp time	150 ml/min INT flow
Char:	500  temp
	50 sec hold time
	30 sec hold time	100ml/min INT flow
Atomize:	2000° temp
	0 sec ramp time
	8 sec ramp time	15 mL/min INT flow

Injection volume: 10 µL 

The 1.0 ppm standard should give a near full scale deflection using these conditions. The entire series of standards should be run at the beginning and the end of the analysis. A standard should be run after every fourth or fifth sample in the sample rings. 

5.6 Calculations 

A linear regression of standard ppm vs standard peak height is performed using the OSHA Automatic AA program. The sample results are calculated based on sample peak heights; a function of sample absorption. 

mg/m³ =

(ppm Te*) sample volume, mL) (Dilution factor) air volume, liters

*blank corrected