Page:NIOSH Manual of Analytical Methods - 5504.pdf/4

 Organotin Compounds (as Sn): Method 5504, Issue 2 dated 15 August 1994 - Page 4 of 6 14. Collect HPLC eluent at the rate of 1 fraction (2 mL) per minute in AAS autosampler (Fig. 1). NOTE: In this example system, the column effluent is fed directly into one of the sample cups. After 1 min, the sample holder rotates and the eluted sample is in a position to be sampled for AA measurement. The furnace injection device withdraws a portion of the sample and places it in the furnace while the next sample is being eluted and collected. 15. Measure total AAS peak area for each organotin compound. NOTE 1: The recorder output will consist of AA peaks which form a chromatographic peak for each organotin compound if a line is drawn connecting the highest points of the AA peaks. Determine total absorbance for a species by the sum of the absorbencies of the corresponding AA peaks. NOTE 2: The characteristics of the graphite tube can influence the results drastically. Pay careful attention to the response of the standards and replace the graphite tube if erratic results and non-reproducible peak areas occur.

CALCULATIONS: 16. Read the mass, µg Sn (corrected for R), for each organotin compound found on the filter (W) and front sorbent (Wf) and back sorbent (Wb) sections, and on the average media blanks [filter (B) and front sorbent (Bf) and back sorbent (Bb) sections] from the calibration graphs. 17. Calculate concentration, C (mg/m3), for each organotin compound as Sn in air as the sum of the particulate concentration and the vapor concentration in the air volume sampled, V (L):

C '

W & B % Wf % W b & Bf & Bb V

, mg/m 3.

NOTE: Wf and Wb will include any analyte originally collected on the filter as particulate, then volatilized during sampling or storage.

EVALUATION OF METHOD: The method was validated with tetrabutyltin (TeBT), tributyltin chloride (TBTC), tricyclohexyltin hydroxide (TCHH), and dibutyltin bis(isooctylmercaptoacetate) (BuIOMA) [1]. The working ranges, validation ranges, and estimated linear working ranges (as tin) for 300-L air samples of these organotin species at an atmospheric temperature and pressure of 20 EC and 756 mm Hg, respectively, appear below:

Species

Validation Range Estimated Linear Working Range

Measurement Precision

Bias

Overall Precision

Accuracy

+1.8 !6.7 !2.3 !1.2

10.0 9.9 7.1 7.4

21.4 26.1 16.2 15.7

(mg/m3) (mg/m3) (µg/mL) (% þ r) (%) (% ÖrT) (± %) _________________________________________________________________________________________________________ TeBT TBTC TCHH BulOMA

0.027-0.112 0.042-0.191 0.071-0.218 0.070-0.220

0.02-0.17 0.01-0.34 0.01-0.34 0.01-0.34

0.05-5.0 0.3-10 0.3-10 0.3-10

8.1 5.9 6.9 7.7

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94