NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

BUTYLTIN TRICHLORIDE in Urine 8320

Formula: C4H9CI3Sn MW: 282.18 CAS: 1118-46-3 RTECS: WH6780000

METHOD: 8320, Issue 1 EVALUATION: FULL Issue 1: 10 January 2019 

OSHA: N/A

NIOSH REL: N/A

OTHER OELs: Because exposure limits and guidelines may 

change over time, NIOSH recommends references [1-3] for 

updated limits and guidelines.

PROPERTIES: Colorless liquid; MP -63  ̊C; BP 93  ̊C @ 10 

mmHg; Density - 1.693 g/mL @ 25  ̊C; VP 0.083 mmHg @ 20  ̊C 

[4]

SYNONYMS: butyltrichlorotin, butyltrichlorostannane, monobutyltin trichloride (MBTC)

SAMPLING

SPECIMEN: Spot urine specimens (before and after 

exposure; end of shift or end of work 

week) [5]

VOLUME: 15 mL minimum

PRESERVATIVE: None

SHIPMENT: Freeze urine: ship frozen in an insulated 

container

SAMPLE

STABILITY: Stable at least 300 days at -20 oC [6]

ACCURACY [6,7]

RANGE 

STUDIED: 0.12-58 μg/5-mL sample

BIAS: 0.063

OVERALL

PRECISION (SS�rrrr): 0.041

ACCURACY: ± 13.0%

MEASUREMENT

TECHNIQUE: GAS CHROMATOGRAPHY/MASS 

SPECTROMETRY-SELECTED ION 

MONITORING (GC/MS-SIM)

ANALYTE: Derivative of butyltin trichloride: 

butyltriethyltin 

EXTRACTION: Liquid-liquid extraction 

DERIVATIZATION: Grignard reaction with ethylmagnesium

bromide

INJECTION VOLUME: 2 μL 

TEMPERATURE: 

INJECTION: 230 oC splitless for 0.75 min

DETECTOR: 285 oC

OVEN: 75 oC (1 min); 75 oC to 225 oC @ 12 oC/min; 

hold 5 min

MASS SELECTIVE 

DETECTOR PARAMETERS: 

SIM IONS (m/z): 178.9, 234.9

DWELL TIME: 200 msec per m/z

CARRIER GAS: Helium at 1.3 mL/min

COLUMN: Capillary, fused silica, phenyl arylene 

polymer virtually equivalent to (5% phenyl)-

methylpolysiloxane (30 m x 0.32 mm ID, 0.5 

μm film)

CALIBRATION: Spikes of known concentrations prepared in 

pooled urine

ESTIMATED LOD: 0.01 μg/5-mL sample [6]

APPLICABILITY: This method can be used for the Determination of butyltin trichloride in urine samples. It may also be useful for 

other butyltin chloride compounds. See Evaluation of Method section for more information.

INTERFERENCES: Because of the separation and mass-selective capabilities of GC/MS, interferences are not anticipated to have 

any impact on the analysis.

OTHER METHODS: None
BUTYLTIN TRICHLORIDE IN URINE: METHOD 8320, Issue 1, 10 January 2019 - Page 2 of 8 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

REAGENTS:

1. Butyltin trichloride, ≥95% purity

2. Ethylmagnesium bromide, 1.0 M solution 

in tetrahydrofuran

3. Helium, UHP or Grade 5 (99.999%) or 

better

4. Sulfuric acid, 1 M: Dilute 5.6 mL conc. 

sulfuric acid to 100 mL deionized water

5. Citric acid/sodium citrate buffer (~pH 2.3): 

Dissolve 20.554 g citric acid monohydrate 

and 0.652 g sodium citrate dihydrate in 

1 L deionized water

6. Toluene, ACS reagent grade or better

7. Tropolone extraction solution: 0.1% in 

toluene: Dissolve 100 mg tropolone (2-

hydroxy-2, 4, 6-cycloheptatrienone, CAS# 

[533-75-5]) in 100 mL toluene

8. Alumina, acidic, Brockman activity I, 80-

200 mesh

9. Sodium sulfate, granular, anhydrous; 

reagent grade or better 

*See SPECIAL PRECAUTIONS.

EQUIPMENT:

1. Centrifuge tubes, 15-mL 

polypropylene with screw caps

2. Centrifuge, capable of at least 

2400 RPM

3. Pipettes, Pasteur, 14.6 cm (53⁄4")

4. Culture tubes, glass, ~8-mL (13 mm x 

100 mm), screw top with PTFE-lined 

caps

5. GC-MS capable of selected ion 

monitoring, column, autosampler and 

data collection system (p. 8320-1)

6. Microliter syringes

7. Volumetric flasks, glass, 5-mL

8. Pipettor, adjustable from 1-5 mL

9. Vortex mixer

10. Tumbler for centrifuge tubes, 

approximately 20 RPM

11. Bottles, polyethylene, 30- or 125-mL

12. Glass wool 

 

SPECIAL PRECAUTIONS: Wear gloves, lab coat, and safety glasses while handling all chemicals and 

human urine products. Disposable plastic, glass, and paper (pipette tips, gloves, etc.) that contact urine 

should be placed in a biohazard bag. Standard precautions should always be used when handling bodily 

fluids and/or extracts of bodily fluids [8]. Handle urine samples and urine extracts using proper gloves. All 

work should be performed in a fume hood.

SAMPLING:

1. Collect urine in a 30-mL or 125-mL polyethylene bottle or other appropriate container.

NOTE: Collect two urine specimens for each worker, one prior to exposure and one after exposure. 

The NIOSH Health Hazard Evaluation found no significant difference between end of shift 

and end of work week [5]. Also, collect and pool urine from unexposed subjects for use as a 

standard and quality control sample matrix. 

2. Freeze the urine (-20 oC or lower) and ship frozen in an insulated container.
BUTYLTIN TRICHLORIDE IN URINE: METHOD 8320, Issue 1, 10 January 2019 - Page 3 of 8

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

SAMPLE PREPARATION:

3. Allow urine to reach room temperature and mix thoroughly.

4. Place 5 mL of the urine specimen in a 15-mL polypropylene centrifuge tube using a pipettor.

5. To the urine specimen, add:

a. 3 mL of ~pH 2.3 citric acid/sodium citrate buffer

b. about 350 mg anhydrous sodium sulfate (to break up emulsions) 

c. 1.5 mL 0.1% tropolone in toluene solution

6. Cap and tumble for one hour at ~20 RPM.

7. Centrifuge for at least 10 min at 2400 RPM (1050 G).

8. Transfer the upper toluene layer to an 8-mL glass culture tube with a PTFE-lined cap using a Pasteur 

pipette.

9. Repeat steps 5c through 8 and combine the extracts.

10. Add about 350 mg anhydrous sodium sulfate to the combined extracts to remove any of the 

aqueous phase that may have been inadvertently transferred.

11. Decant the dried sample from step 10 into a second 8-mL glass culture tube with a PTFE-lined cap.

12. Rinse the sodium sulfate residue in the first tube twice with a small (~300 μL) quantity of toluene 

which is then combined with the dried extract in the second tube.

13. Add 250 μL of the ethylmagnesium bromide solution to the extract, mix, and allow the mixture to 

react for 15-20 minutes.

14. Add 1 mL of 1 M sulfuric acid (to react with the remaining ethylmagnesium bromide) and vortex the 

tube for approximately 30 seconds.

15. Prepare a clean-up column in a 14.6 cm disposable Pasteur pipette by adding, in order, 1) a glass 

wool plug, 2) alumina, acidic, Brockmann activity I, 80-200 mesh, enough to form a column of 

approximately 1 cm, and 3) ~100 mg of anhydrous sodium sulfate.

16. After the layers separate, elute the top toluene layer through this clean-up column.

17. Collect the eluate in a 5-mL volumetric flask.

18. Rinse the tube with the sulfuric acid solution (Step 14) several times (a minimum of two) with small 

amounts (~300 μL) of toluene and elute the rinses through the clean-up column.

19. Flush the remaining sample from the column by adding small portions (~300 μL, a minimum of 

twice) of toluene to the top of the column.

20. Adjust the final volume to 5.0 mL with toluene as needed.

21. Transfer an aliquot of the extract to a GC vial for analysis.

CALIBRATION AND QUALITY CONTROL:

22. Calibrate daily with at least six working standards covering the expected concentration range of the 

samples. Suggested working standard concentration range is 0.007-150 μg/5 mL [6].

a. Prepare each working standard by spiking a known amount of the butyltin trichloride stock 

solution into enough pooled urine to make a total of 5.0 mL.

b. Prepare at least one pooled urine blank by transferring 5.0 mL of pooled urine (the same 

pooled urine used for creating the working standards) into a culture tube.

c. Prepare quality control (QC) samples by spiking known amounts of a separately prepared 

butyltin trichloride stock solution into pooled urine (the same pooled urine used for creating 

the working standards and blanks). It is recommended that two QC levels be prepared; a 

lower level at 3-5X the limit of quantitation (LOQ) and a higher level nearer the top end of 

the calibration curve. Run enough QC samples to be greater than 5% of the sample set. QC 

values should normally be within ±20% of the spiked values. If not, the batch is considered 

out of control, the batch data discarded, and corrective actions taken before more 

specimens are analyzed.

23. Process each working standard, blank, and QC sample using the same procedure as for the samples 

(steps 3 through 21).
BUTYLTIN TRICHLORIDE IN URINE: METHOD 8320, Issue 1, 10 January 2019 - Page 4 of 8

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

24. Prepare calibration curves by plotting peak area (or peak height, although area is recommended) for 

the standards on the y-axis vs. concentration of analyte on the x-axis. The standard curve should 

have a coefficient of determination (r2) of equal to or greater than 0.98 to be acceptable for use. 

Furthermore, when each standard is plugged back into the calibration equation, the value should be 

within ±20% of the expected.

MEASUREMENT:

25. Set the gas chromatograph according to manufacturer’s recommendations and to conditions given 

on the front page of the method. With the chromatographic conditions outlined on page 1, the 

retention time of the butyltin trichloride derivative (butyltriethyltin) was 7.3 min. A sample 

chromatogram is shown in Figure 1.

26. Set the mass spectrometer according to manufacturer’s recommendations and to conditions given 

on the front page of the method. The mass spectrum for the butyltriethyltin can be found in the 

backup data report [6]. The most abundant isotopic mass of this compound is 264. The monitored 

ions are M-85 and M-29.

27. Inject each sample, working standard, blank, and QC sample.

28. Measure peak area or peak height in each chromatogram.

NOTE: If the sample peak area or height is greater than that of the highest standard, dilute the 

sample extract with toluene and reanalyze. Apply the appropriate dilution factor in the 

calculations.

CALCULATION OF ANALYTE PER SAMPLE:

29. Determine mass of analyte in μg per 5-mL sample using the calibration curve prepared in step 24. 

Apply any dilution factor if needed.

NOTE: If the creatinine value of the sample was obtained, the concentration could be reported as 

μg/g creatinine if desired. The mass of analyte in μg/L can be calculated by multiplying the 

result by 200. The result can also be expressed in μg tin/volume by multiplying the μg per 5-

mL sample or μg/L by the butyltin trichloride conversion factor (%tin/mole) of 0.4207.

EVALUATION OF METHOD:

The first procedure considered for this method was a modification of the Chau, et al. protocol using in situ

derivatization of the alkyltin compounds by sodium tetraethylborate [9]. While this procedure was found 

to be generally acceptable, recoveries were found both by Chau and DataChem Laboratories (DCL) to be 

inferior to the tropolone extraction/ethylmagnesium bromide derivatization. A composite procedure made 

up of modifications of elements of both Chau’s protocol and a procedure used by Meinema [10] was 

subsequently used at DCL. Since tin concentrations were expected to be low, a GC/MS-SIM analysis was 

chosen over the GC/FPD procedure. This method was evaluated over the following range: butyltin 

trichloride: 0.12-4.0 μg/5 mL sample. This range represents from 3X the estimated LOQ to 100X the 

estimated LOQ. Six replicates were analyzed at each level. The average recovery at the various levels 

ranged from 103% at 3X LOQ to 110% at 30X LOQ for butyltin trichloride [6]. Recoveries were determined 

by quantitating against spiked and derivatized standards in urine. The analytical range of the method was 

extended during a secondary laboratory evaluation step (known as a User Check). Two higher 

concentration levels were evaluated (12.5 and 60.5 μg/5 mL) by analyzing five replicates at each level. 

These levels showed recoveries of 90.2 and 92.7% with relative standard deviations of 4.0 and 3.6% 

respectively [6]. The Limit of Detection (LOD) and LOQ were determined by analyzing a series of 

derivatized spiked standards with the data fitted to a quadratic or linear curve, then estimated according 

to the Burkart Method [11]. The LOD was determined to be 0.01 μg/5 mL and the LOQ to be 0.04 μg/5 mL. 

A long-term storage study was carried out at the 10X LOQ level. Urine spiked with the analyte was stored at 

-20 oC for 1, 7, 32, 137, and 315 days and then analyzed. No significant losses were observed over the entire 

period [6].
BUTYLTIN TRICHLORIDE IN URINE: METHOD 8320, Issue 1, 10 January 2019 - Page 5 of 8 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

Additional compounds studied:

This method was originally developed to include two other butyltin chlorides: dibutyltin dichloride and 

tributyltin chloride, even though butyltin trichloride is the most occupationally relevant one as it is used in 

the glass industry. The analytical parameters obtained during method development for these two 

additional compounds were also acceptable [6]. However, the data obtained during the secondary 

laboratory evaluation for these additional compounds were not of such a quality that they could be 

considered fully evaluated. Both the method development data and secondary laboratory data can be 

found in the method backup data report [6]. Some of the pertinent analytical parameters for these two 

additional compounds are listed below as well as changes/additions to the written method needed for 

their analysis in case there is a desire to analyze for these compounds. The properties of these additional 

compounds are given in Table 1.

The ranges studied for the additional compounds were 0.18-6.0 μg/5-mL sample (with additional levels of 

11.9 and 57.5 μg/5 mL added during the User Check) for dibutyltin dichloride and 0.15-5.0 μg/5-mL sample

(with additional levels of 12.0 and 58.5 μg/5 mL added during the User Check) for tributyltin chloride.

NOTE: the additional levels added during the User Check were not used in the following accuracy, bias, 

and precision calculations. These values may all be found in the method backup data report [6].

ACCURACY: Dibutyltin dichloride: ± 13.5%

 Tributyltin chloride: ± 8.62%

BIAS: Dibutyltin dichloride: -0.091

Tributyltin chloride: -0.051

OVERALL

PRECISION (Ŝrt): Dibutyltin dichloride: 0.0266

Tributyltin chloride: 0.0215

ESTIMATED LOD: Dibutyltin dichloride: 0.02 μg/5 mL

 Tributyltin chloride: 0.01 μg/5 mL

NOTE: The tributyltin chloride LOD experiment had an interfering ion that caused this number to be more 

approximate than that of the other two compounds. See backup data report [6] for more information.

Recoveries ranged from 88.1% (at 30X LOQ) to 93.9% (at 10X LOQ) for dibutyltin dichloride and from 94.2% 

(at 10X LOQ) to 95.9% (at 100X LOQ) for tributyltin chloride [6].

Changes and additions to the method needed to incorporate these two additional compounds:

The mass spectrometer parameters should be changed to: SIM ions (m/z): 4-9.6 min: 178.9, 234.9, 262.9, 

290.9; 9.6 min to end of run: 234.9, 262.9, 290.9.

Additional reagents required: dibutyltin dichloride, ≥95% purity and tributyltin chloride, ≥95% purity.

Retention times: dibutyltin dichloride derivative (dibutyldiethyltin), 9.2 min; tributyltin chloride derivative 

(tributylethyltin), 10.7 min (these peaks are shown in Figure 1.)

Conversion factors (%tin/mole) to be used if results are expressed in μg tin/volume are 0.3907 for 

dibutyltin dichloride and 0.3647 for tributyltin chloride.
BUTYLTIN TRICHLORIDE IN URINE: METHOD 8320, Issue 1, 10 January 2019 - Page 6 of 8 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

REFERENCES:

[1] ACGIH [2016]. TLVs and BEIs based on the documentation of the Threshold Limit Values for chemical 

substances and physical agents and Biological Exposure Indices. Cincinnati, Ohio: American 

Conference of Governmental Industrial Hygienists, www.acgih.org.

[2] DFG [2014]. List of MAK and BAT values 2014: maximum concentrations and biological tolerance 

values at the workplace. Bonn, Germany: DFG: Deutsche Forschungsgemeinschaft (German Research 

Foundation), http://onlinelibrary.wiley.com/book/10.1002/9783527682027.

[3] SUVA (Swiss National Accident Insurance Fund) [2013]. Protection de la santé au poste de travail. 

Valeurs limites d’exposition aux postes de travail. 3rd Ed. Lucerne, Switzerland: Schweizerische 

Unfallversicherungsanstalt, http://www.suva.ch/english/startseite-en-suva/praevention-ensuva/publications-en-suva.htm.

[4] Sigma-Aldrich [2018]. www.sigmaaldrich.com. 

[5] NIOSH [2005]. Evaluation of monobutyltin trichloride exposure among glass workers. By Dowell CH, 

Page EH, Mueller C, Mortimer V, Snawder J. Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health, Health Hazard Evaluation Report #2003-0016-2959.

[6] Wickman DC, Perkins JB [2005]. Backup data report for butyltin chlorides in urine method 

development, DataChem Laboratories, Inc. under NIOSH contract CDC-200-2001-08000.

[7] NIOSH [1995]. Guidelines for air sampling and analytical method development and evaluation. By 

Kennedy ER, Fischbach TJ, Song R, Eller PM, Shulman SA. Cincinnati, OH: U.S. Department of Health 

and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 95-117.

[8] CDC [2007]. 2007 Guidelines for isolation precautions: preventing transmission of infectious agents 

in healthcare settings. By Siegel JD, Rhinehart E, Jackson M, Chiarello L, and the Healthcare Infection 

Control Practices Advisory Committee. Atlanta, GA: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, 

http://www.cdc.gov/hicpac/2007IP/2007isolationprecautions.html.

[9] Chau YK, Yang F, Brown M [1997]. Evaluation of derivatization techniques for the analysis of 

organotin compounds in biological tissue. Anal Chim Acta 338:51-55.

[10] Meinema HA, Burger-Wiersma T, Versluis-de Haan G, Gevers EC [1978]. Determination of trace 

amounts of butyltin compounds in aqueous systems by gas chromatography/mass spectrometry. 

Environ Sci Technol 12:288-293.

[11] Burkart JA [1986]. General procedures for limit of detection calculations in the industrial hygiene 

chemistry laboratory. Appl Ind Hyg 1(3):153-155.

[12] Chemical Book [2018]. www.chemicalbook.com/ChemicalProductProperty_EN_CB0262161.htm.

[13] Synquest [2018]. www.synquestlabs.com/product/id/56422.html. 

 

 

 
BUTYLTIN TRICHLORIDE IN URINE: METHOD 8320, Issue 1, 10 January 2019 - Page 7 of 8 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

TABLE 1. GENERAL INFORMATION for additional compounds [4]

Dibutyltin dichloride Tributyltin chloride

Formula C8H18CI2Sn C12H27CISn

M.W. 303.84 325.51

CAS# [683-18-1] [1461-22-9]

RTECS WH7100000 WH6820000

Synonyms Dibutyldichlorotin

dibutyldichlorostannane

chlorotributyltin

tributylchlorotin

TBTC

Pestanal®

MP

37-40 °C -9 °C [12]

-19 °C [13]

BP @ mmHg 135 °C @10mm 171-173 °C @ 25mm

Density 1.36 g/cm3 1.20 g/mL

Appearance Beige or colorless solid Clear, light yellow 

liquid

Vapor pressure 0.0012 mmHg @ 25 °C <0.01 mmHg @ 25 °C 
BUTYLTIN TRICHLORIDE IN URINE: METHOD 8320, Issue 1, 10 January 2019 - Page 8 of 8 

NIOSH Manual of Analytical Methods (NMAM), Fifth Edition

FIGURE 1. Chromatogram of the three butyltin derivatives: butyltriethyltin (the derivative of butyltin 

trichloride), dibutyldiethyltin (the derivative of dibutyltin dichloride), and tributylethyltin (the derivative of 

tributyltin chloride)

METHOD WRITTEN BY:

Don C. Wickman and James B. Perkins, DataChem Laboratories, Inc., Salt Lake City, Utah under NIOSH 

Contract CDC-200-2001-08000. Final editing by Dale A. Shoemaker, Ph.D., NIOSH.

Disclaimer: Mention of any company or product does not constitute endorsement by the National

Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. In addition, 

citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring 

organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of 

these Web sites. All Web addresses referenced in this document were accessible at the time of publication.