Tetrakis(hydroxymethyl)phosphonium Chloride (5046)
TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM CHLORIDE
P(CH2 OH)4 + C1–
MW: 190.58
METHOD: 5046, Issue 1
EVALUATION: PARTIAL
OSHA: None NIOSH: None ACGIH: None
SYNONYMS:
CAS: 124-64-1
PROPERTIES:
RTECS: TA2450000 Issue 1: 15 March 2003
hygroscopic, air sensitive solid; MP 151 o C; ionic; does not vaporize; soluble in water, methanol; insoluble in diethyl ether
tetramethylolphosphonium chloride, tetrahydroxymethylphosphonium chloride, THPC, Pyroset TKC, Proban CC, Retardol C, NCI-C55061, Tolcide THPC
SAMPLING SAMPLER:
5046
37-mm filter cassette (open-faced cassette containing two glass fiber filters coated with acidified 2,4-dinitrophenylhydrazine)
MEASUREMENT TECHNIQUE:
HPLC; UV DETECTION
ANALYTE:
2,4-dinitrophenylhydrazone of formaldehyde
EXTRACTION:
4 mL acetonitrile; 60 o C, 1 hour
INJECTION VOLUME:
20 :L
MOBILE PHASE:
45:55 acetonitrile:water @ 1.3 mL/min
COLUMN:
3.9 x 150 mm stainless steel, packed with 5-µm C-18, SymmetryT M or equivalent
DETECTOR:
UV @ 360 nm
CALIBRATION:
DNPH-coated glass fiber filters fortified with THPC (media standards)
RANGE:
6.5 to 60 µg/sample (instrumental)[1]
ESTIMATED LOD:
2 µg/sample
PRECISION (S r ):
0.0585 for 8 to 31 µg per sample
FLOW RATE: 1.0 to 1.7 L/min 3
VOL-MIN: -MAX:
1 L @ 6.5 mg/m 480 L @ 0.15 mg/m3
SHIPMENT:
Ship on ice (0 o C).
SAMPLE STABILITY: BLANKS:
28 days @ 5 o C [1] 2 to 10 field blanks per set 10 media blanks per set ACCURACY
RANGE STUDIED:
Not studied
BIAS:
Not determined
OVERALL PRECISION ( Ö r T ):
Not determined
ACCURACY:
Not determined
APPLICABILITY: The theoretical working range is 0.43 to about 67 mg/m3 for a 15-L air sample. This method may be applicable to other tetrakis(hydroxymethyl)phosphonium salts, such as the sulfate. However, evaluation of this method has been limited to THPC. INTERFERENCES: Formaldehyde gas is an interference. Concentrations of THPC can be corrected for formaldehyde gas by sampling for formaldehyde gas with NMAM 2016 [2]. Ozone has been observed to consume DNPH and to degrade the DNPH derivative of formaldehyde [3]. However, use of an ozone scrubber is not recommended because this scrubber may trap THPC aerosol. Ketones and other aldehydes can react with DNPH; the derivatives produced, however, are separated chromatographically from the analyte of interest. OTHER METHODS: Other methods for THPC in air are unknown. A microanalytical method for tetrakis(hydroxymethyl) phosphonium salts in solution involves ion chromatography, post-column reaction with an acetylacetone reagent to form a formaldehyde derivative, and detection at 425 nm [4].
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM CHLORIDE: METHOD 5046, Issue 1, dated 15 March 2003 - Page 2 of 5
EQUIPMENT:
REAGENTS: 1. Formaldehyde-2,4-dinitrophenylhydrazone, (formaldehyde-DNPH ), 99% pure, Supelco, Bellefonte , PA, or Aldrich C hem ical Co., Milwa ukee, W I. 2. Tetrakis(hydroxymethyl)phosphonium chloride (THPC),* 80% aqueous solution. Aldrich Ch em ical Co., Milwauk ee, W I. NOTE: A sc ertain the correct p ercenta ge in solution by perform ing an assay [poten tiom etric titration of 0.22 g of 80% THPC solution (diluted with DI water and acidified with 10 mL of 25% sulfuric acid) with 0.1 M AgNO 3 and silver electrode] [1,8]. Density of 80% + 2% aqueous solution: 1.30 to 1.40 g/mL @ 20 oC. 3. Acetonitrile,* high purity solvent for HPLC ana lysis, low carbo nyl content. NOTE: Carbonyl content of acetonitrile can be determined by passing 10 mL of the solvent th rough a com m erically available cartridge containing silica gel coated with acidified DNPH and analyzing for formaldehyde-DNPH by HPLC. The concentration of formaldehyde-DNPH should be below the LOD. [2] 4. W ater, deionized (D I water). 5. Calibration stock solution. Accurately weigh 10 m g of form aldehyde-DN PH in a 10-m L volum etric flask. Add acetonitrile to the 10-m L mark. 6. Fortification stock solution, 10 mg/mL. Add 140 µL of 80% solution of THPC to 14.86 g of DI water.
1. Sa m plers, 37-m m , three-piece, plastic cas settes co ntaining two glass fiber filters , a front filter and a back up filter, separate d by 1 cm of sp ace by m ean s of a cen ter ca sse tte piece (spacer). Each filter is coated with 2 mg of acidified 2,4-dinitrophenylhydrazine (com m ercially available from SKC, E ighty Four, PA, as g lutaraldehyde sam pler, cata logue nu m ber 2 25-9 003 .* 2. Personal sampling pump, 1.0 to 1.7 L/min, with flexible connecting tubing. 3. Vials, 4 -m L, glas s, PT FE -lined ru bbe r sep ta in caps for airtight seals. 4. Liquid chrom atograph with UV detector, recorder, integrator, and colum n (p. 5046-1). 5. Syringes, 100-µL, 500-µL, and 10-mL. 6. Volumetric flasks, 25-mL, 10-mL. 7. W ater bath, 60 oC + 3 oC. 8. Syringe filters, PTFE mem brane, 0.45-µm porosity. 9. Forceps. 10. Equipment for NMAM 2016, Issue 2, for form aldehyde gas [2].
See SPECIAL PRECAUTIONS
SPECIAL PRECAUTIONS: On heating, THPC will decompose to form chlorine, amm onia, and oxides of phosph orus . Avoid high tem pera tures for T HP C and c onta ct with a lkalies or stro ng o xidizing a gen ts. THPC causes eye burns and moderate skin irritation. Dermal studies have shown that tetrakis(hydroxymethyl)phosphonium salts are promotors of skin cancer but not initiators. There was no evidence of carcinogenicity of THPC in rats and mice [4]. The liver is a target organ. DNPH is a suspect carcinogen and is light sensitive [7]. Acetonitrile is toxic and is a fire hazard (flash point = 12.8 oC).
SAMPLING: 1. Ca librate each personal sampling pump with a repres en tativ e sampler in line at the desired sampling rate. 2. Rem ove inlet cassette piece from sampler for open-faced sampling. Rem ove cap from outlet of sam pler. Open-faced sampling is recomm ended because excessive quantities of THPC will exha ust the qu antity of DNPH in a small area of the filter during closed-face sampling. 3. Attach sampler to the sampling pump with flexible tubing. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM CHLORIDE: METHOD 5046, Issue 1, dated 15 March 2003 - Page 3 of 5
4.
In a similar fashion, prepare DNPH-coated silica gel samples for air sampling of formaldehyde gas [2]. NOTE: A frit or filter can be added in the inlet to trap T HP C aeros ol and sep arate the THPC from the formaldehyde gas. However, since the necessity of the frit or filter ha s not been dete rm ined, its use is option al. 5. Sample 1 to 480 liters of air at 1.0 to 1.7 L/min for THPC. 6. Conduct side-by-side air sampling for formaldehyde gas for the same period of time. Sample at 0.5 to 1.5 L/m in for fo rm aldehyde gas by NM AM 201 6 [2]. 7. Re place inlet ca sse tte piec e on the T HP C sam pler. Cap the outlet of the T HP C sam pler. Protect THPC sam ples from hea t. 8. Place end caps onto the formaldehyde sampler and seal sam pler in an envelope. Protect formaldehyde sam ples from hea t. 9. Ship THPC and formaldehyde samples in separate containers on ice (0 oC).
SAMPLE PREPARATION: 10. Fo ld the front and back DN PH-c oated filters using 2 pairs of forcep s and place into sepa rate 4-m L vials. Avo id finge r con tact. 11. Ad d 4.00 m L of carbonyl-free aceton itrile to each vial. C ap the vials tightly. 12. Place vials in water bath at 60 oC fo r 1 ho ur. 13. Rem ove vials from water bath and allow to cool to room tem perature. 14. Filter the sample solutions with syringe filters. Collect filtrates in separate autosampler vials. Cap the autosampler vials. NO TE : Follow NM AM 201 6, Issue 2 , for the ana lysis of form aldehyde gas sam ples [2].
CALIBRATION AND QUALITY CONTRO L: 15. Ca librate daily with at leas t six wo rking (m edia) stan dard s over the rang e of interes t. a. Prepare a series of aqueo us TH PC s olutions for fortification of blank D NPH -coated filters (media blanks) by dilution of THPC fortification stock solution (item 6) with DI water. Suggested concentrations of THPC in solution include 400 and 800 µg/m L. M edia blanks and coated filters for actual air sampling should be from the same lot and should be handled and stored in the same m anner. b. Place folded filters in 4-mL vials and fortify with known quantities of THPC solution in the range of 20 to 80 µL. c. Prepare the m edia standard s (steps 11-1 4) an d an alyze (ste ps 1 7-19 ). d. Prepare a calibration graph (pe ak area or height vs. µg TH PC p er sam ple). 16. Determine percent yield of formaldehyde from TH PC in the calibration range (step 15) at least once. a. Ca lculate the concentration of formaldehyde-DNPH derivative in the calibration stock solution (about 1000 µg/m L). Calculate the equivalent concentration of free formaldehyde in solution by multiplying the derivative concentration by 0.143 (molecular weight of formaldehyde divided by the molecula r weight of form aldhyde-DNP H). b. Prepare a series of dilutions [working standards (liquid standards)] from 0.02 to about 1 µg/mL. c. Prepare six samples at the same level by fortifying six DNPH -coated filters with a known quantity of TH PC (step 15). d. Analyze sam ples (steps 17-19 ). e. Calculate the molar quantity of formaldehyde found in each sample. f. Calculate the m olar quantity of TH PC a pplied to each DN PH-c oated filter. g. Consider that one mole of THPC releases one mole of form aldehyde in the presence of DNPH. Calculate the percen t yield of form aldehyde (yield should be 100 %).
MEASUREMENT: 17. Set the liquid chro m atog raph acc ording to manufacturer’s recomm endations and to conditions given on page 5046-1. 18. Inject a 20-µL aliquot of filtered sample solution. 19. Mea sure peak height or peak area. If sample peak is larger than the largest standard peak, dilute an NIOSH Manual of Analytical Methods (NMAM), Fourth Edition TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM CHLORIDE: METHOD 5046, Issue 1, dated 15 March 2003 - Page 4 of 5
aliquot of the remaining sample solution, reanalyze, and apply appropriate dilution factor in the calculations. 20. To ensure validity of the samples, identify those samples which contain more than 1000 µg of THPC per sample. The capacity of the samplers may have been exceeded for these samples, and collection of smaller samples would be warranted.
CALCULATIONS: 21. Determine m ass , :g, of THPC found on the fro nt filter, W F, on the backu p filter, W B, and on the average media blank, B, from the calibration graph. 22. Ca lculate concentration, C, of THPC in the air volume sam ple, V (L). This air concentration of THPC is uncorrected for form aldehyde gas pres ent at the sam pling site (if any).
NO TE : µg/L = m g/m 3 23. Ca lculate the air concentration or average air concentration for formaldehyde gas , C form, in m g/m 3 in sideby-side sam ples collected according to NM AM 2016 [2] (see steps 4 and 6 of N MA M 50 46). 24. Ca lculate the corrected concentration, C’, of THPC (corrected for the concentration of formaldehyde gas in the air). The value of 6.35 is found by dividing the molecular weight of THPC by the molecular weight of formaldehyde.
EVALUATION OF METHOD: THPC aerosol can be determined by measuring the formaldehyde which is released from THPC in the presence of DNPH and heat. However, formaldehyde gas, if present in the air, will be an interference in the measurem ent of T HP C. This method attempts to measure TH PC aerosol by correcting for the presence of formaldehyde gas in the air. Th e sam plers for form aldehyde gas used in NMAM 2016 [2] c onceptu ally would have frits or filters in the inlets to trap THPC aerosol and allow formaldehyde gas to pass through to the beds of DNPH -coated silica gel. However, since the necessity of the frit or filter has not been determined, use of frits or filters is optional. The degree of interference from THPC aerosol in measuring formaldehyde gas by NMAM 2016 has not been determined. This method has not been tested by air sampling for THPC aerosol or by air sam pling fo r form aldehyde gas in a T HP C aeros ol environm ent. This m ethod was evaluated using 37-mm DNPH -coated glass fiber filters in three-piece cassettes and aqueous tetrakis(hydroxymethyl)phosphonium chloride. Average recoveries of 8-, 14-, 20- and 31-µg quantities of THPC from 37-m m D NPH-coated glass fiber filters ranged from 87% to 104% (23 samples, pooled RSD = 5.85%) [1]. Samples of THPC on DNPH-coated filters were stable during storage at 5 oC in the dark; average recoveries of 15.0-µg quantities of THPC from DNPH -coated filters ranged from 108 % to 131% after 7 to 28 days of storage at 5 oC (n = 21 sam ples, RS D = 2.7% to 5.4% ) [1]. The limit of detection and lower limit of quantitation of THPC were 2 and 6.5 µg per filter, respectively. These limits were fou nd by least sq uares calculation s based on six DN PH -coated filters fortified with known quantities of THPC.
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM CHLORIDE: METHOD 5046, Issue 1, dated 15 March 2003 - Page 5 of 5
The possibility of migration of formaldehyde from the front filter to the backup filter during storage at 5 oC in sealed three-piece cassettes was investigated. Front filters in six three-p iece cas settes we re fortified with 31.4-µg quantities of THPC , and the cassettes were sealed. The six cassettes were stored for 10 days at 5 o C in the dark and then front and backup filters were analyzed. Average recoveries of THPC from front and backup filters we re 10 2% a nd 11 % , respectively (RSDs were 5.7% and 23%, respectively). The average total recovery of THPC from front and backup filters was 113% (RSD = 5.0%). These data provide evidence that (a) formaldehyde from TH PC can indeed migrate from one DNPH-coated filter to another and (b) one needs to analyze both the front and backup DNPH-coated filters for THPC in case there is migration. Yields of formaldehyde from TH PC were determined in order to study the stoichiometry of the breakdown of THPC. DNPH-coated glass fiber filters in 4-mL vials were fortified with known quantities of THPC at four levels (n = 23 samples). The sam ples were treated with acetonitrile and heat by the usual procedure and analyzed with liquid standards (standard solutions of form aldehyde-DNPH in acetonitrile). Theoretical quantities of formaldehyde were calculated on the basis that one mole of THPC releases one mole of formaldehyde in the presence of DNPH and heat. The average of the four average yields of formaldehyde was 100 .3% . The upper limit for collection of THPC on a filter is calculated at 1 mg. Since at 100% yield one mole of THPC releases one m ole of formaldehyde in the presence of DNPH and heat, 1 mg of THPC would release 158 µg of form aldehyde, a quantity w hich theoretica lly would react with 1.04 mg of DNPH. One DNPH -coated filter contains 2 mg of DNPH , a quantity which allows for the presence of excess DNPH when 1 m g of THPC is collected.
REFERENCES: [1]
[2]
[3]
[4]
[5] [6] [7] [8]
Tucker SP, Striley CA [2002]. Te trakis(hydroxym ethyl)ph osp hon ium Chloride B ack up D ata Report for Method 5046. National Institute for Occupational Safety and Health, DART, Cincinnati, OH. Unpublished report for evaluation of method. NIOSH [1994]. Formaldehyde by HPLC, m ethod 2016, issue 2, NIOSH M anual of Analytical Methods, 4 th ed., Eller P M and C assinelli ME (eds.), U.S. Department of Health an d Hum an S ervices, P ublic H ealth Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, OH. DHHS (NIOSH) Publication No. 94-113. Kleindienst TE, Corse EW , and Blanchard FT [1998]. Evaluation of the Performance of DNP H-Coated Silica Gel and C 18 Cartridges in the Measurement of Formaldehyde in the Presence and Absence of Ozone. Environmental Science & Technology, 32(1), 124-130. W orld Health Organization [2000]. Environmental Health Criteria 218, International Programm e on Chemical S a f e t y, In t e rn a t io n a l Labour Orga nization, Geneva, http ://www .inc hem .org/d ocum ents/ehc/e hc/eh c218.htm l. Elizey SE Jr. and Connick W J Jr. [1973]. G asom etric Analysis of TH PC., Am erican Dyestuff Rep orter, 62 (6), pp. 47 and 50. Loewe ngart G and Van Duuren BL [1 977 ]. Evaluatio n of Chem ical Flam e R eta rdants for Ca rcinogenic Potential, Jo urna l of Toxicology and E nviron m enta l Hea lth, 2, 539-546. Otson R and F ellin P [19 88]. A Review o f Te chn iques for Me asu rem ent of Airbo rne A ldehydes. Science of the To tal Environm ent, 77 (2/3), 95-131. Aldrich Chem ical Co. [2000]. Potentiometric titration of tetrakis(hydroxymethyl)phosphonium chloride with silver nitrate and silver electrod e, pro duc t 40,486-1 , Lot 10 715 B1, Techn ical Se rvice Departm ent, Aldrich Chem ical Co., Milwaukee, W I (August 18, 2000). Unpublis hed procedure by Fluka in Backup Da ta Repo rt [1].
METHOD DEVELOPED BY: Samuel P. Tucker, Ph.D., NIOSH/DART
NIOSH Manual of Analytical Methods (NMAM), Fourth Edition