2-Amino-2-Methyl-1-Propanol
Method no.: PV2145
Control no.: T-PV2145-01-9203-Ch
Matrix: Air
3
Target concentration: 3 ppm (11 mg/m )
Procedure: Samples are collected by drawing a known volume of air through glass
sampling tubes containing XAD-2 resin coated with 10% (w/w) 1-
naphthylisothiocyanate (NITC). Samples are extracted with
dimethylformamide and analyzed by LC using a UV detector.
Air volume and
sampling rate studied: 10 L at 0.1 L/min
Status of method: Partially evaluated method. This method has been subjected to
established evaluation procedures of the Solvents Branch and is
presented for information and trial use.
March 1992 Mary E. Eide
Solvents Branch
OSHA Analytical Laboratory
Salt Lake City UT 84115-1802
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1. General Discussion
1.1 Background
1.1.1 History
Air samples collected on tubes containing XAD-2 resin coated with NITC were received
at SLTC requesting analysis for 2-amino-2-methyl-1-propanol (AMP). This compound
was collected on the same media used in OSHA Method 60 (Ref. 5.1), for diethylene
triamine, so those extraction and analytical parameters were used as a starting point
for AMP. The AMP was found to readily derivatize with the NITC to form a stable
derivative. The mobile phase of 80:20 isooctane:isopropanol gave a separation for the
AMP peak from interferences from the NITC. The samples were extracted with
dimethylformamide (DMF), with a desorption efficiency mean of 100% for the
concentration range of 224 to 11.2 礸/tube. The retention efficiency study showed no
AMP on the back up section of the spiked tube or back up tube, for tubes spiked with
224 礸 through which10-L humid air had been drawn. The storage study showed no
loss for samples stored for up to 14 days under both refrigerated and ambient
conditions.
1.1.2 Workplace exposure (Ref. 5.2 and 5.3)
AMP is a skin irritant, severe eye irritant, and toxic by ingestion.
1.1.3 Toxic effects (This section is for information only and should not be taken as the basis
of OSHA policy.)(Ref. 5.3 and 5.4)
AMP is used in the synthesis of surface-active agents, vulcanization accelerants, and
pharmaceuticals. AMP is used as an emulsifying agent for cosmetic creams and
lotions, mineral oil formulations, paraffin wax, leather dressings, textile specialties,
polishes, and cleaning compounds. AMP is used as an adsorbent for acidic gases.
1.1.4 Physical properties and other descriptive information (Ref. 5.2, 5.3, and 5.4)
synonyms: 2-aminodimethylethanol; 2-amino-2-
-aminoisobutanol;
methylpropanol; 2-amino-2-methylpropan-1-ol; AMP;
isobutanolamine; isobutanol-2-amine
CAS number: 124-68-5 IMIS: A615
molecular weight: 189.14 vapor density: 3.0
melting point: 30-31癈 boiling point: 165癈
appearance: clear liquid vapor pressure: 1 mmHg @ 25? C
odor: mild ammoniacal flash point: 68?(154.4 ?br>
C F)(cc)
autoignition density: 0.934
temperature: 438癈 (820? F) molecular formula: C4H11NO
solubility: water, alcohol, acetone
structural formula:
NH2
OH
H3C
CH3
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1.2 Limit defining parameters
1.2.1 The detection limit of the analytical procedure is 1 ng, with a 15 礚 injection volume.
This is the smallest amount which could be detected under normal operating
conditions.
1.2.2 The overall detection limit is 0.04 ppm based on a 10 liter air volume.
1.3 Advantages
1.3.1 The sampling procedure is convenient.
1.3.2 The analytical method is reproducible and sensitive.
1.3.3 Reanalysis of samples is possible.
1.3.4 It may be possible to analyze other amines at the same time.
1.3.5 Interferences may be avoided by proper selection of column and LC parameters.
1.4 Disadvantages
None known
2. Sampling procedure
All safety practices that apply to the work area being sampled should be followed. The sampling
equipment should be attached to the worker in such a manner that it will not interfere with work
performance or safety.
2.1 Apparatus
2.1.1 Samples are collected using a personal sampling pump calibrated, with the sampling
device attached, to within ?% of the recommended flow rate.
2.1.2 Samples are collected with 7-cm ?4-mm i.d. ?7-mm o.d. glass sampling tubes packed
with two sections (80/40 mg) of XAD-2 resin coated with 10% by weight 1-
naphthylisothiocyanate. The sections are held in place and separated with glass wool
plugs. For this evaluation, commercially prepared sampling tubes were purchased
from SKC, Inc. (catalog no. 226-30-18).
2.2 Technique
2.2.1 Immediately before sampling, break off the ends of the flame-sealed tube to provide an
opening approximately half the internal diameter of the tube. Wear eye protection
when breaking ends. Use tube holders to minimize the hazard of broken glass. All
tubes should be from the same lot.
2.2.2 The smaller section of the adsorbent tube is used as a back-up and is positioned
nearest the sampling pump. Attach the tube holder to the sampling pump so that the
adsorbent tube is in an approximately vertical position with the inlet facing down during
sampling. Position the sampling pump, tube holder and tubing so they do not impede
work performance or safety.
2.2.3 Draw the air to be sampled directly into the inlet of the tube holder. The air being
sampled is not to be passed through any hose or tubing before entering the sampling
tube.
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2.2.4 After sampling for the appropriate time, remove the adsorbent tube and seal it with
plastic end caps. Seal each sample end-to-end with an OSHA-21 form as soon as
possible.
2.2.5 Submit at least one blank sample with each set of samples. Handle the blank sample
in the same manner as the other samples except draw no air through it.
2.2.6 Record sample air volumes (liters), sampling time (minutes) and sampling rate (L/min)
for each sample, along with any potential interferences on the OSHA-91A form.
2.2.7 Submit the samples to the laboratory for analysis as soon as possible after sampling. If
delay is unavoidable, store the samples at refrigerator temperature. Ship any bulk
samples separate from the air samples.
2.3 Desorption efficiency
2.3.1 A loading of 112 礸 corresponds to 3.07 ppm based on a 10 liter air volume and a 2 mL
desorption volume.
2.3.2 Sampling tubes were spiked with 224, 112, 56, and 11.2 礸 AMP. They were allowed
to equilibrate at room temperature overnight. They were opened, each section placed
in a labeled 4 mL vial, and 2 mL of dimethylformaide was added. They were allowed to
desorb for 30 minutes on a shaker, then analyzed by HPLC. The desorption efficiency
averaged 9% (Table 1)
Table 1
Desorption Efficiency (%) AMP
tube # % Recovered % Recovered % Recovered % Recovered
224 礸 112 礸 56 礸 11.2 礸
1 101 100 99.4 102
2 99.5 102 98.8 99.3
3 98.3 99.2 101 98.9
4 102 98.4 102 101
5 99.5 101 99.6 101
6 99.1 102 100 98.5
average 99.9 100 100 100
overall 100
average
standard ?.29
deviation
2.4 Retention efficiency
2.4.1 Six NITC-coated XAD-2 tubes were spiked with 224 礸 (6.15 ppm) of AMP and allowed
to equilibrate for 4 h. Each spiked tube was placed in series with a second NITC-
coated XAD-2 tube. Each sampling train had 10-L humid air (80% relative humidity at
22 ?pulled through it at 0.1 L/min. The samples were extracted and analyzed. The
C)
mean recovery was 99.8%. There was no analyte found on the backup section of any
of the spiked tubes or on the second tubes.
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Table 2
Retention Efficiency (%) of AMP
sample number
section 1 2 3 4 5 6 mean
front of spiked tube 99.8 100 101 99.6 98.9 99.6 99.8
rear of spiked tube 0.0 0.0 0.0 0.0 0.0 0.0 0.0
front of series tube 0.0 0.0 0.0 0.0 0.0 0.0 0.0
back of series tube 0.0 0.0 0.0 0.0 0.0 0.0 0.0
total 99.8 100 101 99.6 98.9 99.6 99.8
2.5 Sample storage
2.5.1 Fifteen NITC-coated XAD-2 tubes were each spiked with 112 礸 (3.07 ppm) of AMP .
They were allowed to equilibrate for 4 h, then 10-L of air ( 80% relative humidity at 23
癈), was drawn through them. Three samples were analyzed immediately. The
remaining tubes were sealed and six were stored at room temperature (23 ? C), while
the other six were stored at refrigerated temperature (4? C). Three of the samples
stored at room temperature and three of the samples stored at refrigerated temperature
were analyzed after 7 days and the remaining three of each group after 14 days. The
results indicate good storage stability for the time period studied.
Table 3
Storage Test for AMP
time ambient storage refrigerated storage
(days) recovery (%) recovery (%)
0 99.8 101 98.9 99.8 101 98.9
7 100 99.5 99.8 99.7 99.3 101
14 99.1 98.8 101 99.1 98.6 100
2.6 Precision
2.6.1 Precision was calculated using the area counts from six injections of each standard at
concentrations of 5.6, 56, and 112 礸/mL AMP (based on a 10 liter air volume and 2
mL desorption volume these concentrations correspond to 0.31, 3.07, and 6.15 ppm)
(Table 4).
Table 4
Precision
injection number 5.6 礸/mL 5.6 礸/mL 5.6 礸/mL
0.31 ppm 0.31 ppm 0.31 ppm
1 460890 4671239 9320122
2 470011 4692392 9203344
3 468965 4689481 9319256
4 466134 4701042 9265619
5 467035 4681923 9134092
6 466670 4690513 9234715
average 466618 4687765 9262858
standard deviation 3170 10153 48226
2.7 Air volume and sampling rate studied
2.7.1 The air volume studied was 10 liters.
2.7.2 The sampling rate studied was 0.1 L/min.
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2.8 Interferences (sampling)
2.8.1 There are no known compounds which will severely interfere with the collection of
AMP. Other primary and secondary amines will collect on this medium, and form
derivatives with the NITC, affecting the ability of the tube to collect AMP, so sampling
time should be adjusted if high concentrations of amines are expected.
2.8.2 Suspected interferences should be reported to the laboratory with submitted samples.
2.9 Safety precautions
2.9.1 Sampling equipment should be paced on an employee in a manner that does not
interfere with work performance or safety.
2.9.2 Safety glasses should be worn at all times.
3. Analytical Procedure
Adhere to the rules set down in your Chemical Hygiene Plan. Avoid skin contact and inhalation
of all chemicals and review all appropriate MSDSs.
3.1 Apparatus
3.1.1 A liquid chromatograph equipped with a UV detector capable of detecting 254 and 280.
The response is most sensitive at 254 nm. For this evaluation, a Waters M-6000A
pump and pump were used, with a Waters 440 Absorbance Detector, and a Waters
717 plus Autosampler was used.
3.1.2 An LC column capable of separating AMP from the extraction solvent and any potential
interferences. A 4.6 ?250 mm column packed with 5-祄 Bakerbond cyanopropyl (JT
Baker, Phillipsburg, NJ) was used in the evaluation.
3.1.3 An electronic integrator or some other suitable means of measuring peak areas. A
32
Waters Millennium Data System was used in this evaluation.
3.1.4 Glass vials with poly(tetrafluoroethylene)-lined caps. For this evaluation 4-mL vials
were used.
3.1.5 A dispenser capable of delivering 2.0 mL of extracting solvent to prepare standards and
samples. If a dispenser is not available, a 2.0-mL volumetric pipet may be used.
3.1.6 Volumetric flasks - 10-mL and other convenient sizes for preparing standards.
3.2 Reagents
3.2.1 2-Amino-2-methyl-1-propanol, reagent grade.
3.2.2 N,N-Dimethyl formamide (DMF), reagent grade.
3.2.3 Isopropyl alcohol, HPLC grade.
3.2.4 Isooctane, HPLC grade.
3.2.5 1-Naphthylisothiocyanate (NITC), reagent grade
3.2.6 Mobile phase was 80:20 isooctane:isopropyl alcohol.
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3.3 Sample preparation
3.3.1 Remove the plastic end caps from the sample tubes and carefully transfer the
adsorbent sections to separate labeled 4-mL vials. Discard the glass tube and glass
wool plugs.
3.3.2 Add 2.0 mL of DMF to each vial.
3.3.3 Immediately seal the vials with poly(tetrafluoroethylene)-lined caps.
3.3.4 Agitate the vials on a shaker, or a rotator, for 30 minutes.
3.4 Standard preparation
Freshly prepare two stock standards. A stock standard of 2 mg/mL may be prepared
3.4.1
by a) weighing out about 30 mg of NITC in a 10-mL flask, b) weigh out 20 mg AMP by
placing the drops on top of the NITC in the flask, and c) weigh out about 30 mg more
NITC on top of the AMP, making sure that the AMP is covered on all sides by the NITC.
Allow the AMP to react with the NITC for at least 1/2 hour before adding the DMF.
Partially fill the volumetric flask with DMF and allow to sit 30 minutes to begin dissolving
the derivative, then swirl the contents until all of the solids are dissolved, and fill to the
mark with DMF. Do not place the flask in a sonic bath to try to get the derivative to go
into solution, as it will destroy the derivative. There must always be an excess of the
NITC for the derivative to be completely formed. For example, the amount of NITC
needed for the above stock standard would be calculated:
20 mg AMP ?(NITC MW=185.25/AMP MW=89.14) = 42 mg
(Note: there should be an excess of NITC to insure that all of it is reacted, so weigh out
at least 10 mg extra)
In the above stock standard preparation a total of 60 mg NITC was weighed out so that
an excess of NITC was present.
3.3.2 Diluted standards are prepared with a solution of 1 mg/mL NITC in DMF, so that an
excess of NITC is always present. Bracket sample concentrations with working
standard concentrations. If sample concentrations are higher than the concentration
range of prepared standards, either analyze higher standards, or dilute the sample.
The higher standards should be at least as high in concentration as the highest sample.
Diluted samples should be prepared with a solution of 1 mg/mL NITC in the DMF. The
range of standards used in this study was from 0.5 to 224 礸/mL. The instrument is
calibrated on the amount of AMP in each standard.
3.5 Analysis
3.5.1 Liquid chromatograph conditions
column: Bakerbond cyanopropyl (CN) column 4.6 ?250 mm
injection size: 10 礚
mobile phase: 2 mL/min 80:20 isooctane: isopropyl alcohol
detector: UV at 254 and 280 nm
run time: 10 min
retention times: 1.8 min NITC
4.2 min DMF
5.2 min AMP
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1000
NITC
Response (mV)
AMP
600
DMF
200
0 2 4 6 8 10
Time (min)
Figure 3.5.1. A chromatogram of 112 礸/mL AMP in
DMF with NITC at 254 nm..
3.5.2 Peak areas are measured by an integrator or other suitable means.
3.5.3 An external standard (ESTD) calibration method is used. A calibration curve can be
constructed by plotting response of standard injections versus micrograms of analyte
per sample. Bracket the samples with freshly prepared analytical standards over a
range of concentrations.
3.6 Interferences (analytical)
3.6.1 Any compound that produces a LC response and has a similar retention time as the
analyte is a potential interference. If any potential interferences were reported, they
should be considered before samples are extracted. Generally, chromatographic
conditions can be altered to separate an interference from the analyte.
3.6.2 When necessary, the identity or purity of an analyte peak may be confirmed by a
photodiode array scan of the peak, by wavelength ratioing, or by LC/mass spec.
3.7 Calculations
The amount of analyte per sampler is obtained from the appropriate calibration curve in terms of
micrograms per sample, uncorrected for extraction efficiency. This total amount is then
corrected by subtracting the total amount (if any) found on the blank. The air concentration is
calculated using the following formulas.
3
where CM is concentration by weight (mg/m )
M
CM = M is micrograms per sample
VE E V is liters of air sampled
EE is extraction efficiency, in decimal
form
VM C M
where CV is concentration by volume (ppm)
CV =
Mr VM is molar volume at 25 ?and 760 mm = 24.46
C
CM is concentration by weight
Mr is molecular weight = 89.14
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4. Recommendations for further study
Collection, reproducibility, and other detection limit studies need to be performed to make this a
validated method.
5. References
5.1 Elskamp, C., OSHA Method 60 Ethylenediamine, Diethylenetriamine, and Triethylenetetramine,
Organic methods evaluation Branch, OSHA Salt Lake Technical Center, 1986.
5.2 MSDS 2-Amino-2-methyl-1-propanol, Sigma-Aldich Chemical Co., http:www.sigmaaldrich.com
(accessed 2/10/92).
th
5.3 Sax, N.I.; Lewis, R.J.; Hawley's Condensed Chemical Dictionary, 11 ed., Van Nostrand
Reinhold Co., New York, 1987, p 59.
5.4 Budavari, S., Ed., The Merck Index, Merck & Co., Inc., Rahway, NJ, 1989, p 73.
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