SUPPLEMENTAL DATA
LNS Description and Operating Parameters
The TSI 3485 LNS is a precision nebulizer designed to generate particles from a liquid suspension.
A key component is the adjustable dilution capability that enables samples to be diluted by a ratio
of 20:1 to 20,000:1 immediately prior to nebulization. This step ensures only one particle is present
per nebulized droplet, the dilution is done immediately prior to nebulization to minimize any
potential upset of stability of the particle suspension in the sample that could be caused by changing
the chemistry of the sample solution. For consistency the instrument dilution ratio in this study
was nominally 100:1 for the analysis calibration curves samples. A separate set of experiments
was completed to identify the appropriate particle concentrations and dilution factors to minimize
the formation of doublets.
The LNS was operated using the following parameters: dilution ratio 100; dilution flow rate 50
mL/min; sample flow rate 0.500 mL/min; nebulizer flow rate 2.07 mL/min; inspection flow rate
0.81 µL/min; air pressure: 35.0 psig; liquid pressure 18.0 psig; nebulizer temperature 15 ºC;
evaporator temperature 55 ºC. The TSI 3080 Electrostatic Classifier was operated as follows:
impactor inner diameter 0.0710 cm; sheath flow rate 15.0 Lpm. The DMA used in this study was
the Model 3081 and was operated at a sample flow rate of 1.5 Lpm and the voltage scanned from
-10.6v to -9130v. The Water CPC was operated as follows: optics temperature 75 ºC; growth tube
temperature 75 ºC; conditioner temperature 15 ºC; capillary flow rate 300 cm3/min; vacuum 378
mbar; inlet pressure 98.8 mbar; nozzle pressure 104%; sample flow rate 1.5 Lpm. The software
used to operate and acquire data from the LNS was the TSI Liquid Nanoparticle Sizer software
beta version 1.0.4.
The system has a purge cycle to clean the sample lines and surfaces inside the instrument that
contact the sample between the sample bottle and nebulizer. During the purge cycle, UPW is
pumped at nominally 100 mL/min through the system for 84 seconds. This nominally 140 mL of
purged water represents the exchange of more than three orders of magnitude exchange of dead
volume. The effectiveness of the purge cycle was evaluated by analysis of UPW samples run after
a purge cycle that had followed the analysis of high concentration reference standards (i.e. sample
containing 1013particles/mL). Our guideline was to have less than 100 particles/mL within the size
range of 20 to 230 nm. Samples containing high levels of surfactant and/or very high solids
concentration (i.e. 50 wt%) can leave residuals on the soft plastic tubing in the LNS that shed
particles. In some cases our guideline could not be achieved and the plastic tubing in the LNS
had to be replaced.
Description of Water Matrices
Because non-volatile material(s) in the sample and dilution water will become aerosol after
nebulization and drying, the LNS system requires high purity water to reduce potential
background interference. UPW was generated using a custom built, semiconductor grade
water purification system (Smith Engineering Inc. Chaska, MN) that used di-ionized water as
a feed. The DI water has a nominal resistance < 18.2 Mohm-cm. The system is comprised of
deionized (DI) water as a source of water, a storage tank with a nitrogen blanket to prevent the
absorption of carbonate from gaseous CO 2, a re-pressurization pump to provide up to 19 L
min-1 of recirculation flow to continuously cycle the water through the system and achieve a
pressure of 60 PSI. (Note the TSI 3485 system requires this input UPW pressure). A nominal
0.45 µm filter is used for gross particulate removal. A UV light system with a portion of
energy in the 185 and 254 nm regions, to reduce total organic carbon (TOC) and control micro organisms, respectively. Primary and final mixed-bed ion exchange beds to remove dissolved
contaminants from the water. A 0.1 µm pre-filter followed by a 0.02 µm final filter for very
fine particulate removal. High purity Teflon tubing, valves, and fittings used downstream of
the deionizers to minimize leaching of non-volatile residue into the UPW. The suitability of
the UPW is evaluated by analyzing the UPW on the LN-DMA-CPC system and measuring the
number concentration of particles in UPW in the range of 20 to 230 nm. UPW having less
than 100 particles/mL in the 20-230 nm particle size range was suitable for the work done in
this study. This UPW is among the cleanest water that is technically possible to achieve in
lab.
The AM and DM were prepared by ERA Labs (Duluth, MN). The AM was prepared by adding
the following mass of each component to 500 mL of water from a Milli-QTM water purification
system: 6.08 g MgCl2·6H2O, 2.20 g CaCl2·2H2O, 12.75 g NaNO3, 7.35 g MgSO4·7H2O, 0.522
g K2HPO4, 7.50 g NaHCO 3, 92.8 mg H3BO3, 208.0 mg MnCl2·4H2O, 1.64 mg ZnCl2, 79.9 mg
FeCl3·6H2O, 0.714 mg CoCl2·6H2O, 3.63 mg Na2MoO4·2H2O, 0.006 mg CuCl2·2H2O, 150.0
mg Na2EDTA·2H2O, and 1.196 mg Na2SeO4. The DM (also known as lab reconstituted water
(LRW)) was prepared by adding the following mass of each component to 100 L of deionized
water: 20.0 g CaSO4·2H2O, 20.0 g MgSO4, 20.0 g NaHCO3, and 0.30 g KCl. The detailed
chemical composition of the groundwater and wastewater was not determined.
The
groundwater was sourced from a well in Washington County, MN from an aquifer known to
contain carbonate materials.
The wastewater was obtained from the effluent of a
manufacturing plant in Decatur, Al.
The plant has primary and secondary wastewater
treatment and is used to treat water originating from chemical manufacturing and sanitary
sewers.
Determination of particle concentration
The particle number concentrations for individual reference standards were either provided by
the vendor or determined mathematically using weight percent and particle geometry. The 20
nm, 40 nm, and 60 nm PSL standard particle concentrations were calculated using
experimentally determined % dry weights. The 100 nm and 200 nm PSL standard particle
concentrations, as well as the 18 nm, 30 nm, 50 nm and 100 nm silica standard particle
concentrations were calculated using the solids concentration reported on the certificates of
analysis provided by the vendors. The particle concentration of the 28 nm silica standard from
TSI was calculated based on the volume weighted particle concentration provided by the
vendor. Finally, the silver and gold particle concentrations were provided by the vendor
NanoComposix.
Concentration Calibration Curve Data
A series of solutions were prepared in each media using each standard material (i.e. matrix matched standards) to be used to prepare calibration curves. The calibration curves for SiO 2
in the six media validated are shown in the Figure S.1.
The slope and intercepts of these
curves are then used to provide a response factor that is specific for the particular material in
the particular matrix. The slope, intercept, and R 2 values for all the calibration curves are
provided in Table S.1
1015
a. SiO2 in Algae Media
1014
b. SiO in UPW
2
Actual Concentration (#/mL)
Actual Concentration (#/mL)
1014
1013
1012
SiO2 FMT 18 nm
SiO2 FMT 30 nm
SiO2 TSI 28 nm
SiO2 PolySci 50 nm
SiO2 PolySci 100 nm
1011
1010
1013
1012
1011
SiO2 FMT 18 nm
SiO2 FMT 30 nm
SiO2 TSI 28 nm
SiO2 PolySci 50 nm
SiO2 PolySci 100 nm
1010
109
109
109
1010
1011
1012
1013
1014
1015
Blank-corrected Measured Concentration (#/mL)
109
1010
1011
1012
1013
1014
Blank-corrected Measured Concentration (#/mL)
1015
c. SiO2 in Daphnia Media
Actual Concentration (#/mL)
1014
1013
1012
1011
1010
SiO2 FMT 30 nm
SiO2 PolySci 100 nm
109
109
1010
1011
1012
1013
1014
1015
Blank-corrected Measured Concentration (#/mL)
Figure S.1 Concentration Calibration curves for SiO2 standards prepared in the three test media.
Table S.1 Slope, intercept, and R2 values for UPW, AM, and DM concentration calibration curves
Ultra Pure Water (UPW)
2
Algae Media (AM)
Slope
Intercept
FMT 30nm SiO 2
1.1349 -1.4268
1.0693 -0.8118
1.0616 -0.4269
r
0.9842
0.9998
0.9993
1.2943
1.2534
1.0235
Polysciences 50nm SiO 2
1.0001 0.3679
0.9972
Polysciences 100nm SiO 2
0.9648 0.9480
0.8929
0.9731
1.0045
0.9567
0.7852
Material
Slope Intercept
FMT 18nm SiO 2
TSI 28nm SiO2
Thermo 20nm PSL
Thermo 40nm PSL
Thermo 60nm PSL
Thermo 100nm PSL
Thermo 200nm PSL
1.2752
0.1835
-0.0209
0.7542
2.7324
Daphnia Media (DM)
2
2
-3.3866
-3.3676
-0.2047
r
0.9706
0.9854
0.9979
1.1340
-1.8555
0.9937
0.9965
0.2283
0.9988
N/A 2
N/A 2
N/A 2
0.9976
0.9791
0.5669
0.9983
0.9873
0.3489
0.9986
0.9983
0.9986
0.9988
0.9950
0.9910
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
0.9728
1.0003
0.9838
0.9702
0.1111
-0.0398
0.3000
0.5665
0.9997
0.9994
0.9966
0.9633
N/A 1
N/A 1
N/A 1
1.0174
0.9732
0.9860
-0.3517
0.2875
0.2769
0.9986
0.9965
0.9675
1
Sample concentrations less than 3 times blank levels
2
One-point calibration
Slope
Intercept
r
N/A 1
N/A 1
N/A 1
1
1
N/A 1
N/A
N/A
Table S.2 Slope, intercept, and R2 values for DW, PW and WW concentration calibration curves
Drinking Water (DW)
Process Water (PW)
2
Wastewater (WW)
2
2
Material
Slope
Intercept
r
Slope
Intercept
r
Slope
Intercept
r
FMT 18nm SiO2
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
TSI 28nm SiO2
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
FMT 30nm SiO2
Polysciences 50nm
SiO2
Polysciences 100nm
SiO2
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
0.97675
0.459903 0.998966
1.024553 -0.09137
1.034017 -0.33696 0.999639
0.99816
0.97675
0.459903 0.998966
Thermo 20nm PSL
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
N/A 1
Thermo 40nm PSL
1
1
1
1
1
1
1
1
N/A 1
Thermo 60nm PSL
Thermo 100nm PSL
Thermo 200nm PSL
N/A
N/A
N/A
1.058425 -1.05886 0.999217
1.03149 -0.59679 0.998093
0.976263 0.256106 0.993112
1
Sample concentrations less than 3 times blank levels
2
One-point calibration
N/A
N/A
N/A
1.036725 -0.66789 0.995408
0.954687 0.344229 0.997201
0.9762 0.246149 0.99437
N/A
N/A
0.988068 -0.0836 0.998873
0.937519 0.578541 0.995585
0.973449 0.288806 0.993616
Electrospray and Nanometer Aerosol Sampler Operation
The TSI model 3480 Electrospray Aerosol Generator (EAG) was used in combination with the
TSI 3089 Nanometer Aerosol Sampler (NAS) to deposit nanoparticle reference standards onto 3
mm grids for analysis by transmission electron microscopy (TEM). This method is used to
verify nanoparticle size and concentration measurements obtained from the LNS
instrumentation. 100nm PSL reference standards were diluted to a known concentration, and the
solution was pushed through a 40 m capillary to the EAG while applying a voltage of 2.16 kV
to a platinum electrode immersed in the solution and exerting an electric field (391 nA) at the
capillary tip. The resulting aerosol was sent to an EC fitted with a DMA operated at a voltage of
-2,444 V to select 100 nm particles. After the DMA the flow was split; 0.3 LPM was sent to a
TSI 3776 CPC, and the remaining 1.2 Lpm was sent to the NAS (operated with nominally 10,000 V applied to the collection surface to attract the aerosol particles to the strategically
positioned TEM sample grid).