Solubility of CASRN 78-11-5 (PETN) in Hard Water 

Bretni Kennon 

Research Scientist, Dyno Nobel 

Test Substance 

Determine solubility of 1,3-Dinitrato-2,2-bis(nitratomethyl)propane (i.e., pentaerythritol 

tetranitrate; CAS No. 78-11-5. Also known as PETN) 

Remarks: Samples of PETN provided by the Graham, KY Dyno Nobel facility for preparation 

of 5,000 mg PETN/L acetone stock solution arrived wet with an unknown amount of solvent 

(safety precaution). Excess (~10%) was added to help ensure an appropriate concentration. 

Method 

Methods/guidelines followed: 40 CFR 799.6784 shake flask method was used to facilitate 

saturation. EPA METHOD 3535A was used to isolate PETN from the water sample. EPA 

SW-846, Method 8330 B was used for the HPLC analysis. 

Type: Solubility Study, with up to 96 hour solvation times. 

GLP: No 

Year: 2015 

Analytical Monitoring: HPLC analysis was carried out according to EPA 8330B. 

Statistical Methods: Simple average and standard deviation values were calculated for 

triplicate HPLC results. 

Remarks/Modifications: When using the shake flask method in 40 CFR 799.6784, addition 

of five times the solubility limit is required to ensure saturation. With excess solid PETN 

present, a prefiltration before SPE was necessary (1 μm syringe filter). Unfortunately the 

methods and reports from previous testing do not address this. 

Method 8330 B was used for the HPLC analysis, however due to low solubility of PETN in 

water; all samples were dissolved in Methanol and not the mobile phase (50/50 

Water/Methanol). Due to the multi solvent matrix, baseline data around the analyte peak was 

not as flat as desired however successful integration was carried out. 

Samples were prepared with the aid of a Thermotron environmental conditioning chamber 

and stirred at 250 rpm for the stated durations and temperatures. 

Stock PETN solution was stored at 4°C until aliquots were needed, at which time the sample 

was allowed to equilibrate to ambient before handling. Sample extracts were treated in the 

same fashion, with thermal equilibration prior to dilution for HPLC analysis. 
 

Calibration standards ranging from 0.05 mg/L to 10.0 mg/L were called for in the original 

method. The signal size obtained from the 0.05 mg/L sample was negligible and therefore 

removed from the calibration series. Also, with the stronger signals expected from the 

sample extracts, a 20.0 mg/L sample was added for additional calibration verification. 

Results 

Nominal concentrations (as mg/L): 0 (MilliQ water blank), 0 (hard water blank), 5.0, and 

10.0 mg PETN/L. 

Measured concentrations (as mg/L): N.D., N.D., 5.12, and 10.39 mg PETN/L. 

Unit: mg PETN/L (aka ppm) 

Element value (e.g. concentration in mg PETN/L at 24, 48, 72 and 96 hours, etc., based on 

measured or nominal concentrations) 

20°C MilliQ Water: = 1.4713 mg PETN (measured)/L 

20°C Hard Water: = 1.3730 mg PETN (measured)/L 

25°C MilliQ Water: = 2.1103 mg PETN (measured)/L 

25°C Hard Water: = 2.0871 mg PETN (measured)/L 

Conclusions 

After previous studies failed to achieve the literature solubility limit of 2.13 mg/L; this study 

aimed to verify the solubility limit of PETN in both Hard and Milli-Q water at 20°C and 25°C. 

The 25°C samples averaged 2.11 and 2.09 mg/L for Milli-Q and Hard water, respectively, 

which is nearly identical to the reported 2.13 mg/L. HPLC analysis of the 48 samples of 

interest showed 10 samples at or slightly above the literature saturation value, and five more 

between 1.9 mg/L and 2.1 mg/L. As stated above, average check standard values obtained 

were slightly higher than their target analyte levels, which is in agreement with some results 

being slightly higher than the established solubility limit. With the significant number of 

samples at or near the solubility limit, this study has been the most successful thus far. 
 

Table I - 20°C Milli-Q Water Sample Data 

Sample ID Average Water 

Content 

Water Content Std. 

Dev. 

24 hr MQ 20°C 1.9127 0.3907 

48 hr MQ 20°C 1.4187 0.4411 

72 hr MQ 20°C 1.3082 0.1498 

96 hr MQ 20°C 1.2455 0.1223 

20°C MQ Average 1.4713 0.3029 

Table II - 20°C Hard Water Sample Data 

Sample ID Average Water 

Content 

Water Content Std. 

Dev. 

24 hr Hard 20°C 1.3652 0.2509 

48 hr Hard 20°C 1.3840 0.2547 

72 hr Hard 20°C 1.2787 0.0901 

96 hr Hard 20°C 1.4640 0.2775 

20°C Hard Average 1.3730 0.0760 
 

Table III - 25°C Milli-Q Water Sample Data 

Sample ID Average Water Content Water Content Std. Dev. 

24 hr MQ 25°C 2.3656 0.1968 

48 hr MQ 25°C 2.1508 0.4023 

72 hr MQ 25°C 1.9559 0.1812 

96 hr MQ 25°C 1.9688 0.2117 

25°C MQ Average 2.1103 0.1921 

Table IV - 25°C Hard Water Sample Data 

Sample ID Average Water Content Water Content Std. Dev. 

24 hr Hard 25°C 2.0486 0.0207 

48 hr Hard 25°C 2.0810 0.2186 

72 hr Hard 25°C 1.8006 0.1196 

96 hr Hard 25°C 2.4183 0.2390 

25°C Hard Average 2.0871 0.2538