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 a rrived 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 us ed 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 st andard 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 lim it is required to ensure satura tion. 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 succe ssful integration was carried out.

Samples were prepared with the aid of a The rmotron 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 handli ng. Sample extracts were treated in the same fashion, with thermal equilibration pr ior 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 obtai ned from the 0.05 mg/L sample was negligible and therefore removed from the calibration series. Also , with the stronger signal s 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 literat ure 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 fo r Milli-Q and Hard water, respectively, which is nearly identical to the reported 2.13 mg/L. HPLC anal ysis 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 c heck standard values obtained were slightly higher than their target analyte le vels, which is in agreement with some results being slightly higher than the est ablished solubility limit. Wi th the significant number of samples at or near the solubilit y limit, this study has been the mo st 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 0.0760Table 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