Approved Methods for Disinfection Byproduct Compliance Monitoring
Contaminant and methodology1 | EPA method | Standard method2 | SM online9 | ASTM method3 |
TTHM | ||||
P&T/GC/ElCD & PID | 502.24 | |||
P&T/GC/MS | 524.2 | |||
LLE/GC/ECD | 551.1 | |||
HAA5 | ||||
LLE (diazomethane)/GC/ECD | 6251 B5 | 6251 B-94 | ||
SPE (acidic methanol)/GC/ECD | 552.15 | |||
LLE (acidic methanol)/GC/ECD | 552.2, 552.3 | |||
Bromate | ||||
Ion chromatography | 300.1 | D 6581-00 | ||
Ion chromatography & post column reaction | 317.0 Rev 2.06, 326.06 | |||
IC/ICP-MS | 321.86 7 | |||
Chlorite | ||||
Amperometric titration | 4500-ClO2 E8 | 4500-ClO2 E-008 | ||
Spectrophotometry | 327.0 Rev 1.18 | |||
Ion chromatography | 300.0, 300.1, 317.0 Rev 2.0, 326.0 | D 6581-00 |
1 P&T = purge and trap; GC = gas chromatography; ElCD = electrolytic conductivity detector; PID = photoionization detector; MS = mass spectrometer; LLE = liquid/liquid extraction; ECD = electron capture detector; SPE = solid phase extraction; IC = ion chromatography; ICP-MS = inductively coupled plasma/mass spectrometer.
2 19th and 20th editions of Standard Methods for the Examination of Water and Wastewater, 1995 and 1998, respectively, American Public Health Association; either of these editions may be used.
3 Annual Book of ASTM Standards, 2001 or any year containing the cited version of the method, Vol 11.01.
4 If TTHMs are the only analytes being measured in the sample, then a PID is not required.
5 The samples must be extracted within 14 days of sample collection.
6 Ion chromatography & post column reaction or IC/ICP-MS must be used for monitoring of bromate for purposes of demonstrating eligibility of reduced monitoring, as prescribed in § 141.132(b)(3)(ii) .
7 Samples must be preserved at the time of sampling with 50 mg ethylenediamine (EDA)/L of sample and must be analyzed within 28 days.
8 Amperometric titration or spectrophotometry may be used for routine daily monitoring of chlorite at the entrance to the distribution system, as prescribed in § 141.132(b)(2)(i)(A) . Ion chromatography must be used for routine monthly monitoring of chlorite and additional monitoring of chlorite in the distribution system, as prescribed in § 141.132(b)(2)(i)(B) and (b)(2)(ii) .
9 The Standard Methods Online version that is approved is indicated by the last two digits in the method number which is the year of approval by the Standard Method Committee. Standard Methods Online are available at http://www.standardmethods.org.
DBP | Acceptance limits (percent of true value) | Comments |
TTHM | ||
Chloroform | ±20 | Laboratory must meet all 4 individual THM acceptance limits in order to successfully pass a PE sample for TTHM |
Bromodichloromethane | ±20 | |
Dibromochloromethane | ±20 | |
Bromoform | ±20 | |
HAA5 | ||
Monochloroacetic Acid | ±40 | Laboratory must meet the acceptance limits for 4 out of 5 of the HAA5 compounds in order to successfully pass a PE sample for HAA5 |
Dichloroacetic Acid | ±40 | |
Trichloroacetic Acid | ±40 | |
Monobromoacetic Acid | ±40 | |
Dibromoacetic Acid | ±40 | |
Chlorite | ±30 | |
Bromate | ±30 |
DBP | Minimum reporting level (mg/L)1 | Comments |
TTHM2 | ||
Chloroform | 0.0010 | |
Bromodichloromethane | 0.0010 | |
Dibromochloromethane | 0.0010 | |
Bromoform | 0.0010 | |
HAA52 | ||
Monochloroacetic Acid | 0.0020 | |
Dichloroacetic Acid | 0.0010 | |
Trichloroacetic Acid | 0.0010 | |
Monobromoacetic Acid | 0.0010 | |
Dibromoacetic Acid | 0.0010 | |
Chlorite | 0.020 | Applicable to monitoring as prescribed in § 141.132(b)(2)(1)(B) and (b)(2)(ii) . |
Bromate | 0.0050 or 0.0010 | Laboratories that use EPA Methods 317.0 Revision 2.0, 326.0 or 321.8 must meet a 0.0010 mg/L MRL for bromate. |
1 The calibration curve must encompass the regulatory minimum reporting level (MRL) concentration. Data may be reported for concentrations lower than the regulatory MRL as long as the precision and accuracy criteria are met by analyzing an MRL check standard at the lowest reporting limit chosen by the laboratory. The laboratory must verify the accuracy of the calibration curve at the MRL concentration by analyzing an MRL check standard with a concentration less than or equal to 110% of the MRL with each batch of samples. The measured concentration for the MRL check standard must be ±50% of the expected value, if any field sample in the batch has a concentration less than 5 times the regulatory MRL. Method requirements to analyze higher concentration check standards and meet tighter acceptance criteria for them must be met in addition to the MRL check standard requirement.
2 When adding the individual trihalomethane or haloacetic acid concentrations to calculate the TTHM or HAA5 concentrations, respectively, a zero is used for any analytical result that is less than the MRL concentration for that DBP, unless otherwise specified by the State.
Methodology | SM (19th or 20th ed) | SM Online2 | ASTM method | EPA method | Residual measured1 | |||
Free Cl2 | Combined Cl2 | Total Cl2 | ClO2 | |||||
Amperometric Titration | 4500-Cl D | 4500-Cl D-00 | D 1253-86 (96), 03 | X | X | X | ||
Low Level Amperometric Titration | 4500-Cl E | 4500-Cl E-00 | X | |||||
DPD Ferrous Titrimetric | 4500-Cl F | 4500-Cl F-00 | X | X | X | |||
DPD Colorimetric | 4500-Cl G | 4500-Cl G-00 | X | X | X | |||
Syringaldazine (FACTS) | 4500-Cl H | 4500-Cl H-00 | X | |||||
Iodometric Electrode | 4500-Cl I | 4500-Cl I-00 | X | |||||
DPD | 4500-ClO2 D | X | ||||||
Amperometric Method II | 4500-ClO2 E | 4500-ClO2 E-00 | X | |||||
Lissamine Green Spectrophotometric | 327.0 Rev 1.1 | X |
1 X indicates method is approved for measuring specified disinfectant residual. Free chlorine or total chlorine may be measured for demonstrating compliance with the chlorine MRDL and combined chlorine, or total chlorine may be measured for demonstrating compliance with the chloramine MRDL.
2 The Standard Methods Online version that is approved is indicated by the last two digits in the method number which is the year of approval by the Standard Method Committee. Standard Methods Online are available at http://www.standardmethods.org.
40 C.F.R. §141.131