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The Federal Register Notice of January 4, 2006 contained some provisions that became effective April 1, 2007. Many laboratories may have missed these new requirements.
The requirements are part of 40 CFR Part 141.131 (b)(2)(iv) and state the following:
(iv) "Beginning April 1, 2007, report quantitative data for concentrations at least as low as the ones listed in [Table] for all DBP samples analyzed for compliance..." The table referenced in the Federal Register notice is summarized below:
Reporting Limit Requirements
The rule establishes the following Minimum Reporting limits:
Trihalomethanes (THM): 1 ppb (0.001 mg/L):
- Chloroform
- Bromodichloromethane
- Dibromochloromethane
- Bromoform
Haloacetic Acids (HAA): 1 ppb (0.001mg/L):
- Dichloroacetic Acid
- Trichloracetic Acid
- Monobromoacetic Acid
- Dibromoacetic Acid
Haloacetic Acids (HAA): 2ppb (0.002 mg/L):
Chlorite: 20 ppb(0.02 mg/L)
Bromate: 1 ppb (0.001 mg/L) for methods 317.0 rev.2,326.0, or 321.8
Bromate: 5 ppb (0.005 mg/L) for all other methods
Calibration Requirements
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.
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