Changes in Schedule 172 In Reply Refer To: April 20, 1994 Mail Stop 412 OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM 94.12 Subject: Changes in Schedule 172 BACKGROUND Office of Water Quality (OWQ) Technical Memorandum 94.06 announced the availability of Schedule 172 at the National Water Quality Laboratory (NWQL). This schedule was implemented for equipment, field, and other blanks to produce quality-control data to support the new protocol for low-level inorganic analyses. Schedule 172 includes very low-level analyses for major ions, trace elements, and nutrients, and a 2-week turnaround time. PROBLEM WITH ADDING TRACE ELEMENTS Schedule 172 was established to determine if field equipment and sample processing contributes contamination of specified inorganic constituents (see OWQ Technical Memorandum 94.06). Schedule 172 includes two methods--Inductively Coupled Plasma (ICP) and Inductively Coupled Plasma/Mass Spectrometry (ICP/MS)--for the analysis of major ions and trace elements. Both methods use a clean environment for sample pour-up and sample analysis in an attempt to prevent contamination of samples in the laboratory. Since the implementation of Schedule 172, several Districts have requested modifications-- especially the addition of arsenic, selenium, and mercury. The NWQL analyzes these three elements by individual methods rather than by ICP or ICP/MS. Consequently, modifying Schedule 172 to add element-by-element analyses for these three trace elements would create a difficult problem for the NWQL. If these additional analyses were made from the same bottle designated for trace elements under Schedule 172, contamination could occur either in the handling of the bottles for ICP and ICP/MS analyses or during handling for the additional determinations. Therefore, even if trace-element analyses by the ICP and ICP/MS methods were made prior to analysis by the additional methods, the potential for contaminating numerous elements in the sample for possible reruns would be greatly increased. Thus, because of the ways that samples for selenium, arsenic, and mercury are handled and analyzed at the NWQL, these elements will not be added to Schedule 172. DISTRICT POLL By copy of this memo, the Regional Water-Quality Specialists are asked to poll Districts to determine the need to develop low-level schedules for blanks to determine trace elements other than those presently determined by Schedule 172. Please compile the responses by Region and send the results to the Chief, NWQL, by May 2, 1994. If the poll indicates a high-volume need for analyzing additional trace elements in blanks, the NWQL will develop another schedule. If the poll indicates a low-volume need, the NWQL will provide such services through custom analyses. SEPARATION OF TRACE ELEMENTS AND NUTRIENTS INTO SEPARATE SCHEDULES Under Schedule 172, samples for trace elements and nutrients are submitted in different bottles and analyzed separately. This approach was established by the OWQ and the NWQL to facilitate data analysis and reporting on blank samples. However, several Districts have asked why both nutrients and trace elements must be run on all submitted samples. Moreover, this combined schedule has been found to cause a problem for the NWQL because the subsamples arrive in different shipments, yet must be logged in from the same request. Because of the cited problems, the OWQ and the NWQL have decided to separate the analysis of trace elements and nutrients in blanks into separate schedules. There is an existing nutrient schedule (Schedule 452) that provides identical analyses as the nutrient part of Schedule 172. This leaves just the trace elements and major ions to be done under the revised Schedule 172. COMMENT: AN INAPPROPRIATE USE OF SCHEDULE 172 Schedule 172 is inappropriate as a quality control for Graphite Furnace Atomic Absorption (GFAA) or other methods. Schedule 172 was not set up for this purpose and using the ICP/MS results from the schedule as a quality-control check of GFAA cannot guarantee that GFAA will produce the same analytical precision, accuracy, and quality. CONCLUSIONS Programs and projects are asked to observe the following: 1. The Regional Water-Quality Specialists will conduct a poll to determine the volume need for analyses of trace elements presently not included in Schedule 172. If the poll indicates a high-volume need for analyzing additional trace elements in blanks, the NWQL will develop another schedule. If the poll indicates a low-volume need, the NWQL will provide such services through custom analyses. 2. Districts can arrange custom analyses for trace elements (or any other analysis) with the NWQL at any time. Such custom analyses could involve additional costs for establishment of method detection limits, lower level technology, special login and handling charges, and special turnaround times. Contact the Inorganic Program Chief, Merle Shockey (MSHOCKEY) (303) 467-8101 at the NWQL to arrange custom work. 3. Effective May 16, 1994, Schedule 172 will be redefined to include the existing major ions and trace elements only. Nutrients, if desired, must be requested separately as Schedule 452, which--for the duration of fiscal year (FY) 1994--will cost $34.00. The price for Schedule 172 will be reduced so that the sum of the two schedule prices equals the previous Schedule 172 price. Thus, for FY 1994, the revised Schedule 172 will cost $191.00. A separate Analytical Services Request Form must accompany each sample submission for each schedule. 4. Customers must not use the ICP/MS part of Schedule 172 as a quality control for GFAA or other analytical methods. David A. Rickert Chief, Office of Water Quality This memorandum refers to Office of Water Quality Technical Memorandum 94.06. Key Words: National Water Quality Laboratory Distribution: A, B, S, FO, PO, AH