QA/QC program

Once objectives have been defined, a study protocol including an appropriate QA/QC program is developed. Initially, both literature and information searches should be made. If possible, selected field measurements based on an assumed dispersion model can also be made. The objective of the exploratory study is to obtain the best possible answers to the following questions. 

A laboratory QA/QC program is an essential part of a sound management system. It should be used to prevent, detect, and correct problems in the measurement process and/or demonstrate attainment of statistical control through QC samples. The objective of QA/QC programs is to control analytical measurement errors at levels acceptable to the data user and to assure that the analytical results have a high probability of acceptable quality. 

The necessary components of a complete QA/QC program include internal QC criteria that demonstrate acceptable levels of performance, as determined by a QA review (audit). External review of data and procedures is accomplished by the monitoring activities of accreditation organizations such as the Standards Council of Canada (SCC, 2005). This includes laboratory evaluation samples (PT samples, see above) and a periodic (sometimes every 2 years) on-site assessment of all QA/ QC procedures, performed by external assessors from the accrediting organization. 

Jack Hubball is a lead criminalist with the Connecticut State Police Forensic Laboratory. The Chemistry Section of the laboratory provides analyses for organic compounds from a variety of samples submitted from crime scenes. However, the majority of samples are from suspect-arson fire scenes. Many of these samples contain pyrolysis products and/or polymer additives. During his tenure at the Forensic Laboratory, Dr. Hubball has analyzed more than 10,000 items. In addition to his duties as an analyst, he is the quality manager for the Forensic Laboratory and is responsible for most aspects of the lab QA/QC program. He is the laboratory representative to the Connecticut State Police K-9 Unit and provides final testing and third party certification for the accelerant, drug and explosives detection teams. 

In addition to the QA/QC performed by the laboratory, an independent QA/QC program administered by the data users is essentid in evalutating data quality. The "Field" QA/QC checks usually consist of travel blanks, field blanks, decontamination blanks, co-located samples, split samples, and blind standards. Split samples are most important for evaluating laboratory precision and blind standards are most important in assessing laboratory accuracy. The relative percent difference between split samples exceeded the 20 percent criteria at least once for Al, Sb, Be, Cd, Co, Cu, Fe, Mo, and Ag. Overall, few values exceeded the 20% criteria. 

Use of an independent QA/QC program is mandatory to evaluate laboratory quality. Use of blind standards and splits are essential in assessing accuracy and precision. Independent analyses outside the CLP may be necessary to obtain appropriate data for modeling and to more definitively evaluate selected areas. 

Compared to the levels observed in the seventies, the soil contamination with DDT has dropped, but less than expected. It is very likely that the actual values at that time were higher, but also the recent levels need more detailed confirmation, nevertheless the monitoring is supported by QA/QC program. 

Heat flow meter test results generally agree well with those generated hy absolute methods. The technique, which is easier to use and is a universally recognised standard test procedure [45], is also usable either for high accuracy measurements to support VIP analytical modelling/development or for fast tests for QA/QC programs. 

A field quality assurance/quality control (QA/QC) program must ensure the integrity and representativeness of the samples taken from aquatic sources such as surface waters, groundwater, and marine environments. 

The sampling plan must consider the role of good field and laboratory practices. The basic QA/QC field testing and laboratory analytical protocols that will be adopted must be spelt out in the sampling plan. For the laboratory, the scope of both the intra- and interlaboratory QA/QC programs should be referenced, and should be consistent with the size of available resoiu ces. 

Performance and systems audits must be instituted and should become stable and continuing features in the field QA/QC program. 

Quality Control (QC) Samples Specimens, the value of which is unknown to the analyst, but is known to the appropriate QA/QC personnel of a participating laboratory when used as part of a laboratory QA/QC program, the theoretical values of these samples should not be known to the analyst until the analyses are complete. QC samples are to be run in sets consisting of one QC sample from each pool (see definition of pools above). 

To demonstrate compliance with the second of the above criteria, a laboratory should submit to the responsible physician an internal QA/QC plan detailing the standard operating procedures to be adopted for satisfying the recommended QA/QC procedures for the analysis of each specific analyte (CDB, CDU and/or B2MU). Procedures for internal QA/QC programs are detailed in Section 3.3.1 below. 

The status of each participating laboratory should be determined for each analyte (i.e., whether the laboratory satisfies minimum proficiency guidelines based on the proficiency samples sent by the CTQ and the results of the laboratory s internal QA/QC program). To maintain competency for analysis of CDB, CDU and/or B2MU during the first review, the laboratory should satisfy performance requirements for at least 2 of the 3 proficiency samples provided in each of the 3 rounds completed over the 6-month period. Proficiency should be maintained for the analyte(s) for which the laboratory conducts determinations. 

Submit to the responsible physician the results, for the initial 6-month period, of the internal QA/QC program for each analyte for which determinations are to be made (if no commercial analyses have been conducted previously, a minimum of 2 mock standardization trials for each analyte should be completed per month for a 6-month period) ... 

The QA/QC program for CDB and CDU should address, at a minimum, procedures involved in calibration, establishment of control limits, internal QC analyses and maintaining control, and corrective-action protocols. The participating laboratory should develop and maintain procedures to assure that analyses of compliance samples are within control limits, and that these procedures are documented thoroughly in a QA/QC plan. 

A nonmandatory QA/QC protocol is presented in Attachment 1. This attachment is illustrative of the procedures that should be addressed in a proper QA/QC program. 

Results for the previous 2 years of the QC sample analyses conducted under the internal QA/QC program (this information should be Provided for each analyte for which determinations are made and for each analytic instrument used for this purpose, sufficient to demonstrate that internal QA/QC programs are being executed properly, and consistent with data sent to responsible physicians. 

Participating laboratories should maintain these documents QA/QC program plans QA/QC status reports CTQ proficiency program reports and, analytical data reports. The information that should be included in these reports is summarized in Table 2 a copy of each report should be sent to the responsible physician. 

QA/QC Program Plan Once (initially) A detailed description of the QA/QC protocol to be established by the labaratory to maintain control of analyte determinations. 

As noted in Section 3.3.1, a QA/QC program pian shouid be deveioped that documents internai QA/QC procedures (defined under Section 3.3.1) to be impiemented by the participating iaboratory for each anaiyte this pian shouid provide a iist identifying each instrument used in making anaiyte determinations. 

Precision. Based on precision data reported by Pharmacia (1990), a precision value (i.e., CV) of 5% should be achievable over the defined range of the analyte. For internal QC samples (i.e., recommended as part of an internal QA/QC program, section 3.3.1), laboratories should attain precision near 5% over the range of concentrations measured. 

At the beginning of this QA/QC program, control limits should be based on the results of the analysis of 20 quality control samples from each pool of each analyte. For any given pool, the 20 quality control samples should be run on 20 different days. Although no more than one sample should be run from any single pool on a particular day, a laboratory may run quality control samples from different pools on the same day. This constitutes a set of initial characterization runs. 

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