2QUALITY ASSURANCEA system of activities whose purpose is to provide to the producer or the user of a product or service the assurance that it meets the needs of the user.
3Quality Assurance vs. Quality Control An overallmanagement plan toguarantee theintegrity of data(The “system”)A series ofanalyticalmeasurements usedto assess thequality of theanalytical data(The “tools”)
4QUALITY CONTROL CHARTS - Visual representation of actual manufacturing data with respect to the target levels.
5QUALITY CONTROL MEASURES Standards and CalibrationBlanksRecovery StudiesPrecision and Accuracy StudiesMethod Detection Limits
6STANDARDS AND CALIBRATION Prepared vs. Purchased StandardSignals: Peak Area, Beer’s LawCalibration CurvesContinuing Calibration ChecksInternal StandardsPerformance Testing.
7The concentration of the analyte CALIBRATION CURVESGraphical representation of the relationship between:The concentration of the analyteandThe analytical signal
9CONTINUING CALIBRATION VERIFICATION Many methods don’t require that daily calibration curves are preparedA “calibration verification” isanalyzed with each batch of samples
10SAMPLE BATCH 10 - 20 samples (method defined) or less Same matrix Same sample prep and analysisContains a full set ofQC samples
11INTERNAL STANDARDSA compound chemically similar to the analyteNot expected to be present in the sampleCannot interfere in the analysisAdded to the calibration standards and to the samples in identical amounts.
12INTERNAL STANDARDS Refines the calibration process Analytical signals for calibration standards are compared to those for internal standardsEliminates differences in random and systematic errors between samples and standards
13Blind samples submitted to laboratories PERFORMANCE TESTINGBlind samples submitted to laboratories???Labs must periodically analyze with acceptable results in order to maintain accreditation
15LABORATORY REAGENT BLANKS Contains every reagent used in the analysisIs subjected to all analytical proceduresMust give signal below detection limitMost methods require one with every batch
16INSTRUMENT BLANKA clean sample (e.g., distilled water) processed through the instrumental steps of the measurement process; used to determine instrument contamination.
17Prepared in the lab, taken to the field Field Reagent BlanksPrepared in the lab, taken to the fieldOpened at the sampling site, exposed to sampling equipment, returned to the lab.
18RECOVERY STUDIESMatrix SpikesLaboratory Control SamplesSurrogates .
19MATRIX SPIKES Sample spiked with a known amount of analyte Subjected to all sample prep and analytical proceduresDetermines the effect of the matrix on analyte recoveryNormally one per batch
20LABORATORY CONTROL SAMPLE Analyte spiked into reagent waterSubjected to all sample prep andanalytical procedures
21LABORATORY CONTROL SAMPLE Also known as:Laboratory Fortified Blank (LFB)Quality Control Sample (QCS)
22SURROGATES Similar to an internal standard Added to all analytical samples, and to all QC samples to monitor method performance, usually during sample prepMethods often have specific surrogate recovery criteriaMost common in Organic methods
23QUALITY CONTROL MEASURES Standards and CalibrationBlanksRecovery StudiesPrecision and Accuracy StudiesMethod Detection Limits
24PRECISION AND ACCURACY Required for initial certification and annually thereafterA series of four laboratory control samplesMust meet accuracy (recovery) and precision (standard deviation) requirements, often in method
25PRECISION AND ACCURACY Required with a change in instrumentation or personnelSpecific to the analyst
26METHOD DETECTION LIMIT “The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero”
27METHOD DETECTION LIMIT MDLs are determined according to ules from regulating bodySeven replicate laboratory control samples, analyzed for precisionMultiply standard deviation by 3.14 (Student’s t- value)
28METHOD DETECTION LIMIT Must be performed initially for certificationMust meet criteria specified in methodMust be performed with change in instrumentation or test method
29QUALITY ASSESSMENTSThe overall system of activities whose purpose is to provide assurance that the overall control job is being done effectively. Two types: - Evaluation of the precision and accuracy of methods of measurements - Evaluation of the quality of manufactured goods sold for public consumption. (control charts)
30SPECIFICATIONSState how good the numbers should be and what precautions are required in the analytical procedure. Quality Asssurance begins with sampling. False Positive - False Negative -
32WHEN SHOULD METHODS BE VALIDATED? A new method developed for a particular problemEstablished methods revised for a particular problemEstablished methods have changed with timeEstablished method used in different laboratory with different analysts at different times.Establish the equivalence between two methods.
33METHOD VALIDATION USE OBJECTIVES States the pupose for which the results will be used.Example:Analytical data and results will be used to determine whether the new antibacterial ingredient will be effective in removing 99.9% of the gram negative bacteria.
34SPECIFICATIONSwill detail on how the numbers need to be and what precautions are required in the analytical procedures.Specifications might include:Sampling requirements calibration checksAccuracy and precision quality control samplesRate of false resultsSelectivitySensitivityAcceptable blank valuesRecovery of fortification
35METHOD VALIDATIONFOR REGULATORY SUBMISSION, THE FOLLOWING ARE REQUIRED: Method Specificity / Confirmation of identity Linearity Accuracy Precision Range Limit of detection, Limit of quantification Rubostness
36CONFIRMATION OF IDENTITY It is necessary to establish that the signal being produced at the measurement stage, which has been attributed to the analyte, is only due to the analyte and not from the presence of something chemically or physically similar.
37SPECIFICITYSpecificity is the ability of an analytical method to distinguish the analyte from everything else that might be in the sample.
38LINEARITYLINEARITY measure how well a calibration curve follows a straight line. A common measure of linearity is R2, square of the correlation coefficient. Good linear fit when R2 = and above Prepare independently at leas 6 samples + blank and measure linearity.
39SAMPLE PROBLEM:An AAS method to analyze Pb+2 in water has just been developed and is in the process of being validated. The validation protocol states the following criteria to be met (in addition to proof of identity and setting dynamic range): Determine whether the new method is validated. Linearity: R2 > Accuracy: % Recovery = /- 5% Precision: Intermediate Precision, STD < 0.5% Intralab Precision, STD < 2.0% The following validation experiments were done: Linearity Test. Blank samples were spiked with several known amounts of Pb+2. The following data were collected.
41RECOVERY TEST. Blank samples were spiked with 0. 10 and 0 RECOVERY TEST. Blank samples were spiked with 0.10 and 0.15 ppb of Pb+2 and analyzed using the method. The following data were collected.Spiked sample0.10 ppb0.15 ppbAAS Signal1.09021.70021.08061.72321.07811.6996
42Precision. An analyst in the laboratory as well as two ther analysts from different laboratories analyzed the same blank sample spiked with ppm Pb+2 with the following results.RUNSAnalyst ABC10.1220.1200.1320.1240.11920.1280.12630.1290.127
43ACCURACYACCURACY is “nearness to the truth”. Analyze blank , sample and a certified reference material (CRM) and compare the means. Do a recovery test. Analyze a blank sample spiked with 0.5, 1.0, 1.5X level of your analyte. And analyze for % Recovery.
44PRECISIONPRECISION is how well replicate measurements agree with one another, usually express as standard deviation. Instrument precision – reproducibility observed when same quantity of a sample is analyzed using a particular instrument repeatedly (>10 times) Intra-assay precision – analyzing aliquots of a homogeneous material several times by one analyst on one day using same equipment. Inter-lab precision (reproducibility) aliquots of the same sample are analyzed by different analyst in different labs using different (?) instrument
45RANGERANGE is the concentration interval over which linearity, accuracy, and precision are all acceptable. Correlation coefficient of R2 equal or greater than Interlab precision of +/-3% Spike recovery of 100 +/-2%
46LIMITS OF DETECTION AND QUANTITATION The detection limit is the smallest quantity of analyte that is “significantly different” from the blank. LoD: Measure blank samples at least 7 times and get the mean. Do similar analyses with 7 samples with analyte and calculate the standard deviation. LoD = blank mean + 3S LoQ = 6x to 10x the SD of blank sample LoQ = 2x to 3x of LoD
47RUGGEDNESS / ROBUSTNESS Robustness is the ability of an analytical method to be an affected by small deliberate changes in operating parameters.
48STANDARD ADDITION METHOD INTERNAL STANDARD METHOD