Performance Characteristics of Methods of Analysis Used for Regulatory Purposes.Part II. Pesticide Formulations

1991 ◽  
Vol 74 (5) ◽  
pp. 718-744 ◽  
Author(s):  
William Horwttz ◽  
Richard Albert
Keyword(s):  
Performance Characteristics ◽  
International Union ◽  
Method Performance ◽  
Applied Chemistry ◽  
The Past ◽  
Chromatographic Methods ◽  
Decimal Fraction ◽  
Collaborative Studies ◽  
Pesticide Formulations ◽  
Relative Standard

Abstract The precision parameters of the method-performance (collaborative) studies published In the AOAC Journal from 1915 through 1990 for pesticide formulations have been recalculated on a uniform basis by the International Union of Pure and Applied Chemistry 1987 protocol. About 93% of the 953 accepted assays, which are predominantly gravimetric (G), volumetric (V), and gas (GC) and liquid (LC) chromatographic methods, exhibit relative standard deviations among laboratories (RSDR) that are generally less than 2 times the values predicted from the Horwitz equation: RSDR (%) = 2 exp (1 - 0.5 log C), where C is the concentration expressed as a decimal fraction. UV, VIS, and IR spectrophotometrlc (S) methods are somewhat poorer, with about 80% of the reported RSDR values less than twice the predicted RSDR value. The precision parameters of pesticide formulations analyzed by the older methods (G, V, GC) are equivalent to those previously found for drug preparations in the same concentration range; the precision parameters of pesticide formulations analyzed by LC and S are somewhat poorer. Overall, however, the precision parameters of pesticide formulations are generally independent of analyte, method, and matrix, and are primarily a function of concentration. The method-acceptability decisions of the AOAC for pesticide formulations during the past 75 years can be approximated retrospectively by using a criterion for RSDR that is less than 2 times the RSDR calculated from the Horwitz equation.

scholarly journals Determination of Total Fat in Milk- and Soy-Based Infant Formula Powder by Supercritical Fluid Extraction: PVM 2:2002

2003 ◽  
Vol 86 (1) ◽  
pp. 86-95 ◽  
Author(s):  
Denis E LaCroix ◽  
Wayne R Wolf ◽  
Denis E LaCroix ◽  
Wayne R Wolf ◽  
Leslie J D Myer ◽  
...  
Keyword(s):  
Reference Material ◽  
Supercritical Fluid Extraction ◽  
Infant Formula ◽  
Supercritical Fluid ◽  
Performance Characteristics ◽  
Fluid Extraction ◽  
Method Performance ◽  
Relative Standard ◽  
Total Fat

Abstract Commercially available simple benchtop systems using CO2 supercritical fluid extraction (SFE) eliminate expensive organic solvent disposal problems and offer potential to meet a demand for rapid, accurate high-volume gravimetric determinations of total fat content of infant formula powders. A Data Quality Objectives (DQOs) approach was used to evaluate the performance characteristics of instrumental SFE extraction for determination of total gravimetric fat in infant formula. The established DQOs included the following: Accuracy.—Correct values were obtained for a suitable reference material, SRM 1846 Infant Formula [National Institute of Standards and Technology (NIST), Gaithersburg, MD]. Ruggedness.—Variables were defined as (1) extraction time (35 min optimum); (2) ratio of sample size to diatomaceous earth support material (1 g sample/2 g support); (3) ratio of distilled water to alcohol (50% isopropanol optimum for both milk- and soy-based infant formula samples); (4) extraction flow rate was 3–3.5 mL/min optimum. Precision.—Relative standard deviations of multiple determinations fell within the Horwitz limits of acceptability of ≤2.8% at the level of analyte determined (0.34–2.5% obtained). Scope of applicability.—Includes milk- and soy-based infant formula powders. Research data were obtained by use of a commercially available fat analyzer. Samples of the SRM, 2 commercial milk-based and 3 commercial soy-based infant formula products were distributed to 2 additional collaborating laboratories. Very good agreement was obtained among the submitting and collaborating laboratories for these samples. The use of clearly defined DQOs to establish method performance characteristics, along with the commercially available reference material, provided the mechanism for verification and validation of analytical methodology.

History of the IUPAC/ISO/AOAC Harmonization Program

1992 ◽  
Vol 75 (2) ◽  
pp. 368-371 ◽  
Author(s):  
William Horwitz
Keyword(s):  
International Organizations ◽  
Performance Studies ◽  
World Health ◽  
International Union ◽  
Method Performance ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Collaborative Studies ◽  
History Of ◽  
Health Organization

Abstract As a result of the preference of the Joint Food and Agriculture Organization/World Health Organization Codex Alimentarius Program to endorse methods of analysis for which interlaboratory performance parameters are available, many international organizations now conduct method-performance (collaborative) studies. International meetings sponsored by the International Union of Pure and Applied Chemistry, the International Organization for Standardization, and AOAC International have produced a harmonized protocol for the design, conduct, and interpretation of method-performance studies, and this protocol Is being Implemented by many method standardization organizations. The same group of organizations hopes to provide a harmonized protocol for the quality control and quality assurance of laboratory (analyst) performance.

Performance Characteristics of Methods of Analysis Used for Regulatory Purposes.I. Drug Dosage Forms. D. High Pressure Liquid Chromatographic Methods

1985 ◽  
Vol 68 (2) ◽  
pp. 191-198 ◽  
Author(s):  
William Horwitz ◽  
Richard H Albert
Keyword(s):  
High Pressure ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Drug Dosage ◽  
Dosage Forms ◽  
High Pressure Liquid Chromatographic ◽  
Chromatographic Methods ◽  
Collaborative Studies ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract Precision parameters of high pressure liquid chromatographic methods approved by AOAC for the analysis of drug dosage forms were recalculated on a consistent statistical basis, using the computer program "FDACHEMIST." Eleven collaborative studies of 12 compounds in 66 dosage forms analyzed by an average of 9 laboratories per study, with a total of 1150 determinations, were reviewed. For the approved methods and methods awaiting approval (9 studies, 11 compounds, 54 dosage forms, and 959 determinations), the average repeatability relative standard deviation (within-laboratory; RSDo) was 1.0%; reproducibility relative standard deviation (among-laboratories, including within-; RSDX) was 2.5%; the ratio RSD„/RSDX was an unusually low 0.40, with an average outlier rate of 0.6% of the reported values. The line of best fit for RSDX plotted against — log concentration increases with decreasing concentration, extending approximately from RSDX =2% at 100% concentration to RSDX = 3.6% at 0.01% concentration,a change in RSDX of about 0.4% for each 10-fold decrease in concentration,independent of analyte and matrix.

Performance Characteristics of Methods of Analysis Used for Regulatory Purposes. I. Drug Dosage Forms. C. Automated Methods

1985 ◽  
Vol 68 (1) ◽  
pp. 112-121
Author(s):  
William Horwitz ◽  
Richard Albert
Keyword(s):  
Computer Program ◽  
Drug Dosage ◽  
Dosage Forms ◽  
Performance Characteristics ◽  
Methods Of Analysis ◽  
Collaborative Studies ◽  
Relative Standard ◽  
Standard Deviations ◽  
Best Fit ◽  
Automated Methods

Abstract For analysis of drug dosage forms, precision measures of AOAC approved automated methods, usually containing a spectrophotometric or fluorometric measurement step, were recalculated on a consistent statistical basis, using a computer program "FDACHEMIST." Ten collaborative studies of 14 compounds in 38 materials, consisting of various dosage forms, usually in 10 replications by an average of 7 laboratories, with a total of 2461 determinations, were reviewed. The average relative standard deviations within-laboratory (RSD0) and among-laboratories (RSDX) were 1.1 and 1.9%, respectively, and the ratio of RSD„/RSDX was 0.57, with an average outlier rate of 0.57% of the reported values. The line of best fit for RSDX plotted against — log concentration increases slightly with decreasing concentration, extending from an RSDX of about 1.6% at 100% concentration to an RSDX of 2.2% at 0.1% concentration, a change in RSDX of about 0.2% for a 10-fold decrease in concentration, independent of analyte and matrix.

What Is A Chemical Element?

2020 ◽  
Keyword(s):  
Periodic Table ◽  
Chemical Element ◽  
Abstract Concept ◽  
International Union ◽  
Applied Chemistry ◽  
Educational Levels ◽  
Unique Position ◽  
Current State ◽  
Element Carbon ◽  
Definition Of

The term “element” is typically used in two distinct senses. First it is taken to mean isolated simple substances such as the green gas chlorine or the yellow solid sulphur. In some languages, including English, it is also used to denote an underlying abstract concept that subsumes simple substances but possesses no properties as such. The allotropes and isotopes of carbon, for example, all represent elements in the sense of simple substances. However, the unique position for the element carbon in the periodic table refers to the abstract sense of “element.” The dual definition of elements proposed by the International Union for Pure and Applied Chemistry contrasts an abstract meaning and an operational one. Nevertheless, the philosophical aspects of this notion are not fully captured by the IUPAC definition, despite the fact that they were crucial for the construction of the periodic table. This pivotal chemical notion remains ambiguous and such ambiguity raises problems at the epistemic, logical, and educational levels. These aspects are discussed throughout the book, from different perspectives. This collective book provides an overview of the current state of the debate on the notion of chemical element. Its authors are historians of chemistry, philosophers of chemistry, and chemists with epistemological and educational concerns.

scholarly journals Organic–Inorganic Hybrid Materials

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 86
Author(s):  
Jesús-María García-Martínez ◽  
Emilia P. Collar
Keyword(s):  
Hybrid Materials ◽  
Hybrid Material ◽  
International Union ◽  
Applied Chemistry ◽  
Inorganic Hybrid ◽  
Organic Components ◽  
Intimate Mixture ◽  
Inorganic Components

According to the IUPAC (International Union of Pure and Applied Chemistry), a hybrid material is that composed of an intimate mixture of inorganic components, organic components, or both types of components which usually interpenetrate on scales of less than 1 μm [...]

scholarly journals The Development and Validation of a Novel Designer Benzodiazepines Panel by LC–MS-MS

2021 ◽  
Author(s):  
Rebecca A Mastrovito ◽  
Donna M Papsun ◽  
Barry K Logan
Keyword(s):  
Illicit Drug ◽  
Liquid Extraction ◽  
Electrospray Tandem Mass Spectrometry ◽  
Method Performance ◽  
Internal Standards ◽  
Liquid Liquid Extraction ◽  
Relative Standard ◽  
Development And Validation ◽  
Positive Ion ◽  
Designer Benzodiazepines

Abstract Novel illicit benzodiazepines are among the most active areas of new illicit drug manufacture and use. We describe a method for the detection and quantification of etizolam and its metabolite α-hydroxyetizolam, flubromazolam, clonazolam, diclazepam, delorazepam, bromazepam, flubromazepam, phenazepam, flualprazolam, flunitrazolam, and nitrazolam in human whole blood. After addition of internal standards, samples are buffered and extracted using a liquid–liquid extraction. Analysis is performed using positive-ion electrospray tandem mass spectrometry for detection and quantitation. Calibration ranges were established based on the method performance and differed from compound to compound. Replicates at the lowest calibration point for each compound performed within 5% of CV (Coefficient of Variation). The correlation coefficient was >0.990 for all compounds. Relative standard deviation for all compounds was ≤10% of CV and accuracy was  ±10% for both within- and between-run experiments. The maximum average intra- and inter-run imprecision were 5.7%. The maximum average intra- and inter-run imprecision was −8.7%. As part of evaluating the scope for relevancy, samples testing positive in immunoassay but confirmed to be negative in traditional benzodiazepine confirmation method were re-analyzed using this method. The presence of at least one novel benzodiazepine was identified in 70% of these samples. The appearance of these novel “designer” benzodiazepines demonstrates the challenge for toxicology testing and the need for continually updated confirmation methods.

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

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