Procedural revision to the use-dilution methods: establishment of maximum log density value for test microbes on inoculated carriers

(Staphylococcus aureus) and 964.02 (Pseudomonas aeruginosa), were revised in 2009 to include a standardized procedure to measure the log density of the test microbe and to establish a minimum mean log density value of 6.0 (geometric mean of 1.0 x 10(6) CFU/carrier) to qualify the test results. This report proposes setting a maximum mean log density value of 7.0 (geometric mean of 1.0 x 10(7) CFU/carrier) to further standardize the procedure. The minimum value was based on carrier count data collected by four laboratories over an 8-year period (1999-2006). The data have been updated to include an additional 4 years' worth of data (2006-2010) collected by the same laboratories. A total of 512 tests were conducted on products bearing claims against P. aeruginosa and S. aureus with and without an organic soil load (OSL) added to the inoculum (as specified on the product label claim). Six carriers were assayed in each test, for a total of 3072 carriers. Mean log densities for each of the 512 tests were at least 6.0. With the exception of two tests, one for P. aeruginosa without OSL and one for S. aureus with OSL, the mean log densities did not exceed 7.5 (geometric mean of 3.2 x 10(7) CFU/carrier). Across microbes and OSL treatments, the mean log density (+/- SEM) was 6.80 (+/- 0.07) per carrier (a geometric mean of 6.32 x 10(6) CFUlcarrier) and acceptable repeatability (0.28) and reproducibility (0.31) SDs were exhibited. A maximum mean log density per carrier of 7.0 is being proposed here as a validity requirement for S. aureus and P. aeruginosa. A modification to the method to allow for dilution of the final test cultures to achieve carrier counts within 6.0-7.0 logs is also being proposed. Establishing a range of 6.0-7.0 logs will help improve the reliability of the method and should allow for more consistent results within and among laboratories.     

Modifications to the AOAC use-dilution test for quaternary ammonium compound-based disinfectants that significantly improve method reliability

The AOAC use-dilution test (UDT) for bactericidal disinfectant efficacy (Method 964.02) has often been criticized for its extreme variability in test results, particularly for quaternary ammonium compound (QAC)-based disinfectants against Pseudomonas aeruginosa. While efforts are under way to develop a new and better test method for hospital disinfectant products that is globally acceptable, U.S. manufacturers and formulators of QAC products must continue in the interim to measure their product performance against the current UDT method. Therefore, continued variability in the UDT places an unnecessary and unfair burden on U.S. QAC product manufacturers to ensure that their products perform against an, at best, unreliable test method. This article reports on evaluations that were conducted to attempt to identify key sources of UDT method variability and to find ways to mitigate their impact on test outcomes for the method. The results of testing across 4 laboratories, involving over 6015 carriers, determined that operator error was a key factor in test variability. This variability was found to be significantly minimized by the inclusion of a simple culture dilution step. The findings from this study suggest possible refinements to the current AOAC UDT method that would serve to improve the overall ruggedness and reliability of the method and to optimize recovery of cells from the carrier surface, thereby further improving the accuracy and reproducibility of counts and test outcomes until such time as a replacement method is implemented.     

Recovery and sporicidal resistance of various B. subtilis spore preparations on porcelain penicylinders compared with results from AOAC test methods

Sporicidal test results obtained from carriers inoculated with 4 types of defined Bacillus subtilis spore preparations were compared with the standard AOAC sporicidal test using soil extract nutrient broth (SENB) B. subtilis 19659 spores. Recoveries of spores inoculated on penicylinders from B. subtilis clean spores (washed and suspended in water) and B. subtilis 19659 spores inoculated from culture filtrates according to the AOAC method were compared. Spores were exposed to 6 concentrations (0.5-3.0% w/v) of glutaraldehyde in phosphate buffer (pH 7.5) for 10 h. Concentrations were established by titrimetry and liquid chromatography. Recoveries of surviving spores were determined for 3 types of clean B. subtilis var. niger preparations, one clean B. subtilis 19659 preparation, and the SENB B. subtilis 19659 filtrates. Spore carriers, inoculated by the standard AOAC protocol, resulted in as much as a 2-log number difference in runs 1-12, but not more than 0.5 log number for each clean spore preparation. The SENB spores varied most in resistance to glutaraldehyde, with no growth in recovery media from 3 different batches of 1, 1.5, and 2% glutaraldehyde. Separate batches of SENB preparations of B. subtilis 19659 were resistant and destroyed by 1.0% glutaraldehyde, with 3.98 and 6.0 log numbers of spores on penicylinders, respectively. Clean spore preparations of B. subtilis 19659 on porcelain penicylinders were more resistant to glutaraldehyde than were SENB spores. Nutrient agar/Mg/Ca and nutrient agar/Mg spore preparations of B. subtilis var. niger showed the most uniform resistance to glutaraldehyde. Spores with calcium added showed increased resistance to glutaraldehyde. B. subtilis 19659 spores from the Columbia broth spore preparation were the most resistant and were recovered after exposure to 3.0% glutaraldehyde.     

Use of Dacron as an alternative carrier for evaluating oxidizing sterilants in the AOAC sporicidal test

The AOAC sporicidal method (966.04) recommends the use of porcelain penicylinders and black waxed silk sutures as carriers for demonstrating the sporicidal activity of sterilants. However, the silk carriers are not suitable for evaluating the sporicidal efficacy of oxidizing agents, and an inert polyester material (Dacron) is recommended as an alternative. Dacron provides an equivalent microbial and physical challenge to silk. Microbiologically, both materials demonstrated similar HCI resistance, which is required by the AOAC test, as well as equivalent spore loading and spore wash-off. Electron microscopy showed that both materials present the same braided microstructure, providing an equivalent physical challenge to the test sterilant. Dacron was more consistent than silk, and did not require extraction prior to spore loading. The extraction method for black waxed silk was variable and incomplete, which may compromise the activity of oxidizing sterilants and add to method variability. Silk was also structurally altered in the presence of oxidizing sterilants and increased sterilant degradation. Dacron did not affect the sterilant and was inert in the presence of oxidizing agents. Dacron sutures are proposed as inert alternatives to silk for evaluating the sporicidal efficacy of oxidizing agents.     

Trace-analytical methods for monitoring contaminations in semiconductor-grade Si manufacturing

Generating systematic data on incoming materials, processes, production environments and products by contamination monitoring and analyis is the key element of quality assurance in semiconductor fabrication. To be able to match the analytical capabilities to the requirements of improving materials and processes, the level of sophistication of contamination monitoring and analysis systems must be higher than the expected demands in the fabrication line. The accuracy of each analytical method has to be cross-checked by different independent techniques. Accuracy, precision, power of detection, analysis time and expenses should always be tailored to the particular case. All monitoring methods must run under statistical process control. The methods described meet the analytical requirements of the near future in semiconductor grade silicon manufacturing.Glossary AAS Atomic Absorption Spectrometry - ADD Acid-mixture Drop Decomposition of the native oxide and, occasionally of Si surface due to given acid etchant mixtures such as HF+HNO₃ in order to preconcentrate dissolvable metallic impurities of the surface (c.f. MAD, VPD, WSSD) - AEM Analytical Electron Microscopy - AEPS Auger Electron Appearance Potential Spectroscopy (=APAES) - AES Auger Electron Spectroscopy - AFM Atomic Force Microscope - AM Acoustic Microscopy - AMS Accelerator Mass Spectrometry (Tandem-SIMS) - APIMS Atmospheric Pressure Ionization Mass Spectroscopy - ARAES Angle-Resolved Auger Electron Spectroscopy - ARUPS Angle-Resolved Ultraviolet Photoemission Spectroscopy - ATR-FTIR Attenuated Total Reflection Fourier Transform Infrared Spectroscopy - BEEM Ballistic Electron Emission Microscopy - BMD heat induced Bulk Micro-Defects in monocrystalline Si after a specified thermal process cycle, corresponding to SIO_x precipitates in monocrystalline Si [31] - BSE Back Scattered Electrons - CE Capillary Electrophoresis (cf. CIA) - CIA Capillary Ion Analysis (cf. CE) - COP Crystal Originated Particle detected as LPD - CV Capacitance-Voltage measurement - CVD Chemical Vapor (phase) Deposit(ion) - CZ-Si monocrystalline Si grown by Czochralski-method from quartz crucible in a noble gas atmosphere - DCT Coulbe Crystal x-ray Topography - DLTS Deep Level Transient Spectroscopy [72] - DRAM Dynamic Random Access Memories operate as memory devices by storing charge near the Si wafer surface in micro-capacitors. Defects and impurities can cause the loss of the stored charge and a periodic refresh of the signals is required (cf. PTF). - DTDA Differential Thermal Desorption Analysis [73] - DZ Denuded Zone, i.e. a subsurface layer free of SiO_x precipitates - EBIC Electron Beam Induced Conductivity - EDS Energy Dispersive Spectroscopy - EDAX Energy Dispersive Analysis of X-rays - EELS Electron Energy Loss Spectroscopy - EG Extrinsic Gettering, i.e. removal of metals from the active device region by dislocation stress in the back side of the wafer - Elymat Electrolytical Metal Tracer [69] - EMP Electron MicroProbe - EPA Electron Probe Analysis - EPMA Electron Probe Micro-Analysis - ERDA Elastic Recoil Detection Analysis - ESCA Electron Spectroscopy for Chemical Analysis (= XPS) - ETV Electro Thermal Vaporization - fab manufacturing process or fabrication line of microchips - FESEM Field Emission Scanning Electron Microscopy - FIB Focused Ion Beam - FIM Field Ion Microscopy - FLAA FlameLess Atomic Absorption - FMEA Failure Mode and Effect Analysis - ()-FTIR (Microspot) Fourier Transform InfraRed Spectroscopy - FTPL Fourier Transform PhotoLuminescence - FZ-Si monocrystalline Si grown by float zone method from a polycrystalline Si rod in an rf-coil - GDMS Glow Discharge Mass Spectrometry - GFA Gas Fusion Analysis (heat extraction of O_i from Si by graphite reduction, [75]) - GF-AAS Graphite Furnace AAS - GLP Good Laboratory Practice (protocol defining general operations) - GMP Good Measurement Practice (protocol defining technique-specific operations) - GOI Gate Oxide Integrity test - Graff test surface precipitation of metallic silicide due to quenching annealed (1100°C) Si wafer, detection by Sirtl etch, cf. TEG haze test [76, 77] - HeD He thermal Desorption spectroscopy - HIBS Heavy Ion Backscattering Spectrometry - HREELS High-Resolution Electron Energy Loss Spectroscopy - HREM High Resolution Electron Microscopy index for interstitials (O_i, Si_i etc.) in monocrystalline Si - IC Ion Chromatography - ICISS Impact-Collision Ion-Scattering Spectroscopy - ICP-OES Inductively Coupled Plasma Optical Emission Spectrometry - ICP-MS Inductively Coupled Plasma Mass Spectrometry - IG Intrinsic Gettering, removal of metallic impurities from the device active region and trap them in the bulk using supersaturated O_i in Si and inducing SiO_x precipitation by thermal annealing - INNA Instrumental Neutron Activation Analysis [70, 71] - IR InfraRed Spectroscopy - IRAS Infrared Reflection Adsorption Spectroscopy - ISS Ion-Scattering Spectroscopy (cf. RBS) - LAMMA Laser (Ablation) Microprobe Mass Analyzer - LANG scanning Lang x-ray topography - LAR-RBS Lateral and Angle Resolved RBS-Imaging [78] - LEED Low Energy Electron Diffraction - LM-PC (non-contact) Laser/Microwave PhotoConductance - LOD Limit Of Detection (2–3 of noise level, [12]) - LOQ Limit Of Quantification (>6 of noise level, Fig. 2/3, [11, 13] - LPD Ligh Point Defect, sites scattering laser beam on monocrystalline Si surface (particles, pits, dimples, scratches, nm-terrasses, etc.) - LST Laser Scattering Topography - LT-FTIR Low Temperature Fourier Transform InfraRed Spectroscopy - LTV Local Thickness Variation - LPI-SNMS Laser Resonance Ionization SNMS - MAD Mixed Acid Droplet (cf. ADD, VPD, WSSD) - MAKYOH magic mirror optical surface reflection method (Jpn.) - Mb megabit, quantum of digital unit of information, number of memory addresses of a microchip, 4 Mb is about the information capacity of 250 pages/DIN A4 - ME Monochromatic Ellipsometry - MOR Modulated Optical Reflectance - MOS MetalOxide Semiconductor (transistor) - NRA Nuclear Reaction Analysis - NRIS NonResonant Ionization Spectroscopy - OF Orientation Flat to position Si wafers due crystal orientation - OM Optical Microscopy (usually differential interference/phase contrast Nomarski microscopy) - MOS-CAP/TAU Metal Oxide Semiconductor Capacitance/generation lifetime test for minority carrier - OSF hermal Oxidation-induced Stacking Fault in monocrystalline Si [31] - -PCD Microwawe reflection Photo Conductive Decay - PAM PhotoAcoustic Microscopy - PAS Positron Annihilation Spectroscopy - PCMS Plasma Chromatography Mass Spectroscopy - PC-SIMS Polyencapsulation Secondary Ion Mass Spectroscopy - PET Puddle Etch Test (HF/HNO₃-dissolution of 10 mm spots on as-sliced, as-lapped, as-etched wafers, [43]) - PFZ Precipitation Free Zone (cf. DZ) - PIXE Particle Induced X-ray Emission - PL PhotoLuminescence - POD Power Of Detection (LOD with real sample matrices, [14]) - 4-PP 4-Point Probe - PSI Phase Shift Interferometry - PSP Protocol for Specific Purposes (defining entire measurement program) - PTF Pause Time Failure can occur between periodic refresh of the stored data (cf. DRAM) - -Raman Raman Microprobe - RBS Rutherford BackScattering (cf. ISS) - RHEED Reflection High Energy Electron Diffraction - RIS Resonant Backscattering Ion Spectroscopy - SALI Surface Analysis by Laser Ionization - SAM Scanning Auger Microprobe/Microscopy - Schimmel etch defect/preferential etching for Si(100) [79] - Secco etch defect/preferential etching for Si(100) [79] - SEM Scanning Electron Microscopy - SERS Surface-Enhanced Raman Spectroscopy - SIMS Secondary Ion Mass Spectroscopy - SIRIS Sputter Initiated Resonant Ionization Spectroscopy - SIRM Scanning InfraRed Microscopy - Sirtl etch defect/preferential etching for Si(111) [79] - SOM-DPC Scanning Opt. Micr. Differential Phase Contrast - SNMS Sputtered Neutral Mass Spectroscopy - SOP Standard Operation Procedure (defining sampling and measurement process) - SPC Statistical Process Control - SPM Scanning Photon Microscope - SPV Surface Photo-Voltage - SRP Spreading Resistance Profiling - SSD Solid State Detector or Device - STM Scanning Tunneling Microscopy - S-ULSI Super-Ultra Scale Integration (Density)=16 Mb - SXES Soft X-ray Emission Spectroscopy - TCS Total Customer Satisfaction, the hotly pursued goal of all vendors of industrial goods - TDS Thermal Desorption Spectroscopy - TDBD Time Dependent Break-Down voltage - TDDB Time Dependent Dielectric Break-down voltage - TPD Temperature-Programmed Desorption - TEG haze test according to Telefunken Electronic Ges (cf. Graff-test) - TEM Transmission Electron Microscopy - TOF-SIMS Time of Flight Secondary Ion Mass Spectroscopy - TQM Total Quality Management - TTV Total Thickness Variation - TXRF Total Reflection X-Ray Fluorescence [80] - TREX Total Reflection Energy Dispersive X-ray fluorescence - ULSI Ultra-Large Scale Integration (Density)=4 Mb - UPS Ultraviolet Photoelectron Spectroscopy - US UltraSonic - VLSI Very Large Scale Integration (Density)=1 Mb - VPD Vapor Phase Decomposition (vapor phase reaction of HF with native Si-oxide and scanning the surface with a UPW or H₂O₂ solution droplet [38, 53], cf. ADD, MAD, WSSD) - Wright etch defect/preferential etching for Si(100) and Si(111) [79] - WSA Wafer Surface Analysis - WSSD Wafer Surface Scanner Device (automated VPD) - XPS X-ray Photoelectron Spectroscopy - XRD X-ray Diffraction - XRF X-ray Fluorescence - XRT X-ray Topography - XTEM X-ray Transmission Electron Microscopy     

A new evaporation procedure for monitoring of iodine-125 in liquid waste

A simplified monitoring method of 125I in liquid waste was devised. The waste water of 200 cm3 was taken on a Saran (polyvinylidene chloride) film covering a stainless steel vat. A stable iodine (20 mg) and sodium hydroxide (1 mmol) was added. The water was evaporated using an infra-red lamp. After heating to dryness, the Saran film was folded and transferred into a polyethylene tube. The radioactivity of 125I was counted with a well type NaI(Tl) scintillation counter. When a multi-channel analyzer was available for counting, an absolute decay rate of 125I was calculated with single and sum photo-peak counts. The radioactivity of 125I counted by a single-channel counter must be corrected with the counting efficiency of about 55%, with a special emphasis of a self absorption of photons. The recovery of 125I for concentrations below the permissible level was more than 98%.     

Improved calorimetric procedure for monitoring the approach to thermodynamic equilibrium in glassy polymers

Techniques for measuring the enthalpy change during isothermal aging of polymer glasses are discussed. Critical analysis of conventional scanning calorimetry reveals that its accuracy may be suspect under certain circumstances due to the thermal lag inherent in a temperature scanning experiment. An additional problem is that the conventional technique is restricted to certain kinds of paths for reaching the aging temperature. It is proposed that both problems can be overcome by analyzing the output of a scanning calorimeter not only during steady heating but also during the transients at the beginning and end of a heating scan. This data analysis method represents an extension of a method used previously by others in accurate measurements of the much larger heat of fusion of crystalline polymers. Practical feasibility of the improved technique is demonstrated by preliminary measurements of enthalpy relaxation during aging of well-characterized polystyrene at 80°C. In particular, the initial departure from equilibrium of a glass prepared by 5°C/min cooling from the liquid state is found to be 6.9 ± 0.6 J/g. This measured value agrees with a value calculated on the basis of the glass transition temperature corresponding to 5°C/min cooling and heat-capacity data from the literature.     

High-performance liquid chromatographic procedure for routine residue monitoring of seven sulfonamides in milk

A simplified method for routine monitoring of 7 residual sulfonamides (SAs) (sulfadiazine (SDZ), sulfamerazine (SMR), sulfadimidine (SDD), sulfamonomethoxine (SMM), sulfamethoxazole (SMX), sulfadimethoxine (SDM), and sulfaquinoxaline (SQ)) in milk using high-performance liquid chromatography (HPLC) with a photodiode array detector is described. The spiked and blank samples were cleaned up by using an Ultrafree-MC/PL centrifugal ultrafiltration unit. For determination/identification, a Mightysil RP-4 GP column and a mobile phase of 25% (v/v) ethanol in water with a photodiode array detector were used. Average recoveries from milk samples spiked with 0.05, 0.1, 0.2, and 0.5 microg mL(-1) of each drug were >82%. The inter- and intra-assay variabilities were 2.0-3.1%. The practical detection limits for 7 SAs were 0.005-0.02 microg mL(-1). The total time and amount of solvent required for the analysis of one sample were <40 min and <6 mL of ethanol, respectively. No toxic solvents were used.     

Simplified determining procedure for routine residue monitoring of sulphamethazine and sulphadimethoxine in milk

A simplified determining/identifying method for residual sulphamethazine (SMZ) and sulphadimethoxine (SDM) in milk by using a high-performance liquid chromatography (HPLC) with a photo-diode array detector was presented. Both sulphonamides in cow's milk samples were extracted by only stirring with ethanol followed by an Ultrafree-MC/Biomax as a centrifugal ultra-filtration unit. For determination/identification of SMZ and SDM, a Mightysil RP-18 GP Aqua column and a mobile phase of 25% (v/v) ethanol solution (in water) with a photo-diode array detector was used. Average recoveries from spiked SMZ and SDM (10-1000 ng/ml each drug) were > or = 83% with the relative standard deviations between 1.4 and 3.7%. The limit of quantitation (LOQ) were calculated to be 5 ng/ml for SMZ and 10 ng/ml for SDM, respectively. The values were below the MRL/tolerance (SMZ, 25 ng/ml; SDM, 10 ng/ml). The total time and solvent required for the analysis of one sample were <35 min and <2 ml of only ethanol, respectively. No toxic solvents were used. The developed procedure was harmless to the human and environment.     

Polymer microspheres for replacement of biological carriers in test systems operating on the principle of latex agglutination reaction

The results of the study of various modification methods of polymer microspheres for their use in immunochemical reactions as bioligand carriers are reported. Ion etching and electron microscopy were used to show that the copolymer microspheres have a porous structure non-uniform in density. The Maillard reaction was used for the first time in the modification of copolymer microspheres by dextrans of different molecular weight as a simplest way of covalent immobilization of saccharides on their surface. The physicochemical properties of polystyrene-divinylbenzene and polyglycidyl methacrylate-ethylene glycol dimethacrylate microspheres modified with diamines and dextrans were determined for the first time. The conditions under which the bioligand (diphtheria toxoid) immobilized on their surface retained the native conformation and the diagnostics obtained on their basis have high sensitivity were revealed.

     

2,3,7-Trihydroxyfluorones immobilized on cellulose matrices in test methods for determining rare elements

It was shown that 2,3,7-trihydroxyfluorones immobilized by adsorption on cellulose matrices can be used as reagents for the test determination of Mo(VI), Ti(IV), Ge(IV), Hf(IV), Nb(V), Ta(V), W(VI), Bi(III), V(IV), and Zr(IV). The change of the protolytic and complexing properties of trihydroxyfluorones immobilized on cellulose matrices was considered in comparison to corresponding properties in a solution. It was found that the reactions of trihydroxyfluorones with rare elements on cellulose matrices and in a solution exhibit similar effects upon the addition of cetylpyridinium. These effects are the bathochromic shift of the absorption maxima of the reagents and their complexes with analytes and the extension of the range of optimum acidity for complex formation. The complexation of salicylfluorones with the titanium(IV) in solution and on cellulose paper was studied by IR spectrometry. Phenylfluorone immobilized on a mixed-fiber cloth as used in test determinations of (mg/L) 0.05–5 Ti(IV), V(IV), Hf(IV), Nb(V), and Mo(VI); 0.01–5 Ge(IV) and Zr(IV); 0.05–1 Bi(III) and W(VI); and 0.1–5 Ta(V) by the color intensity of the indicator matrix after passing through 20 mL of a test solution. It was shown that phenylfluorone immobilized on cellulose paper can be used to determine (mg/L) 0.05–50 Ti(IV), 0.5–1000 Ge(IV), 0.5–500 Zr(IV), 5–200 Bi(III), 0.1–50 Mo(VI), 0.1–1000 V(IV), 0.1–100 Nb(V), 0.1–800 Hf(IV), 1–100 Ta(V), and 1–800 W(VI) by the length of the colored zone of a test strip after it was brought into contact with a test solution.     

A test for monitoring traces of cholinesterase inhibitors in surface waters

Summary The inhibitory effect on cholinesterase activity is the only common attribute of organophosphorus pesticides and carbamates. Therefore a screening test based on cholinesterase assay is suitable for detection of total pesticides in the pollution control of surface waters. The reaction-rate cholinesterase assay in which acetylthiocholine iodide is used as substrate and 5,5-dithio-bis (2-nitrobenzoic acid) (Ellman's reagent) as indicator, with spectrophotometric monitoring at 412 nm for 2 min is applied. The detection limits for various pesticides in aqueous solutions have been determined. The results are comparable to those of gas Chromatographic analyses and for carbamates are even better. The sensitivity can be improved by two orders of magnitude by preconcentration on Amberlite XAD-4 column. The collection efficiency of about 80% for all the pesticides tested has been confirmed by gas chromatography. A rapid and simple field test is based on the same assay system. The reaction is stopped by complete inhibition of the enzyme and the colour is compared visually with that of standards prepared by dilution of the initial enzyme solution, and the comparison is facilitated by use of a red filter (_max 555 nm). A relative standard deviation of 5.5% was obtained for 3 series of sample covering the range 0–100% inhibition, 9 experiments done by 6 persons.

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Nachweis von Spuren Cholinesterase hemmender Faktoren in Oberflächenwässern

Zusammenfassung Der hemmende Effekt gegenüber Cholinesterase ist das einzige gemeinsame Kennzeichen phosphor-organischer Pestizide und Carbamate. Der Nachweis mit Cholinesterase eignet sich daher für den Nachweis von Pestiziden bei der Reinheitskontrolle von Oberflächengewässern. Der Nachweis mit Acetylthiocholinjodid als Substrat und 5,5-Dithio-bis(2-nitrobenzoe-säure) (Ellmans Reagens) als Indikator durch spektrophotometrische Bestimmung bei 412 nm wurde angewendet. Die Erfassungsgrenzen für verschiedene Pestizide in wäßriger Lösung wurden bestimmt. Die Ergebnisse sind mit denen gaschromatographischer Analysen vergleichbar, für Carbamate sogar besser. Die Empfindlichkeit kann durch Anreicherung mit Amberlit XAD-4 um zwei Größenordnungen verbessert werden. Die Anreicherung um ungefähr 80% wurde gaschromatographisch für alle untersuchten Pestizide bestätigt. Ein schneller und einfacher Feldversuch beruht auf demselben Reaktionsvorgang. Die Reaktion wird durch vollständige Hemmung des Enzyms abgebrochen und die Farbe visuell verglichen mit verdünnten Standardlösungen der ursprünglichen Enzymlösung. Dieser Vergleich wird durch ein Rotfilter (_max 555 nm) erleichtert. Eine relative Standardabweichung von 5,5% wurde für 3 Probenreihen mit einem Hemmungseffekt von 0–100% erhalten, wobei 6 Personen 9 Versuche durchführten.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Analytical methods for monitoring contaminants in food—An industrial perspective

Incoming legislation on the registration, evaluation, authorisation and restriction of chemical substances places responsibility on the chemical industry, including downstream users of chemicals, to provide appropriate safety information with which to improve the protection of human health and the environment through the better and earlier identification of the intrinsic properties of chemical substances. Food consumption is only one of several potential exposure routes, but if industrial chemicals enter the food chain, the diet may be a significant pathway of human exposure. Consequently strong measures are taken to protect the integrity of the human food chain and these are constantly revised to address perceived chemical safety threats. In order to understand the risk presented by the possible presence of a chemical residue in food, knowledge is required of its toxicology and of the level of exposure. Reliable exposure assessment requires robust analytical methodology. Existing standards for the validation and performance evaluation of methods have led to improved analytical capability and better inter-laboratory agreement of results. However, increasing the availability of robust, cost-effective methodology should be the benchmark for future developments in the field of food chemical residue analysis. Chromatography meets the needs of target analyses well and largely provides the selectivity of measurement needed to assess compliance with food regulatory limits. However, to keep pace with the increased need for expanded analytical capability – faster throughput, more analytes per sample – chromatographic separation capability still needs to grow. In this respect, orthogonal separation techniques and multi-dimensional chromatography are key tools for the future.     

Determining the procedure for routine residue monitoring of sulfamethazine in edible animal tissues.

A simplified method to determine/identify residual sulfamethazine (SMZ) in edible tissues from cattle, pigs, chickens and sheep by a high-performance liquid chromatography (HPLC) with a photo-diode array detector is presented. The sample preparation was performed by homogenizing with 30% (v/v) ethanol in water followed by an Ultrafree-MC/PL as a centrifugal ultra-filtration unit. For determination/identification of SMZ, a reversed-phase C(4) column and a mobile phase of 15% (v/v) ethanol in water with a photo-diode array detector was used. Average recoveries from spiked SMZ (0.1-1.0 mg kg(-1)) were >or=80% with coefficients of variation between 1.3 and 4.3%. The limits of quantitation were calculated to be 0.057-0.060 mg kg(-1). The total time and solvent required for the analysis of one sample were <40 min and <2 mL of ethanol, respectively.     

Standardization on stanag test methods for ease of compatibility and thermal studies

MDF cements using the blends of sulfoaluminate ferrite belite (SAFB) clinkers and ordinary Portland cement (OPC) in mass ratio 85:15 with Al₂O₃, and starch, polyphosphate (poly-P) or butylacrylate/acrylonitrile were subjected to moist atmospheres (ambient, 52 and 100% relative humidity (RH)) to investigate their moisture resistance. Their chemical, thermal, electron microscopic and magnetic properties were also studied before and after moisture attack. Butylacrylate/acrylonitrile (BA/AN) copolymer was found to be the most suitable for MDF cement synthesis since the sample containing BA/AN showed the best moisture resistant. There are significant differences in scanning electron microscopy (SEM) of MDF cements before and after moisture attack and with different polymers. New data on the paramagnetic nonhysteresis magnetization curves for all the samples are observed. The MDF cements synthesized from SAFB clinker with dissolved poly-P give the best signal/noise (S/N) ratio. Three main temperature regions on TG curves of both series of MDF cements are observed. In the inter-phase section of MDF cements, the content of classical cement hydrates decomposing by 250°C is increased. Combustion of organic material took place by 550°C. In the temperature range 550-800°C, the decomposition of CaCO₃ occurs.     

A statistical procedure for the assessment of bias in analytical methods using conditional probabilities

Accreditation and Quality Assurance - A new approach is described for the simultaneous treatment of bias and imprecision in clinical chemistry. The approach makes use of the general law of...     

Adsorption-spectrometric and test methods for determining perchlorate ions with thionine on polyurethane foam

Conditions were studied for the extraction of perchlorates from water by the adsorption of their ion associate with the thionine dye on polyurethane foam. The adsorption properties of polyurethane foam were studied by measuring the diffuse reflectance of perchlorate ion associates with thionine adsorbed on pellets of this material. The use and performance characteristics of procedures were studied for the extraction-photometric (to 0.05 mg/L), adsorption-spectrometric (to 1.5 mg/L), and semiquantitative visual test (to 2 mg/L) determination of perchlorates in natural water.     

Plates for thin-layer chromatography with adsorption-immobilized reagents in chemical test analysis methods

The use of plates for thin-layer chromatography (TLC) with adsorption-immobilized organic reagents in chemical test methods for analysis is considered. Triarylmethane, triazine, eirodine, acridine, and rhodamine dyes are used for immobilization. The degree of retention of the reagents is 52–98%. It is found that the absorption spectra of these reagents on TLC plates exhibit a hypsochromic shift of absorption bands by 8–30 nm in comparison with their absorption spectra in solutions. The retention is higher for the reagents that exhibit a hypsochromic shift of absorption bands on TLC plates. The sorption isotherms of the reagents on TLC plates are obtained and analyzed. Test methods have been developed for the determination of 1–200 mg/L Au(III) and 0.1–5 M acids and alkalies with the use of reagent TLC plates. The relative standard deviation of the results of analysis is no larger than 10%; the time of analysis is 3–7 min.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 291–296.Original Russian Text Copyright © 2005 by Amelin, Tretyakov.     

Development of an SPME-GC-MS/MS procedure for the monitoring of 2-phenoxyethanol in anaesthetised fish

2-Phenoxyethanol (ethylene glycol monophenyl ether, C(8)H(10)O(2)) is a promising anaesthetic agent used in fisheries and aquaculture. The aim of this study was to develop a fast and easy method to determine 2-phenoxyethanol residue levels in fish tissue and blood plasma, and, subsequently, to use the method to monitor the dynamics of 2-phenoxyethanol residues in fish treated with anaesthetic. We developed a new procedure that employs solid phase microextraction (SPME) of the target analyte from the sample headspace followed by gas chromatography-mass spectrometry (GC-MS). Both sample handling, aimed at maximum transfer of 2-phenoxyethanol into the headspace, and SPME-GC-MS conditions were carefully optimised. Using a divinylbenzene/Carboxen/polydimethylsiloxane (PDMS/CAR/DVB) fiber for 60 min sampling at 30 degrees C and an ion trap detector operated in MS/MS mode, we obtained detection (LOD) and quantification (LOQ) limits of 0.03 and 0.1 mg kg(-1) of sample, respectively. The method was linear in a range of 0.1-250 mg kg(-1) and, depending on the sample matrix and spiking level, a repeatability (expressed as relative standard deviation, R.S.D.) of between 3% and 11% was obtained.