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1.
A statistical analysis of multi-point calibration procedure for practical measurement of pH under laboratory conditions is
given. The procedure is shown to provide the necessary elements for simple assignment of an uncertainty to a pH measurement
– an essential element of quality control. Performance of ordinary least squares regression for prediction of confidence limits
is compared to orthogonal regression, inverse regression and Monte Carlo simulations. In case of pH measurement by multi-point
calibration procedure, methods considering uncertainties in both axes are found to be statistically more satisfactory than
ordinary least squares regression. By analysis of 50 pH calibration data, randomly selected from 250 5-point glass electrode
calibrations, it is found that the practical differences, however, are of minor importance. The significance of uncertainty
in pH is demonstrated for an example from metal ion speciation in aqueous solution.
Received September 20, 1999. Revision April 19, 2000. 相似文献
2.
Penka Shegunova Ofelia Bercaru Berit Sejerøe-Olsen 《Accreditation and quality assurance》2008,13(1):11-18
Estimation of measurement uncertainty has become a more regularly performed part of the whole analytical process. However,
there is still much on-going discussion in the scientific community about ways of building up the uncertainty budget. This
study describes two approaches for estimation of measurement uncertainty in organic analysis: one which can be used for single
sets of measurements and the other based on validation studies. In both cases the main contributions to the uncertainty are
presented and discussed for the analysis of PCBs in mussel tissue, but the approaches can be extended to other organic pollutants
in environmental/food samples. The main contributions to the uncertainty budget arise from calibration, sample preparation,
and GC–MS measurements. A comparison of the relevant sources and their contributions to the expanded uncertainty is presented. 相似文献
3.
Aguinaga N Campillo N Viñas P Hernández-Córdoba M 《Analytical and bioanalytical chemistry》2008,391(4):1419-1424
This paper describes a headspace solid-phase microextraction (HS-SPME) procedure coupled to gas chromatography with mass spectrometric
detection (GC–MS) for the determination of eight PAHs in aquatic species. The influence of various parameters on the PAH extraction
efficiency was carefully examined. At 75 °C and for an extraction time of 60 min, a polydimethylsiloxane–divinylbenzene (PDMS/DVB)
fiber coating was found to be most suitable. Under the optimized conditions, detection limits ranged from 8 to 450 pg g−1, depending on the compound and the sample matrix. The repeatability varied between 7 and 15% (RSD). Accuracy was tested using
the NIST SRM 1974b reference material. The method was successfully applied to different samples, and the studied PAHs were
detected in several of the samples.
Figure Headspace SPME sampling followed by GC–MS facilitates routine monitoring of PAHs in aquatic species 相似文献
4.
Mol HG Rooseboom A van Dam R Roding M Arondeus K Sunarto S 《Analytical and bioanalytical chemistry》2007,389(6):1715-1754
The ethyl acetate-based multi-residue method for determination of pesticide residues in produce has been modified for gas
chromatographic (GC) analysis by implementation of dispersive solid-phase extraction (using primary–secondary amine and graphitized
carbon black) and large-volume (20 μL) injection. The same extract, before clean-up and after a change of solvent, was also
analyzed by liquid chromatography with tandem mass spectrometry (LC–MS–MS). All aspects related to sample preparation were
re-assessed with regard to ease and speed of the analysis. The principle of the extraction procedure (solvent, salt) was not
changed, to avoid the possibility invalidating data acquired over past decades. The modifications were made with techniques
currently commonly applied in routine laboratories, GC–MS and LC–MS–MS, in mind. The modified method enables processing (from
homogenization until final extracts for both GC and LC) of 30 samples per eight hours per person. Limits of quantification
(LOQs) of 0.01 mg kg−1 were achieved with both GC–MS (full-scan acquisition, 10 mg matrix equivalent injected) and LC–MS–MS (2 mg injected) for
most of the pesticides. Validation data for 341 pesticides and degradation products are presented. A compilation of analytical
quality-control data for pesticides routinely analyzed by GC–MS (135 compounds) and LC–MS–MS (136 compounds) in over 100 different
matrices, obtained over a period of 15 months, are also presented and discussed. At the 0.05 mg kg−1 level acceptable recoveries were obtained for 93% (GC–MS) and 92% (LC–MS–MS) of pesticide–matrix combinations. 相似文献
5.
Florent Lafay Emmanuelle Vulliet Marie-Magdeleine Flament-Waton 《Analytical and bioanalytical chemistry》2010,396(2):937-941
A simple, rapid, sensitive, and non-consuming solvent method for the determination of cotinine in urine was developed, based
on sample preparation by the relatively new technique microextraction in packed sorbent (MEPS) and analysis by GC–MS. This
optimized method was compared with conventional solid-phase extraction/liquid–liquid extraction method used as reference.
The wide linear range (5–5,000 ng/mL) and high sensitivity of the MEPS method (limit of detection 0.8 ng/mL) allow application
to analysis of urine from smokers as well as non-smokers susceptible to passive smoking. 相似文献
6.
Delhomme O Raeppel C Teigné D Briand O Millet M 《Analytical and bioanalytical chemistry》2011,399(3):1325-1334
To measure dermal exposure of a non-agricultural occupationally exposed population to pesticides, a new method has been developed
for analysis of 13 pesticides from different classes (fungicides, herbicides, insecticides) on dermal patches. The method
includes extraction of the patches and analysis of the pesticides by GC–MS and/or HPLC–fluorescence. Water-soluble pesticides
(glyphosate and glufosinate) on patches were ultrasonically extracted twice with ultra-pure water for 10 min and analysed
by HPLC–fluorescence after derivatisation with FMOC. Organic-soluble pesticides (bifenthrin, cyprodinil, difufenicanil, fludioxonil,
oxadiazon, pyriproxyfen, clopyralid, 2,4-D, fluroxypyr, 2,4-MCPA, and triclopyr) were extracted ultrasonically twice for 10 min
with 70:30 dichloromethane–acetonitrile and analysed by GC–MS directly or after derivatisation with N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide. Detection limits varied between 3 and 4 μg L−1 for water-soluble pesticides and between 1 and 10 μg L−1 for organic-soluble pesticides. 相似文献
7.
Sturgeon RE Wahlen R Brandsch T Fairman B Wolf-Briche C Alonso JI González PR Encinar JR Sanz-Medel A Inagaki K Takatsu A Lalere B Monperrus M Zuloaga O Krupp E Amouroux D Donard OF Schimmel H Sejerøe-Olsen B Konieczka P Schultze P Taylor P Hearn R Mackay L Myors R Win T Liebich A Philipp R Yang L Willie S 《Analytical and bioanalytical chemistry》2003,376(6):780-787
The capabilities of National Metrology Institutes (NMIs—those which are members of the Comité Consultatif pour la Quantité de Matière (CCQM)of the CIPM) and selected outside "expert" laboratories to quantitate (C4H9)3Sn+ (TBT) in a prepared marine sediment were assessed. This exercise was sanctioned by the 7th CCQM meeting, April 4–6, 2001, as an activity of the Inorganic Analysis Working Group and was jointly piloted by the Institute for National Measurement Standards of the National Research Council of Canada (NRC) and the Laboratory of the Government Chemist (LGC), UK. A total of 11 laboratories submitted results (7 NMIs, and 4 external labs). Two external laboratories utilized a standard calibration approach based on a natural abundance TBT standard, whereas all NMIs relied upon isotope dilution mass spectrometry for quantitation. For this purpose, a species specific 117Sn-enriched TBT standard was supplied by the LGC. No sample preparation methodology was prescribed by the piloting laboratories and, by consequence, a variety of approaches was adopted by the participants, including mechanical shaking, sonication, accelerated solvent extraction, microwave assisted extraction and heating in combination with Grignard derivatization, ethylation and direct sampling. Detection techniques included ICP–MS (with GC and HPLC sample introduction), GC–MS, GC–AED and GC–FPD. Recovery of TBT from a control standard (NRCC CRM PACS-2 marine sediment) averaged 93.5±2.4% (n=14). Results for the pilot material averaged 0.680±0.015 µmol kg–1 (n=14; 80.7±1.8 µg kg–1) with a median value of 0.676 µmol kg–1. Overall, performance was substantially better than state-of-the-art expectations and the satisfactory agreement amongst participants permitted scheduling of a follow-up Key comparison for TBT (K-28), a Pilot intercomparison for DBT (P-43), and certification of the test sediment for TBT content and its release as a new Certified Reference Material (HIPA-1) with a TBT content of 0.679±0.089 µmol kg–1 (expanded uncertainty, k=2, as Sn) (80.5±10.6 µg kg–1).Electronic Supplementary Material Supplementary material is available in the online version of this article at . 相似文献
8.
Naumann R Alexander-Weber Ch Eberhardt R Giera J Spitzer P 《Analytical and bioanalytical chemistry》2002,374(5):778-786
Routine pH measurements are carried out with pH meter-glass electrode assemblies. In most cases the glass and reference electrodes are thereby fashioned into a single probe, the so-called 'combination electrode' or simply 'the pH electrode'. The use of these electrodes is subject to various effects, described below, producing uncertainties of unknown magnitude. Therefore, the measurement of pH of a sample requires a suitable calibration by certified standard buffer solutions (CRMs) traceable to primary pH standards. The procedures in use are based on calibrations at one point, at two points bracketing the sample pH and at a series of points, the so-called multi-point calibration. The multi-point calibration (MPC) is recommended if minimum uncertainty and maximum consistency are required over a wide range of unknown pH values. Details of uncertainty computations for the two-point and MPC procedure are given. Furthermore, the multi-point calibration is a useful tool to characterise the performance of pH electrodes. This is demonstrated with different commercial pH electrodes. ELECTRONIC SUPPLEMENTARY MATERIAL is available if you access this article at http://dx.doi.org/10.1007/s00216-002-1506-5. On that page (frame on the left side), a link takes you directly to the supplementary material. 相似文献
9.
Assessment of commutability for candidate certified reference material ERM-BB130 “chloramphenicol in pork” 总被引:1,自引:0,他引:1
Reinhard Zeleny Håkan Emteborg Heinz Schimmel 《Analytical and bioanalytical chemistry》2010,398(3):1457-1465
Chloramphenicol (CAP), an effective antibiotic against many microorganisms, is meanwhile banned in the EU for treatment of
food-producing animals due to adverse health effects. The Institute for Reference Materials and Measurements (IRMM) is currently
developing a certified reference material (CRM) for CAP in pork, intended for validation and method performance verifications
of analytical methods. The material will be certified using liquid chromatography–tandem mass spectrometry (LC–MS/MS) and
gas chromatography–mass spectrometry (GC–MS) methods and has a target CAP level around the minimum required performance limit
(MRPL) of 0.3 μg/kg. To prove that the material can be applied as a quality control tool for screening methods, a commutability
study was conducted, involving five commercially available enzyme-linked immunosorbent assay kits and one biosensor assay
(BiaCore kit). Meat homogenates (cryo-milled wet tissue) with CAP concentrations around the MRPL and the candidate CRM (lyophilised
powder) were measured by LC–MS/MS and GC–MS as well as the six screening methods. Pairwise method comparisons of results obtained
for the two sample types showed that the CRM can successfully be applied as quality control (QC) sample to all six screening
methods. The study suggests that ERM-BB130 is sufficiently commutable with the investigated assays and that laboratories applying
one of the investigated kits therefore benefit from using ERM-BB130 to demonstrate the correctness of their results. However,
differences among the assays were observed, either in the abundance of bias between screening and confirmatory LC and GC methods,
the repeatability of test results, or goodness of fit between the methods. 相似文献
10.
A new electro solid-phase microextraction (El-SPME) technique using homemade pencil-lead fibers has been developed as an effective
means of selective extraction of methamphetamine before analysis by gas chromatography (GC) and gas chromatography–mass spectrometry
(GC–MS). The methamphetamine was extracted by use of a laboratory-made El-SPME cell with three electrodes—the pencil-lead
SPME fiber, Ag/AgCl, and platinum as working, reference, and auxiliary electrodes, respectively. A negative potential was
applied to the homemade pencil-lead fiber during extraction. Experimental conditions, for example type of pencil-lead fiber,
conditions for modification of the fiber, extraction time, applied potential, pH, and gas chromatographic conditions were
optimized. Methamphetamine was identified by GC–MS. Screening of the extracted compounds showed that the proposed El-SPME
technique is much more selective than direct SPME using a commercially available polyacrylate fiber. Under the optimum conditions
the calibration plot for the compound was linear in the range 50–3,200 ng mL−1 and the detection limit was 34 ng mL−1. 相似文献
11.
The significance of forensic arson analysis accelerates the applications of new technologies in this area. Based on the previously
reported application of differential mobility spectrometry (DMS) as a detection method for gas chromatography (GC) in arson
analysis, the performances of DMS and mass spectrometry (MS) were compared using a novel chemometric tool, projected difference
resolutions (PDRs). The PDR results show that one-way mass spectra data exhibit higher resolution than DMS data, while total
ion chromatograms from GC–DMS show higher resolution than that from GC/MS for differentiating seven kinds of ignitable liquids.
Combining the information from both chromatography and spectra, two-way data always have higher resolution than one-way data
for these two detection methods, and GC/MS would exhibit better performance than GC–DMS according to the minimum resolution
value. To verify the PDR results, a fuzzy rule-building expert system was applied for classifying these seven kinds of ignitable
liquids from fire debris based on GC–DMS and GC/MS data, respectively. The prediction accuracies were consistent with PDR
results, which proved that PDR is a powerful tool in comparing the performances of different analysis methods for pattern
recognition.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Applications of LC/ESI-MS/MS and UHPLC QqTOF MS for the determination of 148 pesticides in fruits and vegetables 总被引:1,自引:0,他引:1
This paper presented the applications of liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS)
and ultra-high-pressure liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC QqTOF
MS) for the determination of 148 pesticides in fruits and vegetables. Pesticides were extracted from fruits and vegetables
using a buffered QuEChERS method. Quantification was achieved using matrix-matched standard calibration curves with isotopically
labeled standards or a chemical analog as internal standards in an analytical range from 5 to 500 μg/kg. The method performance
parameters including overall recovery, intermediate precision, and measurement uncertainty were evaluated according to a statistically
designed experiment, i.e., a nested design. For LC/ESI-MS/MS, 95% of the pesticides had recoveries between 81% and 110%; 97%
had an intermediate precision ≤20%; and 95% (in fruits) or 93% (in vegetables) showed measurement uncertainty ≤40%. Compared
to LC/ESI-MS/MS, UHPLC QqTOF MS showed a relatively poor repeatability and large measurement uncertainty. About 93% (in fruits)
or 94% (in vegetables) of the pesticides had recoveries between 81% and 110%; 86% (in fruits) or 90% (in vegetables) had an
intermediate precision ≤20%; and 79% (in fruits) or 88% (in vegetables) showed measurement uncertainty ≤40%. LC/ESI-MS/MS
proved to be the first choice for quantification or pre-target analysis due to its superior sensitivity and good repeatability.
UHPLC QqTOF MS provided accurate mass measurement and isotopic patterns, and was an ideal tool for post-target screening and
confirmation. 相似文献
13.
Jakubowska N Polkowska Z Kujawski W Konieczka P Namieśnik J 《Analytical and bioanalytical chemistry》2007,388(3):691-698
The analysis of volatile organic compounds in samples of biological fluids characterized by complex matrices is highly challenging.
This paper presents a comparison of the results obtained in this field using three solvent-free techniques: thin-layer headspace
with autogenous generation of liquid sorbent (TLHS) and membrane separation of the trace substances (pervaporation, PV), both
of which are coupled to direct aqueous injection gas chromatography–electron capture detection (TLHS–DAI–GC–ECD and PV–DAI–GC–ECD),
as well as conventional static headspace analysis followed by GC analysis with ECD detection (HS–GC–ECD). Basic validation
parameters of the HS–GC–ECD, TLHS–DAI–GC–ECD and PV–DAI–GC–ECD procedures were calculated for water and urine samples. The
calibration curves for all procedures were linear within the concentration range examined. The intermediate precisions of
the procedures were good and reached about 10% (for all analytes) for HS–GC–ECD and TLHS–DAI–GC–ECD. The poorest results were
obtained for PV–DAI–GC–ECD: about 20% for all analytes. The lowest method detection limits were obtained for the TLHS–DAI–GC–ECD
procedure: below 0.0022 μg/L for all analytes. The enrichment factors did not differ significantly between water and urine
samples, indicating little or no matrix effect in all procedures. 相似文献
14.
Krystyna Srogi 《Mikrochimica acta》2006,154(3-4):191-212
This article reviews the analysis of drugs and drug metabolites in hair by chromatographic procedures, including the pretreatment
steps, and the extraction methods. The general tendency in the last years, to highly sophisticated techniques (GC–MS–NCI,
HPLC–MS, GC–MS–MS) illustrates the constant fight for sensitivity. 相似文献
15.
An efficient microwave-assisted extraction (MAE) procedure coupled to gas chromatography–mass spectrometry (GC–MS) with electron
impact (EI) and chemical ionization (CI) has been developed to determine five organophosphate flame retardants (OPFRs) in
marine and river sediments. The effects of various operating parameters on the quantitative extraction of the OPFRs through
MAE were systematically investigated. Selected OPFRs were extracted from the sediments through MAE using 40 mL of acetone
at 120 °C for 20 min. The limits of quantitation ranged from 0.1 to 0.4 ng/g (dry weight) in 2 g of the sediment samples.
Moreover, as the chlorinated alkyl phosphates present no molecular ions in EI, GC–MS with furan-CI (furan-CI) was applied
to confirm their determination in complex environmental samples. The recoveries of the selected OPFRs in spiked sediment samples
ranged from 62% to 106% (relative standard derivation, 1−11%). The total concentrations of the selected OPFR residues in marine
and river sediments ranged from 1.0 to 12.6 ng/g. 相似文献
16.
The method is based on catalysed ignition of a sample portion in a flow of oxygen, capture of mercury by an amalgamator and
measurement of the mercury vapour's absorbance after thermic release from the amalgamator. Three powdered food samples, a
certified reference material (CRM) human hair and a reference material (RM) urine (liquid) were measured in the first range
of the instrument (the possible contents determined according to our measurement procedure were 0.0003–0.5 ppm). The calibration
function used was a line passing through the origin. The combined standard uncertainties of the mercury determinations were
computed from uncertainty components of five quantities: absorbance of the sample, absorbance of the sample blank, slope of
the calibration line, correction factor of the abscissa axis, and mass or volume of the sample. The most important uncertainty
component is the uncertainty of the sample absorbance measurement which amounts to 52% of the determination uncertainty at
the minimum (RM urine) and about 90% at the maximum (in our laboratory homogenized powdered food samples; analysis of variance
showed their homogeneity to be insufficient). The results of the CRM and RM analyses do not indicate a significant systematic
error for this determination. The relative expanded uncertainty (coefficient was 2) of the determination increases from 9
to 13% for the insufficiently homogenized samples with decreasing mercury content (range of 0.004–0.03 ppm); higher homogeneity
of samples results in a decrease of the expanded uncertainty, e.g. 4.6% for the liquid sample (RM urine).
Received: 26 April 1999 / Accepted: 30 August 1999 相似文献
17.
E. Pitarch T. Portolés J. M. Marín M. Ibáñez F. Albarrán F. Hernández 《Analytical and bioanalytical chemistry》2010,397(7):2763-2776
The presence of a wide variety of organic pollutants with different physicochemical characteristics has been investigated
in wastewater samples from a municipal solid-waste-treatment plant in Castellón, Spain. An advanced analytical strategy was
applied—combined used of two powerful and complementary techniques, GC and LC, both hyphenated with tandem mass spectrometry
with triple-quadrupole analyzers. The GC–MS–MS method was based on sample extraction using C18 SPE cartridges and enabled the determination of approximately 60 compounds from different chemical families, for example
PAHs, octyl/nonylphenols, PCBs, organochlorine compounds, insecticides, herbicides, and PBDEs. Most of the compounds selected
are included as priority contaminants in the European Union (EU) Water Directive. The UHPLC–MS–MS method, which provided high
chromatographic resolution and sensitivity and short analysis time, used sample extraction with Oasis HLB SPE cartridges and
enabled the determination of 37 (more polar) pesticides. The methodology developed was applied to the analysis of 41 water
samples (20 untreated raw leachates and 21 treated samples) collected between March 2007 and February 2009. Amounts of the
contaminants investigated rarely exceeded 0.5 μg L−1 in the treated (reverse osmosis) water samples analyzed. As expected, in untreated leachates the number of compounds detected
and the concentrations found were notably higher than in treated waters. The most commonly detected pollutants were herbicides
(simazine, terbuthylazine, terbutryn, terbumeton, terbacil, and diuron), fungicides (thiabendazole and carbendazim), and 4-t-octylphenol. The results obtained proved that use of reverse osmosis for water treatment was efficient and notably reduced
the amounts of organic contaminants found in raw leachate samples. In order to investigate the presence of other non-target
contaminants, water samples were also analyzed by using GC–TOF MS and LC–QTOF MS. Several organic pollutants that did not
form a part of the previous list of target contaminants were identified in the samples, because of the high sensitivity of
TOF MS in full-spectrum acquisition mode and the valuable accurate-mass information provided by these instruments. The insecticide
diazinon, the fungicide diphenylamide, the UV filter benzophenone, N-butylbenzenesulfonamide (N-BBSA), the insect repellent diethyltoluamide, caffeine, and the pharmaceuticals erythromycin,
benzenesulfonanilide, ibuprofen, atenolol, and paracetamol were some of the compounds identified in the water samples analyzed. 相似文献
18.
Vijayakumar Sarannya Palanichamy Sivasamy Nagarajan David Mathan Thangamani Rajkumar Durairaj Ponraju Chinnaswamy Thangavel Vijayakumar 《Journal of Thermal Analysis and Calorimetry》2010,101(3):1071-1077
Bicyclic compounds containing phosphorus on their skeleton such as 2,4,6-trioxa-1-phosphabicyclo[2,2,2]octane-4-methanol phosphate
(PEPA) having three active ingredients required for intumescence have been synthesized. The structural characterization of
PEPA was carried out by FT-IR, 1H and 13C NMR. The thermal behaviour of the material was studied using TGA, TGA–MS and pyrolysis GC–MS. Thermogravimetric analysis
reveals that PEPA undergoes several stages of degradation with a char of about 12% at 800 °C. The TGA–MS studies indicate
that the material degrades with the liberation of water, formaldehyde, alkene and alcohols as the major degradation products.
Pyrolysis GC–MS results reveal that PEPA isomerizes in the acidic medium. PEPA and/or isomers of PEPA react with formaldehyde,
one of the degradation products, to form cross-linked structure and cyclic products with the elimination of water molecule.
The thermal degradation mechanisms for PEPA are presented and discussed. 相似文献
19.
A study of the performance of different uncertainty evaluation strategies among 163 voluntary respondents from food proficiency
schemes is presented. Strategies included use of: single-laboratory validation data, quality control data, past proficiency
testing data, reproducibility data, a measurement equation and the dispersion of replicate observations on the test material.
Most performed reasonably well, but the dispersion of replicate observations underestimated uncertainty by a factor of approximately
3. Intended compliance with accreditation requirements was associated with significantly improved uncertainty evaluation performance,
while intended compliance with the ISO “Guide to the expression of uncertainty in measurement” had no significant effect.
Substituting estimates based on the Horwitz or Horwitz–Thompson models or on PT target standard deviation for the respondents’
own estimates of uncertainty led to a marked reduction in poor zeta scores and significant improvement in dispersion of zeta
scores. 相似文献
20.
Ana G. Correia Ricardo J. N. Bettencourt da Silva Filipe Pedra M. João Nunes 《Accreditation and quality assurance》2014,19(2):87-97
Directive 86/278/EEC sets maximum levels of heavy metals in sewage sludge used in agriculture to regulate the risk of using these organic soil improvers. The assessment of the compliance of soil improvers with this legislation should be supported on measurements with adequately low uncertainty. This work presents a strategy for assessing the performance of the determination of aqua regia extractable Cu, Zn and Cr in organic soil improvers and urban sewage sludges following EN 13650 standard. The measurement procedure validation involves checking the adequacy of the linear weighted regression model for ICP–OES calibration, the determination of the limit of quantification, the assessment of measurement repeatability, intermediate precision and trueness, and the evaluation of the measurement uncertainty using the differential approach. Routine tests quality control, including the estimated measurement uncertainty, is checked through the analysis of control standards, equivalent to calibrators, and reference materials from proficiency tests. Since the estimated relative expanded uncertainty is smaller than the defined target value (40 %), measurements are fit for assessing compliance of the mass fraction of heavy metals in organic soil improvers with the council directive. 相似文献