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PubMed1996

In vitro susceptibility of 124 Xanthomonas maltophilia (Stenotrophomonas maltophilia) isolates: comparison of the agar dilution method with the E-test and two agar diffusion methods.

The in vitro susceptibility of 124 Xanthomonas maltophilia isolates was tested by four methods: Agar dilution (reference method), E-test, a disk diffusion and a tablet diffusion method. Trimethoprim-sulfamethoxazole had the highest activity against X. maltophilia, followed by a combination of aztreonam-clavulanic acid at different ratios, the ratio 1:1 being the most active with a susceptibility rate of 85% as compared to 2% for aztreonam alone. Addition of the beta-lactamase inhibitor tazobactam to piperacillin enhanced the rate of susceptible isolates from 31% to 53%, Relatively few isolates were susceptible to ciprofloxacin (27%) and gentamicin (9%). Generally, the disk diffusion method had a considerably higher frequency of "very major" discrepancies when compared with the agar dilution method than with the other methods. The susceptibility of X. maltophilia to trimethoprim-sulfamethoxazole and ciprofloxacin could reliably be determined by all the diffusion methods tested, but otherwise the agar dilution method is to be preferred. A standardized and reliable diffusion method for susceptibility testing of X. maltophilia remains to be found. Trimethoprim-sulfamethoxazole must be considered the drug of choice in the treatment of severe X. maltophilia infections. The combination aztreonam-clavulanic acid is promising, but must be proved in a clinical setting.

Anti-Bacterial Agents↗

PubMed1996

Radioimmunological analysis of cyproterone acetate in human serum. Comparison with a gas chromatographic/mass spectrometric method and influence of each method on the outcome of a bioequivalence trial.

Cyproterone acetate (CAS 427-51-0, CPA) is a steroid hormone with antiandrogenic and progestogenic properties, which has been used in the therapy of prostate carcinoma in men, and for the treatment of severe acne and hirsutism in women. The aim of the present study was to compare two equally sensitive analytical methods, a radioimmunoassay (RIA) and a gas chromatographic/mass spectrometric method (GC/MS), for the quantitative determination of CPA in human serum samples and to assess their suitability for bioequivalence trials. To this end, serum samples which had been collected during a study on the bioequivalence oaf two CPA-containing formulations (Androcur 100 and Androcur 50) were analysed using both methods. Basic pharmacokinetic parameters, like Cmax, tmax, t1/2 and AUC were calculated from each data set and corresponding parameters were compared by statistical methods. A comparison of the drug concentration-time curves obtained with both analytical methods revealed that in particular at later sampling times (48 to 120 h post dose) concentration values generated by RIA were slightly higher by about 20-40% than those measured with GC/MS. This indicates the presence of cross-reacting metabolite(s), most likely the 15 beta-hydroxy-cyproterone acetate. Accordingly, the values of Cmax, AUC(0-120 h) and AUC were overestimated by the RIA method by about 10-20%, 5% and 10%, respectively. However, there was a high correlation between corresponding parameters derived from RIA and GC/MS analysis. Although AUC values were slightly overestimated with the RIA method was used, this had no influence on the decision about bioequivalence because the mean ratio of the target variables Cmax and AUC was not affected. The variance of the pharmacokinetic parameters which is relevant for the bioequivalence test were even lower for RIA based values than those calculated after GC/MS analysis. In conclusion, it was found that although the GC/MS method is superior to RIA in terms of specificity, both methods were equally suited to demonstrate the bioequivalence of the two CPA-containing formulations. Thus, in future studies of this kind, the more simple RIA may be used instead of GC/MS.

Adult↗

PubMed1992

A randomized and blinded comparison of three bleeding time techniques: the Ivy method, and the Simplate II method in two directions.

We compared the Ivy bleeding time method and two alternatives of the Simplate II method (incisions in horizontal and vertical direction) with each other, with regard to the sensitivity, the specificity, the costs and the burden for the patient. In the aspirin study an aspirin-induced bleeding defect was used. Seventy-two healthy volunteers were randomized to receive either 500 mg acetylsalicylic acid (ASA) or a placebo. Double blinding was maintained throughout the study. In the anticoagulation study 62 patients participated, who received oral anticoagulants (OAC) for various reasons. All participants received two bleeding time methods. The burden for the participants of each method was screened by a small standard questionnaire. The differences in sensitivity and specificity between the three methods proved minimal. The Ivy method was more often preferred by the participants than the Simplate methods. Since a choice on the basis of sensitivity and specificity appears not possible, we prefer the Ivy method because of lower costs and less burden.

Adult↗

PubMed2003

[Advanced method for calculating the scatter signal contribution in CT detectors by the Monte Carlo method].

Multislice spiral CT scanners allow to acquire multiple slices simultaneously. With increasing numbers of slices, not only the total extent of slice collimation increases, but also the contribution of scatter radiation to the detector signal. A fast method for calculating the scatter signal would offer the possibility to correct the measured detector signal. Monte Carlo methods allow to simulate the paths of photons through a 3D volume, both in a patient- and scanner-specific fashion. If a scatter photon leaves the volume, its path can be followed and its interaction with an element of the detector be checked. This conventional way of calculating the scatter signal is time-consuming. In order to reduce the calculation time, a more efficient method was developed (Method of Weights). Every time an interaction occurs inside of the 3D volume, the probability of a detector hit due to photon scattering is calculated for each detector channel. The respective value is added to the scatter signal per detector with the corresponding weight. Simulated values of scatter-to-primary-signal ratios were confirmed by data available in the literature. Both the conventional and fast methods for the calculation of scatter signals yielded identical values within the range of statistical accuracy. Assuming the same computing time, the standard deviation for the conventional method was 5 times higher than for the fast one. The presented method allows to significantly reduce the computation time. It may therefore provide a basis for "real time" methods to correct for the scatter signal, especially in case of increasing numbers of slices.

Humans↗

PubMed2000

In vitro methods for measuring the dry matter digestibility of ruminant feedstuffs: comparison of methods and inoculum source.

We conducted this study to evaluate the new in vitro system, DAISY", to determine dry matter (DM) digestibility in ruminant feedstuffs. Results from the DAISY" were compared to those obtained by the traditional Tilly and Terry method. The traditional method buffer was used for both methods. We also compared two sources of rumen inoculum from sheep and dairy cows. Seventeen different feeds were tested, grouped into roughage, concentrate, and CP supplements. The experiment was replicated on two different occasions for all feeds and the two sources of inoculum. The source of inoculum and the time at which it was collected had no effect on the in vitro DM digestibility of the feedstuffs in either of the methods. The DAISY" DM digestibility value compared well with the traditional method values for the roughage group; however, for some feedstuffs in the concentrate and CP supplement groups, the DAISY" values were significantly higher than the traditional method values. Regression analysis of the feeds that resulted in similar values with the two methods revealed that the DAISY" method can be used to predict in vitro digestibility with relatively small variation.

Animal Feed↗

PubMed2003

Liquid chromatography/tandem mass spectrometry methods for quantitation of mevalonic acid in human plasma and urine: method validation, demonstration of using a surrogate analyte, and demonstration of unacceptable matrix effect in spite of use of a stable isotope analog internal standard.

Selective, accurate, and reproducible liquid chromatography/tandem mass spectrometry (LC/MS/MS) methods were developed and validated for the determination of mevalonic acid, an intermediate in the biosynthesis of cholesterol and therefore a useful biomarker in the development of cholesterol lowering drugs, in human plasma and urine. A hepta-deuterated analog of mevalonic acid was used as the internal standard. For both methods, calibration standards were prepared in water, instead of human plasma and urine, due to unacceptably high levels of endogenous mevalonic acid. The lower quality control (QC) samples were prepared in water while the higher QC samples were prepared in the biological matrices. For the isolation/purification of mevalonic acid from the plasma and urine matrices, the samples were first acidified to convert the acid analyte into its lactone form. For the plasma samples, the lactone analyte was retained on and then eluted off a polymeric solid-phase extraction (SPE) sorbent. For the urine method, the sample containing the lactone analyte was passed through a C-18 SPE column, which did not retain the analyte, with the subsequent analyte retention on and then elution off a polymeric SPE sorbent. Chromatographic separation was achieved isocratically on a polar-endcapped C-18 analytical column with a water/methanol mobile phase containing 0.5 mM formic acid. Detection was by negative-ion electrospray tandem mass spectrometry. The standard curve range was 0.500-20.0 ng/mL for the plasma method and 25.0-1,000 ng/mL for the urine method. Excellent accuracy and precision were obtained for both methods at all concentration levels tested. It was interesting to note that for certain batches of urine, when a larger sample volume was used for analysis, a high degree of matrix effect was observed which resulted not only in the attenuation of the absolute response, but also in a change of analyte/internal standard response ratio. This demonstrated that, under certain conditions, the use of a stable isotope analog internal standard does not, contrary to conventional thinking, guarantee the constancy of the analyte/internal response ratio, which is a prerequisite for a rugged bioanalytical method. On the other hand, under conditions where the sample matrix does not have such a deleterious effect, we have found that a stable isotope analog could serve as a surrogate (substitute) analyte. Thus, we have shown that using calibration standards prepared by spiking plasma with tri-deuterated or tetra-deuterated mevalonic acid, instead of mevalonic acid itself (the analyte), plasma QC samples that contain mevalonic acid can be successfully analyzed for the accurate and precise quantitation of mevalonic acid. The use of a surrogate analyte provides the opportunity to gauge the daily performance of the method for the low concentration levels prepared in the biological matrix, which otherwise is not achievable because of the endogenous concentrations of the analyte in the biological matrices.

Chromatography, Liquid↗

PubMed2002

A strategy for a post-method-validation use of incurred biological samples for establishing the acceptability of a liquid chromatography/tandem mass-spectrometric method for quantitation of drugs in biological samples.

Validated liquid chromatography/tandem mass spectrometric (LC/MS/MS) methods are now widely used for quantitation of drugs in post-dose (incurred) biological samples for the assessment of pharmacokinetic parameters, bioavailability and bioequivalence. In accordance with the practice currently accepted within the pharmaceutical industry and the regulatory bodies, validation of a bioanalytical LC/MS/MS method is performed using standards and quality control (QC) samples prepared by spiking the drug (the analyte) into the appropriate blank biological matrix (e.g. human plasma). The method is then declared to be adequately validated for analyzing incurred biological samples. However, unlike QC samples, incurred samples may contain an epimer or another type of isomer of the drug, such as a Z or E isomer. Such a metabolite will obviously interfere with the selected reaction monitoring (SRM) transition used for the quantitation of the drug. The incurred sample may also contain a non-isomeric metabolite having a molecular mass different from that of the drug (such an acylglucuronide metabolite) that can still contribute to (and hence interfere with) the SRM transition used for the quantitation of the drug. The potential for the SRM interference increases with the use of LC/MS/MS bioanalytical methods with very short run times (e.g. 0.5 min). In addition, a metabolite can potentially undergo degradation or conversion to revert back to the drug during the multiple steps of sample preparation that precede the introduction of the processed sample into the LC/MS/MS system. In this paper, we recommend a set of procedures to undertake with incurred samples, as soon as such samples are available, in order to establish the validity of an LC/MS/MS method for analyzing real-life samples. First, it is recommended that the stability of incurred samples be investigated 'as is' and after sample preparation. Second, it is recommended that potential SRM interference be investigated by analyzing the incurred samples using the same LC/MS/MS method but with the additional incorporation of the SRM transitions attributable to putative metabolites (multi-SRM method). The metabolites monitored will depend on the expected metabolic products of the drug, which are predictable based on the functional groups present in the chemical structure of the drug. Third, it is recommended that potential SRM interference be further investigated by analyzing the incurred samples using the multi-SRM LC/MS/MS method following the modification of chromatographic conditions to enhance chromatographic separation of the drug from any putative metabolites. We will demonstrate the application of the proposed strategy by using a carboxylic acid containing drug candidate and its acylglucuronide as a putative metabolite. Plasma samples from the first-in-man (FIM) study of the drug candidate were used as the incurred samples.

Animals↗

PubMed1989

Validation of a new closed circuit indirect calorimetry method compared with the open Douglas bag method.

New equipment designed for the routine measurement of oxygen uptake (VO2) using a closed circuit method has been validated by comparing it with a standard Douglas bag method. The equipment (The Caloric Measurement Unit, CMU) has been tested in 10 critically ill patients during mechanical ventilation (MV) and in 10 spontaneously breathing healthy subjects. Determinations of VO2 and of the resting energy expenditure (REE) were measured in duplicate with the standard method and once with the CMU. Six additional patients receiving MV were studied with the CMU to evaluate the reproducibility and the effect of FIO2 = 1 vs FIO2 = 0.43 on VO2 measurements. Considering the whole group of 10 patients and 10 subjects, the mean difference of VO2 between both methods was -2 +/- 21 ml/min (95% confidence interval, -11.8 to 7.8 ml/min, p = 0.6) standard deviation. Both methods had a similar reproducibility and the mean difference of VO2 measured at the two different FIO2 with the CMU was -3.2 +/- 11 ml/min (95% confidence interval, -14.7 to 8.4 ml/min, p = 0.5). No statistically significant difference was found between derived REE values obtained from either method. These data show a good correlation between the two methods suggesting that CMU may be used in place of the standard method with the same accuracy in measurement of VO2 even at FIO2 = 1.

Adult↗

PubMed2000

Experiences with a compound method for estimating the time since death. II. Integration of non-temperature-based methods.

The period since death was estimated at the scene in 72 consecutive cases using the temperature-based nomogram method as the primary method and supplemented by examination of criteria such as lividity, rigor mortis, mechanical and electrical excitability of skeletal muscle and chemical excitability of the iris. A case-oriented, computer-assisted selection of the non-temperature-based methods and integration of the results into a common result of the compound method was made following a special logistic. The limits of the period since death as estimated by the nomogram were improved in 49 cases by including the non-temperature-based methods and also provided results in 4 cases where the temperature method could not be used. In a further 6 cases the non-temperature-based methods confirmed the limits estimated by the temperature method but in 14 cases a useful result could not be obtained. In only one of the cases investigated was the upper limit of the period since death, as estimated by the criterion re-establishment of rigor (8 h post-mortem), in contradiction with the period determined by the police investigations (9.4 h post-mortem).

Autopsy↗

PubMed1999

New method of assessing outcome of treatment for cervical myelopathy (M/T method)--preliminary report.

In some patients with cervical radiculomyelopathy, neurological examination reveals extreme muscle weakness in an upper extremity with no, or a relatively insignificant, sensory deficit. In assessment of treatment outcome in these patients, the previous method used is thought to be unsuitable. We developed a new method of assessment (the M/T method) in which the recovery of upper extremity muscle weakness is assessed. The purpose of this study was to evaluate this new method. In the M/T method, change in the function of the spinal cord, including the anterior root, is expressed as an index number (recovery rate) in relation to the time-course. The function of the nerve tissue is expressed as the value for the manual muscle testing (MMT) of muscle power, and the muscle tested is represented by one that has the least MMT value before treatment. The unit of measurement of the time-course is 3 months. The index is the difference between the MMT value at the time of follow-up and that before treatment, divided by the number of time units after treatment. The index can be expressed in both fractional and decimal forms. Fractions are useful for examining an individual patient's progress and the decimal form is useful for comparing the data of multiple patients. The M/T method was employed in 16 patients (13 men, 3 women; age, 45-79 years; follow-up, 6 months - 8 years) whose chief complaints were muscle weakness in the upper extremities and who had undergone double-door laminoplasty. Seven patients had an M/T index of 1 or more; the score was 4 in one patient, 2 in four patients, and 1 in two patients. Two patients had an M/T index between 0 and 1; 0.17 and 0.25. Five patients had an index value of 0. The M/T index in two patients was less than 0; -0. 17 and -0.11. Using the M/T method, recovery can be presented as an index number, and as a result, it is easy to compare differences in the recovery rate among patients. The M/T method is useful for evaluation of the viability of the spinal cord, including the anterior root; in particular for those patients in whom neurological examination reveals extreme muscle weakness in an upper extremity with no, or a relatively insignificant, sensory deficit.

Aged↗

PubMed1994

A stereophotogrammetric method for determining in situ contact areas in diarthrodial joints, and a comparison with other methods.

Determination of contact areas in diarthrodial joints is necessary for understanding the state of stress within the articular cartilage layers and the supporting bony structures. The present study describes the use of a stereophotogrammetry (SPG) system [Huiskes et al., J. Biomechanics 18, 559-570 (1985) and Ateshian et al., J. Biomechanics 24, 761-776 (1991)] for determining contact areas in diarthrodial joints, using a surface proximity concept similar to the one used by Scherrer et al. [ASME J. biomech. Engng 101, 271-278 (1979)]. This method consists of evaluating the proximity of the articular surfaces to determine joint contact areas using precise geometric models of the joint surfaces obtained from the SPG system, and precise kinematic data, also obtained from SPG. In this study, the SPG method for determining contact areas is compared to other commonly used methods such as dye staining, silicone rubber casting and Fuji film contact measurement techniques which have been often used and reported by other investigators. The bovine glenohumeral joint and the bovine lateral tibiofemoral articulation (without the meniscus) were used to represent congruent and incongruent joints, respectively. While all the methods yielded consistent contact patterns for the incongruent tibiofemoral articulations, the results for the congruent bovine glenohumeral joints showed that the SPG and Fuji film methods were in better agreement than those obtained from the dye staining and silicone rubber casting methods. The advantages of the new SPG method are that it can be used for intact joints, and used repeatedly and quickly thus making contact-area movement analyses possible [Soslowsky et al., J. orthop. Res. 10, 524-534 (1992)]. The results of this comparison study show that the SPG technique is a reliable and versatile method for determining contact areas in diarthrodial joints.

Animals↗

PubMed1996

Comparison of the hydrophobic grid-membrane filter DNA probe method and the Health Protection Branch standard method for the detection of Listeria monocytogenes in foods.

The standard Health Protection Branch (HPB) method for the detection of L. monocytogenes in foods involves lengthy enrichment, selection and biochemical testing, requiring up to 8 days to complete. A hydrophobic grid-membrane filter (HGMF) method employing a digoxigenin-labelled listeriolysin O probe required 5 days to complete, and included an image-analysis system for electronic data acquisition. A total of 200 food samples encompassing 8 high-risk food groups (soft and semi-soft cheeses, packaged raw vegetables, frozen cooked shrimp, ground poultry, ground pork, ground beef, jellied meats, and pâté) were screened for the presence of L. monocytogenes by the two methods. Overall, 32 (16%) and 30 (15%) of the naturally-contaminated food samples tested positive for L. monocytogenes by the HPB and DNA methods, respectively. The DNA probe method was highly specific in discriminating L. monocytogenes from other Listeria spp. present in 50 of the samples tested. Results showed 94% sensitivity and 100% specificity between the two methods. The HGMF DNA probe method is an efficient and reliable alternative to the HPB standard method for detecting L. monocytogenes in foods.

DNA Probes↗

PubMedDate not supplied

Young smokers' attitudes about methods for quitting smoking: barriers and benefits to using assisted methods.

There is currently little information about how smokers choose a particular method to stop smoking. Young adult smokers rated likelihood of success as the most important criteria for choosing a stop-smoking method but saw only a small difference in likelihood of success between common assisted and unassisted methods. They rated cost, convenience, and quitting on own as other important criteria. Almost all would choose an unassisted method for their next quit attempt. The smokers then rated their probability of using a stop-smoking program or a nicotine patch under various conditions of cost, convenience, and increased likelihood of success. The results showed that the smokers indicated a moderate-high probability of using the two assisted methods under assumptions of convenience and likelihood of success that are currently realistic. However, they were extremely sensitive to cost of the method. When the stop-smoking program or nicotine patch was free, the estimated probability of use was over 50% for all tested conditions; however, at a cost of +25 the estimated probability dropped below 20% for all conditions. Young smokers would be likely to choose assisted methods when attempting to stop if they appreciated the increased likelihood of success with these methods and if the cost was not high.

Administration, Cutaneous↗

PubMed2004

Evaluation of two gas chromatography-olfactometry methods: the detection frequency and perceived intensity method.

Two gas chromatography-olfactometry methods were evaluated in terms of repeatability, range of sensitivity and discriminating properties. Six volatile flavour compounds at various concentration levels were analysed by a panel of eight assessors using the detection frequency method and the perceived intensity method. The coefficient of variance, averaged over the individual compounds for three replicate samples, was 16% for the detection frequency method and 28% for the intensity method. The average correlation coefficient of the individual compounds with concentration was 0.93 (range 0.88-0.99) for the intensities. They were slightly higher than those for the detection frequencies (0.91, range 0.81-0.97). The detection frequency method was more accurate in terms of repeatability, and the intensity method was more accurate with regard to discrimination between concentration levels. The range of sensitivity was similar for both methods.

Chromatography, Gas↗

PubMed2000

Comparison of the effectiveness of a telephone 24-hour dietary recall method vs an in-person method among urban African-American women.

OBJECTIVE: To examine the comparative accuracy of telephone and in-person 24-hour dietary recall methods. SUBJECTS: One hundred eighty-five African-American females, aged 40 years and older, recruited from Sunday church services in Baltimore City, Md. METHODS: Participants were trained to estimate portion size with plastic food models and a 2-dimensional food recall booklet. Dietary intake was then assessed with 2 in-person 24-hour dietary recalls and 1 telephone 24-hour dietary recall, all using a computer-assisted, multiple pass approach. Results from the 2 in-person recalls were averaged and compared with the results from the telephone recall. STATISTICAL ANALYSES: Cross-tabulation, paired t test, Pearson's correlation, chance-corrected agreement, and stepwise linear regression analyses were performed. RESULTS: There were no significant differences between the telephone and in-person methods for any nutrient. Agreement between methods was moderate for all major dietary components, with corrected correlations between methods ranging from 0.26 to 0.97 (P<.001), and kappas ranging from 0.155 to 0.372 (P<.01). Levels of low-energy reporting were high (88% telephone, 91% in-person), though there were no significant differences between methods. CONCLUSIONS: The telephone 24-hour dietary recall method appears to be comparable to the standard in-person method among older African-American women. Portion-size training in person may make subsequent telephone dietary recalls acceptable in this population.

Adult↗

PubMed2000

Birth control method choice and use of barrier methods for sexually transmitted disease prevention among low-income African-American women.

In a prospective study of 1122 women attending a sexually transmitted disease (STD) clinic in Alabama, consistent use of the male condom and vaginal microbicide/spermicides was promoted to reduce STD risk. This analysis evaluated: 1) baseline characteristics that may influence birth control method choice; and 2) the association of birth control method and other baseline characteristics with consistency of barrier use during follow up. Birth control method was associated with sociodemographic variables, sexual, and reproductive history. Women who adopted user-independent methods (tubal ligation, implants, injectable hormones) appear to have completed their family plan. Oral contraceptive users were of higher socioeconomic status and at lower STD risk. Barrier method users and women who used no method were young and at higher STD risk. Consistency of condom/spermicide use increased in all groups. Barrier method users were more likely than other women to use condoms and spermicides during the study. Women who used no birth control method at baseline experienced the largest increase in barrier use during follow up, although their barrier use rates were lower than in other groups. The synergism between the intention to prevent pregnancy and the intention to prevent STD should be considered in the design of interventions promoting condom use.

Adolescent↗

PubMed2001

Determination and comparison of competitive isotherms by rectangular pulse method and frontal velocity analysis method.

Two different approaches, the rectangular pulse method and a new method, the frontal velocity analysis method are applied to the determination of competitive isotherms for two systems on ODS-silica. Both sets of experimental data are found to fit well to the competitive-Langmuir isotherm equation. The data obtained from the rectangular pulse method and the frontal velocity analysis method are in general agreement with each other and the best coefficients of the competitive isotherms obtained with the two methods are close. This shows that the simpler and easier method, the frontal velocity analysis method can be used to determine binary competitive isotherms.

Adsorption↗

PubMed2003

Determination of dithiocarbamate pesticides in occupational hygiene sampling devices using the isooctane method and comparison with an automatic thermal desorption (ATD) method.

Two new methods for the determination of dithiocarbamate pesticides in occupational hygiene sampling devices are described. Dithiocarbamate spiked occupational hygiene sampling devices, consisting of glass fibre (GF/A) filters, cotton pads, cotton gloves and disposable overalls, were reduced under acidic conditions and the CS2 evolved as a decomposition product was extracted into isooctane. The isooctane was then analysed using gas chromatography with mass spectrometry, for CS2, which provided a quantitative result for dithiocarbamates. Recoveries obtained were generally within a 70-110% range and reproducibilities better than 15% RSD were typically achieved. The method has been successfully applied to samples collected during occupational exposure surveys. A second method employing automatic thermal desorption-gas chromatography-mass spectrometry (ATD-GC-MS) has also been developed and applied to the direct analysis of GF/A (airborne) samples. The method relies on the thermal degradation of dithiocarbamates to release CS2, which is used to quantify the analytes. Thiram spiked GF/A filters gave an average recovery of 107% with an RSD of 4%. The performance of the two analytical methods were directly compared by analysing sub-portions of GF/A filters collected during a survey to evaluate occupational exposures to thiram during seed treatment operations. Both methods performed well for the analysis of airborne (GF/A) samples and produced results in good agreement. ATD-GC-MS is the preferred method for studies involving GF/A (airborne) samples only. Because of the wider applicability of the isooctane method for other sampling devices, it is the preferred choice when carrying out surveys which require a dermal as well as respirable exposure assessment.

Carbamates↗