Direct Automated EMIT® d.a.u. Analysis of N,N-Dimethylformamide-Modified Serum, Plasma, and Postmortem Blood for Benzodiazepines, Benzoylecgonine, Cannabinoids, and Opiates*

Blum, Lee M.; Klinger, Robert A.; Rieders, Fredric

doi:10.1093/jat/13.5.285

Cited by 21 publications

(2 citation statements)

References 6 publications

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“…Slightom et al [10][11][12] applied the EMIT assay to blood and tissues subjected to liquid/liquid extraction. Most adaptations are based on the precipitation of blood samples with water-miscible solvents, such as methanol [13][14][15], acetone [16] or dimethylformamide [17]. All the above-mentioned methods concerned the EMIT assay and demonstrated full applicability of urine assays to blood.…”

Section: Introductionmentioning

confidence: 99%

The screening for common drugs of abuse in whole blood by means of EMIT-ETS and FPIA-ADx urine immunoassays

et al. 1992

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The purpose of the paper was to compare the performance of ETS (EMIT) and ADx (FPIA) analyzers for screening blood samples for drugs of abuse after 2 alternative pretreatment procedures (acetone precipitation and ultrafiltration). Cannabinoids, benzodiazepines and benzoylecgonine were not detectable with both assays after ultrafiltration. The detectability of morphine in blood ultrafiltrates was distinctly lower than after acetone precipitation. The comparison of results obtained with ETS and ADx after acetone precipitation showed that ETS assay is slightly more sensitive but ADx is slightly more reproducible. Both assays may be used for blood examination with similar cut-off values. The ETS analyzer gave much better analytical performance (speed, flexibility) and lower reagent costs than the ADx analyzer.

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Section: Introductionmentioning

confidence: 99%

The screening for common drugs of abuse in whole blood by means of EMIT-ETS and FPIA-ADx urine immunoassays

et al. 1992

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“…Therefore existing urine assays had been adapted for the examination of blood samples. Previously reported methods for the screening of whole blood for common drugs of abuse include EMIT and FPIA immunoassays after precipitation of the blood samples with either methanol (Peel et al, 1981;Asselin et al, 1988;Gjerde et al, 1990), acetone (Lewellen et al, 1988;Bogusz et al, 1990;Maier et al, 1992); N,N-dimethylformamide (Blum et al, 1989;Klinger et al, 1990), trichloroacetic acid (McCord, 1988) or liquidlliquid extraction (Slightom et al, 1978;Slightom et al, 1982). The purpose of this paper was to develop a method based on a homogenous immunoassay for the rapid screening of opiates, benzodiazepines, benzoylecgonine, barbiturates and methadone from autopsy, police and hospital blood samples.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Polarization Immunoassay for the Detection of Drugs of Abuse in Human Whole Blood

Keller¹,

Schneider²,

Dirnhofer

et al. 2000

Med Sci Law

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Fluorescence polarization immunoassay (FPIA) is a technique which has been known for a number of years. Since the development of the fundamental principles of fluorescence polarization by Perrin in a series of papers beginning in 1926, immunological techniques using labelled reactants have gained an extraordinary importance in the field of medical research and in routine diagnosis. As one of the non-radioactive immunological techniques, FPIA has found broad application in clinical and forensic toxicology. The authors report a new method to quickly screen autopsy, police and hospital blood samples for opiates, benzodiazepines, benzoylecgonine, barbiturates and methadone after Extrelut extraction utilising the FPIA methodology.

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Immunoassays in Forensic Toxicology

Moody¹

2000

Encyclopedia of Analytical Chemistry

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Forensic toxicology encompasses the determination of the presence and concentration of drugs, other xenobiotics and their metabolites in physiological fluids and organs and the interpretation of these findings as they may impact on legal issues. These include medical examiner investigations, driving under the influence and other transportation accident investigations, workplace pre‐employment, random and for‐cause drug testing and judicial monitoring of arrestees and parolees. Similar techniques are employed in emergency room clinical toxicology and to monitor the efficacy of substance abuse treatment. The introduction of immunoassays into forensic toxicology in the early 1970s has had a major impact on the speed and efficiency that samples can be screened for the presence of certain drug classes. For the most part, forensic toxicologists use commercial immunoassays directed primarily towards abused drugs. Commercial immunoassays developed for therapeutic monitoring of other drugs, veterinary drugs and pesticides, as well as immunoassays developed in research laboratories for specialized studies, may find a role in the forensic toxicology laboratory for specialized cases. Most immunoassays used for forensic toxicology are competitive. An antigen structurally similar to the target compound is conjugated to a signalling molecule and competes with target drug in a sample for antibody binding. Immunoassays are also classified as homogeneous and heterogeneous. Homogeneous assays do not separate the original sample from the final detection sample. They must use a signal that changes when antibody is bound. Homogeneous immunoassays include enzyme immunoassay (EIA) (enzyme activity decreases when bound), fluorescent polarization immunoassay (FPIA) (emission in a polar field increases when bound) and kinetic interaction of microparticles in solution (KIMS) immunoassay (lattice formation inhibited when bound). Heterogenous immunoassays include radioimmunoassay (RIA) and enzyme‐linked immunosorbent assay (ELISA) where unbound radiolabeled antigen and enzyme conjugated antigen, respectively, are removed from the sample before measurement. In general, the homogeneous immunoassays are more ameniable to full automation, and thereby quicker throughput. The heterogeneous immunoassays are less susceptible to matrix interference, and thereby more versatile with nonurine matrices. While most commercial immunoassays have been developed for a urine matrix, they have been applied by forensic toxicologists to other matrices, including blood, hair, saliva, sweat, tissue homogenates, blood stains and most other physiological samples that may be of value in the investigation. The use of nonurine matrices must contend with two factors. With the exception of parenchymal tissues, the concentration of the target compound is often lower and the sensitivity of the immunoassay may be limiting. In addition, the nonurine matrix usually is much more complex in its composition. Sample pretreatments that range from simple deproteinations to multistep extractions to remove matrix components and/or concentrate the sample are often required. The heterogenous RIAs and ELISAs usually require less rigorous, if any, pretreatments. Interpretation of immunoassay results must take into consideration the limits of detection of the assay, the cross‐reactivity of the antibody(ies) and the potential for interference. Appropriate controls should be included to demonstrate adequate signal separation from blanks (drug‐free sample in the same matrix). The concentration of the low control is often determined by the sensitivity of the assay, or in workplace testing programs by administratively determined cutoffs that draw the line between a negative and presumptive positive. The ability of the antibody to detect compounds other than the target compound (its cross‐reactivity) can be a useful characteristic or, when the drugs that can be confirmed are limited, a nuisance. The amphetamines, barbiturates and benzodiazepines, in particular, all have a number of licit (and for amphetamines illicit) analogs that could be present in a sample. Cross‐reactivities are antibody‐source (i.e. manufacturer) dependent. Further testing to determine the immunoreactive compound often requires rigorous methodologies. In some instances, the potency of the drug and its poor cross‐reactivity make detection by immunoassay difficult (e.g. nitrosobenzodiazepines). Interference in immunoassays may arise from compounds that appear in the matrix during disease states, or those that are intentionally added to a sample in the hope of negating a positive test. These act through many different mechanisms and may decrease or increase the immunoassay test result. Immunoassays have added an extremely useful tool to the forensic toxicology investigation. They can be used to screen rapidly a large number of samples for the potential presence of a drug group. With rare exceptions (emergencies, limited sample volume), their use without a confirmation assay (e.g. gas or liquid chromatography/mass spectrometry (LC/MS)) is unwarranted, as it leads to a risk of improper test result interpretation.

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Direct Automated EMIT® d.a.u. Analysis of N,N-Dimethylformamide-Modified Serum, Plasma, and Postmortem Blood for Benzodiazepines, Benzoylecgonine, Cannabinoids, and Opiates*

Cited by 21 publications

References 6 publications

The screening for common drugs of abuse in whole blood by means of EMIT-ETS and FPIA-ADx urine immunoassays

The screening for common drugs of abuse in whole blood by means of EMIT-ETS and FPIA-ADx urine immunoassays

Fluorescence Polarization Immunoassay for the Detection of Drugs of Abuse in Human Whole Blood

Immunoassays in Forensic Toxicology

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