Proficiency testing (external quality assessment) of drug detection in oral fluid

Eighteen external quality assessment (proficiency testing) samples were prepared from client specimens collected with the Intercept oral fluid collection device and by spiking drug-free oral fluid. Samples were circulated in pairs at quarterly intervals to 13 UK and USA based laboratories for analysis by a panel of OraSure micro-plate Intercept enzyme immunoassay kits and hyphenated mass spectrophotometric techniques. During the survey, there was a single case of non-specificity in a false report for methadone. The major errors were of lack of sensitivity relative to the concentration thresholds specified for the immunoassays. The sensitivity for overall "present"/"not found" reports calculated as true positives/(true positives+false negatives) were for the amphetamine specific assay 50%, methyl-amphetamines 93%, barbiturates 64%, cannabinoids 73%, cocaine and metabolites 100%, benzodiazepines 69%, methadone 95%, opiates 79% (opiates excluding oxycodone 93%), phencyclidine 93% and human gamma-globulin 97%. A small number of the sensitivity errors were attributable to errors in chromatographic confirmation techniques.     

Mitochondrial DNA error prophylaxis: assessing the causes of errors in the GEP'02-03 proficiency testing trial

A qualitative and quantitative analytical method was developed and validated for the determination of 49 licit and illicit drugs in oral fluid. Small oral fluid samples, volume 1mL, were collected from volunteers using a modified Omni-Sal device and the analytes were extracted from an oral fluid/buffer mixture using a single Bond Elut Certify solid phase extraction cartridge. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) and gas chromatography-repetitive full scan mass spectrometry (GC-MS) were used in parallel to analyze the extracts for the targeted drugs. Extracts were analyzed by GC-MS in their underivatized form and as their pentafluoropropionyl derivatives. Deuterated internal standards were used for quantification of drugs of abuse by LC-MS-MS to minimize matrix effects. Methadone-d(9) and tumoxetine were used as the internal standards for quantification of non-derivatized and derivatized analytes respectively by GC-MS. Linearity was demonstrated over the range 5-200 ng/mL and limits of detection were less than 4 ng/mL for each drug analyzed. The method demonstrated acceptable recoveries for most of the analytes and good intra- and inter-day precision. Acquisition of data by repetitive full scan GC-MS allows the addition of further analytes to the target menu.     

Mobile phase influence on electrospray ionization for the analysis of smokeless powders by gradient reversed phase high-performance liquid chromatography-ESIMS

The solution parameters associated with gradient elution reversed phase high-performance liquid chromatography (HPLC) were characterized by evaluating the electrospray ionization mass spectrometry (ESIMS) response of selected smokeless powder additives. Using direct liquid infusion, the positive ion ESIMS responses were determined for three general classes of powder constituents: dialkylphthalate acid esters, N,N'-dialkyl-N,N'-diphenyl urea based stabilizers and nitroso-, nitro-, and dinitro- derivatives of diphenylamine. The relative ESIMS intensities of the powder components were investigated as a function of three solution parameters: ammonium acetate concentration, pH, and percent methanol. The effect of the ammonium acetate concentration demonstrates that the electrolyte is required for efficient ionization and the ESIMS intensity was optimal at a concentration of 2mM for the selected compounds, except 2,4'-dinitrodiphenylamine. The aqueous solution pH, corresponding to the available protons in solution, did not have a significant effect on the ESIMS intensity of the analytes. The percent methanol was evaluated with both decreasing and constant electrolyte concentrations to demonstrate the effects of droplet stability and ion transfer into the gas phase. These findings were applied to the analysis of the selected smokeless powder additives using HPLC-ESIMS to illustrate increased sensitivity for the protonated molecules.     

Measurement Properties of the Communities That Care<Superscript>®</Superscript> Youth Survey Across Demographic Groups

Prevention science has produced information about risk and protective factors that predict adolescent drug use and related problem behaviors. This paper investigates the Communities That Care Youth Survey that measures multiple risk and protective factors. Using a sample of 172,628 students who participated in surveys administered in seven states in 1998, analyses were conducted to test the factor structure of these risk and protective factors and to test the equivalence of the factor models across five racial/ethnic groups (African Americans, Asians or Pacific Islanders, Caucasians, Hispanic Americans, and Native Americans), four grade levels (6th, 8th, 10th, and 12th) and both gender groups. Results support the construct validity of the surveys risk and protective factor scales and indicate that the measures are equally reliable across males and females and five racial/ethnic groups. Implications of these findings for science-based prevention planning are discussed.     

Assets of new retired-worker beneficiaries: findings from the New Beneficiary Survey

Most new retired workers in 1982 owned some type of asset, usually a savings, checking, or credit union account, according to data obtained by the Social Security Administration (SSA) in its New Beneficiary Survey. Many recently retired workers also owned their home, often mortgage-free. Homeownership was their most significant asset in terms of its median value. Comparatively few retirees owned property other than a home, though for owners of such property, the median value was substantial. Married couples, whose assets included those of both partners, more frequently owned assets and their assets had higher median values than did unmarried individuals. A comparison of retired workers with persons aged 65 or older who were enrolled in the Medicare program but who had not yet received retired-worker benefits showed that these Medicare-only enrollees were much better off, both in the likelihood of owning assets and in having higher median values for their assets. Individuals who retired before reaching age 65 and therefore received a reduced social security benefit were not as well off as those whose first benefit was paid at age 65 or older. Overall, the asset situation of new retired workers in 1982 was better than that of men and unmarried women aged 58-63 in 1969, even when the 1969 assets were adjusted to constant 1982 dollars.