Evaluation of Detection Techniques and Laboratory Proficiency in Testing for Drugs of Abuse in Urine: An External Quality Assessment Scheme Using Clinically Realistic Urine Samples

1999 ◽  
Vol 36 (5) ◽  
pp. 592-600 ◽  
Author(s):  
J. F. Wilson ◽  
B. L. Smith ◽  
Keyword(s):  
Quality Assessment ◽  
Drugs Of Abuse ◽  
External Quality Assessment ◽  
Urine Samples ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Detection Techniques

ORALVEQ: External quality assessment scheme of drugs of abuse in oral fluid

2008 ◽  
Vol 182 (1-3) ◽  
pp. 35-40 ◽  
Author(s):  
M. Ventura ◽  
R. Ventura ◽  
S. Pichini ◽  
S. Leal ◽  
P. Zuccaro ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Oral Fluid ◽  
Drugs Of Abuse ◽  
External Quality Assessment ◽  
External Quality ◽  
External Quality Assessment Scheme

Performance of techniques used to detect drugs of abuse in urine: study based on external quality assessment

1991 ◽  
Vol 37 (3) ◽  
pp. 442-447 ◽  
Author(s):  
J F Wilson ◽  
J Williams ◽  
G Walker ◽  
P A Toseland ◽  
B L Smith ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Drugs Of Abuse ◽  
External Quality Assessment ◽  
Gas Liquid Chromatography ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Chromatographic Techniques ◽  
Layer Chromatography ◽  
Significant Interference ◽  
Related Compounds

Abstract Twenty-five samples of lyophilized urine from the U.K. External Quality Assessment Scheme for Drugs of Abuse were analyzed by an average of 95 laboratories between April 1987 and December 1989. Samples contained mixtures of analytes and included replicated concentrations of morphine, methadone, amphetamine, and cocaine at 0, 1, 2, and 5 mg/L and of benzoylecgonine at 0, 0.4, 1, 2, and 4 mg/L. Some chromatographic techniques were inadequate for detecting morphine, amphetamine, cocaine, and benzoylecgonine at the lower concentrations of analytes studied: gas-liquid chromatography was least sensitive for morphine; in-house thin-layer chromatography (TLC) was least sensitive for the other analytes. Few significant differences in specificity were detected between techniques, although significant interference from structurally related compounds was demonstrated in assays of morphine, methadone, and amphetamine. Exceptions were the Boehringer (BCL) test for opiates and TLC applied to amphetamine and benzoylecgonine, which demonstrated considerable lack of specificity.

scholarly journals External Quality Assessment of Techniques for the Detection of Drugs of Abuse in Urine

1994 ◽  
Vol 31 (4) ◽  
pp. 335-342 ◽  
Author(s):  
J F Wilson ◽  
B L Smith ◽  
P A Toseland ◽  
J Williams ◽  
D Burnett ◽  
...  
Keyword(s):  
Quality Assessment ◽  
High Performance ◽  
Drugs Of Abuse ◽  
External Quality Assessment ◽  
Cross Reactivity ◽  
Clinical Samples ◽  
External Quality ◽  
True Negative ◽  
External Quality Assessment Scheme ◽  
The Uk

Five chromatographic and six immunoassay techniques were compared using data reported by 131 participants in the UK National External Quality Assessment Scheme for Drugs of Abuse in Urine. Twenty Five samples were studied containing none or one of three concentrations of amphetamine, barbiturates, benzodiazepines, benzoylecgonine, methadone and morphine. Technique sensitivity and specificity achieved with realistic clinical samples of 25 mL vol were assessed as the percentage of true positive and true negative tests, respectively. Thin-layer chromatography was inadequate for the detection of several analytes, the sensitivity for 0 · 5 mg/L of benzoylecgonine being < 30%, and for 1 · 5 mg/L of amphetamine < 86%. Gas chromatography with mass spectrometry was significantly less sensitive than other techniques for the detection of 0·5 mg/L of benzoylecgonine (71%) and 1 · 5 mg/L of morphine (88%). High-performance liquid chromatography was the most sensitive for amphetamine. Immunoassays performed well when operating above then-specified cut-off concentrations but, because they are directed to quinalbarbitone showed reduced cross-reactivity with amylobarbitone, the barbiturate more commonly prescribed in the UK.

The effect of acidification and oxalate concentration on urine calcium measurements in EQAS materials and patient samples

2012 ◽  
Vol 50 (2) ◽  
Author(s):  
Adriaan J. van Gammeren ◽  
Corrie van Haperen ◽  
Aldy W.H.M. Kuypers
Keyword(s):  
Calcium Oxalate ◽  
Quality Assessment ◽  
Calcium Level ◽  
External Quality Assessment ◽  
Urine Samples ◽  
Sodium Oxalate ◽  
Urine Calcium ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Before And After

AbstractAn increase in urine calcium compared to the consensus value was observed in some urine samples of the Dutch External Quality Assessment Scheme (EQAS). It appeared that the increase was due to the addition of oxalate by the EQAS organizers and preanalytical acidification of the samples by some of the participants. Because of this observation, the effect of urine acidification on urine calcium level in EQAS and patient samples with added oxalate was investigated.Twenty-four EQAS urine samples and 20 patient urine samples were subject to recovery measurements of urine calcium before and after addition of sodium oxalate and acidification.Differences in urine calcium between acidified and non-acidified samples up to 30.9% have been observed in EQAS samples with added oxalate. Patient samples show differences up to 80%. Differences between acidified and non-acidified samples are minimal for low calcium oxalate levels but increase with higher levels. Samples without added oxalate show equal urine calcium results between acidified and non-acidified samples.Urine calcium results are decreased in non-acidified samples with an excess of oxalate. In case of hyperoxaluria, acidification of patient urine collections and EQAS samples is recommended for correct urine calcium values.

Establishing an Accuracy Basis for the Vitamin D External Quality Assessment Scheme (DEQAS)

2017 ◽  
Vol 100 (5) ◽  
pp. 1277-1287 ◽  
Author(s):  
Carolyn Q Burdette ◽  
Johanna E Camara ◽  
Federica Nalin ◽  
Jeanita Pritchett ◽  
Lane C Sander ◽  
...  
Keyword(s):  
Vitamin D ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Measurement Procedure ◽  
Binding Assays ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Hydroxyvitamin D ◽  
Target Values ◽  
High Concentrations

Abstract Until recently, the Vitamin D External Quality Assessment Scheme (DEQAS) assessed the performance of various assays for the determination of serum total 25-hydroxyvitamin D [25(OH)D] by using a consensus mean based on the all-laboratory trimmed mean (ALTM) of the approximately 1000 participants' results. Since October 2012, the National Institute of Standardsand Technology (NIST), as part of the Vitamin D Standardization Program, has participated in DEQAS by analyzing the quarterly serum sample sets using an isotope dilution LC-tandem MS (ID LC-MS/MS) reference measurement procedure to assign an accuracy-based target value for serum total 25(OH)D. NIST has analyzed90 DEQAS samples (18 exercises × 5 samples/exercise) to assign target values. The NIST-assigned values are compared with the ALTM and the biases assessed for various assays used by the participants, e.g., LC-MS/MS, HPLC, and several ligand-binding assays. The NIST-value assignment process and the resultsof the analyses of the 90 DEQAS samples are summarized. The absolute mean bias between the NIST-assignedvalues and the ALTM was 5.6%, with 10% of the samples having biases &gt;10%. Benefits of the accuracy-based target values are presented, including for sample sets with high concentrations of 25(OH)D2 and 3-epi-25(OH)D3.

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