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The ARK Fentanyl II Assay is an immunoassay intended for the qualitative detection of fentanyl in human urine at a cutoff concentration of 1.0 ng/mL. The assay is intended for use in laboratories with automated clinical chemistry analyzers. This in vitro diagnostic device is for prescription use only.

The ARK Fentanyl II Assay provides only a preliminary analytical result. A more specific alternative chemical method must be used in order to obtain a confirmed positive analytical result. Gas Chromatography/Mass Spectrometry (GC/MS) or Liquid Chromatography/tandem Mass Spectrometry (LC-MS/MS) is the preferred confirmatory method. Clinical consideration and professional judgment should be exercised with any drug test result, particularly when the preliminary test result is positive.

The ARK Fentanyl II Assay is a homogeneous enzyme immunoassay technique used for the analysis of a specific compound in human urine. The assay is based on competition between drug in the specimen and drug labeled with recombinant glucose-6-phosphate dehydrogenase (rG6PDH) for antibody binding sites. As the latter binds antibody, enzyme activity decreases. In the presence of drug from the specimen, enzyme activity increases and is directly related to the drug concentration. Active enzyme converts nicotinamide adenine dinucleotide (NAD) to NADH in the presence of glucose-6-phosphate (G6P), resulting in an absorbance change that is measured spectrophotometrically. Endogenous serum G6PDH does not interfere because the coenzyme NAD functions only with the bacterial enzyme used in the assay.

The ARK Fentanyl II Assay consists of reagents R1 anti-fentanyl monoclonal antibodies with substrate and R2 fentanyl derivative labeled with bacterial recombinant G6PDH enzyme.

1. Acceptance Criteria and Reported Device Performance for ARKTM Fentanyl II Assay

The provided text details the performance characteristics of the ARKTM Fentanyl II Assay, which is an immunoassay for the qualitative detection of fentanyl in human urine at a cutoff concentration of 1.0 ng/mL. The study evaluates precision, analytical specificity (cross-reactivity with structurally similar compounds and lack of interference from structurally unrelated compounds and endogenous substances), and method comparison with LC-MS/MS.

Here's a table summarizing the acceptance criteria (implied by the data presentation for each test) and the reported device performance:

• 0.25 ng/mL (-75%): 160 Negative (out of 160)
• 0.50 ng/mL (-50%): 160 Negative (out of 160)
• 0.75 ng/mL (-25%): 160 Negative (out of 160)
• 1.00 ng/mL (Cutoff): 84 Negative; 76 Positive (out of 160)
• 1.25 ng/mL (+25%): 160 Positive (out of 160)
• 1.50 ng/mL (+50%): 160 Positive (out of 160)
• 1.75 ng/mL (+75%): 160 Positive (out of 160)
• 2.00 ng/mL (+100%): 160 Positive (out of 160) |
  | | Samples above the cutoff (e.g., +25%, +50%, +75%, +100% of cutoff) should consistently test Positive. | |
  | | Samples at the cutoff should show a mix of Negative and Positive results, indicating proper cutoff discrimination. | |
  | Analytical Specificity | Norfentanyl (major metabolite) should show some cross-reactivity. Other fentanyl structural analogs/metabolites may show varying degrees of cross-reactivity. Structurally similar opioids and functional analogs should be negative at high concentrations. | - Norfentanyl: 7% cross-reactivity at 15 ng/mL.
• Acetyl fentanyl, Isobutyryl fentanyl: 90.91% cross-reactivity at 1.1 ng/mL.
• Furanyl fentanyl, Para-fluoro fentanyl: 66.67% cross-reactivity at 1.5 ng/mL.
• Other similar compounds (e.g., Carfentanil, Sufentanil, Alfentanil): show very low to 1.5 ng/mL`: 0 Negative, 62 Positive (62 concordant positives)
• Discordant Results Explanation: The 1 discordant positive at

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