The Barbiturate Enzyme Immunoassay is a homogeneous enzyme immunoassay with a 200 ng/mL and/or 300 ng/mL cutoffs. The assay is intended for use in the qualitative and semiquantitative analyses of barbiturates in human urine. The assay is designed for professional use with a number of automated clinical chemistry analyzers. Measurements obtained by this device are used in the diagnosis and treatment of barbiturate use or overdose and in monitoring levels of barbiturate to ensure appropriate therapy. The Barbiturate Enzyme Immunoassay provides only a preliminary analytical test result. A more specific alternative chemical method must be used to obtain a confirmed analytical result. Gas chromatography/mass spectrometry (GC/MS) is the preferred confirmatory method. Clinical consideration and professional judgment should be applied to any drug-ofabuse test result, particularly when preliminary positive results are used.
Device Story
Homogeneous enzyme immunoassay for barbiturate detection in human urine; utilizes automated clinical chemistry analyzers. Input: human urine sample; Reagents: R1 (tris-based buffer) and R2 (alcohol dehydrogenase, NAD, stabilizers). Principle: competitive binding between sample drug and drug-labeled G6PDH enzyme for fixed antibody; enzyme activity inversely proportional to drug concentration. Output: spectrophotometric absorbance change at 340 nm; qualitative (positive/negative) or semi-quantitative (estimated concentration) result. Used by laboratory professionals in clinical settings. Output informs clinical decision-making regarding barbiturate use/overdose; requires confirmatory testing via GC/MS for definitive diagnosis.
Clinical Evidence
No clinical studies performed. Evidence based on analytical performance: precision (CVs 0.60-1.05% qualitative; 2.83-4.85% semi-quantitative), linearity (R²=0.996), and method comparison. Comparison against predicate (n=105) and GC/MS (n=105) demonstrated high concordance. Discrepancies in method comparison were resolved via GC/MS confirmation, showing the subject device's ability to detect specific barbiturates (e.g., phenobarbital) that the predicate did not.
Technological Characteristics
Liquid, ready-to-use homogeneous enzyme immunoassay. Sensing principle: spectrophotometric measurement of G6PDH enzyme activity at 340 nm. Calibrators and controls are human urine-based. Designed for use on automated clinical chemistry analyzers. No specific software algorithm class or connectivity described; device is a reagent kit.
Indications for Use
Indicated for qualitative and semi-quantitative detection of barbiturates in human urine for professional use in clinical settings to aid in diagnosis/treatment of barbiturate use or overdose. Prescription use only. Preliminary result only; requires confirmation by alternative chemical method (e.g., GC/MS).
Regulatory Classification
Identification
A barbiturate test system is a device intended to measure barbiturates, a class of hypnotic and sedative drugs, in serum, urine, and gastric contents. Measurements obtained by this device are used in the diagnosis and treatment of barbiturate use or overdose and in monitoring levels of barbiturate to ensure appropriate therapy.
Special Controls
*Classification.* Class II (special controls). A barbiturate test system is not exempt if it is intended for any use other than employment or insurance testing or is intended for Federal drug testing programs. The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 862.9, provided the test system is intended for employment and insurance testing and includes a statement in the labeling that the device is intended solely for use in employment and insurance testing, and does not include devices intended for Federal drug testing programs (*e.g.,* programs run by the Substance Abuse and Mental Health Services Administration (SAMHSA), the Department of Transportation (DOT), and the U.S. military).
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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
DEVICE ONLY TEMPLATE
A. 510(k) Number:
K032764
B. Analyte:
Barbiturates
C. Type of Test:
Homogeneous Enzyme Immunoassay for the qualitative and semi-quantitative measurement of barbiturates
D. Applicant:
Lin-Zhi International, Inc.
E. Proprietary and Established Names:
Barbiturate Enzyme Immunoassay
Barbiturate Drugs of Abuse Calibrators and Controls
F. Regulatory Information:
1. Regulation section:
CFR 862.3150, Barbiturate test system
862.3200, Clinical toxicology calibrator
862.3280, Clinical toxicology control material
2. Classification:
Class II (reagents and calibrators)
Class I (controls)
3. Product Code:
DIS, DLJ, LAS
4. Panel:
Clinical Toxicology
G. Intended Use:
1. Indication(s) for use:
The Barbiturate Enzyme Immunoassay is a homogeneous enzyme immunoassay with a 200 ng/mL and/or 300 ng/mL cutoffs. The assay is intended for use in the qualitative and semi-quantitative analyses of barbiturates in human urine. The assay is designed for professional use with a number of automated clinical chemistry analyzers.
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Measurements obtained by this device are used in the diagnosis and treatment of barbiturate use or overdose and in monitoring levels of barbiturate to ensure appropriate therapy.
2. Special condition for use statement(s):
Prescription use only.
The Barbiturate Enzyme Immunoassay provides only a preliminary analytical result. A more specific alternative chemical method must be used in order to obtain a confirmed analytical result. Gas Chromatography/mass spectrometry (GC/MS) is the preferred confirmatory method. Other chemical confirmation methods are available. Clinical consideration and professional judgment should be applied to any drug of abuse test result, particularly when the preliminary test result is positive.
Semi-quantitative analysis is helpful in estimating the concentrations of drugs in the samples. This can aid users in preparing dilutions of the samples for further analysis.
3. Special instrument Requirements:
Analyzers using this device must be able to maintain a constant temperature, pipette samples, mix reagents, measure enzyme rates at 340 nm, and time the reaction accurately.
H. Device Description:
The Barbiturate Enzyme Immunoassay calibrators have secobarbital concentrations of 0 (negative), 100, 200, 300, and 1000 ng/mL in human urine with sodium azide added as a preservative. The Assay controls have concentrations of 100, 200, 300, and 400 ng/mL
The Buffer Reagent (R1) contains tris-based buffer (50nM) with sodium azide. The Enzyme Reagent (R2) contains alcohol dehydrogenase (ADH), nicotinamide adenine dinucleotide (NAD, 10 nM), stabilizers, and sodium azide.
I. Substantial Equivalence Information:
1. Predicate device name(s):
Emit® II Plus Barbiturate Assay (Syva-Dade Behring)
2. Predicate K number(s):
K010934
3. Comparison with predicate:
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| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended Use | Same | Qualitative and semi-quantitative determination of barbiturates in urine |
| Cutoff | Same | 200 and 300 ng/mL |
| Semi-quant Calibration | Same | 5 levels |
| Calibrators and Controls | Same | Secobarbital |
| Differences | | |
| Item | Device | Predicate |
| Specific Calibrator Concentrations (ng/mL) | 0, 100, 200, 300, 1000 | 0, 100, 200, 300, 800 |
| Specific Control Concentrations (ng/mL) | 100, 200, 300, 400 | 150, 225, 250, 375 |
| Sensitivity (ng/mL) | 25 | 20 |
| Antibodies | Monoclonal to Secobarbital Polyclonal to Phenobarbital | Polyclonal to secobarbital |
J. Standard/Guidance Document Referenced (if applicable):
None Referenced
K. Test Principle:
The barbiturate assay is a well-established homogeneous enzyme immunoassay with ready-to-use liquid reagent. The assay is based on competition between drug in the sample and drug labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for a fixed amount of antibody in the reagent. Enzyme activity decreases upon binding to the antibody, and the drug concentration in the sample is measured in terms of enzyme activity. In the absence of drug in the sample, barbiturate-labeled G6PDH conjugate is bound to antibody, and the enzyme activity is inhibited. Alternately, when drug is present in the sample, antibody binds to the free drug and the unbound barbiturate-labeled G6PDH exhibits its maximal enzyme activity. Active enzyme converts nicotinamide adenine dinucleotide (NAD) to NADH, resulting in an absorbance change that can be measured spectrophotometrically at 340 nm.
L. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
With-in run precision in the qualitative mode was assessed by measuring mA/min at 0, 100, 200, 300, 400, and 1000 ng/mL, where n=21 for all concentrations. The Coefficients of Variation (CV)
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ranged from 0.60 to 1.05. Between-run precision in the qualitative mode was assessed by measuring the same concentrations in 12 runs over a three week period. For n=12, the CVs ranged from 0.35 to 0.83.
The precision and accuracy of the qualitative mode was also assessed by analyzing samples at concentrations of 40, 80, 150, 250, 375, 500, 700, and 900 ng/mL. All samples were correctly identified as positive or negative using both the 200 and 300 ng/mL cutoffs.
With-in run precision in the semi-quantitative mode was assessed by assaying the 100, 200, 300, and 400 ng/mL controls, where n=21 for all concentrations. The Coefficients of Variation (CV) ranged from 2.83 to 4.79. Between-run precision in the semi-quantitative mode was assessed by measuring the same concentrations in 12 runs over a three week period. For n=12, the CVs ranged from 3.08 to 4.85.
b. Linearity/assay reportable range:
Linearity was assessed by spiking secobarbital into negative urine samples and measuring the recovery. The equation of the line of target vs. measured was y = 1.0005x + 6.47 with R² = 0.996
Results were as follows:
| Target (ng/mL) | Measured (ng/mL) | % Recovery |
| --- | --- | --- |
| 40 | 45.2 | 113 |
| 80 | 86.7 | 108 |
| 150 | 151.2 | 101 |
| 250 | 257.2 | 103 |
| 375 | 396.8 | 106 |
| 500 | 516.2 | 103 |
| 700 | 697.3 | 100 |
| 900 | 887.6 | 99 |
c. Traceability (controls, calibrators, or method):
Traceable to USP reference standard
d. Detection limit:
The functional sensitivity was determined to be 25 ng/mL
e. Analytical specificity:
Potential cross-reactivity was tested with various barbiturate-related compounds and with compounds structurally unrelated to barbiturates. Results were as follows:
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| Barbiturate Compound | Conc. Equiv. to 200 ng/mL cutoff | % Cross-reactivity | Conc. Equiv. to 300 ng/mL cutoff | % Cross-reactivity |
| --- | --- | --- | --- | --- |
| Secobarbital | 200 | 100 | 300 | 100 |
| Allobarbital | 1000 | 20 | 1700 | 18 |
| Amobarbital | 2000 | 10 | 5000 | 6 |
| Aprobarbital | 450 | 44 | 700 | 43 |
| Barbital | 7000 | 3 | 13000 | 2.3 |
| Butabarbital | 800 | 25 | 1200 | 25 |
| Butalbital | 470 | 43 | 1000 | 33 |
| Cyclopentobarbital | 250 | 80 | 600 | 50 |
| Pentobarbital | 650 | 31 | 1000 | 33 |
| Phenobarbital | 400 | 50 | 1100 | 27 |
| Thiopental | 1300 | 1.5 | 25000 | 1.2 |
The following compounds were tested for cross-reactivity at a concentration of 1000 µg/mL. All tested negative at the 200 and 300 ng/mL cutoff:
Acetaminophen, ASA, Amitryptyline, Amphetamine, Benzoylecgonine, Caffeine, Chlorpromazine, Cocaine, Codeine, Dextromethorphan, Ephedrine, Imipramine, Meperidine, Methadone, Methamphetamine, Methaqualone, Morphine, Nortryptyline, Promethazine, Propoxyphene, Valproic Acid, Lidocaine, Chloramphenamine, Ecgonine, Bupropion, Ranitidine.
f. Assay cut-off:
The user may choose a 200 or 300 ng/mL cutoff
2. Comparison studies:
a. Method comparison with predicate device:
The device was compared to the predicate in the qualitative mode. Results were as follows:
| 200 ng/mL Cutoff | Predicate (Syva) | | |
| --- | --- | --- | --- |
| LZI Barbiturate | | Positive | Negative |
| | Positive | 41 | 4* |
| | Negative | 0 | 60 |
| 300 ng/mL Cutoff | Predicate (Syva) | | |
| --- | --- | --- | --- |
| LZI Barbiturate | | Positive | Negative |
| | Positive | 39 | 4* |
| | Negative | 0 | 62 |
* These samples were further tested by HPLC or GC/MS and were confirmed to contain only Phenobarbital. The reagents in the predicate device do not contain antibodies to Phenobarbital.
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The device was also compared to the GC-MS in the qualitative mode. Results were as follows:
| 200 ng/mL Cutoff | GC-MS | | |
| --- | --- | --- | --- |
| LZI Barbiturate | | Positive | Negative |
| | Positive | 42 | 3* |
| | Negative | 1** | 59 |
* measured by GC-MS, butalbital concentrations ranged from 178 to 383 ng/mL
** measured by GC-MS, Phenobarbital concentration was 422 ng/mL
| 300 ng/mL Cutoff | GC-MS | | |
| --- | --- | --- | --- |
| LZI Barbiturate | | Positive | Negative |
| | Positive | 38 | 4* |
| | Negative | 0 | 63 |
* measured by GC-MS, butalbital concentrations ranged from 178 to 621 ng/mL
b. Matrix comparison:
N/A
3. Clinical studies:
a. Clinical sensitivity:
N/A
b. Clinical specificity:
N/A
c. Other clinical supportive data (when a and b are not applicable):
4. Clinical cut-off:
N/A
5. Expected values/Reference range:
A positive result indicates barbiturate use. This assay cannot distinguish between licit and illicit use of barbiturates.
M. Conclusion:
Based upon the information provided for the file, I recommend that the LZI Barbiturate Enzyme Immunoassay is substantially equivalent to the predicate device
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Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
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Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
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What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
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Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.