SNAPduo™ ST Plus Test

Detects more beta-lactam and tetracycline residues including cephalexin at or below established maximum residue limits.

  • Test cold milk right from the truck, refrigerator or bulk tank
  • Robust and flexible
  • Cow, Goat, Sheep, Mare, Buffalo, Camel
  • Variety of milk types (Normal, UHT, Sterilised, reconstituted milk powder, thawed, skimmed)
  • Read results after 6-8 minutes
  • ILVO validated
  • Lowest rate of false positives

* Availability / Distribution: Outside the U.S. and Canada 

All IDEXX ST tests are submitted for ILVO validation.


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Test details

Part numbers and sizes

99-0009837 (30 tests)

Related products

Sensitivity Table


Drug European MRL FDA Tolerance European MRL
Benzylpenicillin 4 ppb 0 ppb* 2 ppb
Ampicillin 4 ppb 10 ppb 4 ppb
Amoxicillin 4 ppb 10 ppb 3 ppb
Oxacillin 30 ppb   3 ppb
Cloxacillin 30 ppb 10 ppb 4 ppb
Dicloxacillin 30 ppb   4 ppb
Nafcillin 30 ppb   3 ppb
Ceftiofur 100 ppb 100 ppb 8 ppb
Cephapirin 60 ppb 20 ppb 30 ppb
Desacetyl cephapirin 60 ppb   ≤60 ppb
Desfuroylceftiofur 100 ppb  100 ppb 25 ppb
Cefquinome 20 ppb   16 ppb
Cefalonium 20 ppb   14 ppb
Cefazolin 50 ppb   20 ppb
Cefacetrile 125 ppb   50 ppb
Cephalexin 100 ppb   30 ppb
Cefoperazone 50 ppb   35 ppb
Cefuroxime -   8 ppb
Tetracycline 100 ppb 300 ppb§ 16 ppb
Oxytetracycline 100 ppb 300 ppb§ 18 ppb
Chlortetracycline 100 ppb 300 ppb§ 40 ppb
Doxycycline   25 ppb

*The FDA has established a target testing level of 5 ppb for penicillin
†MRL is established for cephapirin as the sum of cephapirin and desacetylcephapirin
‡FDA tolerance is established for ceftiofur as the marker residue, desfuroylceftiofur
§FDA tolerance of 300ppb includes both the sum and the individual residues of chlortetracycline, oxytetracycline and tetracycline

Questions & Answers

About SNAP ST tests 

Note: IDEXX SNAP ST tests are not available in the U.S. or Canada.

The SNAP Beta-Lactam ST Plus Test and the SNAPduo ST Plus Test contain a proprietary reformulated conjugate pellet that accurately and reliably detects beta-lactam and tetracycline antibiotic residues including cephalexin without heat or incubation, allowing you to test cold milk directly from the truck, refrigerator or bulk tank. The IDEXX SNAP Beta-Lactam ST Plus Test performance has been validated by an independent lab (ILVO).

SNAP ST Plus tests are completed in 6-8 minutes.

To achieve optimal results close to the Maximum Residue Limits, using a heater block is not recommended. If a heater block is used by mistake, follow the prescribed protocol to retest the sample without the heater block.

Tests that were taken out of refrigeration to be used during the day may be returned to refrigeration as long as the room temperature during the day did not exceed 30°C.

For optimal results, run the test on a flat, level surface.

Refrigerate all SNAP test materials at 2–8°C (36–46°F). Tests can be kept at 15-30°C (59-86°F) during the day of use. SNAP ST Plus tests may be stored at 15–22°C (59–72°F) for up to 30 days. Check labeling for test-specific instructions. Remove only the number of tests to be used for the day.

Yes, the test is designed for use under normal ambient conditions (15–30°C). Remove the number of devices needed for the day from refrigeration and allow them to warm to room temperature for at least 15 minutes before using.
Before you test:

  1. Verify that the SNAP device has coloured spots in the results window and activation circle.
  2. Make sure the pellet is moving freely in the bottom of the sample tube.

After the reagent pellet has dissolved, pour the entire contents of the sample tube into the sample well of the SNAP device. Remain with the device and watch the sample flow across the results window toward the blue activation circle. When the blue activation circle begins to disappear, press the activator firmly until the device "snaps" and the activator is flush with the body of the SNAP device. Activate (snap) the device when the edge of the circle nearest the sample begins to turn from dark blue to white. Do not let the circle completely disappear.

SNAP technical top - When to "SNAP"



Ordering and shipping

You can place your order with our Customer Service department by calling 00800-727-43399 (Monday through Friday, 8:00 a.m. to 6:00 p.m. ET). Orders can also be sent via email to

Please contact your local IDEXX customer service for any order.

In most cases, we process orders the same day we receive them. To ensure we receive any changes as soon as possible, please call one of our customer service representatives at 00800-727-43399 (Monday through Friday, 8:00 a.m. to 6:00 p.m. ET).

Still have questions?
IDEXX backs all tests with a dedicated team of professionals available to answer your product, regulatory and dairy-industry questions. Call IDEXX Technical Services at 00800-727-43399, Monday through Friday, 8:00 a.m. to 5:00p.m. ET; or complete the contact form.