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Click HERE for an example of the Cleveland Reference Chemistry Results (PDF)

1999 Raw Milk Infrared Control Samples – Use Guide for Order 124/135 Handlers
Federal Milk Market Administrator – Seattle, WA November 1, 2000

Introduction

In January of 1999, the Seattle Market Administrator developed a raw milk infrared control sample program for the benefit of federal order 124 and 131 handlers subject to pay test verification. Participation in the program is strictly voluntary and there is no direct charge for this service. This guide is intended for all laboratory managers. It describes the nature of the new control samples and how handler labs can derive maximum benefit from their usage.

Sample Description

Number of samples: 12
Approx. sample volume: 60 ml
Vial coding: by color (new sets marked by different color stripe on white vial)
Source: Ohio Market Administrator (Ohio-based dairy farms)
Distribution frequency: 2 sets of 12 every two weeks
Target delivery arrival date: Wednesday via FEDEX (freight billed directly to MA)
Target delivery temperature: <40^oF (wet ice used)
Target reference chemistry: available by 11:00 am Friday (via Internet, fax, or website)
Reference chemistry source: Seattle + Cleveland + Chicago + Louisville MA Labs (each lab performs measurements in duplicate)
Approx. component ranges
Fat: 2.0%
Protein: 1.0+%
Preservative: Bronopol
Expected shelf life: 18 days minimum

Recommended Usage Parameters (based on Seattle MA Lab protocols)

Tempering temperature: 108^oF (42^oC)
IR readings per sample: 2-3 (for best results, omit the 1st reading to minimize carry-over effects)
Instrument zero: Zero all channels prior to calibration; check zeros at finish and rerun or make corrections to sample readings if necessary.
Primary reference results: fat by ether extraction (4-lab mean; each lab runs duplicates), true protein* by kjeldahl direct analysis (4-lab mean), total solids by oven drying (4-lab mean)
Secondary reference values: ash = 0.5379 + 0.0596*protein
                                                        lactose = TS – fat – protein – ash - 0.19
                                                        other solids = TS – fat – protein
                                                             (= lactose +   ash + 0.19)
                                                        SNF = TS – fat (= lactose + ash + 0.19
                                                            +   protein)
(since lactose is determined by difference, all reference chemical values should be internally consistent -- i.e., all terms in above equations must add and subtract perfectly)

*effective January 1, 1999

Daily Calibration Check – possible approaches

{Handler labs differ widely in their calibration procedures. A few calibrate daily using a sophisticated array of controls and in-house pilot samples. Others calibrate biweekly using commercially available controls. The options listed below illustrate the broad range of approaches possible given a new MA control set. Since the MA cannot supply enough controls for daily calibration (the most rigorous approach), all lab managers who choose to use the new controls should consider how to ensure the accuracy of their particular IR between weekly (or biweekly) formal calibrations.}

optimum: daily calibration on MA controls (as performed by Seattle Lab)

approach A: weekly MA-based calibration immediately followed by a run of raw milk check samples (check samples should possess good range and must be stable over a week). The same check samples are then run first thing daily. If there is a sufficient number of check samples (e.g. 6-10), mathematical adjustments to slope and bias can be made whenever necessary. If check samples are few (e.g. 3-5) and a drift is indicated, recalibration using MA controls may be warranted.

approach B: same as option A but with biweekly MA-based calibration. Spare MA set is reserved for a marked shift (e.g. due, for example, to instrument service).

approach C: weekly or biweekly MA-based calibration with no daily checks other than intermittent check or "pilot" samples (e.g. use of a large stock of raw or homogenized milk every 30 minutes). This option recommended only if IR is demonstrably stable. An unusual shift in check sample or pilot should signal a recalibration.

Evaluation of Control Sample and IR Performance

With each biweekly reference chemistry mailing, you will find a questionnaire page relating to your IR calibration. This is a completely optional service. You may:

ignore it
use the e-mail version (in Excel) to plot your IR results against chemistry and personally investigate the quality of your calibration
fill it in and send it to us for troubleshooting help when you're experiencing difficulties
submit it regularly and request 6-month summaries of your IR calibration performance

In principle, regular use of the questionnaire (or similar records of your own) can be used for

Ongoing evaluation of control sample quality and stability of calibration parameters
Assessment of individual IR ability to achieve linear response
Charting of individual IR instruments for tendency to drift

MA Contacts

For general questions, missing reference chemistry, replacement/additional control samples, sample integrity problems (e.g. leakers, cracked vials, too warm) , incorrect or altered shipping information

Please call: Seattle MA Lab
telephone: 877-252-9557 or 425-487-6009
fax: 425-487-2775
e-mail: seattlelab@fmmaseattle.com

For: Shipping containers (PLEASE RETURN BOXES BIWEEKLY via FEDEX to CLEVELAND!)

Ship to: Bob Malinak

                    USDA-AMS-Mideast FMMA Lab
                    1325 Industrial Parkway North
                    Brunswick, OH 44212
                    Phone: 330-225-4758
                    Fax: 330-220-6732

Use FEDEX Priority Overnight or Standard Overnight

Bill to: third party, call Seattle MA Lab @ 1(877) 252-9557
for the FEDEX account number.

(if you prefer to use another carrier (e.g. UPS ground), this is fine, however, the Seattle MA office will only cover FEDEX shipping charges)

For Lost shipments

Please call: Cleveland MA Lab (Bob Malinak - control sample coordinator)
telephone: 330-225-4758, ext. 117
fax: 330-220-6732 (lab fax)

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