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86 WINES&VINES November 2016 WINEMAKING absorbance difference of 0.02. This indicates the ability of this reaction to detect the pres- ence of sulfites down to 6.8 ppm with a 0.1 ml sample or down as low as 0.34 ppm by simply changing the sample size to 2 ml. Lower limits of detection for two other assays of major wine analytes are: 1) Acetic acid, which has a lower limit of detection of 0.254 mg/L using an absorbance difference of 0.02 and the maximum sample volume of 2 ml. 2) L-malic acid, which has a lower limit of detection of 0.25 mg/L using an absorbance difference of 0.01 and the maximum sample volume of 2 ml. From these data, one can anticipate an analytical range for just about any foreseeable amount of target ana- lyte a wine will contain. At these levels, sample- to-sample variance will be within the range of reasonable expectations of accuracy. In preparing the reaction mixture for these enzymatic analyses, one uses the cuvette to introduce the components of the reaction mix- ture. A standard sample size for most tests is 0.1 ml, and the total volume is usually between 2 ml and 3 ml. The other components consist of buffers and supporting reagents that allow the enzyme to function. Other than possibly the buffer, these reagents, including the enzyme, hardly ever total more than a few tenths of a milliliter. The rest of the volume for the reaction is water. In the case where the quantity of the analyte being measured is lower than the lower limit of detection for the assay and therefore too low to register a minimum change in absor- bance, the only way to get that change is to increase the volume of the sample size. This increase in sample size must have a compensa- tory maintenance of the total volume of the test (usually by reduction in the amount of water). In this manner, the calculated amount of analyte can be quantitatively measured. It follows that precision in the addition of all the reagents is critical. All calculations are based on a very specific volume. A key parameter required to obtain the optimum efficiency of an enzyme reaction is temperature. To assure that the test reactions reach full completion in the times suggested, it is best to have an incubation temperature set as recommended for the test being performed. For this purpose, the MegaQuant Wave has an integrated temperature block on the instru- ment that will accept the round 12 mm tubes. This block's temperature can be set by the control panel's utilities function, which allows the test's incubation temperature to be the same from test to test for each sample. The above discussion shows the depth of in- formation these new instruments can provide the winery so they can understand the wines' com- ponents and make informed decisions about how to produce better wines. The software installed on the MegaQuant Wave stores 120 test settings in the instrument. An additional program called SFCapture is available for download and allows ANALYSIS KITS FOR SPECTROMETERS Test Kits** Megazyme Randox Chemwell* Astoria-Pacific Acetaldehyde Acetic acid Acetic acid Alkalinity Acetic acid Ammonia Acetaldehyde Alpha Amylase Ammonia Calcium Amylase Ammonia α-Amylase CO 2 Total Ascorbic acid Bitterness β-Amylase Chloride Alkalinity Boron Amylose/Amylopectin Copper Ammonia Bromide Amyloglucosidase Fructose + Glucose L-Arginine Calcium Arabinan Glucose Cellulase Chloride L-Arabinose/D Glactose Glycerol Chloride Color L-Arginine/Urea/Ammonia Iron Chlorine Cyanide L-Ascorbic acid L-Lactic acid Cyanide Ethanol L-Asparagine/ L-Glutamine/Ammonia Malic acid Ethanol Free Amino Nitrogen Aspartame Magnesium Fructose + Glucose Glucose Citric acid Potassium Glucose β-Glucan Ethanol Sodium Lactose/ D-Galactose Iodine Formic acid Total antioxidant status Lactic acid Iron, Total D-Fructose L-Malic acid Lithium L-Fructose Nitrite Magnesium Glucomannan Nitrate Niacin Malt β-Glucanase/ Lichenase Assay Nitrogen by OPA Nitrite β-Glucanase Nitrogen, TK Nitrate D-Glucose Orthophosphate Nitrogen, Total (Per.) Glucose oxidase Phenol Nitrogen, TK α-Glucuonidase Phosphorus, Total (Per.) Orthophosphate Glycerol PANOPA Phenol D-Lactic acid Silica Phosphorus (TK) L-Lactic acid Sulfite, Free Potassium D-Malic acid Sulfite, Total P 2 O 5 L-Malic acid Tartaric acid Protein PANOPA Reducing Sugars D-Sorbitol Reducing Sugars, Total Succinic acid Riboflavin Sucrose Selenium Sulfite Silicate Tartaric acid Sodium Urea Sulfate Sulfide Sulfite, Free Sulfite, Total Thiamin Total hardness Urea Vitamin C *Chemwell is distributed by more than one company. Not all kits listed are available from one supplier. **Each supplier has additional kits available that target other industries, Check with your representative for other kits that might be useful for your analytical purposes.